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Closed-loop transformation of raw materials into high-value-added products is highly desired for the sustainable development of the society but is seldom achieved. Here, a low-cost, solvent-free and "zero-waste" mechanochemical protocol is reported for the large-scale preparation of cathode materials for sodium-ion batteries (SIBs). This process ensures full utilization of raw materials, effectively reduces water consumption, and simplifies the operating process. Benefiting from the synergistic effect between the cubic Prussian blue analogs (c-NFFHCF) and dehydrated polyanionic sulfates (m-NFS), the generated composite exhibits promising wide-temperature electrochemical performance and excellent practical application potential. The synergistic effect between m-NFS and c-NFFHCF in the composite is revealed through multiple in situ characterizations and density functional theory calculations. The proposed mechanochemical strategy can be scaled to a kilogram-grade level, providing a sustainable method for the value-added utilization of the by-products during Prussian blue analogs synthesis, advancing the design of "zero-waste" cathode materials for low-cost practical SIBs., (© 2025 Wiley‐VCH GmbH.)

Sodium-ion batteries (SIBs) have attracted great attention due to their advantages on resource abundance, cost and safety. Layered oxide cathodes (LOCs) of SIBs possess high theoretical capacity, facile synthesis and low cost, and are promising candidates for large scale energy storage application. Increasing operating voltage is an effective strategy to achieve higher specific capacity and also high energy density of SIBs. However, at high operating voltages, LOCs will undergo a series of phase transitions in bulk phase, leading to huge change of volume and layer spacings accompanied by severe lattice stress and cracking formation. Degeneration of surface also occurs between LOCs and electrolytes, resulting in sustained growth of cathode electrolyte interphase (CEI) and release of O 2 and CO 2 . These induce structural destruction and electrochemical performance degradation in high voltage regions. Recently, many strategies have been proposed to improve electrochemical performance of LOCs under high voltages, including bulk element doping, structural design, surface coating and gradient doping. This review describes pivotal challenges and occurrence mechanisms at high voltages, and summarizes strategies to improve stability of bulk and surface. Viewpoints will be provided to promote development of high energy density SIBs., (© 2024 Wiley-VCH GmbH.)

All-solid-state batteries (ASSBs) are pursued due to their potential for better safety and high energy density. However, the energy density of the cathode for ASSBs does not seem to be satisfactory due to the low utilization of active materials (AMs) at high loading. With small amount of solid electrolyte (SE) powder in the cathode, poor electrochemical performance is often observed due to contact loss and non-homogeneous distribution of AMs and SEs, leading to high tortuosity and limitation of lithium and electron transport pathways. Here, we propose a novel cathode design that can achieve high volumetric energy density of 1258 Wh L -1 at high AM content of 85 wt% by synergizing the merits of AM@SE core-shell composite particles with conformally coated thin SE shell prepared from mechanofusion process and small SE particles. The core-shell structure with an intimate and thin SE shell guarantees high ionic conduction pathway while unharming the electronic conduction. In addition, small SE particles play the role of a filler that reduces the packing porosity in the cathode composite electrode as well as between the cathode and the SE separator layer. The systematic demonstration of the optimization process may provide understanding and guidance on the design of electrodes for ASSBs with high electrode density, capacity, and ultimately energy density., Competing Interests: Declarations. Conflict of Interest: The authors declare no interest conflict. They have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2025. The Author(s).)

Vanadium-based Na superionic conductor (NASICON) type materials (Na x VM(PO 4 ) 3 , M = transition metals) have attracted extensive attention when used as sodium-ion batteries (SIBs) cathodes due to their stable structures and large Na + diffusion channels. However, the materials have poor electrical conductivity and mediocre energy density, which hinder their practical applications. Activating the V 4+ /V 5+ redox couple (V 4+ /V 5+ ≈4.1 V vs Na + /Na) is an effective way to elevate the energy density of SIBs, whereas the irreversible phase transition of V 4+ /V 5+ and severe structural distortion will inevitably result in fast capacity fading and unsatisfactory rate capability. Herein, a high entropy regulation strategy is proposed to optimize the detailed crystal structure and improve the reversibility of crystalline phase transformation and electrical conductivity of the material. With the activated reversible V 4+ /V 5+ redox couple, stable structure, and fast electrochemical kinetics, the high entropy material Na 3.2 V 1.5 Fe 0.1 Al 0.1 Cr 0.1 Mn 0.1 Cu 0.1 (PO 4 ) 3 (NVMP-HE) exhibits an outstanding electrochemical performance with highly reversible specific capacity of 120.1 mAh g -1 at 0.1 C and excellent cycling stability (92.4% retention after 1000 cycles at 20 C). Besides, the in situ X-ray diffraction (XRD) measurement reveals that a smooth three-phase transition reaction is involved in this high-entropy cathode and the existence of mesophase facilitates a fast phase transition., (© 2025 Wiley‐VCH GmbH.)

Although lithium-sulfur batteries have satisfactory theoretical specific capacity and energy density, they are difficult to further commercialize due to the shuttle effect of soluble polysulfides and slow sulfur oxidation kinetics. Based on this, in this work, the catalyst MXene-VS 4 -SnS 2 (MVS), a dual heterostructured catalyst with ohmic contacts, is prepared by a one-step hydrothermal method and electrostatic self-adsorption for lithium-sulfur battery cathode materials. Experimental and theoretical results show that the ohmic contact induces spontaneous charge rearrangement, resulting in the formation of a fast charge transfer pathway at the MVS heterojunction interface, which helps to reduce the energy barrier for polysulfide reduction and Li 2 S oxidation during the discharge/charge process. In addition, the inherent sulfophilicity of VS 4 and SnS 2 promotes the conversion of S species, while the pleated MXene nanosheets not only provide a highly conductive network for the active sulfur but also retain a rich internal space to maintain the integrity of the cathode structure during the continuous cycling process. As a result, the MVS cathode exhibits excellent electrochemical performance even under high sulfur loading. The integration of excellent performance with a facile synthesis process provides a promising approach for designing highly efficient electrocatalysts suitable for the energy field., (© 2024 Wiley‐VCH GmbH.)

Advances in lithium-metal anodes have inspired interest in discovery of Li-free cathodes, most of which are natively found in their charged state. This is in contrast to today's commercial lithium-ion battery cathodes, which are more stable in their discharged state. In this study, we combine calculated cathode voltage information from both categories of cathode materials, covering 5577 and 2423 total unique structure pairs, respectively. The resulting voltage distributions with respect to the redox pairs and anion types for both classes of compounds emphasize design principles for high-voltage cathodes, which favor later Period 4 transition metals in their higher oxidation states and more electronegative anions like fluorine or polyanion groups. Generally, cathodes that are found in their charged, delithiated state are shown to exhibit voltages lower than those that are most stable in their lithiated state, in agreement with thermodynamic expectations. Deviations from this trend are found to originate from different anion distributions between redox pairs. In addition, a machine learning model for voltage prediction based on chemical formulas is trained and shows state-of-the-art performance when compared to two established composition-based ML models for material properties predictions, Roost and CrabNet.

Cathode materials are usually the key to determining battery capacity, suitable cathode materials are an important prerequisite to meet the needs of large-scale energy storage systems in the future. Polyanionic compounds have significant advantages in metal ion storage, such as high operating voltage, excellent structural stability, safety, low cost, and environmental friendliness, and can be excellent cathode options for rechargeable metal-ion batteries. Although some polyanionic compounds have been commercialized, there are still some shortcomings in electronic conductivity, reversible specific capacity, and rate performance, which obviously limits the development of polyanionic compound cathodes in large-scale energy storage systems. Up to now, many strategies including structural design, ion doping, surface coating, and electrolyte optimization have been explored to improve the above defects. Based on the above contents, this paper briefly reviews the research progress and optimization strategies of typical polyanionic compound cathodes in the fields of lithium-ion batteries (LIBs) and other promising metal ion batteries (sodium ion batteries (SIBs), potassium ion batteries (PIBs), magnesium ion batteries (MIBs), calcium ion batteries (CIBs), zinc ion batteries (ZIBs), aluminum ion batteries (AIBs), etc.), aiming to provide a valuable reference for accelerating the commercial application of polyanionic compound cathodes in rechargeable battery systems., (© 2024 Wiley‐VCH GmbH.)

Sodium-ion batteries (SIBs) have captured widespread attention for grid-scale energy storage owing to the wide distribution and low cost of sodium resources. Delivery of high energy density with stable retention remains a challenge in developing cathode candidates for rechargeable SIBs. Inspired by the concept of "cationic potential", here, we present a hierarchical crystalline domain in hexagonal particles with target chemical composition (Na 0.8 Li 0.03 Mg 0.05 Ni 0.28 Fe 0.05 Mn 0.54 Ti 0.05 O 2 ) from the inner bulk O3 phase (71.1 wt %) to the outer P2-type shell (28.9 wt %) of the structure. Benefiting from the mitigated mechanical stress of the predominant bulk O3 phase under the protection of the surficial P2 crystalline domain at the microscale during Na + (de)intercalation, the brittle fracture, plastic yielding, and structural damage of the bulk O3 phase are effectively prohibited during battery cycling, thereby achieving good structural integrity. As a consequence, the biphasic P2/O3-Na 0.8 Li 0.03 Mg 0.05 Ni 0.28 Fe 0.05 Mn 0.54 Ti 0.05 O 2 material exhibits satisfactory electrochemical properties, with a high energy density of 506 Wh kg -1 and good capacity retention of 85.5% over 200 cycles. This work highlights the importance of tailoring the crystalline domain to mitigate the reaction-induced stress and particle fracture of layered biphasic cathode materials for high-energy SIBs.

High-performance and cost-efficient electrocatalysts and electrodes are needed to improve the hydrogen evolution reaction (HER) for the hydrogen (H 2 ) generation in electrolysers, including microbial electrolysis cells (MECs). In this study, free-standing carbon nanofiber (CNF) films with supported cobalt phosphide nanoparticles have been prepared by means of an up-scalable electrospinning process followed by a thermal treatment under controlled conditions. The produced cobalt phosphide-supported CNF films show to be nanoporous (pore volume up to 0.33 cm 3 g -1 ) with a high surface area (up to 502 m 2 g -1 ) and with a suitable catalyst mass loading (up to 0.49 mg cm -2 ). Values of overpotential less than 140 mV at 10 mA cm -2 have been reached for the HER in alkaline media (1 M KOH), which demonstrates a high activity. The high electrical conductivity together with the mechanical stability of the free-standing CNF films allowed their direct use as cathodes in a MEC reactor, resulting in an exceptionally low voltage operation (0.75 V) with a current density demand of 5.4 A m -2 . This enabled the production of H 2 with an energy consumption below 30 kWh kg -1 H 2 , which is highly efficient.

Covalent organic frameworks (COFs) hold great promise for rechargeable batteries. However, the synthesis of COFs with abundant active sites, excellent stability, and increased conductivity remains a challenge. Here, chemically stable fully sp 2 carbon-conjugated COFs (sp 2 c-COFs) with multiple active sites are designed by the polymerization of benzo[1,2-b:3,4-b':5,6-b'']trithiophene-2,5,8-tricarbaldehyde) (BTT) and s-indacene-1,3,5,7(2H,6H)-tetrone (ICTO) (denoted as BTT-ICTO). The morphology and structure of the COF are precisely regulated from "butterfly-shaped" to "cable-like" through an in situ controllable growth strategy, significantly promoting the exposure and utilization of active sites. When the unique "cable-like" BTT-ICTO@CNT is employed as lithium-ion batteries (LIBs) cathode, it exhibits exceptional capacity (396 mAh g -1 at 0.1 A g -1 with 97.9 % active sites utilization rate), superb rate capacity (227 mAh g -1 at 5.0 A g -1 ), and excellent cycling performance (184 mAh g -1 over 8000 cycles at 2.0 A g -1 with 0.00365 % decay rate per cycle). The lithium storage mechanism of BTT-ICTO is exhaustively revealed by in situ Fourier transform infrared, in situ Raman, and density functional theory calculations. This work provides in-depth insights into fully sp 2 c-COFs with multiple active sites for high-performance LIBs., (© 2024 Wiley-VCH GmbH.)

The interlayer distances in layered electrode materials, influenced by the chemical composition of the confined interlayer regions, have a significant impact on their electrochemical performance. Chemical preintercalation of inorganic metal ions affects the interlayer spacing, yet expansion is limited by the hydrated ion radii. Herein, we demonstrate that using varying concentrations of decyltrimethylammonium (DTA + ) and cetyltrimethylammonium (CTA + ) cations in chemical preintercalation synthesis followed by hydrothermal treatment, the interlayer distance of hybrid bilayered vanadium oxides (BVOs) can be tuned between 11.1 Å and 35.6 Å. Our analyses reveal that these variations in interlayer spacing are due to different amounts of structural water and alkylammonium cations confined within the interlayer regions. Increased concentrations of alkylammonium cations not only expand the interlayer spacing but also induce local bending and disordering of the V-O bilayers. Electrochemical cycling of hybrid BVO electrodes in non-aqueous lithium-ion cells show that specific capacities decrease as interlayer regions expand, suggesting that the densely packed alkylammonium cations obstruct intercalation sites and hinder Li + ion transport. Furthermore, we found that greater layer separation facilitates the dissolution of active material into the electrolyte, resulting in rapid capacity decay during extended cycling. This study emphasizes that layered electrode materials require both spacious interlayer regions as well as high structural and chemical stabilities, providing guidelines for structural engineering of organic-inorganic hybrids., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Micrometer-sized single crystal cathodes have garnered significant interest as promising cathode materials for lithium-ion batteries due to their ability to reduce surface area exposure to electrolytes and suppress side reactions, thereby enhancing electrochemical performance. One of the challenging issues with single crystal cathode materials is synthesizing monodisperse and discrete single crystals rather than agglomerated quasi-single crystals. However, conventional solid-state synthesis of most single crystals results in severe agglomeration and cation mixing, as it requires high temperatures to promote particle growth to several micrometers. In this study, a novel morphology-conserving reaction strategy that employs octahedron single crystal intermediates is introduced to synthesize discrete, monodisperse LiNi 0.97 Co 0.02 Mn 0.01 O 2 octahedron single crystals. This scalable and cost-effective approach involves using rock-salt Ni 0.97 Co 0.02 Mn 0.01 O 1+ x octahedrons as single crystal intermediates, which are transformed in unreactive unary lithium salt melts (LiCl and Li 2 SO 4 ) from spherical Ni 0.97 Co 0.02 Mn 0.01 (OH) 2 obtained via coprecipitation. These intermediates are then subjected to a stoichiometric amount of Li precursor in a conventional solid-state synthesis to produce layered LiNi 0.97 Co 0.02 Mn 0.01 O 2 . This process is a morphology-conserving lithiation reaction, leading to the formation of discrete and monodisperse LiNi 0.97 Co 0.02 Mn 0.01 O 2 octahedron single crystals. The resultant LiNi 0.97 Co 0.02 Mn 0.01 O 2 single crystals demonstrate superior electrochemical performance, including stable capacity retention over 150 cycles, which surpasses that of typical quasi-single crystals produced through conventional methods. This is attributed to negligible crack formation during cycling, in contrast to significant cracking observed in conventional quasi-single crystals. This implies that single-crystal forms are preferred over agglomerated quasi-single crystal forms for enhancing cycle performance. These findings provide valuable insights into the industrial synthesis of discrete and monodisperse ultrahigh-nickel oxide cathode materials.

The slow reaction kinetics and severe shuttle effect of lithium polysulfide make Li-S battery electrochemical performance difficult to meet the demands of large electronic devices such as electric vehicles. Based on this, an electrocatalyst constructed by metal phase material (MoS 2 ) and semiconductor phase material (SnS 2 ) with ohmic contact is designed for inhibiting the dissolution of lithium polysulfide with improving the reaction kinetics. According to the density-functional theory calculations, it is found that the heterostructured samples with ohmic contacts can effectively reduce the reaction-free energy of lithium polysulfide to accelerate the sulfur redox reaction, in addition to the excellent electron conduction to reduce the overall activation energy. The metallic sulfide can add more sulfophilic sites to promote the capture of polysulfide. Thanks to the ohmic contact design, the carbon nanotube-MoS 2 -SnS 2 achieved a specific capacity of 1437.2 mAh g -1 at 0.1 C current density and 805.5 mAh g -1 after 500 cycles at 1 C current density and is also tested as a pouch cell, which proves to be valuable for practical applications. This work provides a new idea for designing an advanced and efficient polysulfide catalyst based on ohmic contact., (© 2024 Wiley‐VCH GmbH.)

Sodium-ion battery (SIB) is a candidate for the stationary energy storage systems because of the low cost and high abundance of sodium. However, the energy density and lifespan of SIBs suffer severely from the irreversible consumption of the Na-ions for the formation of the solid electrolyte interphase (SEI) layer and other side reactions on the electrodes. Here, Na 3.5 C 6 O 6 is proposed as an air-stable high-efficiency sacrificial additive in the cathode to compensate for the lost sodium. It is characteristic of low desodiation (oxidation) potential (3.4-3.6 V vs. Na + /Na) and high irreversible desodiation capacity (theoretically 378 mAh g -1 ). The feasibility of using Na 3.5 C 6 O 6 as a sodium compensation additive is verified with the improved electrochemical performances of a Na 2/3 Ni 1/3 Mn 1/3 Ti 1/3 O 2 ǀǀhard carbon cells and cells using other cathode materials. In addition, the structure of Na 3.5 C 6 O 6 and its desodiation path are also clarified on the basis of comprehensive physical characterizations and the density functional theory (DFT) calculations. This additive decomposes completely to supply abundant Na ions during the initial charge without leaving any electrochemically inert species in the cathode. Its decomposition product C 6 O 6 enters the carbonate electrolyte without bringing any detectable negative effects. These findings open a new avenue for elevating the energy density and/or prolonging the lifetime of the high-energy-density secondary batteries., (© 2024 Wiley‐VCH GmbH.)

The burgeoning accumulation of spent lithium-ion batteries (LIBs), a byproduct from the widespread adoption of portable electronics and electric vehicles, necessitates efficient recycling strategies. Direct recycling represents a promising strategy to maximize the value of LIB waste and minimize harmful environmental outcomes. However, current efforts to large-scale direct recycling face challenges stemming from heterophase residues (e.g., Li 2 CO 3 , LiOH) in the recycled products and uncontrolled interfacial instability, often requiring repeated washing that generates significant wastewater. Here, a refined direct recycling process is proposed to improve cathode interface stability by leveraging in situ reaction between surface residual lithium species and a weak inorganic acid to form a conformal Li + conductive coating that stabilizes the regenerated Ni-rich cathodes with significantly reduced water footprint. The findings reveal that the conductive coating also prevents direct contact between contaminants and the cathode surface, thus improving the ambient storage stability. By eliminating the need for extensive washing, this intensified recycling process offers a more sustainable approach with the potential to transition from laboratory to industrial-scale applications, improving both product quality and environmental sustainability., (© 2024 Wiley‐VCH GmbH.)

It has been suggested that sodium layered transition metal oxides could potentially serve as excellent cathodes for sodium-ion batteries (SIBs) because of their appropriate operating potentials and high capacities. However, the growing reliance on energy requirements has necessitated a higher energy density of SIBs. It has been demonstrated that activating oxygen-related activities for SIBs is a viable method to improve energy density. Herein, we suggest applying the synergy of Li and Zn codoping to activate the anionic redox reactions (ARRs) and improve their reversibility in Na 0.75 Ni 0.3 Mn 0.7 O 2 . The dual ion doping alleviates the phase transition and inhibits the Na + /vacancy arrangements, consequently improving the rate capacity and cyclic stability. The Na 0.75 Li 0.15 Ni 0.1 Zn 0.05 Mn 0.7 O 2 delivers a discharge capacity of 134 mA h g -1 and no significant capacity loss at 100 mA g -1 between 2 and 4.5 V after 200 cycles. More importantly, the density functional theory (DFT) calculation proves that the codoping strategy triggers more ARRs compared to single-element doping, thereby providing enhanced capacity. The codoping induced oxygen redox strategies will create a new path for rational design of cathodes to enhance the energy density for SIBs.

Potassium-ion batteries (KIBs) can offer high energy density, cyclability, and operational safety while being economical due to the natural abundance of potassium. Utilizing graphite as an anode, suitable cathodes can realize full cells. Searching for potential cathodes, this work introduces P3-type K 0.5 Ni 1/3 Mn 2/3 O 2 layered oxide as a potential candidate synthesized by a simple solid-state method. The material works as a 3.2 V cathode combining Ni redox at high voltage and Mn redox at low voltage and exhibits highly reversible K + ion (de)insertion at ambient and elevated (40-50 °C) temperatures. First-principles calculations suggest the ground state in-plane Mn-Ni ordering in the MO 2 sheets is strongly correlated to the K-content in the framework, leading to an interwoven and alternative row ordering of Ni-Mn in K 0.5 Ni 1/3 Mn 2/3 O 2 . Postmortem and electrochemical titration reveal the occurrence of a solid solution mechanism during K + (de)insertion. The findings suggest that the Ni addition can effectively tune the electronic and structural properties of the cathode, leading to improved electrochemical performance. This work provides new insights in the quest to develop potential low-cost Co-free KIB cathodes for practical applications in stationary energy storage., (© 2024 Wiley‐VCH GmbH.)

δ-MnO 2 is a promising cathode material for aqueous aluminium-ion batteries (AAIBs) for its layered crystalline structure with large interlayer spacing. However, the excellent Al ion storage performance of δ-MnO 2 cathode remains elusive due to the frustrating structural collapse during the intercalation of high ionic potential Al ion species. Here, it is discovered that introducing heterogeneous metal dopants with high bond dissociation energy when bonded to oxygen can significantly reinforce the structural stability of δ-MnO 2 frameworks. This reinforcement translates to stable cycling properties and high specific capacity in AAIBs. Vanadium-doped δ-MnO 2 (V-δ-MnO 2 ) can deliver a high specific capacity of 518 mAh g -1 at 200 mA g -1 with remarkable cycling stability for 400 cycles and improved rate capabilities (468, 339, and 285 mAh g -1 at 0.5, 1, and 2 A g -1 , respectively), outperforming other doped δ-MnO 2 materials and the reported AAIB cathodes. Theoretical and experimental studies indicate that V doping can substantially improve the cohesive energy of δ-MnO 2 lattices, enhance their interaction with Al ion species, and increase electrical conductivity, collectively contributing to high ion storage performance. These findings provide inspiration for the development of high-performance cathodes for battery applications., (© 2024 The Authors. Small published by Wiley‐VCH GmbH.)

Rechargeable multivalent-ion batteries are attractive alternatives to Li-ion batteries to mitigate their issues with metal resources and metal anodes. However, many challenges remain before they can be practically used due to the low solid-state mobility of multivalent ions. In this study, a promising material identified by high-throughput computational screening is investigated, ε-VOPO 4 , as a Mg cathode. The experimental and computational evaluation of ε-VOPO 4 suggests that it may provide an energy density of >200 Wh kg -1 based on the average voltage of a complete cycle, significantly more than that of well-known Chevrel compounds. Furthermore, this study finds that Mg-ion diffusion can be enhanced by co-intercalation of Li or Na, pointing at interesting correlation dynamics of slow and fast ions., (© 2024 The Authors. Advanced Science published by Wiley‐VCH GmbH.)

As a crucial component responsible for the oxygen reduction reaction (ORR), cobalt-rich perovskite-type cathode materials have been extensively investigated in protonic ceramic fuel cell (PCFC). However, their widespread application at a commercial scale is considerably hindered by the high cost and inadequate stability. In response to these weaknesses, the study presents a novel cobalt-free perovskite oxide, Ba 0.95 La 0.05 (Fe 0.8 Zn 0.2 ) 0.95 O 3-δ (BLFZ0.95), with the triple-conducting (H + |O 2- |e - ) property as an active and robust air electrode for PCFC. The B-site deficiency state contributes significantly to the optimization of crystal and electronic structure, as well as the increase in oxygen vacancy concentration, thus in turn favoring the catalytic capacity. As a result, the as-obtained BLFZ0.95 electrode demonstrates exceptional electrochemical performance at 700 °C, representing extremely low area-specific resistance of 0.04 Ω cm 2 in humid air (3 vol.% H 2 O), extraordinarily high peak power density of 1114 mW cm -2 , and improved resistance against CO 2 poisoning. Furthermore, the outstanding long-term durability is achieved without visible deterioration in both symmetrical and single cell modes. This study presents a simple but crucial case for rational design of cobalt-free perovskite cathode materials with appreciable performance via B-site deficiency regulation., (© 2024 Wiley‐VCH GmbH.)

The O-type layered nickel oxides suffer from undesired cooperative Jahn-Teller distortion stemming from Ni 3+ ions and undergo multiple biphasic structural transformations during the insertion/extraction of large Na + ions, posing a significant challenge to stabilize the structural integrity. We present here a systematic investigation of the impact of substituting 5 % divalent (Mg 2+ ) or trivalent (Al 3+ or Co 3+ ) ions for Ni 3+ to alleviate Na + ion ordering and perturb the Jahn-Teller effect to enhance structural stability. We gauge a fundamental understanding of the Mg-O and Na-O or Mg-O-Na bonding interactions, noting that the ionicity of the Mg-O bond deshields the electronic cloud of oxygen from Na + ions. Furthermore, calculations of the Van Vleck distortion modes reveal a relaxation of NiO 6 octahedra from Jahn-Teller distortion and a reduced electron density at the interlayer with Mg 2+ substitution. Long-range (operando X-ray diffraction) and short-range (magic angle spinning nuclear magnetic resonance) structural analyses provide insights into reduced ordering, allowing a stable continuous solid solution. Overall, Mg-substitution results in a high-capacity retention of ~96 % even after 100 cycles, showcasing the potential of this strategy for overcoming the structural instabilities and enhancing the performance of sodium-ion batteries., (© 2024 Wiley-VCH GmbH.)

Alkali metal-sulfur batteries (particularly, lithium/sodium- sulfur (Li/Na-S)) have attracted much attention because of their high energy density, the natural abundance of sulfur, and environmental friendliness. However, Li/Na-S batteries still face big challenges, such as limited cycle life, poor conductivity, large volume changes, and the "shuttle effect" caused by the high solubility of Li/Na-polysulfides. Herein, novel organosulfur-containing materials, i.e., bis(4-hydroxy-2,2,6,6-tetramethylpiperidin-1-yl)disulfide (BiTEMPS-OH) and 2,4-thiophene/arene copolymer (TAC) are proposed as cathode materials for Li and Na batteries. BiTEMPS-OH shows an initial discharge/charge capacity of 353/192 mAh g -1 and a capacity of 62 mAh g -1 after 200 cycles at 100 mA g -1 in ether-based Li-ion electrolyte. Meanwhile, TAC has an initial discharge/charge capacity of 270/248 mAh g -1 and better cycling performance (106 mAh g -1 after 200 cycles) than BiTEMPS-OH in the same electrolyte. However, the rate capability of TAC is limited by the slow diffusion of Li-ions. Both materials show inferior electrochemical performances in Na battery cells compared to the Li analogs. X-ray powder diffraction reveals that BiTEMPS-OH loses its crystalline structure permanently upon cycling in Li battery cells. X-ray photoelectron spectroscopy demonstrates the cleavage and partially reversible formation of S-S bonds in BiTEMPS-OH and the formation/decomposition of thick solid electrolyte interphase on the electrode surface of TAC., (© 2024 The Authors. Small published by Wiley‐VCH GmbH.)

2D conjugated metal-organic frameworks (2D c-MOFs) have garnered significant attention as promising electroactive materials for energy storage. However, their further applications are hindered by low capacity, limited cycling life, and underutilization of the active sites. Herein, Cu-TBA (TBA = octahydroxyltetrabenzoanthracene) with large conjugation units (narrow energy gap) and a unique rhombus topology is introduced as the cathode material for sodium-ion batteries (SIBs). Notably, Cu-TBA with a rhombus topology exhibits a high specific surface area (613 m 2  g -1 ) and metallic band structure. Additionally, Cu-TBA outperforms its hexagonal counterpart, Cu-HHTP (HHTP = 2,3,6,7,10,11-hexahydroxyltriphenylene), demonstrating superior reversible capacity (153.6 mAh g -1 at 50 mA g -1 ) and outstanding cyclability with minimal capacity decay even after 3000 cycles at 1 A g -1 . This work elucidates a new strategy to enhance the electrochemical performance of 2D c-MOFs cathode materials by narrowing the energy gap of organic linkers, effectively expanding the utilization of 2D c-MOFs for SIBs., (© 2024 Wiley‐VCH GmbH.)

Pristine iron triad metal-organic frameworks (MOFs), i.e., Fe-MOFs, Co-MOFs, Ni-MOFs, and heterometallic iron triad MOFs, are utilized as versatile and promising cathodes for alkali metal-ion batteries, owing to their distinctive structure characteristics, including modifiable and designable composition, multi-electron redox-active sites, exceptional porosity, and stable construction facilitating rapid ion diffusion. Notably, pristine iron triad MOFs cathodes have recently achieved significant milestones in electrochemical energy storage due to their exceptional electrochemical properties. Here, the recent advances in pristine iron triad MOFs cathodes for alkali metal-ion batteries are summarized. The redox reaction mechanisms and essential strategies to boost the electrochemical behaviors in associated electrochemical energy storage devices are also explored. Furthermore, insights into the future prospects related to pristine iron triad MOFs cathodes for lithium-ion, sodium-ion, and potassium-ion batteries are also delivered., (© 2024 Wiley‐VCH GmbH.)

Compositing different crystal structures of layered transition metal oxides (LTMOs) is an emerging strategy to improve the electrochemical performance of LTMOs in sodium-ion batteries. Herein, a cobalt-free P2/P3-layered spinel composite, P2/P3-LS-Na 1/2 Mn 2/3 Ni 1/6 Fe 1/6 O 2 (LS-NMNF), is synthesized, and the synergistic effects from the P2/P3 and spinel phases were investigated. The material delivers an initial discharge capacity of 143 mAh g -1 in the voltage range of 1.5-4.0 V and displays a capacity retention of 73% at the 50 th cycle. The material shows a discharge capacity of 72 mAh g -1 at 5C. This superior rate performance by the material could be by virtue of the increased electronic conductivity contribution of the incorporated spinel phase. The charge compensation mechanism of the material is investigated by in operando X-ray absorption spectroscopy (in a voltage range of 1.5-4.5 V vs Na + /Na), which revealed the contribution of all transition metals toward the generated capacity. The crystal structure evolution of each phase during electrochemical cycling was analyzed by in operando X-ray diffraction. Unlike in the case of many reported P2/P3 composite cathode materials and spinel-incorporated cobalt-containing P2/P3 composites, the formation of a P'2 phase at the end of discharge is absent here.

Lithium-ion batteries (LIBs) has extensively utilized in electric vehicles and portable electronics due to their high energy density and prolonged lifespan. However, the current commercial LIBs are plagued by relatively low energy density. High-entropy materials with multiple components have emerged as an efficient strategic approach for developing novel materials that effectively improve the overall performance of LIBs. This article provides a comprehensive review the recent advancements in rational design of innovative high-entropy materials for LIBs, as well as the exceptional lithium ion storage mechanism for high-entropy electrodes and considerable ionic conductivity for high-entropy electrolytes. This review also analyses the prominent effects of individual components on the high-entropy materials' exceptional capacity, considerable structural stability, rapid lithium ion diffusion, and excellent ionic conductivity. Furthermore, this review presents the synthesis methods and their influence on the morphology and properties of high-entropy materials. Ultimately, the remaining challenges and future research directions are outlined, aimed at developing more effective high-entropy materials and improving the overall electrochemical performance of LIBs., (© 2024 IOP Publishing Ltd.)

Lithium-sulfur (Li-S) batteries, which store energy through reversible redox reactions with multiple electron transfers, are seen as one of the promising energy storage systems of the future due to their outstanding advantages. However, the shuttle effect, volume expansion, low conductivity of sulfur cathodes, and uncontrollable dendrite phenomenon of the lithium anodes have hindered the further application of Li-S batteries. In order to solve the problems and clarify the electrochemical reaction mechanism, various types of materials, such as metal compounds and carbon materials, are used in Li-S batteries. Polymers, as a class of inexpensive, lightweight, and electrochemically stable materials, enable the construction of low-cost, high-specific capacity Li-S batteries. Moreover, polymers can be multifunctionalized by obtaining rich structures through molecular design, allowing them to be applied not only in cathodes, but also in binders and solid-state electrolytes to optimize electrochemical performance from multiple perspectives. The most widely used areas related to polymer applications in Li-S batteries, including cathodes and electrolytes, are selected for a comprehensive overview, and the relevant mechanisms of polymer action in different components are discussed. Finally, the prospects for the practical application of polymers in Li-S batteries are presented in terms of advanced characterization and mechanistic analysis., (© 2024 Wiley‐VCH GmbH.)

Applying solar energy into energy storage battery systems is challenging in achieving green and sustainable development, however, the efficient progress of photo-assisted metal-air batteries is restricted by the rapid recombination of photogenerated electrons and holes upon the photocathode. Herein, a 1D-ordered MoS 2 nanotube (MoS 2 -ONT) with confined mass transfer can be used to extend the lifetime of photogenerated carriers, which is capable of overcoming the challenge of rapid recombination of electron and holes. The tubular confined space cannot only promote the orderly separation and migration of charge carriers but also realize the accumulation of charge and the rapid activation of oxygen molecules. The concave surface of MoS 2 -ONT can improve the carrier separation ability and prolong the carrier lifetime. Meanwhile, the ordered tubular confined space can effectively realize the rapid transfer of charge, ion, and oxygen. Under light irradiation, a fast oxygen reduction reaction kinetics of 70 mW cm -2 for photo-assisted Zn-air battery is achieved, which is the highest value reported for photo-assisted Zn-air batteries. Significantly, the photo-assisted Li-O 2 battery based on MoS 2 -ONT also shows superior rate capability and other exciting battery performance. This work shows the universality of the confined carrier separation strategy in photo-assisted metal-air batteries., (© 2023 Wiley‐VCH GmbH.)

Lithium-sulfur batteries (LSBs) with ultra-high energy density (2600 W h kg -1 ) and readily available raw materials are emerging as a potential alternative device with low cost for lithium-ion batteries. However, the insulation of sulfur and the unavoidable shuttle effect leads to slow reaction kinetics of LSBs, which in turn cause various roadblocks including poor rate capability, inferior cycling stability, and low coulombic efficiency. The most effective way to solve the issues mentioned above is to rationally design and control the synthesis of the cathode host for LSBs. Transition metal phosphides (TMPs) with good electrical conductivity and dual adsorption-conversion capabilities for polysulfide (PS) are regarded as promising cathode hosts for new-generation LSBs. In this review, the main obstacles to commercializing the LSBs and the development processes of their cathode host are first elaborated. Then, the sulfur fixation principles, and synthesis methods of the TMPs are briefly summarized and the recent progress of TMPs in LSBs is reviewed in detail. Finally, a perspective on the future research directions of LSBs is provided., (© 2023 Wiley‐VCH GmbH.)

Sodium-ion batteries (SIBs) are widely considered a hopeful alternative to lithium-ion battery technology. However, they still face challenges, such as low rate capability, unsatisfactory cycling stability, and inferior variable-temperature performance. In this study, a hierarchical Na 3 V 2 (PO 4 ) 2 F 3 (NVPF) @reduced graphene oxide (rGO)/carbon nanotube (CNT) composite (NVPF@rGO/CNT) is successfully constructed. This composite features 0D Na 3 V 2 (PO 4 ) 2 F 3 nanoparticles are coated by a cross-linked 3D conductive network composed of 2D rGO and 1D CNT. Furthermore, the intrinsic Na + storage mechanism of NVPF@rGO/CNT through comprehensive characterizations is unveiled. The synthesized NVPF@rGO/CNT exhibits fast ionic/electronic transport and excellent structural stability within wide working temperatures (-40-50 °C), owing to the zero-strain NVPF and the coated rGO/CNT conductive network that reduces diffusion distance for ions and electrons. Moreover, the stable integration between NVPF and rGO/CNT enables outstanding structural stability to alleviate strain and stress induced during the cycle. Additionally, a practice full cell is assembled employing a hard carbon anode paired with an NVPF@rGO/CNT cathode, which provides a decent capacity of 105.2 mAh g -1 at 0.2 C, thereby attaining an ideal energy density of 242.7 Wh kg -1 . This work provides valuable insights into developing high-energy and power-density cathode materials for SIBs., (© 2023 Wiley-VCH GmbH.)

Restricted by the available energy storage modes, currently rechargeable aluminum-ion batteries (RABs) can only provide a very limited experimental capacity, regardless of the very high gravimetric capacity of Al (2980 mAh g -1 ). Here, a novel complexation mechanism is reported for energy storage in RABs by utilizing 0D fullerene C 70 as the cathode. This mechanism enables remarkable discharge voltage (≈1.65 V) and especially a record-high reversible specific capacity (750 mAh g -1 at 200 mA g -1 ) of RABs. By means of in situ Raman monitoring, mass spectrometry, and density functional theory (DFT) calculations, it is found that this elevated capacity is attributed to the direct complexation of one C 70 molecule with 23.5 (super)halogen moieties (superhalogen AlCl 4 and/or halogen Cl) in average, forming (super)halogenated C 70 ·(AlCl 4 ) m Cl n-m complexes. Upon discharging, decomplexation of C 70 ·(AlCl 4 ) m Cl n-m releases AlCl 4 - /Cl - ions while preserving the intact fullerene cage. This work provides a new route to realize high-capacity and long-life batteries following the complexation mechanism., (© 2023 Wiley-VCH GmbH.)

Aqueous zinc ion battery (AZIBs) has attracted the attention of many researchers because of its safety, economy, environmental protection, and high ionic conductivity of electrolytes. However, the battery greatly suffers from zinc dendrite produced by zinc metal anode leading to poor cycle life and even unsafe problems, which limit its further development for various important applications. It is known that the success of the commercialization of lithium-ion batteries (LIBs) is mainly due to replacement of lithium metal anode with graphite, which avoids the formation of Li dendrite. Therefore, it is an important step to develop aqueous zinc ion anode to replace conventional zinc metal one with zinc-metal free anode material. In this review, the working principle and development prospect of "rocking-chair" AZIBs are introduced. The research progress of different types of zinc metal-free anode materials and cathode materials in "rocking-chair" AZIBs is reviewed. Finally, the limitations and challenges of the Zn metal-free "rocking-chair" AZIBs as well as solutions are deeply discussed, aiming to provide new strategies for the development of advanced zinc-ion batteries., (© 2023 Wiley-VCH GmbH.)

Rechargeable aluminum batteries (RABs) are an emerging energy storage device owing to the vast Al resources, low cost, and high safety. However, the poor cyclability and inferior reversible capacity of cathode materials have limited the enhancement of RABs performance. Herein, a high configurational entropy strategy is presented to improve the electrochemical properties of RABs for the first time. The high-entropy (Fe, Mn, Ni, Zn, Mg) 3 O 4 cathode exhibits an ultra-stable cycling ability (109 mAh g -1 after 3000 cycles), high specific capacity (268 mAh g -1 at 0.5 A g -1 ), and rapid ion diffusion. Ex situ characterizations indicate that the operational mechanism of (Fe, Mn, Ni, Zn, Mg) 3 O 4 cathode is mainly based on the redox process of Fe, Mn, and Ni. Theoretical calculations demonstrate that the oxygen vacancies make a positive contribution to adjusting the distribution of electronic states, which is crucial for enhancing the reaction kinetics at the electrolyte and cathode interface. These findings not only propose a promising cathode material for RABs, but also provide the first elucidation of the operational mechanism and intrinsic information of high-entropy electrodes in multivalent ion batteries., (© 2023 Wiley-VCH GmbH.)

Aqueous zinc-ion batteries (AZIBs) are gaining popularity for their cost-effectiveness, safety, and utilization of abundant resources. MXenes, which possess outstanding conductivity, controllable surface chemistry, and structural adaptability, are widely recognized as a highly versatile platform for AZIBs. MXenes offer a unique set of functions for AZIBs, yet their significance has not been systematically recognized and summarized. This review article provides an up-to-date overview of MXenes-based electrode materials for AZIBs, with a focus on the unique functions of MXenes in these materials. The discussion starts with MXenes and their derivatives on the cathode side, where they serve as a 2D conductive substrate, 3D framework, flexible support, and coating layer. MXenes can act as both the active material and a precursor to the active material in the cathode. On the anode side, the functions of MXenes include active material host, zinc metal surface protection, electrolyte additive, and separator modification. The review also highlights technical challenges and key hurdles that MXenes currently face in AZIBs., (© 2023 The Authors. Advanced Science published by Wiley-VCH GmbH.)

The design of binders plays a pivotal role in achieving enduring high power in lithium-ion batteries (LIBs) and extending their overall lifespan. This review underscores the indispensable characteristics that a binder must possess when utilized in LIBs, considering factors such as electrochemical, thermal, and dispersion stability, compatibility with electrolytes, solubility in solvents, mechanical properties, and conductivity. In the case of anode materials, binders with robust mechanical properties and elasticity are imperative to uphold electrode integrity, particularly in materials subjected to substantial volume changes. For cathode materials, the selection of a binder hinges on the crystal structure of the cathode material. Other vital considerations in binder design encompass cost effectiveness, adhesion, processability, and environmental friendliness. Incorporating low-cost, eco-friendly, and biodegradable polymers can significantly contribute to sustainable battery development. This review serves as an invaluable resource for comprehending the prerequisites of binder design in high-performance LIBs and offers insights into binder selection for diverse electrode materials. The findings and principles articulated in this review can be extrapolated to other advanced battery systems, charting a course for developing next-generation batteries characterized by enhanced performance and sustainability.

Employing porous structures is essential in high-performance electrochemical energy devices. However, obtaining uniform functional coatings on high-tortuosity structures can be challenging, even with specialized processes such as atomic layer deposition (ALD). Herein, a novel method for achieving a porous composite electrode for solid oxide fuel cells by coating La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 -δ (LSCF) powders with ZrO 2 using a powder ALD process is presented. Unlike conventional ALD, powder ALD can be used to fabricate extremely uniform coatings on porous electrodes with a thickness of tens of micrometers. The powder ALD ZrO 2 coating is found to effectively suppress chemical degradation of the LSCF electrodes. The cell with the powder ALD coated cathode shows a 2.2 times higher maximum power density and 60% lower thermal degradation in activation resistance than the bare LSCF cathode cell at 700-750 °C. The result demonstrated in this study is expected to have significant implications for high-performance and durable electrodes in energy conversion/storage devices., (© 2023 Wiley-VCH GmbH.)

Employing high voltage cobalt-free spinel LiNi 0.5 Mn 1.5 O 4 (LNMO) as a cathode is promising for high energy density and cost-effectiveness, but it has challenges in all-solid-state batteries (ASSBs). Here, it is revealed that the limitation of lithium argyrodite sulfide solid electrolyte (Li 6 PS 5 Cl) with the LNMO cathode is due to the intrinsic chemical incompatibility and poor oxidative stability. Through a careful analysis of the interphase of LNMO, it is elucidated that even the halide solid electrolyte (Li 3 InCl 6 ) with high oxidative stability can be decomposed to form resistive interphase layers with LNMO in ASSBs. Interestingly, with Fe-doping and a Li 3 PO 4 protective layer coating, LNMO with Li 3 InCl 6 displays stable cycle performance with a stabilized interphase at a high voltage (≈4.7 V) in ASSBs. The enhanced interfacial stability with the extended electrochemical stability window through doping and coating enables high electrochemical stability with LNMO in ASSBs. This work provides guidance for employing high-voltage cathodes in ASSBs and highlights the importance of stable interphases to enable stable cycling in ASSBs., (© 2023 Wiley-VCH GmbH.)

The eco-friendliness, safety, and affordability of aqueous potassium batteries (AKIBs) have made them popular for large-scale energy storage devices. However, the cycling and rate performance of research materials, particularly cobalt hexacyanoferrate, have yet to meet satisfactory standards. Herein, a room-temperature drafted K 1.66 Fe 0.25 Co 0.75 [Fe(CN) 6 ]·0.83H 2 O (KFCHCF) sample is reported using an in situ substitution strategy. A higher concentration of ferrocyanide ions decreases the water content and increases the potassium content, while citric acid works as a chelating agent and is responsible for Fe-substitution in the KFCHCF sample. The resultant KFCHCF sample exhibits good rate performance, and about 97% and 90.6% of discharge capacity are conserved after 400 and 1000 cycles at 100 and 200 mA g -1 , respectively. The full cell using the KFCHCF cathode and 1,4,5,8-naphthalenetetracarboxylic dianhydride-derived polyimide (PNTCDA) anode maintains ≈74.93% and 74.35% of discharge capacity at 200 mA g -1 and 1000 mA g -1 for 1000 and >10,000 cycles, respectively. Furthermore, ex situ characterizations demonstrate the high reversibility of K-ions and structural stability during the charge-discharge process. Such high performance is attributed to the fast K-ion migration and crystal structure stabilization caused by in situ Fe-substitution in the KFCHCF sample. Other hexacyanoferrates can be synthesized using this method and used in grid-scale storage systems., (© 2023 Wiley-VCH GmbH.)

The significant attraction toward aqueous proton batteries (APBs) is attributable to their expedited kinetics, elevated safety profile, and economical feasibility. Nevertheless, their practical implement is significantly blocked by the unsatisfactory energy density due to the limited cathode materials. Herein, vanadium hexacyanoferrate Prussian blue analog (VOHCF) is introduced as a potentially favorable cathode material for APBs. The findings demonstrate that this VOHCF electrode exhibits a notable reversible capacity of 102.7 mAh g -1 and exceptional cycling stability, with 95.4% capacity retention over 10 000 cycles at 10 A g -1 . It is noteworthy that this is the detailed instance of VOHCF being proposed as a cathode for APBs. Combining the in situ characterization techniques and theoretical simulations, the origins of excellent proton storage performance are revealed as the multiple redox mechanisms with double active centers of ─C≡N group and V═O bond in VOHCF as well as the robust structure stability. A proton full cell with excellent performance is further achieved by coupling the VOHCF cathode and diquinoxalino[2,3-a:2',3'-c] phenazine (HATN) anode, demonstrating the great potential of VOHCF in practical applications. This work could provide fundamental understanding to the development of feasible cathode materials for proton storage device., (© 2023 Wiley-VCH GmbH.)

Vanadium-based oxides have attracted much attention because of their rich valences and adjustable structures. The high theoretical specific capacity contributed by the two-electron-transfer process (V 5+ /V 3+ ) makes it an ideal cathode material for aqueous zinc-ion batteries. However, slow diffusion kinetics and poor structural stability limit the application of vanadium-based oxides. Herein, a strategy for intercalating organic matter between vanadium-based oxide layers is proposed to attain high rate performance and long cycling life. The V 3 O 7 ·H 2 O is synthesized in situ on the carbon cloth to form an open porous structure, which provides sufficient contact areas with electrolyte and facilitates zinc ion transport. On the molecular level, the added organic matter p-aminophenol (pAP) not only plays a supporting role in the V 3 O 7 ·H 2 O layer, but also shows a regulatory effect on the V 5+ /V 4+ redox process due to the reducing functional group on pAP. The novel composite electrode with porous structure exhibits outstanding reversible specific capacity (386.7 mAh g -1 , 0.1 A g -1 ) at a high load of 6.5 mg cm -2 , and superior capacity retention of 80% at 3 A g -1 for 2100 cycles., (© 2023 Wiley-VCH GmbH.)

Zinc ion hybrid capacitors (ZIHCs) are encouraging energy storage devices for large-scale applications. Nevertheless, the electrochemical performance of ZIHCs is often limited by the cathode materials which show low energy density and rate capability practically. One of the efficient strategies to overcome these challenges is the development of advanced carbon cathode materials with abundant physi/chemisorption sites. Herein, we develop a sulfate template strategy to prepare sulfur and oxygen doped carbon nanosheets (SOCNs) as a potential cathode active material for ZIHCs. The as-prepared SOCNs exhibit porous architectures with a large surface area of 1877 m 2 g -1 , substantial structural defects, and high heteroatom-doped contents (O: 7.9 at%, S: 0.7 at%). These exceptional features are vital to enhancing Zn ion storage. Consequently, the SOCN cathode shows a high capacity of 151 mAh g -1 at 0.1 A g -1 , high cycle stability with 83% capacity retention at 5 A g -1 after 4000 cycles, and a superior energy density of 103.1 Wh kg -1 . We also investigate the dynamic adsorption/desorption behaviors of Zn ions and anions of the ZIHCs carbon electrodes during the process of charge and discharge by ex-situ experiments. This work highlights the significance of the integration with a large specific surface area and bountiful heteroatoms in carbon electrodes for achieving high-performance ZIHCs., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

The challenge with aqueous zinc-ion batteries (ZIBs) lies in finding suitable cathode materials that can provide high capacity and fast kinetics. Herein, two-dimensional topological Bi 2 Se 3 with acceptable Bi-vacancies for ZIBs cathode (Cu-Bi 2-x Se 3 ) is constructed through one-step hydrothermal process accompanied by Cu heteroatom introduction. The cation-deficient Cu-Bi 2-x Se 3 nanosheets (≈4 nm) bring improved conductivity from large surface topological metal states contribution and enhanced bulk conductivity. Besides, the increased adsorption energy and reduced Zn 2+ migration barrier demonstrated by density-functional theory (DFT) calculations illustrate the decreased Coulombic ion-lattice repulsion of Cu-Bi 2-x Se 3 . Therefore, Cu-Bi 2-x Se 3 exhibits both enhanced ion and electron transport capability, leading to more carrier reversible insertion proved by in situ synchrotron X-ray diffraction (SXRD). These features endow Cu-Bi 2-x Se 3 with sufficient specific capacity (320 mA h g -1 at 0.1 A g -1 ), high-rate performance (97 mA h g -1 at 10 A g -1 ), and reliable cycling stability (70 mA h g -1 at 10 A g -1 after 4000 cycles). Furthermore, quasi-solid-state fiber-shaped ZIBs employing the Cu-Bi 2-x Se 3 cathode demonstrate respectable performance and superior flexibility even under high mass loading. This work implements a conceptually innovative strategy represented by cation defect design in topological insulator cathode for achieving high-performance battery electrochemistry., (© 2023 The Authors. Advanced Materials published by Wiley-VCH GmbH.)

Pyrochlore-type iron (III) hydroxy fluorides (Pyr-IHF) are appealing low-cost stationary energy storage materials due to the virtually unlimited supply of their constituent elements, their high energy densities, and fast Li-ion diffusion. However, the prohibitively high costs of synthesis and cathode architecture currently prevent their commercial use in low-cost Li-ion batteries. Herein, a facile and cost-effective dissolution-precipitation synthesis of Pyr-IHF from soluble iron (III) fluoride precursors is presented. High capacity retention by synthesized Pyr-IHF of >80% after 600 cycles at a high current density of 1 A g -1 is obtained, without elaborate electrode engineering. Operando synchrotron X-ray diffraction guides the selective synthesis of Pyr-IHF such that different water contents can be tested for their effect on the rate capability. Li-ion diffusion is found to occur in the 3D hexagonal channels of Pyr-IHF, formed by corner-sharing FeF 6-x (OH) x octahedra., (© 2023 The Authors. Advanced Materials published by Wiley-VCH GmbH.)

Due to their high reactivity and theoretical capacity, chalcogen elements have been favored and applied in many battery studies. However, the high surface charge density and high solubility of these elements as electrode materials have hindered their deeper exploration due to the shuttle effect. In this article, organic structural triphenylphosphine is used as a molecular main chain structure, and chalcogen elements O, S, and Se are introduced to combine with P as active sites. This approach not only takes advantage of the beneficial effects of the aromatic ring on the physical and chemical properties of the chalcogen element but also allows for the optimization of its advantages. By utilizing Triphenylphosphine selenide (TP-Se) as the cathode material in aluminum-ion batteries(AIBs), a high-performance Al-organic battery was fabricated, which exhibited a high initial capacity of 180.6 mAh g -1 and stable cycling for up to 1000 cycles. Based on density functional theory (DFT) calculations, TP-Se exhibits a smaller energy gap, which renders it favorable for chemical reactions. Moreover, the calculated results suggest that TP-Se tends to undergo redox reactions with AlCl 2 + . The molecular structure of triphenylphosphine and its combination with Se offers an enticing pathway for designing cathode materials in aluminum-organic batteries., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

The manganese-based layered oxides as a promising cathode material for potassium ion batteries (PIBs) have attracted considerable interest owing to their simple synthesis, high specific capacity, and low cost. However, due to the irreversible phase transition and the Jahn-Teller distortion of the Mn 3+ , its application in potassium ion batteries is limited, leading to slow potassium ion kinetics and severe capacity attenuation. Here, entropy-tuning by changing the content of cathode material composition is proposed to address the above challenges. Compared to low and high entropy variants of K 0.45 Mn x Co (1- x )/4 Mg (1- x )/4 Cu (1- x )/4 Ti (1- x )/4 O 2 , where x = 0.8, 0.6, and 0.4, the medium entropy K 0.45 Mn 0.6 Co 0.1 Mg 0.1 Cu 0.1 Ti 0.1 O 2 shows more balanced electrochemical properties in the PIBs. Benefiting from entropy-tuned suppression of the Jahn-Teller distortion of the Mn 3+ , the K 0.45 Mn 0.6 Co 0.1 Mg 0.1 Cu 0.1 Ti 0.1 O 2 can achieve a high K + ion transport rate and alleviated volume variation while retaining high specific capacity. Accordingly, the medium entropy K 0.45 Mn 0.6 Co 0.1 Mg 0.1 Cu 0.1 Ti 0.1 O 2 cathode in the full cell exhibits a high capacity of 100 mAh g -1 at 50 mA g -1 , delivers superior rate capability (65.8 mAh g -1 at 500 mA g -1 ) and cycling stability (67.8 mAh g -1 after 350 cycles at 100 mA g -1 ). The entropy-tuning strategy is expected to open new avenues in designing PIB cathode materials and beyond., (© 2023 Wiley-VCH GmbH.)

Li-CO 2 battery with high energy density has aroused great interest recently, large-scale applications are hindered by the limited cathode catalysis performance and execrably cycle performance. Herein, Mo 3 P/Mo Mott-Schottky heterojunction nanorod electrocatalyst with abundant porous structure is fabricated and served as cathodes for Li-CO 2 batteries. The Mo 3 P/Mo cathodes exhibit ultra-high discharge specific capacity of 10 577 mAh g -1 , low polarization voltage of 0.15 V, and high energy efficiency of up to 94.7%. Mott-Schottky heterojunction formed by Mo and Mo 3 P drives electron transfer and optimizes the surface electronic structure, which is beneficial to accelerate the interface reaction kinetics. Distinctively, during the discharge process, the C 2 O 4 2- intermediates combine with Mo atoms to form a stable Mo-O coupling bridge on the catalyst surface, which effectively facilitate the formation and stabilization of Li 2 C 2 O 4 products. In addition, the construction of the Mo-O coupling bridge between the Mott-Schottky heterojunction and Li 2 C 2 O 4 promotes the reversible formation and decomposition of discharge products and optimizes the polarization performance of the Li-CO 2 battery. This work provides another pathway for the development of heterostructure engineering electrocatalysts for high-performance Li-CO 2 batteries., (© 2023 Wiley-VCH GmbH.)

Owing to their intrinsic safety and sustainability, aqueous proton batteries have emerged as promising energy devices. Nevertheless, the corrosion or dissolution of electrode materials in acidic electrolytes must be addressed before practical applications. In this study, a cathode material based on a redox-active 2D covalent organic framework (TPAD-COF) with aniline-fused quinonoid units featuring inherently regular open porous channels and excellent stability is developed. The TPAD-COF cathode delivers a high capacity of 126 mAh g -1 at 0.2 A g -1 , paired with long-term cycling stability with capacity retention of 84% after 5000 cycles at 2 A g -1 . Comprehensive ex situ spectroscopy studies correlated with density functional theory (DFT) calculations reveal that both the -NH- and C=O groups of the aniline-fused quinonoid units exhibit prominent redox activity of six electrons during the charge/discharge processes. Furthermore, the assembled punch battery consisting of a TPAD-COF//anthraquinone (AQ) all-organic system delivers a discharge capacity of 115 mAh g -1 at 0.5 A g -1 after 130 cycles, implying the potential application of the TPAD-COF cathode in aqueous proton batteries. This study provides a new perspective on the design of electrode materials for aqueous proton batteries with long-term cycling performance and high capacity., (© 2023 Wiley-VCH GmbH.)

Ba 1- x La x FeO 3-δ perovskites (BLF) capable of conducting electrons, protons, and oxygen ions are promising oxygen electrodes for efficient solid oxide cells (fuel cells or electrolyzers), an integral part of prospected large-scale power-to-gas energy storage systems. We investigated the compatibility of BLF with lanthanum content between 5 and 50%, in contact with oxide-ion-conducting Ce 0.8 Gd 0.2 O 2-δ and proton-conducting BaZr 0.825 Y 0.175 O 3-δ electrolytes, annealing the electrode-electrolyte bilayers at high temperature to simulate thermal stresses of fabrication and prolonged operation. By employing both bulk X-ray diffraction and synchrotron X-ray microspectroscopy, we present a space-resolved picture of the interaction between electrode and electrolyte as what concerns cation interdiffusion, exsolution, and phase stability. We found that the phase stability of BLF in contact with other phases is correlated with the Goldschmidt tolerance factor, in turn determined by the La/Ba ratio, and appropriate doping strategies with oversized cations (Zn 2+ , Y 3+ ) could improve structural stability. While extensive reactivity and/or interdiffusion was often observed, we put forward that most products of interfacial reactions, including proton-conducting Ba(Ce,Gd)O 3-δ and mixed-conducting (Ba,La)(Fe,Zr,Y)O 3-δ , may not be very detrimental for practical cell operation.

Microbial fuel cells (MFCs) have great potential as a new energy technology that utilizes microorganisms to produce electrical energy by decomposing organic matter. A cathode catalyst is key to achieving an accelerated cathodic oxygen reduction reaction (ORR) in MFCs. We prepared a Zr-based metal organic-framework-derived silver-iron co-doped bimetallic material based on electrospun nanofibers by promoting the in situ growth of UiO-66-NH 2 on polyacrylonitrile (PAN) nanofibers and named it as CNFs-Ag/Fe-m:n doped catalyst (m:n were 0, 1:1, 1:2, 1:3, and 2:1, respectively). Experimental results combined with density functional theory (DFT) calculations reveal that a moderate amount of Fe doped in CNFs-Ag-1:1 reduces the Gibbs free energy in the last step of the ORR. This indicates that Fe doping improves the performance of the catalytic ORR, and MFCs equipped with CNFs-Ag/Fe-1:1 exhibit a maximum power density of 737. 45 mW m -2 , significantly higher than that obtained for MFCs using commercial Pt/C (457.99 mW m -2 )., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Phase transformation─a universal phenomenon in materials─plays a key role in determining their properties. Resolving complex phase domains in materials is critical to fostering a new fundamental understanding that facilitates new material development. So far, although conventional classification strategies such as order-parameter methods have been developed to distinguish remarkably disparate phases, highly accurate and efficient phase segmentation for material systems composed of multiphases remains unavailable. Here, by coupling hard-attention-enhanced U-Net network and geometry simulation with atomic-resolution transmission electron microscopy, we successfully developed a deep-learning tool enabling automated atom-by-atom phase segmentation of intertwined phase domains in technologically important cathode materials for lithium-ion batteries. The new strategy outperforms traditional methods and quantitatively elucidates the correlation between the multiple phases formed during battery operation. Our work demonstrates how deep learning can be employed to foster an in-depth understanding of phase transformation-related key issues in complex materials.