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A spatially efficient “tube-in-tube” carbonaceous host decorated with defective metallic nitride nanoparticles (Fe2N1−x-NCT) is constructed to alleviate the insufficient sulfur utilization and inferior cycling issues of lithium sulfur batteries.

The rational design of economic and high-performance electrocatalytic water-splitting systems is of great significance for energy and environmental sustainability. Developing a sustainable energy conversion-assisted electrocatalytic process provides a promising novel approach to effectively boost its performance. Herein, a self-sustained water-splitting system originated from the heterostructure of perovskite oxide with 2D Ti₃C₂Tₓ MXene on Ni foam (La₁-ₓSrₓCoO₃/Ti₃C₂Tₓ MXene/Ni) that shows high activity for solar-powered water evaporation and simultaneous electrocatalytic water splitting is presented. The all-in-one interfacial electrocatalyst exhibits highly improved oxygen evolution reaction (OER) performance with a low overpotential of 279 mV at 10 mA cm⁻² and a small Tafel slope of 74.3 mV dec⁻¹, superior to previously reported perovskite oxide-based electrocatalysts. Density functional theory calculations reveal that the integration of La₀.₉Sr₀.₁CoO₃ with Ti₃C₂Tₓ MXene can lower the energy barrier for the electron transfer and decrease the OER overpotential, while COMSOL simulations unveil that interfacial solar evaporation could induce OH⁻ enrichment near the catalyst surfaces and enhance the convection flow above the catalysts to remove the generated gas, remarkably accelerating the kinetics of electrocatalytic water splitting. Refereed/Peer-reviewed

Lithium–sulfur (Li–S) batteries have attracted much attention attributed to their high theoretical energy density, whereas the parasitic shuttling behavior of lithium polysulfides (LiPS) hinders th...

The in situ growth of active materials on 3D current collectors (such as Ni foams) presents facile and efficient access to high-performance supercapacitors. However, the low surface area of current collectors limits the mass loading, microstructure, and capacitive performance of active materials thereon. Herein, we develop a novel surface modification with hierarchical N-rich carbon nanosheets on Ni foams via a simple sol-gel method. At the same time, its favorable effects on mass loading and utilization are demonstrated using NiCoMn-carbonate hydroxide (NCM) as a model active material. Specifically, the carbon modification greatly boosts the current collector's specific surface area and enables the growth of dense NCM nanoneedles with controllable mass loading ranging from 5.2 to 23.1 mg cm-2. Meanwhile, the correlation between mass loading and utilization is systematically studied, which shows the well-maintained energy storage efficiency due to the conducive surface modification. As a result, excellent performance with the ultrahigh area-specific capacity of 19.36 F cm-2 at 2 mA cm-2 in the three-electrode configuration and remarkable area-specific energy density of 1352 μW h cm-2 in the solid-state asymmetric device can be achieved, demonstrating a prospective pathway toward facile and effective current collector designs for high-energy/power-density supercapacitors.

The notorious shuttle effect has long been obstructing lithium-sulfur (Li-S) batteries from yielding the expected high energy density and long lifespan. Herein, we develop a multifunctional polysulfide barrier reinforced by the graphitic carbon nitride/carbon nanotube (g-C3N4/CNT) composite toward inhibited shuttling behavior and improved battery performance. The obtained g-C3N4 delivers a unique sponge-like architecture with massive ion transfer pathways and fully exposed active interfaces, while the abundant C-N heteroatomic structures impose strong chemical immobilization toward lithium polysulfides. Combined with the highly conductive agent, the g-C3N4/CNT reinforced separator is endowed with great capability of confining and reutilizing the active sulfur within the cathode, thus contributing to an efficient and stable sulfur electrochemistry. Benefiting from these synergistic attributes, Li-S cells based on g-C3N4/CNT separator exhibit an excellent cyclability with a minimum decay rate of 0.03% per cycle over 500 cycles and decent rate capability up to 2 C. Moreover, a high areal capacity of 7.69 mAh cm−2 can be achieved under a raised sulfur loading up to 10.1 mg cm−2, demonstrating a facile and efficient pathway toward superior Li-S batteries.

Advanced host materials are requisite for both cathode and anode in the development of high-performance lithium–sulfur (Li–S) batteries. Herein, for the first time, we report a unique niobium oxide matrix with amorphous/crystalline hetero-conjunctions (A/T-Nb2O5) as a two-in-one host in a Li–S system. The heterostructure is constructed by simply regulating the calcination temperature at a modest level to generate partially-crystalized Nb2O5, rather than completely crystalline or amorphous. As the cathode matrix, the heterostructured design is unveiled, combining the preferably high sulfur affinity and fast ion transfer from the amorphous and crystalline phase, respectively, thus rendering a simultaneous stabilization and catalyzation for sulfur electrochemistry with excellent cyclability over 800 cycles and rate capability up to 3C. On the other hand, the as-developed A/T-Nb2O5 is found capable of facilitating the Li redox kinetics and uniformizing the Li nucleation/growth behaviors when applied as the anode matrix, contributing to durable Li plating/stripping at varied capacity limit up to 10 mA h cm−2. Collectively, these advantageous features are integrated into a S–A/T-Nb2O5|Li–A/T-Nb2O5 full-cell configuration, which realizes decent areal capacity, cyclability, and rate capability under a high sulfur loading of 5 mg cm−2, demonstrating an instructive paradigm for rational material engineering in Li–S batteries.

Stable solid electrolyte interface (SEI) is highly sought after for lithium metal batteries (LMB) owing to its efficient electrolyte consumption suppression and Li dendrite growth inhibition. However, current design strategies can hardly endow a multifunctional SEI formation due to the non-uniform, low flexible film formation and limited capability to alter Li nucleation/growth orientation, which results in unconstrained dendrite growth and short cycling stability. Herein, we present a novel strategy to employ electrolyte additives containing catechol and acrylic groups to construct a stable multifunctional SEI by in-situ anionic polymerization. This self-smoothing and robust SEI offers multiple sites for Li adsorption and steric repulsion to constrain nucleation/growth process, leading to homogenized Li nanosphere formation. This isotropic nanosphere offers non-preferred Li growth orientation, rendering uniform Li deposition to achieve a dendrite-free anode. Attributed to these superiorities, a remarkable cycling performance can be obtained, i.e., high current density up to 10 mA cm−2, ultra-long cycle life over 8500 hrs operation, high cumulative capacity over 4.25 Ah cm−2 and stable cycling under 60 °C. A prolonged lifespan can also be achieved in Li-S and Li-LiFePO4 cells under lean electrolyte content, low N/P ratio or high temperature conditions. This facile strategy also promotes the practical application of LMB and enlightens the SEI design in related fields., Stable solid electrolyte interface (SEI) is heavily investigated due to its role in improving lithium metal batteries. Here, the authors present a new strategy by employing electrolyte additives to construct stable multifunctional SEI via in situ anionic polymerization.

Summary Polysulfide retention and catalysis are currently among the most important factors toward solving much of the technical challenges of lithium-sulfur (Li-S) batteries. Taking advantage of the electronic structure specific to tantalum, we explore the application of amorphous tantalum oxide with oxygen vacancies embedded inside a microporous carbon matrix as an electrocatalyst for the Li-S system. Through a pore-constriction mechanism, the dimensions of tantalum oxide are controlled to be nanosized with abundant polysulfide-retaining and catalytically active sites. High cycle and rate performances were achieved at practically relevant sulfur loadings and electrolyte content. We believe our identification of tantalum as a new catalyst material for Li-S batteries will incite more investigation into the specific selection of transition metals based on their electronic structures. Meanwhile, the “ship in a bottle” strategy will enlighten the structure design for energy conversion and storage systems.

Lithium–sulfur (Li–S) battery is a potential energy storage technology with high energy density and low cost. However, the gap between theoretical expectation and practical performance limits its wide implementation. Herein, we report a nitrogen-doped porous carbon derived from biomass pomelo peel as sulfur host material for Li–S batteries. The hierarchical porous architecture and the polar surface introduced by N-doping render a favorable combination of physical and chemical sulfur confinements as well as an expedite electron/ion transfer, thus contributing to a facilitated and stabilized sulfur electrochemistry. As a result, the corresponding sulfur composite electrodes exhibit an ultrahigh initial capacity of 1534.6 mAh g−1, high coulombic efficiency over 98% upon 300 cycles, and decent rate capability up to 2 C. This work provides an economical and effective strategy for the fabrication of advanced carbonaceous sulfur host material as well as the significant improvement of Li–S battery performance.

The construction of robust (quasi)-solid-state electrolyte (SSE) for flexible lithium-metal batteries is desirable but extremely challenging. Herein, a novel, flexible, and robust quasi-solid-state electrolyte (QSSE) with a "tree-trunk" design is reported for ultralong-life lithium-metal batteries (LMBs). An in-situ-grown metal-organic framework (MOF) layer covers the cellulose-based framework to form hierarchical ion-channels, enabling rapid ionic transfer kinetics and excellent durability. A conductivity of 1.36 × 10

Lithium-sulfur (Li-S) batteries have attracted much attention attributed to their high theoretical energy density, whereas the parasitic shuttling behavior of lithium polysulfides (LiPS) hinders this technology from yielding practically competitive performance. Targeting this critical challenge, we develop an advanced polysulfide barrier by modifying the conventional separator with CNTs-interspersed V

The notorious shuttling behaviors and sluggish conversion kinetics of the intermediate lithium polysulfides (LPS) are hindering the practical application of lithium sulfur (Li-S) batteries. Herein, an ultrafine, amorphous, and oxygen-deficient niobium pentoxide nanocluster embedded in microporous carbon nanospheres (A-Nb2O5-x@MCS) was developed as a multifunctional sulfur immobilizer and promoter toward superior shuttle inhibition and conversion catalyzation of LPS. The A-Nb2O5-x nanocluster implanted framework uniformizes sulfur distribution, exposes vast active interfaces, and offers a reduced ion/electron transportation pathway for expedited redox reaction. Moreover, the low crystallinity feature of A-Nb2O5-x manipulates the LPS chemical affinity, while the defect chemistry enhances the intrinsic conductivity and catalytic activity for rapid electrochemical conversions. Attributed to these superiorities, A-Nb2O5-x@MCS delivers good Li-S battery performances, that is, high areal capacity of 6.62 mAh cm-2 under high sulfur loading and low electrolyte/sulfur ratio, superb rate capability, and cyclability over 1200 cycles with an ultralow capacity fading rate of 0.024% per cycle. This work provides a synergistic regulation on crystallinity and oxygen deficiency toward rapid and durable sulfur electrochemistry, holding a great promise in developing practically viable Li-S batteries and enlightening material engineering in related energy storage and conversion areas.

Rational regulation on polysulfide behaviors is of great significance in pursuit of reliable solution-based lithium-sulfur (Li-S) battery chemistry. Herein, we develop a unique polymeric zwitterion (PZI) to establish a smart polysulfide regulation in Li-S batteries. The zwitterionic nature of PZI integrates sulfophilicity and lithiophilicity in the matrix, fostering an ionic environment for selective ion transfer through the chemical interactions with lithium polysulfides (LiPS). When implemented as a functional interlayer in the cell configuration, PZI empowers strong obstruction against polysulfide permeation but simultaneously allows fast Li+ conduction, thus contributing to significant shuttle inhibition as well as the resultant facile and stable sulfur electrochemistry. The PZI-based cells realize excellent cyclability over 1000 cycles with a minimum capacity fading rate of 0.012% per cycle and favorable rate capability up to 5 C. Moreover, a high areal capacity retention of 5.3 mAh cm-2 after 300 cycles can be also obtained under raised sulfur loading and limited electrolyte, demonstrating great promise in developing high-efficiency and long-lasting Li-S batteries.

A unique zinc–hexamethylenetetramine coordination complex (ZnHMT) has been developed through a facile and fast solution-based method. The ZnHMT complex delivers an exquisite flower-like nanoarchitecture assembled by ultrathin nanosheets, which not only facilitates the electrolyte infiltration and ion transfer, but also implements efficient exposure of active interfaces. Meanwhile, the strong chemical interactions between ZnHMT and polysulfides render potent sulfur immobilizations, contributing to effective inhibition of the shuttling behavior. As a result, Li–S cells with a ZnHMT-based interlayer achieve excellent cyclability over 1000 cycles, superb rate capability up to 5C and a high areal capacity of 5.9 mA h cm−2 under raised sulfur loading.

It is essential to stabilize the surface of P2 layered cathode materials at high cut-off voltages (>4.3 V) in order to construct high-energy sodium ion batteries (SIB) that are promising for commercial application. When the voltage exceeds 4.3 V, large volume changes due to phase transitions and active species dissolution affect the structural stability of high voltage cathodes. In this study, we report a novel method of enhancing the electrochemical cycling performance of P2-type Na2/3(Mn0.54Ni0.13Co0.13)O2 (NNMC) materials through ion-conductive polyimide (PI) encapsulation. The electrochemical performance of ultrathin PI coated NNMC (PI-NNMC) is one of the best reported in the literature among layered cathodes in terms of cyclic stability (82% after 100 cycles at 0.16 A g−1) at a high voltage range between 2 and 4.5 V, compared to the pristine (46%) and Al2O3-coated NNMC (70%). At high current (5C), the NNMC-PI electrode demonstrates superior cyclability by retaining 70% of its capacity after 500 cycles. The ultrathin PI layer possesses excellent surface protection, high ionic conductivity (vs Al2O3 coating) and facile ion transport, thus enabling a fast and durable redox electrochemistry in NNMC materials for high-performance sodium storage above 4.3 V.

As numerous efforts have been devoted to the construction of nano-structured sulfur electrodes, the rational design of multi-functional separator is attracting an increasing research enthusiasm recently as another promising approach towards high-performance lithium-sulfur (Li-S) batteries. Herein, red phosphorus nanoparticles are employed, for the first time, to establish a metal-free and cost-effective multifunctional separator, which not only efficiently immobilizes the lithium polysulfides but also facilitates the ion conduction for fast and durable sulfur redox reactions. The computational and experimental results reveal that red phosphorus is capable of chemically confining the polysulfides through a combination of the Lewis acid-base interaction and sulfur-chain catenation, while the highly conductive Li3PO4 is generated during the cell operation and facilitates ion transportation. Attributed to these unique features, the cells based on the as-developed separator exhibit a high sulfur utilization of 1287 mAh g−1 at 0.1 C, superb rate capability of 809 mAh g−1 at up to 2 C, and excellent cycling performance with 82% capacity retention after 500 cycles at 1 C. This facile and low-cost strategy not only offers an effective pathway towards enhancement in battery performance, but could also inspire new thinking on developing metal-free functional agents for improved sulfur electrochemistry.

In article number 2003400, Zhongwei Chen, Yongguang Zhang, and co‐workers report a bimetallic NiCo‐layered double hydroxide (NiCo‐LDH) with a unique hierarchical micro‐nano architecture as an excellent lithium polysulfide adsorbent to immobilize the sulfur species, as well as an efficient catalyst to promote the sulfur conversion reaction kinetics. This work offers a deepened understanding on LDH‐based sulfur electrochemistry. [Image: see text]

Rational construction of sulfur electrodes is essential in pursuit of practically viable lithium–sulfur (Li–S) batteries. Herein, bimetallic NiCo‐layered double hydroxide (NiCo‐LDH) with a unique hierarchical micro‐nano architecture is developed as an advanced sulfur reservoir for Li–S batteries. Compared with the monometallic Co‐layered double hydroxide (Co‐LDH) counterpart, the bimetallic configuration realizes much enriched, miniaturized, and vertically aligned LDH nanosheets assembled in hollow polyhedral nanoarchitecture, which geometrically benefits the interface exposure for host–guest interactions. Beyond that, the introduction of secondary metal intensifies the chemical interactions between layered double hydroxide (LDH) and sulfur species, which implements strong sulfur immobilization and catalyzation for rapid and durable sulfur electrochemistry. Furthermore, the favorable NiCo‐LDH is architecturally upgraded into closely packed micro‐nano clusters with facilitated long‐range electron/ion conduction and robust structural integrity. Due to these attributes, the corresponding Li–S cells realize excellent cyclability over 800 cycles with a minimum capacity fading of 0.04% per cycle and good rate capability up to 2 C. Moreover, highly reversible areal capacity of 4.3 mAh cm−2 can be achieved under a raised sulfur loading of 5.5 mg cm−2. This work provides not only an effective architectural design but also a deepened understanding on bimetallic LDH sulfur reservoir for high‐performance Li–S batteries., A unique NiCo‐LDH@rGO micro‐nano hierarchical composite is developed as a synergistic sulfur immobilizer and promoter to realize high‐efficiency lithium–sulfur battery chemistry. The unique architecture of NiCo‐LDH@rGO and its strong chemical interactions with the intermediate polysulfides afford large space for sulfur, enable expedite ion/mass transfer, and effectively restrain and catalyze the conversion of polysulfide.

The development of high-energy-density Li metal batteries are hindered by electrolyte consumption and uneven lithium deposition due to the unstable lithium-electrolyte interface (SEI). In this work, tetraglyme is introduced into ester electrolyte to regulate the Li

Ultramicroporous carbon materials play a critical role in CO2 capture and separation, however facile approaches to design ultramicroporous carbon with controllable amount, ratio and size of pores are still challenging. Herein, a novel strategy to design carbon nanospheres with abundant, uniform, and tunable ultramicroporosity was developed based on an in-situ ionic activation methodology. The adjustable ion-exchange capacity derived from oxidative functionalization was found capable of substantially governing the ionic activation and precisely regulating the ultramicroporosity in the resultant product. An ultrahigh ultramicropore content of 95.5% was achieved for the optimally-designed carbon nanospheres, which demonstrated excellent CO2 capture performances with extremely high capacities of 1.58 mmol g−1 at typical flue gas conditions and 4.30 mmol g−1 at 25 °C and ambient pressure. Beyond that, the CO2 adsorption mechanism in ultramicropore was also investigated through molecular dynamics simulation to guide the pore size optimization. This work provides a novel and facile guideline to engineer carbon materials with abundant and tunable ultramicroporosity towards superior CO2 capture performance, which also delivers great potential in extensive applications such as water purification, catalysis, and energy storage.

Metal-metal batteries such as the 3 V Cu-Al system are highly desirable for large-scale energy storage owing to their low cost and excellent scalability of Cu and Al foils. However, the dissolved Cu cations will crossover from the cathode to the anode leading to poor electrochemical performance. In this work, it is demonstrated that the reversibility of the Cu-Al battery depends strongly on the interaction of the Cu ions with the electrolyte solvent and subsequently the affinity of the solvated Cu ion with the membrane separator. Specifically, a series of common carbonate-based electrolyte solvents are investigated via molecular dynamics and contact angle measurements to understand the interaction between the solvents and a polypropylene (PP) membrane, as well as that between cations and solvent. Among different solvents, fluoroethylene carbonate (FEC) is shown to drastically enhance the coulombic efficiency to 97%, compared to that of 27% with dimethyl carbonate. Remarkable cyclability of a 3 V Cu-Al battery with 3 m LiTFSI FEC and PP membrane up to 1000 cycles is further demonstrated. This finding opens new opportunities for the development of low-cost, high performance Cu-Al systems for stationary applications.

In this work, we put forward a novel cathode host for Li-S batteries by loading titanium nitride (TiN) nanoparticles into the pores of N-doped carbon as a proof-of-concept. The selection of TiN arises from its strong binding ability with polysulfide and its exceptionally high conductivity of 5 × 10 6 S/m. As for N-doped porous carbon, it provides necessary physical adsorption and extra chemical adsorption sites from the N-doping. Besides the above advantages, the most substantial merit endowed to this structure is the pore-loaded TiN design. The carbon pore size confines the TiN precursors to the nanoscale and prevents otherwise subsequent agglomeration of TiN nanoparticles. Moreover, the pore-loaded TiN design, with fully exposed adsorptive surface and highly dispersed adsorptive sites, guards against the blocking of future sulfur infiltration and Li + diffusion. The advantages of the TiN loaded N-doped carbon are finally confirmed by electrochemical evaluations. The capacity is found up to be 1338 mAh/g at a current density of 0.2 C and 690 mAh/g at a current density of 5 C (where 1 C = 1672 mAh/g). For durability evaluations, the capacity is maintained at 700 mAh/g after 800 cycles with a mere decay of 0.04% per cycle. Lastly, the feasibility of a high mass loading with 7 mg/cm 2 is demonstrated.

The advances of lithium–sulfur (Li–S) batteries have long been challenged by the polysulfides shuttling and the intrinsically sluggish sulfur redox kinetics. Herein, Ag-decorated N-doped carbon (Ag-CNx) is prepared through magnesiothermic reduction followed by a “silver mirror” reaction. Attributed to the high conductivity, porous architecture, strong absorbability, and catalytic effect, the as-developed Ag-CNx, as an interlayer material in Li–S configuration, well confines active species within the cathodic side and simultaneously promotes the sulfur conversions bidirectionally to the final S/Li2S product. As a result, fast and durable Li–S electrochemistry can be realized, exhibiting excellent cyclability over 550 cycles, superb rate capability up to 5C, and decent areal capacity of 4.8 mAh cm−2 under raised sulfur loading of 4.1 mg cm−2. This work provides a facile and effective pathway toward multifunctional that combines chemical binding and electrocatalysis, holding great promise in future development of high-performance Li–S batteries.

Selections of metallic cathode materials and modulations of metal–sulfur bonding strength are crucial for sulfur immobilization in development of high-performance lithium–sulfur (Li–S) batteries with low cost. By combining theoretical calculations and experiments, herein we reveal the relationship between intrinsic electronic structure and metal–S bonding strength, which links to energy density and durability of Li–S batteries. Through first-principles calculations, we simulate sulfur clusters (S1, S2, S4, and S8) immobilization on metal (Cu, Ni, and Sn) slab surfaces with and without graphene substrate. For sulfur clusters, the metal–Sx (x = 1, 2, 4, and 8) bonding strength is in the sequence of Ni > Cu > Sn without graphene substrate. Nevertheless, the sequence changes (Ni > Sn > Cu) in the presence of graphene substrate due to different amounts of charge transfer between these metal clusters and graphene. Guided by these theoretical results, metal (Cu, Ni, Sn)/graphene (G) composites are synthesized an...

The rational design of cathode host materials is significant in fulfilling high-efficiency sulfur electrochemistry as well as boosting the energy density of lithium–sulfur (Li–S) batteries. Herein, we develop a stringed “tube on cube” nanohybrid (CPZC) with a ternary hierarchical architecture, which contains a fibrous carbon skeleton, highly porous carbon cube filler, and abundant CNT tentacles as an advanced matrix for sulfur electrodes. The as-developed CPZC delivers excellent conductivity, abundant active interfaces, and strong confinement to polysulfide, and thus is capable of significantly expediting the sulfur redox kinetics and promoting battery durability. The fabricated sulfur electrode achieves a superb rate capability up to 10C, outstanding cyclability over 2000 cycles, and more importantly, excellent performance under high a sulfur loading and sparing electrolyte with a high energy density of 348.8 W h kg−1 and 327.6 W h L−1 at the system level, which reveals its potential in promoting the practical application of Li–S batteries.

A novel class of functional additives for lithium sulfur batteries was studied. In particular, the facile operation of adding LiCoO2 (LCO) to the sulfur cathode achieves a remarkably improved cycling performance i.e. an ultralow capacity degradation of 0.034% per cycle at a 2C rate over 1200 cycles with a LCO addition of only 3 wt%.

The low electronic conductivity of sulfur and the diffusion and shuttle of polysulfide intermediates are the main obstacles of the cathode that restrain the progress of lithium–sulfur (Li–S) batteries. To address the two main predicaments, we explored a dual functional 3D hierarchical filter element structured Mo2C nanosheet based sulfur electrode. The Mo2C based sulfur electrodes fulfill the requirements of conductivity (30 S cm−1) and entrapment of diffusing polysulfide intermediates, and meanwhile possess the advantages of high crystallinity and large specific surface area. As a filter and reservoir for polysulfides, Mo2C nanosheets possess a strong chemical interaction with polysulfides to mitigate the shuttling of polysulfides. The dual functional Mo2C nanosheet based electrode exhibited a high initial discharge capacity of ca. 1200 mA h g−1 and ca. 800 mA h g−1 after 300 cycles at 0.2C. Moreover, the flexibility of the sulfur electrode is explored through an in situ fabrication on carbon cloth in a soft-package configuration.

Lithium-sulfur (Li-S) batteries hold great promise as energy storage systems because of their low cost and high theoretical energy density. Here, we evaluate Li-S batteries at a system level for the current most critical and challenging applications.

Two-dimensional (2D) molybdenum nitride (MoN) nanosheets are promising anode materials for improved lithium-ion batteries. However, the reported synthesis methods of MoN generally rely on high-temperature and complex procedures with low cost efficiency. Herein, we report a facile one-pot synthesis of 2D MoN nanosheets at a low temperature of 400 °C via a solid-state reaction of molybdenum disulfide, sulfur and sodium amide in an autoclave. When employed as the anode material for lithium ion batteries, the as-developed MoN electrode exhibits outstanding cyclability with a high capacity retention of 898 mA h g-1 over 400 cycles at a current rate of 200 mA g-1 as well as a superb rate capability with a capacity of 505 mA h g-1 at a high rate up to 2 A g-1. The excellent lithium storage performance of the MoN electrode is attributed to its advantageously high conductivity and unique 2D nanostructure.

Lithium-ion batteries (LIBs) dominate the current electrical and electronic markets. However, the energy density that approaches the theoretical limit for conventional LIBs struggles to meet the future energy demand. Herein,5 oxygen-deficient cobalt oxide nanospheres in three-dimensional ordered mesoporous architecture (3DOM Co3O4−X) are developed via a simple nanocasting method, which serve as advanced anode materials for superior lithium storage. The unique highly porous and robust construction facilitates the mass transfer, restrains the volume expansion, and exposes vast interfaces for reversible lithiation/delithiation, while the oxygen vacancies in Co3O4−X lattice promote the electron/ion conductions and enrich the active sites for conversion reactions. Benefiting from these synergistic attributes, the 3DOM Co3O4−X electrodes retain a highly reversible capacity of 629.1 mA h g−1 after 1000 cycles at 2 A g−1, which significantly outperform the Co3O4 nanoparticle counterpart. This work demonstrates a highly promising material advancement combining architecture and defect engineering towards high-performance LIBs.

The development of society has an increasing demand for clean energy. Sodium ion batteries (SIB) have emerged because of their abundant sodium reserves and low cost. However, there is still a gap in performance between sodium-ion batteries and lithium-ion batteries. Orthogonal Nb2O5 (T-Nb2O5) is a promising sodium carrier due to its good intercalation/deintercalation characteristics and surface capacitance reaction. However, T-Nb2O5 as electrode material suffers from the low conductivity, and the crystalline phase will change to amorphous during the charge and discharge process, resulting in poor electrochemical performance of SIB. Therefore, this work has carefully designed a 3D ordered macroporous amorphous Nb2O5 (3DOM A-Nb2O5) with rich mesoporosity as anode material for superior sodium storage. Unsaturation defects in A-Nb2O5 alter the electronic structure, thereby improving electrical conductivity. Meanwhile, the hierarchical porous structure facilitates the insertion and extraction of sodium ions, with the structural integrity can be well maintained upon long cycles at high current density. As a result, the 3DOM A-Nb2O5 electrode exhibits excellent cycle performance with high capacity retention of 131 mAh g−1 after 500 cycles at 5 A g−1.

Inspired by the excellent absorption capability of spongelike bacterial cellulose (BC), three-dimensional hierarchical porous carbon fibers doped with an ultrahigh content of N (21.2 atom %) (i.e., nitrogen-doped carbon fibers, NDCFs) were synthesized by an adsorption–swelling strategy using BC as the carbonaceous material. When used as anode materials for sodium-ion batteries, the NDCFs deliver a high reversible capacity of 86.2 mAh g–1 even after 2000 cycles at a high current density of 10.0 A g–1. It is proposed that the excellent Na+ storage performance is mainly due to the defective surface of the NDCFs created by the high content of N dopant. Density functional theory (DFT) calculations show that the defect sites created by N doping can strongly “host” Na+ and therefore contribute to the enhanced storage capacity.

Rational design of free-standing porous carbon materials with large specific surface area and high conductivity is a great need for ligh-weight suprecapacitors. Here, we report a flexible porous carbon film composed of metal–organic framework (MOF)-derived porous carbon polyhedrons and carbon nanotubes (CNTs) as binder-free supercapacitor electrode for the first time. Due to the synergistic combination of carbon polyhedrons and CNT, the obtained carbon electrode shows a specific capacitance of 381.2 F g–1 at 5 mV s–1 and 194.8 F g–1 at 2 A g–1 and outstanding cycling stability with a Coulombic effciency above 95% after 10000 cycles at 10 A g–1. The assembled aqueous symmetrical supercapacitor exhibits an energy density of 9.1 Wh kg–1 with a power density of 3500 W kg–1. The work opens a new way to design flexible MOF-based hierarchical porous carbon film as binder-free electrodes for high-performance energy storage devices.