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A separator modification strategy was proposed by placing nitrogen-doped carbon fibers (NCF700) in the middle of the separator to prevent direct contact between the coating and the rigid zinc metal anode, resulting in coating cracks. The NCF700 coating can homogenize the electric field distribution and increase the transference number of zinc ions. Therefore, the battery assembled with the NCF700 coated separator exhibits superior cycling stability compared to the bare separator. [ABSTRACT FROM AUTHOR]

Rechargeable Zn‐based batteries provide a compelling supplement to subsistent energy storage devices owing to their high energy density, good safety, and low cost. Nevertheless, inherent imperfections such as dendrite growth, side reactions, and andante reaction kinetics, severely impede their commercialization. As new 0D nanomaterials, carbon dots (CDs) with unique characteristics and excellent electrochemical activity, exhibit promising potential exploitation in electrochemistry and electrocatalysis areas. Herein, the adhibition of CDs in resolving the aforementioned drawbacks of Zn‐based batteries is introduced. To begin with, concepts, physicochemical properties, and synthetic methods of CDs are discussed. Next, recent developments and advances exploiting CDs in respectively ameliorating the performance of the Zn anode, the cathode, and electrolytes of Zn ion batteries and bifunctional electrocatalytic activities including oxygen reduction reaction and oxygen evolution reaction for Zn‐air batteries, are roundly reviewed and minutely generalized. Finally, current challenges and prospects are surveyed as well, aiming to offer a reference for the blossom of advanced Zn‐based batteries. [ABSTRACT FROM AUTHOR]

Zinc‐ion batteries (ZIBs) have become a global research hotspot in recent years due to their eco‐friendliness, safety, abundant resources, and low cost. However, some significant challenges seriously affect their overall performance, thus hindering their further development and practical applications. Recently, multifunctional and adjustable 2D carbides and nitrides (MXenes) are extensively used for the modification of ZIBs, and fruitful achievements are achieved. In order to make a systematic understanding of these studies, it is highly desirable to provide an overview of MXenes based on their modification methods and action mechanisms. In this review, a basic introduction to ZIBs and MXenes is presented and the main modification approaches of MXenes in solving the issues of ZIBs are discussed in detail, including activation and composite strategies of the cathode, interface engineering, structural optimization, and zinc metal‐free anode strategy of the anode, solid‐state strategy of the electrolyte, and functionalized strategy of the separator. Importantly, the functions and related mechanisms of MXenes in various components of ZIBs are analyzed in depth. Finally, the pathways for MXenes in solving the issues of ZIBs are summarized, and their future directions are prospected. [ABSTRACT FROM AUTHOR]

The electric eel is known as the most powerful creature to generate electricity with a discharge voltage up to 860 V and peak current up to 1 A. These surprising properties are the results of billions of years of evolution on the electrical biological structure and bulk, and now have triggered great research interest in electric eel biomimetics for designing innovated configurations and components of energy storage and conversion devices. In this review, first, the bioelectrical behavior of electric eels is surveyed, followed by the physiological structure to reveal the discharge characteristics and principles of electric organs and electrocytes. Additionally, underlying electrochemical mechanisms and models for calculating the potential and current of electrocytes are presented. Central to this review is the recent progress of electric‐eel‐inspired innovations and applications for energy storage and conversion, particularly including novel power sources, triboelectric nanogenerators, and nanochannel ion‐selective membranes for salinity gradient energy harvesting. Finally, insights on the challenges at the moment and the perspectives on the future research prospects are critically compiled. It is suggested that energy‐related electric eel biomimetics will greatly boost the development of next‐generation high performance, green, and functional electronics. [ABSTRACT FROM AUTHOR]

Direct regeneration is an effective strategy of spent lithium iron phosphate (S-LFP), with the principal aspect being the selection of the lithium source and reductant. Here, assisted with a thermodynamically favourable reaction involving a bifunctional organic lithium salt (lithium citrate), the single-step regeneration of S-LFP is successfully achieved. The structure and composition of the regenerated LFP are significantly restored, demonstrating excellent electrochemical performance (142.7 mA h g−1) with no degradation after 200 cycles. [ABSTRACT FROM AUTHOR]

Garnet solid‐state electrolyte Li6.5La3Zr1.5Ta0.5O12 (LLZTO) holds significant promise. However, the practical utilization has been seriously impeded by the poor contact of Li|garnet and electron leakage. Herein, one new type of garnet‐based solid‐state battery is proposed with high performance through the disparity in interfacial energy, induced by the reaction between trace fluorinated carbon dots (FCDs) and Li. The work of adhesion of Li|garnet is increased by the acquired Li‐FCD composite, which facilitates an intimate Li|garnet interface with the promoted uniform Li+ deposition, revealed by density functional theory (DFT) calculations. It is further validated that a concentrated C−Li2O−LiF component at the Li|garnet interface is spontaneously constructed, due to the significant disparity in interfacial energy between C−Li2O−LiF|LLZTO and C−Li2O−LiF|Li. Furthermore, The electron transport and Li dendrites penetration are effectively hindered by the formed Li2O and LiF. The Li‐FCD|LLZTO|Li‐FCD symmetrical cells demonstrate stable cycling performance for over 3000 hours at 0.3 mA cm−2 and 800 hours at 0.5 mA cm−2. Furthermore, the LFP|garnet|Li‐FCD full cell exhibits remarkable cycling performance (91.6 % capacity retention after 500 cycles at 1 C). Our research has revealed a novel approach to establish a dendrite‐free Li|garnet interface, laying the groundwork for future advancements in garnet‐based solid‐state batteries. [ABSTRACT FROM AUTHOR]

Garnet solid‐state electrolyte Li6.5La3Zr1.5Ta0.5O12 (LLZTO) holds significant promise. However, the practical utilization has been seriously impeded by the poor contact of Li|garnet and electron leakage. Herein, one new type of garnet‐based solid‐state battery is proposed with high performance through the disparity in interfacial energy, induced by the reaction between trace fluorinated carbon dots (FCDs) and Li. The work of adhesion of Li|garnet is increased by the acquired Li‐FCD composite, which facilitates an intimate Li|garnet interface with the promoted uniform Li+ deposition, revealed by density functional theory (DFT) calculations. It is further validated that a concentrated C−Li2O−LiF component at the Li|garnet interface is spontaneously constructed, due to the significant disparity in interfacial energy between C−Li2O−LiF|LLZTO and C−Li2O−LiF|Li. Furthermore, The electron transport and Li dendrites penetration are effectively hindered by the formed Li2O and LiF. The Li‐FCD|LLZTO|Li‐FCD symmetrical cells demonstrate stable cycling performance for over 3000 hours at 0.3 mA cm−2 and 800 hours at 0.5 mA cm−2. Furthermore, the LFP|garnet|Li‐FCD full cell exhibits remarkable cycling performance (91.6 % capacity retention after 500 cycles at 1 C). Our research has revealed a novel approach to establish a dendrite‐free Li|garnet interface, laying the groundwork for future advancements in garnet‐based solid‐state batteries. [ABSTRACT FROM AUTHOR]

Garnet solid state electrolytes (SSEs) have emerged as propitious candidates for solid‐state batteries (SSBs) with exceptional ionic conductivity and excellent (electro)chemical stability. However, the Li|garnet interface contact deterioration still remains a major challenge resulting in Li dendrite propagation. Herein, a method is proposed to strengthen the adhesion of garnet SSE and Li by incorporating Sr3N2 into the Li metal. Density functional theory (DFT) calculations reveal that the interfacial formation energy of Li|garnet is decreased by the obtained Li‐Sr‐N (LSN) composite, which can enable a shift from poor contact to intimate bonding at the Li|garnet interface and a homogenous Li+ flux as well as electric field distribution. Simultaneously, the produced Li3N and LiSrN, which are known for their strong Li adsorption affinity and rapid Li+ transfer kinetics, actively govern the Li plating process. Thereby this rational design brings a notable reduction in interfacial impedance (4.5 Ω cm2), along with the increased critical current density (1.3 mA cm−2) and enhanced cycle stability (1200 h at 0.3 mA cm−2). Furthermore, The LFP|garnet|LSN full cell has demonstrated remarkable cycling performance (95.9% capacity retention after 200 cycles at 1 C) and favorable rate capability (150.2 mAh g−1 at 0.1 C and 134.9 mAh g−1 at 1 C). The research provides a new sight into lithium modification that can restrain Li|garnet interface deterioration and lay the groundwork for future advancements in high‐performance garnet‐ based SSBs. [ABSTRACT FROM AUTHOR]

Transition metal sulfides (TMSs) still confront the challenges of capacity fading and inferior fast‐charging capability for sodium storage. The rational design of heterostructures enables a new approach to conquer these drawbacks. In this work, a hierarchical structure consisting of SnS2 nanosheets and FeS2 microrods with triphasic heterostructures is proposed by the facile secondary growth and sulfidation process. The introduction of tin sources regulates the proportion of pyrite and marcasite phases, thereby achieving the triphasic heterostructures comprising pyrite, marcasite FeS2, and SnS2. When served as anode material for sodium‐ion batteries, the optimized sample exhibits a high reversible capacity (901 mAh g−1) and durable cycling performances (827 mAh g−1 after 200 cycles at 1 A g−1 and 742 mAh g−1 after 700 cycles at 5 A g−1). Paring with the commercial Na3V2(PO3)3 cathodes, the full‐cell also delivers extraordinary cyclic stability with a high capacity of 618 mAh g−1 (based on the weight of anode material) after 200 cycles at 1 A g−1 (98.7% capacity retention). The hierarchical structure with adjustably triphasic heterogeneous interfaces alleviates the volumetric expansion and interfacial passivation of active material, while modulating the energy band structure and inducing the build‐in electric fields to boost Na+/electrons transport rate. [ABSTRACT FROM AUTHOR]

Aqueous rechargeable batteries (ARBs) have attracted wide attention due to their rich resources, environmental friendliness, and safety. The high ionic conductivity, safety and interfacial wettability of the aqueous electrolyte are essential for energy storage devices. However, the narrow electrochemical stability window (ESW) of the aqueous electrolyte and the side reactions of the electrode/electrolyte lead to the low energy density of the ARBs. In the past studies, the above problems were generally solved by improving the ion transport characteristics of the electrolyte and the electrode/electrolyte interface. Herein, we discuss the background, limitations, and key concepts for performance improvement of aqueous electrolytes, aiming to provide a comprehensive perspective and inspiration for further research on aqueous electrolytes and promote their development and application in the field of energy storage. [ABSTRACT FROM AUTHOR]

Niobium oxides have fascinated numerous interests for ultrafast sodium‐ion batteries due to their impressive stability, fast pseudocapacitive kinetics, and high safety features. However, the poor intrinsic electronic conductivity and unrevealed mechanisms largely limit their further applications. Here, inspired by density functional theory (DFT) calculations, the introduction of conductor heterostructure (Nb2O5/NbSe2) can largely decrease the bulk phase inserted energy of Na+ from 9.88 to −3.54 eV, as well as promote the delocalization of electron, greatly improving the electrical conductivity of Nb2O5. As expected, the as‐obtained orthorhombic niobium pentoxide (T‐Nb2O5‐x‐NbSe2@C) delivers a high conductivity of 3.69 S cm−1, exhibiting a great improvement of four orders magnitude than that of the parent Nb2O5 (1.87 × 10−4 S cm−1). Impressively, T‐Nb2O5‐x‐NbSe2@C possesses a high reversible capacity of 249 mAh g−1 at 0.1 A g−1, as well as excellent rate performance of 63 mAh g−1 at 5.0 A g−1, nearly twins the capacity of parent porous Nb2O5. Furthermore, the periodic evolutions of the main peaks for targeted electrodes during repeated charging/discharging processes have been further revealed by in situ XRD, demonstrating a highly reversible inserted/extracted storage mechanism of Na+. This work provides a novel method to improve the conductivity of materials by constructing conductor heterojunction. [ABSTRACT FROM AUTHOR]

The utilization rate of active sites in cathode materials for Zn‐based batteries is a key factor determining the reversible capacities. However, a long‐neglected issue of the strong electrostatic repulsions among divalent Zn2+ in hosts inevitably causes the squander of some active sites (i.e. gap sites). Herein, we address this conundrum by unraveling the "gap‐filling" mechanism of multiple charge carriers in aqueous Zn‐MoS2 batteries. The tailored MoS2/(reduced graphene quantum dots) hybrid features an ultra‐large interlayer spacing (2.34 nm), superior electrical conductivity/hydrophilicity, and robust layered structure, demonstrating highly reversible NH4+/Zn2+/H+ co‐insertion/extraction chemistry in the 1 M ZnSO4+0.5 M (NH4)2SO4 aqueous electrolyte. The NH4+ and H+ ions can act as gap fillers to fully utilize the active sites and screen electrostatic interactions to accelerate the Zn2+ diffusion. Thus, unprecedentedly high rate capability (439.5 and 104.3 mAh g−1 at 0.1 and 30 A g−1, respectively) and ultra‐long cycling life (8000 cycles) are achieved. [ABSTRACT FROM AUTHOR]

The utilization rate of active sites in cathode materials for Zn‐based batteries is a key factor determining the reversible capacities. However, a long‐neglected issue of the strong electrostatic repulsions among divalent Zn2+ in hosts inevitably causes the squander of some active sites (i.e. gap sites). Herein, we address this conundrum by unraveling the "gap‐filling" mechanism of multiple charge carriers in aqueous Zn‐MoS2 batteries. The tailored MoS2/(reduced graphene quantum dots) hybrid features an ultra‐large interlayer spacing (2.34 nm), superior electrical conductivity/hydrophilicity, and robust layered structure, demonstrating highly reversible NH4+/Zn2+/H+ co‐insertion/extraction chemistry in the 1 M ZnSO4+0.5 M (NH4)2SO4 aqueous electrolyte. The NH4+ and H+ ions can act as gap fillers to fully utilize the active sites and screen electrostatic interactions to accelerate the Zn2+ diffusion. Thus, unprecedentedly high rate capability (439.5 and 104.3 mAh g−1 at 0.1 and 30 A g−1, respectively) and ultra‐long cycling life (8000 cycles) are achieved. [ABSTRACT FROM AUTHOR]

Aqueous zinc‐ion batteries (ZIBs) are promising candidates for grid‐energy storage due to their safety and cost‐effectiveness. However, the detrimental hydrogen evolution reaction (HER) and dendrite growth on Zn‐metal anodes severely limit their applications. Herein, trace hydrophobic hyamine (HQA, 0.78 mmol L−1) is introduced as an electrolyte additive to improve the electrochemical performance of the Zn anode. Experiments and theoretical calculations revealed that cationic HQA can preferentially adsorb onto the anode surface to inhibit the HER and promote the uniform distribution of Zn ions by forming a water‐lean electric double layer (EDL). Moreover, the oriented adsorption of HQA induced exposure of the Zn (002) plane and prevented dendrite growth. Therefore, the symmetric cells using the HQA‐containing electrolyte exhibited stable cycle performance for more than 1600 h. Even at a high‐density current of 5 mA cm−2, it has a high cumulative capacity of 3250 mAh cm−2. It exhibited an excellent deep‐discharge performance (80%) with a stable cycle for 175 h. The Zn||NH4V4O10 full cell exhibited a high specific capacity and cycle stability at 4.0 A g−1 due to the excellent reversibility of Zn anode. These results provide a new and low‐cost approach for electrolyte design and EDL optimization of high‐performance zinc‐ion batteries. [ABSTRACT FROM AUTHOR]

Antimony（Sb） has high theoretical specific capacity and moderate reaction potential, but poor cycling stability and rate performance caused by large volume expansion and sluggish reaction kinetics limit its development in alkali‐ion batteries. The construction of carbon/Sb composites can solve this problem, but the traditional single carbon composite and poor Sb/carbon interface have limited promotion. Here, under the guidance of theoretical calculations, a strategy of hierarchical double carbon composite is proposed to enhance the performance of Sb anode, and systematically reveal the lithium/sodium ions (Li+/Na+) storage mechanism of Sb in complex composite system. Sb nanoparticles (Sb NPs) are encapsulated in carbon sphere matrix with strong interfacial chemical bond to form the first level composite material, and then the highly conductive and mechanically strong graphene is used as a three‐dimensional skeleton network to connect the first level composite to form the second level composite material. The hierarchical double carbon/Sb composite exhibits excellent rate (228 mAh g−1 @ 20 A g−1) and long cycling performance (373.7 mAh g−1 @ 2 A g−1 after 2200 cycles, capacity retention of 93.1%). This work may expand structural design and interface regulation of Sb/C composites and providing theoretical guidance for metal anodes development. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Rationally developing efficient and durable bifunctional catalysts toward oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is critical for rechargeable zinc‐air batteries (ZABs). Herein, a bead‐like CoSe2@NC@NCNFs bifunctional catalyst was designed and fabricated by confining cubic CoSe2 nanoparticles to three‐dimensional (3D) porous MOFs‐derived nitrogen‐doped carbon (NC) and one‐dimensional (1D) N‐doped carbon nanofibers (NCNFs) through a facile encapsulate strategy. The 1D/3D continuous network structure contributes to the improvement of specific surface area and electronic conductivity, while the strong synergistic effect between CoSe2 sites and Co‐Nx‐C sites can effectively enhance electron/mass transfer and reduce the diffusion resistance. The as‐constructed CoSe2@NC@NCNFs catalyst exhibits high catalytic activity and stability toward ORR/OER with a high half‐wave potential of 0.80 V (vs. RHE) in ORR and a low overpotential of 280 mV at 10 mA·cm−2 in OER. More encouragingly, the rechargeable ZABs with CoSe2@NC@NCNFs cathode deliver high peak power densities (126.8 mW·cm−2), large specific capacities (763.1 mA·h·g−1), and robust charge‐discharge cycling stability over 240 cycles. This study provides a facile strategy for designing efficient bifunctional catalysts for rechargeable energy conversion applications. [ABSTRACT FROM AUTHOR]

Hard carbon (HC) is widely regarded as the most promising anode material for sodium‐ion batteries (SIBs). For improving the sodium storage capacity of HC anode, current research primarily focuses on the high‐voltage slope region. Actually, increasing the storage capability in the low‐voltage plateau region is more important for enhancing the energy density of full cells. Therefore, in this study, HC anode with rich closed pore structure is designed and constructed with the help of carbon dots (CDs), and it is demonstrated that the presence of closed pore structure can provide more sodium storage sites in the plateau region, resulting in an obvious increase of sodium storage capacity. Moreover, the pore‐filling and intercalation mechanism for sodium storage in plateau region is revealed by in situ Raman spectroscopy and ex situ transmission electron microscopy (TEM). It is worth noting that the increase in capacity induced by closed pore‐filling is not accompanied by a decrease in initial coulombic efficiency (ICE), due to the fact that the introduction of closed pores does not increase the contact area between electrode and electrolyte. This work presents novel concepts for the structural design of HC and provides valuable insights into the effective utilization of plateau region in SIBs. [ABSTRACT FROM AUTHOR]

Sodium‐ion batteries (SIBs) have rapidly risen to the forefront of energy storage systems as a promising supplementary for Lithium‐ion batteries (LIBs). Na3V2(PO4)2F3 (NVPF) as a common cathode of SIBs, features the merits of high operating voltage, small volume change and favorable specific energy density. However, it suffers from poor cycling stability and rate performance induced by its low intrinsic conductivity. Herein, we propose an ingenious strategy targeting superior SIBs through cross‐linked NVPF with multi‐dimensional nanocarbon frameworks composed of amorphous carbon and carbon nanotubes (NVPF@C@CNTs). This rational design ensures favorable particle size for shortened sodium ion transmission pathway as well as improved electronic transfer network, thus leading to enhanced charge transfer kinetics and superior cycling stability. Benefited from this unique structure, significantly improved electrochemical properties are obtained, including high specific capacity (126.9 mAh g−1 at 1 C, 1 C = 128 mA g−1) and remarkably improved long‐term cycling stability with 93.9% capacity retention after 1000 cycles at 20 C. The energy density of 286.8 Wh kg−1 can be reached for full cells with hard carbon as anode (NVPF@C@CNTs//HC). Additionally, the electrochemical performance of the full cell at high temperature is also investigated (95.3 mAh g−1 after 100 cycles at 1 C at 50 °C). Such nanoscale dual‐carbon networks engineering and thorough discussion of ion diffusion kinetics might make contributions to accelerating the process of phosphate cathodes in SIBs for large‐scale energy storages. [ABSTRACT FROM AUTHOR]

Designing Sb/carbon composite is an effective strategy to enhance the cycle stability and rate capability of Sb anodes for sodium ion batteries. However, the introduction of carbon often leads to a loss in specific capacity and initial Coulombic efficiency (ICE). In this work, a new perspective is adopted by focusing on improving the "sloping capacity" contribution of carbon (C) in Sb/C composites, rather than solely increasing the platform capacity of Sb as traditionally done. Theoretical predictions indicate that constructing Sb/C composites with high Sb and carbon interfacial areas can provide more Na adsorption sites, thus enhancing the "sloping capacity" of amorphous carbon. Guided by DFT, a rational Sb/C/NSCDs‐2(N) is successfully developed by self‐embedding Sb nanodots into 2D‐amorphous carbon sheets doped with N/S. Sb/C/NSCDs‐2(N) exhibits abundant Sb/carbon interfacial areas and excellent nanoscale effects, demonstrating ideal electrochemical sodium storage performances. Impressively, the Sb/C/NSCDs‐2(N) provides a "sloping capacity" close to 160 mAh g−1. Significantly, owing to the fact that these interfaces and defects are not in direct contact with the electrolyte, the side reaction of electrolyte is effectively inhibited, leading to no decrease of ICE. [ABSTRACT FROM AUTHOR]

Further commercialization of Ni‐rich layered cathodes is hindered by severe structure/interface degradation and kinetic hindrance that occur during electrochemical operation, which leads to safety risks and reduced range in electric vehicles (EVs). Herein, by selecting elements with different solubility properties, a multifunctional strategy that synchronously fabricates perovskite‐type SrZrO3 coating and Sr/Zr co‐doping is employed to strengthen the structure/interface stability and the Li+ transport mobility of LiNi0.85Co0.10Mn0.05O2 (NCM). Perovskite‐type SrZrO3 protective layers formed on the particle surface can substantially mitigate the unexpected interfacial side reactions and surface phase transitions. In addition, a robust crystal framework is constructed by optimizing local O coordination through the introduction of strong Zr−O bonds. Notably, Li+ diffusion kinetics is effectively improved due to expanded cell parameters and O‐Li‐O slab spacing with the incorporation of large‐diameter Sr pillar ions, as revealed by X‐ray diffraction. As a result, the Sr/Zr‐modified NCM achieves a remarkable capacity retention of 99.4% after 200 cycles at 1 C, and a high rate capacity of 168.9 mAh g−1 at 10 C. This work opens new avenues to develop high‐performance NCM cathodes with high energy and high power for EVs with long calendar life. [ABSTRACT FROM AUTHOR]

Titanium oxides have been considered promising anode materials for lithium-ion batteries (LIBs). However, the poor conductivity and low specific capacity of bulk titanium oxides limit their application. In this study, a carbon dot-modified TiO2@SiO2 aerogel was successfully fabricated through a facile ambient pressure drying strategy and used as an anode material of LIBs. Benefiting from the crosslinking of carbon dots and the surface modification of SiO2, the as-prepared hierarchical aerogel exhibited a high initial discharge capacity of 974 mAh g−1 and maintained a capacity of 299 mAh g−1 after 100 cycles at 0.1 A g−1. It also retained a discharge capacity of 111 mAh g−1 with a CE of 99.9% at 3 A g−1. The carbon dot-modified cross-linking skeleton contributes to the structural integrity of the TiO2@SiO2 aerogel during repeated insertion/extraction of lithium ions, guaranteeing outstanding cycling and high-rate performance. This ambient pressure drying strategy provides a facile and feasible way to produce high-performance aerogel anode materials for lithium-ion storage.Highlights: Carbon dots-modified TiO2@SiO2 aerogel was fabricated via ambient pressure drying. The hierarchical aerogel shows high initial discharge capacity of 974 mAh g−1. TiO2@SiO2 aerogel exhibits structural integrity and outstanding cycling performance. [ABSTRACT FROM AUTHOR]

Metal‐organic frameworks (MOFs) have been proposed as novel fillers for constructing polymer solid electrolytes based composite electrolytes. However, MOFs are generally used as passive fillers, in‐depth revealing the binding mode between MOFs and polyethylene oxide (PEO), the critical role of MOFs in facilitating Li+ transport in solid electrolytes is full of challenges. Herein, inspired by density functional theory (DFT) the 2D‐MOF with rich unsaturated metal coordination sites that can bind the O atom in PEO through the metal–oxygen bond, anchor TFSI− to release Li+, resulting in a remarkable Li+ transference number of 0.58, is reported according well with the experimental results and molecular dynamics (MD) simulation. Impressively, after the introduction of the 2D‐MOF, the Li+ can rapidly hop along the benzene ring center within the 2D‐MOF plane, and the interface between the benzene ring and PEO can also serve as a fast Li+ migration pathway, delivering multiple ion‐transport channels, which present a high ion conductivity of 4.6 × 10−5 S cm−1 (25 °C). The lithium symmetric battery is stable for 1300 h at 60 °C, 0.1 mA cm−2. The assembled lithium metal solid state battery maintains high capacity of 162.8 mAh g−1 after 500 cycles at 60 °C and 0.5 C. This multiple ion‐transport channels approach brings new ideas for designing advanced solid electrolytes. [ABSTRACT FROM AUTHOR]

Developing electrode materials with high tap density, low cost, and superior performance poses a formidable challenge in electrochemistry. The impressive performance exhibited by most electrodes comes at the expense of tap density and cost, severely limiting their practical applications. Here, combining computational and experimental results, an approach for the electrode materials with high tap density and rich heterostructure (Cu2S/Na2Sn) from cheap copper smelting slag enabled by an electrochemical process is proposed, reducing the diffusion energy barrier from 0.82 to 0.28 eV for Na+, as well as delivering an impressively high tap density of 3.32 g cm−3. Furthermore, the electrochemical activation process that irreversibly generates more stable Cu2S and Na2Sn after the first charge progress of parent materials is also revealed by in/ex situ analytical techniques. As expected, assembled sodium ion capacitors (SICs) achieve high energy density (74.4 Wh kg−1) at high power density (20 000 W kg−1) with outstanding capacity retention of 81.5% after 10 000 cycles, delivering over 76% of its energy density in 13.4 s, which surpasses the performance achieved by state‐of‐the‐art SICs. This work not only provides novel insights into irreversibly conversion‐type anodes but also introduces a method for efficient value‐added utilization of smelting slag. [ABSTRACT FROM AUTHOR]

Sodium layered oxides feature in high capacity and diverse composition, however, are plagued by various issues including limited kinetics and interfacial instability with residual alkali. Conventional substitution/doping and heterogeneous coating are promising to tackle the problems of bulk and surface, respectively, but normally insufficient to address both. Herein, a post‐substitution strategy is proposed to modify primary sodium‐layered‐oxide particles that can simultaneously deal with bulk and surficial issues. As a typical example, post Ti‐substitution for O3‐NaNi1/3Fe1/3Mn1/3O2 is successfully performed by adjusting thermodynamic driving force, resulting in depth‐controllable Ti infusion from surface to bulk, as proved by energy dispersive spectroscopy maps collected at the cross‐section. Residual alkali species are efficiently diminished and benefited from the surface‐to‐bulk osmotic reaction, significantly improving Coulombic efficiency. Moreover, remarkable enhancements in reversible capacity (135 mAh g−1 at C/10), rate capability (74% retention at 5 C), and long‐term cycling stability (80% retention after 300 cycles at 2 C) are achieved by manipulating gradient‐like Ti distribution in a primary particle that brings with increased kinetics and strengthened interfacial stability, surpassing those given by rough heterotic coating and homogeneous Ti‐substitution. Such post‐substitution is expected to provide a universal strategy to modify primary layered‐oxide particles for developing advanced cathode materials of SIBs. [ABSTRACT FROM AUTHOR]

Hybrid supercapacitors (HSCs) comprising a battery‐type cathode and capacitive anode have recently become a research hotspot. Nevertheless, the low capacity utilization, poor kinetic behavior, and unstable structure of a single battery‐type oxide cathode restrict the overall performance of the device. Herein, the carbon quantum dots (CQDs) modified NiO/Co3O4 heterostructured flower‐like microspheres are constructed, and enhanced specific capacity, rate capability, and cycling performance are achieved when used as the cathode for HSCs. This is attributed to the fact that the modification of bifunctional CQDs as size regulators and conductive agents and the construction of heterostructure can not only improve the specific surface area and provide more electroactive sites, thereby enhancing the charge storage performance but also regulate the electronic structure and boost the interface charge transfer capability and electronic conductivity, thereby boosting the reaction kinetics and cycle stability. The enhanced electrochemical kinetic behavior is revealed by electrochemical kinetic analyses based on cyclic voltammetry, electrochemical impedance spectroscopy tests and density functional theory calculations. Meanwhile, the electrochemical reaction process and energy storage mechanism are illustrated by ex‐situ X‐ray diffraction and X‐ray photoelectron spectroscopy characterizations. Furthermore, an HSC is further constructed using the CQDs/NiO/Co3O4 heterostructured flower‐like microspheres as the cathode, simultaneously achieving high energy density (40.9 Wh kg−1), high power density (24 kW kg−1), and splendid cyclic stability (94.2% capacity retention after 5000 cycles at 10 A g−1). These synergistic modification strategies of bifunctional CQDs modification and heterostructure design provide a valuable direction for the design and development of HSCs with both high energy density and high power density. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) have been widely adopted in various fields (catalysis, sensor, energy storage, etc.) during the last decade owing to the trait of abundant surface chemistry, porous structure, easy‐to‐adjust pore size, and diverse functional groups. However, the limited active sites and the poor conductivity hinder the relative practical application. 2D MOFs can shorten the ion transport path with the merit of layered structure. The large surface area can increase the number of active sites as well as effectively utilize the sufficient active sites, exhibiting enormous potential in the field of energy storage systems (EESs). In this review, the characteristics of the 2D MOFs have been introduced, and the systematic synthesis methods (top‐down and bottom‐up) of 2D MOFs are presented, providing fundamental understanding for the construction of 2D MOFs. Moreover, the applications of 2D MOFs in energy storage fields such as supercapacitors and batteries are demonstrated in detail. Finally, the future development prospects have been proposed, offering guidelines for the rational utilization of 2D MOFs and promoting the understanding of 2D MOFs in EESs. [ABSTRACT FROM AUTHOR]

O3-type NaNi1/3Fe1/3Mn1/3O2 (NFM) is one of the most representative cathode materials with low cost and high capacity advantages. However, the sluggish diffusion kinetics and severe cathode–electrolyte interfacial reaction are serious roadblocks to commercialization. Hereby, a novel method of in situ V-modification is well-designed to play dual roles in reconstructing the crystal lattice and interface structure. Notably, the broadened layer spacing of O–Na–O and shortened TM–O bond are attributed to successful doping of V5+ into the bulk, accelerating the transmission of sodium ions and improving the structure stability. Concomitantly, the construction of a thin surface coating layer is beneficial for mitigating volume expansion and inhibiting structural degradation, which is validated by in situ X-ray diffraction coupled with the synchrotron X-ray absorption spectroscopy. Consequently, the rationally designed V-modified NFM cathode exhibits excellent cycling performances, exhibiting great capacity retention of 75.8% after 500 cycles at 2C in a half cell, and 85.6% capacity retention is observed after 150 cycles at 1C in the full cell. This work provides new insights into the development of O3-type layered oxide cathodes toward long-cycle life applications for large-scale energy storage systems. [ABSTRACT FROM AUTHOR]

High‐voltage aqueous rechargeable energy storage devices with safety and high specific energy are hopeful candidates for the future energy storage system. However, the electrochemical stability window of aqueous electrolytes is a great challenge. Herein, inspired by density functional theory (DFT), polyethylene glycol (PEG) can interact strongly with water molecules, effectively reconstructing the hydrogen bond network. In addition, N, N‐dimethylformamide (DMF) can coordinate with Zn2+, assisting in the rapid desolvation of Zn2+ and stable plating/stripping process. Remarkably, by introducing PEG400 and DMF as co‐solvents into the electrolyte, a wide electrochemical window of 4.27 V can be achieved. The shift in spectra indicate the transformation in the number and strength of hydrogen bonds, verifying the reconstruction of hydrogen bond network, which can largely inhibit the activity of water molecule, according well with the molecular dynamics simulations (MD) and online electrochemical mass spectroscopy (OEMS). Based on this electrolyte, symmetric Zn cells survived up to 5000 h at 1 mA cm−2, and high voltage aqueous zinc ion supercapacitors assembled with Zn anode and activated carbon cathode achieved 800 cycles at 0.1 A g−1. This work provides a feasible approach for constructing high‐voltage alkali metal ion supercapacitors through reconstruction strategy of hydrogen bond network. [ABSTRACT FROM AUTHOR]

High‐voltage aqueous rechargeable energy storage devices with safety and high specific energy are hopeful candidates for the future energy storage system. However, the electrochemical stability window of aqueous electrolytes is a great challenge. Herein, inspired by density functional theory (DFT), polyethylene glycol (PEG) can interact strongly with water molecules, effectively reconstructing the hydrogen bond network. In addition, N, N‐dimethylformamide (DMF) can coordinate with Zn2+, assisting in the rapid desolvation of Zn2+ and stable plating/stripping process. Remarkably, by introducing PEG400 and DMF as co‐solvents into the electrolyte, a wide electrochemical window of 4.27 V can be achieved. The shift in spectra indicate the transformation in the number and strength of hydrogen bonds, verifying the reconstruction of hydrogen bond network, which can largely inhibit the activity of water molecule, according well with the molecular dynamics simulations (MD) and online electrochemical mass spectroscopy (OEMS). Based on this electrolyte, symmetric Zn cells survived up to 5000 h at 1 mA cm−2, and high voltage aqueous zinc ion supercapacitors assembled with Zn anode and activated carbon cathode achieved 800 cycles at 0.1 A g−1. This work provides a feasible approach for constructing high‐voltage alkali metal ion supercapacitors through reconstruction strategy of hydrogen bond network. [ABSTRACT FROM AUTHOR]

The difficulty in matching cathode and anode kinetics due to slow ion transport in anodes constrains the development of lithium‐ion capacitors. Heterogeneous structures with built‐in electric field can promote lithium‐ion migration and improve the anode reaction kinetics. However, the valence evolution of metal elements in heterostructures during charging/discharging processes is often overlooked. Inspired by theoretical calculations, transition metal selenides heterostructures (FeSe2/CoSe2) with low migration energy barriers (Eb = 0.35 eV) are successfully engineered and fabricated. As expected, the designed heterostructure material exhibits outstanding rate performance (512 mAh g−1 at 30 A g−1) and ultra‐high pseudocapacitance contribution (98.02% at 1.0 mV s−1), exceeding the state‐of‐the‐art values for anodes. Impressively, synchrotron X‐ray absorption spectroscopy (SXAS) and ex situ XPS find that the valence states of the Fe and Co elements in the heterogeneous structure gradually increase as charging and discharging proceeds, inducing a continuous climb in reversible specific capacity, while further reducing the migration energy barrier in the heterogeneous structure (Eb = 0.20 eV). This work reveals that the valence states of iron and cobalt elements increase as charging and discharging proceeds, providing theoretical guidance for improving the anode kinetics and revealing the capacity rise mechanism of other transition metal compounds. [ABSTRACT FROM AUTHOR]

The TiO2 anode for sodium-ion batteries (SIBs) is currently drawing increased attention owing to its stable cycling performance. However, the storage performance is still extremely inadequate, especially for its low initial coulombic efficiency (ICE). In order to further improve the ICE, a good match of the electrolyte and binder is crucial, due to the fact that a solid electrolyte interface (SEI) is irreversibly formed on the surface, which will be very important for its reversible capacity. As an attempt, TiO2 nanocrystallites are prepared by an electrochemical method. When applied as the anode for SIBs, the TiO2 electrode with the sodium carboxymethylcellulose binder and ether-based electrolyte presents an impressive capacity of 166.23 mA h g−1 at 2C after 4800 cycles, much higher than that with the polyvinylidene fluoride binder and carbonate-based electrolyte. A series of characterization studies reveal that the charge transfer at the interface between the electrolyte and electrode and the SEI film are the key factors determining the electrochemical properties. Importantly, the dual optimization of the binder and electrolyte is revealed to be an effective means to enhance the ICE of TiO2 up to 81.6%, thus greatly contributing to better guidance on the design of TiO2 anodes with ultra-high ICE for SIBs. [ABSTRACT FROM AUTHOR]

Relaxor ferroelectric polymer P(VDF-TrFE-CTFE) is attracting increasing attention for electronic applications due to its high dielectric constant and relaxation characteristic. However, the low breakdown strength and premature saturation of polarization of this polymer have hampered its practical application severely. In this work, carbon quantum dots (CQDs) with functional groups and size of about 5 nm have been incorporated to overcome these issues. The nanocomposite with 0.1 wt% CQDs presents significantly improved breakdown strength and discharge energy density. Its breakdown strength (Eb) has been increased by 30.7% up to 340 kV mm−1. Due to the Coulomb blockade effect, the electrons can be restrained in the deep traps, which is favorable for the improvement of breakdown strength. Besides, the abundant functional groups around CQDs are beneficial to form adequate hydrogen bonds, resulting in increased crystallinity and breakdown strength as well. Additionally, the discharge energy density has been improved by 41.7% up to 6.8 J cm−3. The study demonstrates the effective enhancement of breakdown strength and energy density by ultralow loading of CQDs for P(VDF-TrFE-CTFE) polymer. [ABSTRACT FROM AUTHOR]

Aqueous zinc anode has been re‐evaluated due to the superiority in tackling safety and cost concerns. However, the limited lifespan originating from Zn dendritic and side reactions largely hamper commercial development. Currently, the coating prepared by simple slurry mixing is leaky and ineffectively isolate sulfate and water. Herein, inspired by the DFT calculations and the easy hydrolysis characteristic of MIL‐125 (Ti), an in‐situ grown high‐dense TiO2‐x solid electrolyte interphase (HDSEI) with rich oxygen vacancies is successfully constructed in an aqueous electrolyte, in which the oxygen vacancies not only strengthen the hydrogen binding force thereby inhibiting the hydrogen precipitation by‐reaction, but also reduce the migration energy barrier of zinc ions and enhance the mechanical properties. Profiting from the HDSEI, symmetric Zn cells survive up to remarkable 4200 h at 1 mA cm−2, nearly 42‐times than that of bare Zn anodes. In situ optical microscopy clearly reveals that the in situ grown HDSEI homogenizes the zinc deposition process, while bare zinc without HDSEI shows significant dendrites, confirming the protective nature of HDSEI. Furthermore, full Zn ion capacitors can deliver excellent electrochemical performance, providing a feasible in situ approach to construct HDSEI to implement dendrite‐free metal anodes. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The severe dendrite growth on zinc anode in alkaline electrolyte brings great challenge to the development of zinc‐based batteries. It is a simple and effective strategy to inhibit zinc dendrite formation by introducing additives into the electrolyte. In this study, N, S‐doped carbon dots (TU‐CQDs) were synthesized and used as additives to regulate zinc deposition in a typical KOH electrolyte. The experimental and three‐dimensional transient nucleation model disclosed that the special functional groups of carbon dots can change the electrode surface state and the coordination behaviors of zinc species in the electrolyte. Therefore, TU‐CQDs can not only inhibit the hydrogen evolution reaction, but also achieve uniform zinc deposition. The in‐situ synchrotron radiation X‐ray imaging elucidated that TU‐CQDs can effectively inhibit the dendrite growth and improve the reversibility of zinc plating/stripping process. This work provides a feasible route for regulating the reversibility of zinc metal anode in alkaline electrolyte. [ABSTRACT FROM AUTHOR]

Aqueous Zn‐ion energy‐storage deviceswith metal Zn as anodes, including batteries and capacitors (ZIBs and ZICs), is largely hindered by dendritic growth and low coulombic efficiency since the side reactions between Zn anodes and electrolyte, originating fromthat targeted and efficient isolation of H2O and SO42− is extremely challenging. Herein, inspired by density functional theory (DFT) that the 2D angstrom level metal‐organic framework(2D‐MOF) is highly selective for the passage of ions, simultaneously excluding the SO42− and H2O but allowing Zn2+ selective conduction. Moreover, 2D‐MOF exhibits better mechanical strength compared with 3D‐MOF, which is more conducive to inhibit dendrite growth. Impressively, benefiting from the 2D‐MOFlayer, symmetric Zn cells survived up to 2000 h at 4 mA cm−2,near 20‐times that of bare Zn anodes. Coupling it with cathode for ZICs and ZIBs, excellent electrochemical performances are presented. Importantly, symmetric Na cells with 2D‐MOF as ionic sieve membrane also deliver small polarization and outstanding performance, indicating that this study provides an efficient strategy to develop long‐life metal anode. [ABSTRACT FROM AUTHOR]

Although lithium-sulfur (Li-S) batteries with high specific energy exhibit great potential for next-generation energy-storage systems, their practical applications are limited by the growth of Li dendrites and lithium polysulfides (LiPSs) shuttling. Herein, a highly porous red phosphorus sponge (HPPS) with well distributed pore structure was efficiently prepared via a facile and large-scale hydrothermal process for polysulfides adsorption and dendrite suppression. As experimental demonstrated, the porous red phosphorus modified separator with increased active site greatly promotes the chemisorption of LiPSs to efficiently immobilize the active sulfur within the cathode section, while Li metal anode activated by Li3P interlayer with abundant ionically conductive channels significantly eliminates the barrier for uniform Li+ permeation across the interlayer, contributing to the enhanced stability for both S cathode and Li anode. Mediated by the HPPS, long-term stability of 1,200 h with minor voltage hysteresis is achieved in symmetric cells with Li3P@Li electrode while Li-S half-cell based on HPPS modified separator delivers an outperformed reversibility of 783.0 mAh·g−1 after 300 cycles as well as high-rate performance of 694.5 mAh·g−1 at 3 C, which further boosts the HPPS tuned full cells in practical S loading (3 mg·cm−2) and thin Li3P@Li electrode (100 µm) with a capacity retention of 71.8% after 200 cycles at 0.5 C. This work provides a cost-effective and metal free mediator for simultaneously alleviating the fundamental issues of both S cathode and Li anode towards high energy density and long cycle life Li-S full batteries. [ABSTRACT FROM AUTHOR]

Fe‐Mn based layered oxides are recognized as promising cathode materials for sodium‐ion batteries (SIBs) with high capacities and earth‐abundant ingredients. However, their real‐world applications are still constrained by fast capacity decay accompanied with the requirements of deeper insights into the principles behind. Herein, taking O3‐NaxFe1/2Mn1/2O2 as a classic sample, the capacity fading mechanism of Fe‐Mn based layered oxides is comprehensively investigated through combined techniques. For the first time, it is revealed that Fe migration is merely triggered after the oxidation of ≈0.3 mol Fe3+ based on solid proofs from ex situ X‐ray absorption spectroscopy and Mössbauer spectroscopy, which implies the crucial role of the accumulated structural distortion induced by Jahn–Teller active Fe4+. O3‐P3 phase transition during cycling is obviously constrained along with Fe migration as evidenced by in situ/ex situ X‐ray diffraction, well interpreting the intensified polarization and the resulting large capacity loss. More importantly, within the desodiation depth (≈80% of sodium extraction) where Fe migration is almost absent, the capacity fading is dominantly rooted in the Fe4+ activated and Mn‐dissolution aggravated surface passivation as confirmed by mass/X‐ray spectroscopies and electrochemical analysis. These renewed understandings of the fast capacity decay in Fe‐Mn based layered oxides offer clearer clues for designing desirable cathodes for SIBs. [ABSTRACT FROM AUTHOR]

The extensive applications of spinel LiMn2O4 (LMO) are severely plagued by grievous capacity degradation and structural collapse, mainly ascribed to deleterious Jahn−Teller distortion and subsequent dissolution of Mn2+. Herein, highly stable LMO with atomic interlocking effect is rationally designed via engineering Al into the unoccupied 16c sites. The local coordination environment of the surficial MnO6 octahedron is reconstructed by robust Al−O band coherency, giving strengthened lattice oxygen skeleton and constraining heterophase evolution with the suppression of Jahn−Teller distortion, validated by theoretical calculations coupled with synchrotron X‐ray absorption spectrum. Concomitantly, with the occupation of Al in interstitial site, the migration of Mn is effectively restrained, directly observed by scanning transmission electron microscopy, leading to the inhibition of inactivation as well as dissolution loss of Mn. Resultantly, splendid long cycling stability of Al‐LMO after 1000 loops with only 0.019% capacity fading per cycle is presented. Given this, this elaborate study can provide an ingenious avenue for regulating the structure/interface chemistry architecture in electrode materials. [ABSTRACT FROM AUTHOR]

Highlights: Oxygen-respirable sponge was constructed by carbon dots-assisted synthesis strategy. The hydrophilicity and aerophilicity of Co@C–O–Cs active sites boost oxygen diffusion and the bifunctional oxygen reduction reaction and oxygen evolution reaction activities. Co@C–O–Cs-based Zn-air battery (ZAB) displays excellent specific capacity and stability, and the all-solid-state Co@C–O–Cs-based ZAB exhibits excellent flexibility. Efficient bifunctional catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are vital for rechargeable Zn-air batteries (ZABs). Herein, an oxygen-respirable sponge-like Co@C–O–Cs catalyst with oxygen-rich active sites was designed and constructed for both ORR and OER by a facile carbon dot-assisted strategy. The aerophilic triphase interface of Co@C–O–Cs cathode efficiently boosts oxygen diffusion and transfer. The theoretical calculations and experimental studies revealed that the Co–C–COC active sites can redistribute the local charge density and lower the reaction energy barrier. The Co@C–O–Cs catalyst displays superior bifunctional catalytic activities with a half-wave potential of 0.82 V for ORR and an ultralow overpotential of 294 mV at 10 mA cm−2 for OER. Moreover, it can drive the liquid ZABs with high peak power density (106.4 mW cm−2), specific capacity (720.7 mAh g−1), outstanding long-term cycle stability (over 750 cycles at 10 mA cm−2), and exhibits excellent feasibility in flexible all-solid-state ZABs. These findings provide new insights into the rational design of efficient bifunctional oxygen catalysts in rechargeable metal-air batteries. [ABSTRACT FROM AUTHOR]