Nitrogen Doped γ‐Graphyne: A Novel Anode for High‐Capacity Rechargeable Alkali‐Ion Batteries

High energy density is the major demand for next‐generation rechargeable batteries, while the intrinsic low alkali metal adsorption of traditional carbon–based electrode remains the main challenge. Here, the mechanochemical route is proposed to prepare nitrogen doped γ‐graphyne (NGY) and its high capacity is demonstrated in lithium (LIBs)/sodium (SIBs) ion batteries. The sample delivers large reversible Li (1037 mAh g^?1) and Na (570.4 mAh g^?1) storage capacities at 100 mA g^?1 and presents excellent rate capabilities (526 mAh g^?1 for LIBs and 180.2 mAh g^?1 for SIBs) at 5 A g^?1. The superior Li/Na storage mechanisms of NGY are revealed by its 2D morphology evolution, quantitative kinetics, and theoretical calculations. The effects on the diffusion barriers (E_b) and adsorption energies (E_ad) of Li/Na atoms in NGY are also studied and imine‐N is demonstrated to be the ideal doping format to enhance the Li/Na storage performance. Besides, the Li/Na adsorption routes in NGY are optimized according to the experimental and the first‐principles calculation results. This work provides a facile way to fabricate high capacity electrodes in LIBs/SIBs, which is also instructive for the design of other heteroatomic doped electrodes.     

Ultrathin 2D Mesoporous TiO2/rGO Heterostructure for High‐Performance Lithium Storage

Lithium‐ion batteries (LIBs) have been widely applied and studied as an effective energy supplement for a variety of electronic devices. Titanium dioxide (TiO₂), with a high theoretical capacity (335 mAh g^?1) and low volume expansion ratio upon lithiation, has been considered as one of the most promising anode materials for LIBs. However, the application of TiO₂ is hindered by its low electrical conductivity and slow ionic diffusion rate. Herein, a 2D ultrathin mesoporous TiO₂/reduced graphene (rGO) heterostructure is fabricated via a layer‐by‐layer assembly process. The synergistic effect of ultrathin mesoporous TiO₂ and the rGO nanosheets significantly enhances the ionic diffusion and electron conductivity of the composite. The introduced 2D mesoporous heterostructure delivers a significantly improved capacity of 350 mAh g^?1 at a current density of 200 mA g^?1 and excellent cycling stability, with a capacity of 245 mAh g^?1 maintained over 1000 cycles at a high current density of 1 A g^?1. The in situ transmission electron microscopy analysis indicates that the volume of the as‐prepared 2D heterostructures changes slightly upon the insertion and extraction of Li⁺, thus contributing to the enhanced long‐cycle performance.     

In Situ Encapsulating α‐MnS into N,S‐Codoped Nanotube‐Like Carbon as Advanced Anode Material: α → β Phase Transition Promoted Cycling Stability and Superior Li/Na‐Storage Performance in Half/Full Cells

Incorporation of N,S‐codoped nanotube‐like carbon (N,S‐NTC) can endow electrode materials with superior electrochemical properties owing to the unique nanoarchitecture and improved kinetics. Herein, α‐MnS nanoparticles (NPs) are in situ encapsulated into N,S‐NTC, preparing an advanced anode material (α‐MnS@N,S‐NTC) for lithium‐ion/sodium‐ion batteries (LIBs/SIBs). It is for the first time revealed that electrochemical α → β phase transition of MnS NPs during the 1st cycle effectively promotes Li‐storage properties, which is deduced by the studies of ex situ X‐ray diffraction/high‐resolution transmission electron microscopy and electrode kinetics. As a result, the optimized α‐MnS@N,S‐NTC electrode delivers a high Li‐storage capacity (1415 mA h g^?1 at 50 mA g^?1), excellent rate capability (430 mA h g^?1 at 10 A g^?1), and long‐term cycling stability (no obvious capacity decay over 5000 cycles at 1 A g^?1) with retained morphology. In addition, the N,S‐NTC‐based encapsulation plays the key roles on enhancing the electrochemical properties due to its high conductivity and unique 1D nanoarchitecture with excellent protective effects to active MnS NPs. Furthermore, α‐MnS@N,S‐NTC also delivers high Na‐storage capacity (536 mA h g^?1 at 50 mA g^?1) without the occurrence of such α → β phase transition and excellent full‐cell performances as coupling with commercial LiFePO₄ and LiNi_0.6Co_0.2Mn_0.2O₂ cathodes in LIBs as well as Na₃V₂(PO₄)₂O₂F cathode in SIBs.     

Porous Carbon Nanofibers Encapsulated with Peapod‐Like Hematite Nanoparticles for High‐Rate and Long‐Life Battery Anodes

Fe₂O₃ is regarded as a promising anode material for lithium‐ion batteries (LIBs) and sodium‐ion batteries (SIBs) due to its high specific capacity. The large volume change during discharge and charge processes, however, induces significant cracking of the Fe₂O₃ anodes, leading to rapid fading of the capacity. Herein, a novel peapod‐like nanostructured material, consisting of Fe₂O₃ nanoparticles homogeneously encapsulated in the hollow interior of N‐doped porous carbon nanofibers, as a high‐performance anode material is reported. The distinctive structure not only provides enough voids to accommodate the volume expansion of the pea‐like Fe₂O₃ nanoparticles but also offers a continuous conducting framework for electron transport and accessible nanoporous channels for fast diffusion and transport of Li/Na‐ions. As a consequence, this peapod‐like structure exhibits a stable discharge capacity of 1434 mAh g^?1 (at 100 mA g^?1) and 806 mAh g^?1 (at 200 mA g^?1) over 100 cycles as anode materials for LIBs and SIBs, respectively. More importantly, a stable capacity of 958 mAh g^?1 after 1000 cycles and 396 mAh g^?1 after 1500 cycles can be achieved for LIBs and SIBs, respectively, at a large current density of 2000 mA g^?1. This study provides a promising strategy for developing long‐cycle‐life LIBs and SIBs.     

Core–Shell Structure and Interaction Mechanism of γ‐MnO2 Coated Sulfur for Improved Lithium‐Sulfur Batteries

Lithium‐sulfur batteries have attracted worldwide interest due to their high theoretical capacity of 1672 mAh g^?1 and low cost. However, the practical applications are hampered by capacity decay, mainly attributed to the polysulfide shuttle. Here, the authors have fabricated a solid core–shell γ‐MnO₂‐coated sulfur nanocomposite through the redox reaction between KMnO₄ and MnSO₄. The multifunctional MnO₂ shell facilitates electron and Li⁺ transport as well as efficiently prevents polysulfide dissolution via physical confinement and chemical interaction. Moreover, the γ‐MnO₂ crystallographic form also provides one‐dimensional (1D) tunnels for the Li⁺ incorporation to alleviate insoluble Li₂S₂/Li₂S deposition at high discharge rate. More importantly, the MnO₂ phase transformation to Mn₃O₄ occurs during the redox reaction between polysulfides and γ‐MnO₂ is first thoroughly investigated. The S@γ‐MnO₂ composite exhibits a good capacity retention of 82% after 300 cycles (0.5 C) and a fade rate of 0.07% per cycle over 600 cycles (1 C). The degradation mechanism can probably be elucidated that the decomposition of the surface Mn₃O₄ phase is the cause of polysulfide dissolution. The recent work thus sheds new light on the hitherto unknown surface interaction mechanism and the degradation mechanism of Li‐S cells.     

Bioinspired Redox‐Active Catechol‐Bearing Polymers as Ultrarobust Organic Cathodes for Lithium Storage

Redox‐active catechols are bioinspired precursors for ortho ‐quinones that are characterized by higher discharge potentials than para ‐quinones, the latter being extensively used as organic cathode materials for lithium ion batteries (LIBs). Here, this study demonstrates that the rational molecular design of copolymers bearing catechol‐ and Li⁺ ion‐conducting anionic pendants endow redox‐active polymers (RAPs) with ultrarobust electrochemical energy storage features when combined to carbon nanotubes as a flexible, binder‐, and metal current collector‐free buckypaper electrode. The importance of the structure and functionality of the RAPs on the battery performances in LIBs is discussed. The structure‐optimized RAPs can store high‐capacities of 360 mA h g^?1 at 5C and 320 mA h g^?1 at 30C in LIBs. The high ion and electron mobilities within the buckypaper also enable to register 96 mA h g^?1 (24% capacity retention) at an extreme C‐rate of 600C (6 s for total discharge). Moreover, excellent cyclability is noted with a capacity retention of 98% over 3400 cycles at 30C. The high capacity, superior active‐material utilization, ultralong cyclability, and excellent rate performances of RAPs‐based electrode clearly rival most of the state‐of‐the‐art Li⁺ ion organic cathodes, and opens up new horizons for large‐scalable fabrication of electrode materials for ultrarobust Li storage.     

A Universal Strategy for Hollow Metal Oxide Nanoparticles Encapsulated into B/N Co‐Doped Graphitic Nanotubes as High‐Performance Lithium‐Ion Battery Anodes

Yolk–shell nanostructures have received great attention for boosting the performance of lithium‐ion batteries because of their obvious advantages in solving the problems associated with large volume change, low conductivity, and short diffusion path for Li⁺ ion transport. A universal strategy for making hollow transition metal oxide (TMO) nanoparticles (NPs) encapsulated into B, N co‐doped graphitic nanotubes (TMO@BNG (TMO = CoO, Ni₂O₃, Mn₃O₄) through combining pyrolysis with an oxidation method is reported herein. The as‐made TMO@BNG exhibits the TMO‐dependent lithium‐ion storage ability, in which CoO@BNG nanotubes exhibit highest lithium‐ion storage capacity of 1554 mA h g^?1 at the current density of 96 mA g^?1, good rate ability (410 mA h g^?1 at 1.75 A g^?1), and high stability (almost 96% storage capacity retention after 480 cycles). The present work highlights the importance of introducing hollow TMO NPs with thin wall into BNG with large surface area for boosting LIBs in the terms of storage capacity, rate capability, and cycling stability.     

MOF‐Derived CuS@Cu‐BTC Composites as High‐Performance Anodes for Lithium‐Ion Batteries

The CuS(x wt%)@Cu‐BTC (BTC = 1,3,5‐benzenetricarboxylate; x = 3, 10, 33, 58, 70, 99.9) materials are synthesized by a facile sulfidation reaction. The composites are composed of octahedral Cu₃(BTC)₂·(H₂O)₃ (Cu‐BTC) with a large specific surface area and CuS with a high conductivity. The as‐prepared CuS@Cu‐BTC products are first applied as the anodes of lithium‐ion batteries (LIBs). The synergistic effect between Cu‐BTC and CuS components can not only accommodate the volume change and stress relaxation of electrodes but also facilitate the fast transport of Li ions. Thus, it can greatly suppress the transformation process from Li₂S to polysulfides by improving the reversibility of the conversion reaction. Benefiting from the unique structural features, the optimal CuS(70 wt%)@Cu‐BTC sample exhibits a remarkably improved electrochemical performance, showing an over‐theoretical capacity up to 1609 mAh g^?1 after 200 cycles (100 mA g^?1) with an excellent rate‐capability of ≈490 mAh g^?1 at 1000 mA g^?1. The outstanding LIB properties indicate that the CuS(70 wt%)@Cu‐BTC sample is a highly desirable electrode material candidate for high‐performance LIBs.     

Flexible and Binder‐Free Electrodes of Sb/rGO and Na3V2(PO4)3/rGO Nanocomposites for Sodium‐Ion Batteries

Flexible power sources have shown great promise in next‐generation bendable, implantable, and wearable electronic systems. Here, flexible and binder‐free electrodes of Na₃V₂(PO₄)₃/reduced graphene oxide (NVP/rGO) and Sb/rGO nanocomposites for sodium‐ion batteries are reported. The Sb/rGO and NVP/rGO paper electrodes with high flexibility and tailorability can be easily fabricated. Sb and NVP nanoparticles are embedded homogenously in the interconnected framework of rGO nanosheets, which provides structurally stable hosts for Na‐ion intercalation and deintercalation. The NVP/rGO paper‐like cathode delivers a reversible capacity of 113 mAh g^?1 at 100 mA g^?1 and high capacity retention of ≈96.6% after 120 cycles. The Sb/rGO paper‐like anode gives a highly reversible capacity of 612 mAh g^?1 at 100 mA g^?1, an excellent rate capacity up to 30 C, and a good cycle performance. Moreover, the sodium‐ion full cell of NVP/rGO//Sb/rGO has been fabricated, delivering a highly reversible capacity of ≈400 mAh g^?1 at a current density of 100 mA g^?1 after 100 charge/discharge cycles. This work may provide promising electrode candidates for developing next‐generation energy‐storage devices with high capacity and long cycle life.     

High Performance Lithium‐Ion Batteries Using Layered 2H‐MoTe2 as Anode

The major challenges faced by candidate electrode materials in lithium‐ion batteries (LIBs) include their low electronic and ionic conductivities. 2D van der Waals materials with good electronic conductivity and weak interlayer interaction have been intensively studied in the electrochemical processes involving ion migrations. In particular, molybdenum ditelluride (MoTe₂) has emerged as a new material for energy storage applications. Though 2H‐MoTe₂ with hexagonal semiconducting phase is expected to facilitate more efficient ion insertion/deinsertion than the monoclinic semi‐metallic phase, its application as an anode in LIB has been elusive. Here, 2H‐MoTe₂, prepared by a solid‐state synthesis route, has been employed as an efficient anode with remarkable Li⁺ storage capacity. The as‐prepared 2H‐MoTe₂ electrodes exhibit an initial specific capacity of 432 mAh g^?1 and retain a high reversible specific capacity of 291 mAh g^?1 after 260 cycles at 1.0 A g^?1. Further, a full‐cell prototype is demonstrated by using 2H‐MoTe₂ anode with lithium cobalt oxide cathode, showing a high energy density of 454 Wh kg^?1 (based on the MoTe₂ mass) and capacity retention of 80% over 100 cycles. Synchrotron‐based in situ X‐ray absorption near‐edge structures have revealed the unique lithium reaction pathway and storage mechanism, which is supported by density functional theory based calculations.     

Atomic Cobalt Covalently Engineered Interlayers for Superior Lithium‐Ion Storage

With the unique‐layered structure, MXenes show potential as electrodes in energy‐storage devices including lithium‐ion (Li⁺) capacitors and batteries. However, the low Li⁺‐storage capacity hinders the application of MXenes in place of commercial carbon materials. Here, the vanadium carbide (V₂C) MXene with engineered interlayer spacing for desirable storage capacity is demonstrated. The interlayer distance of pristine V₂C MXene is controllably tuned to 0.735 nm resulting in improved Li‐ion capacity of 686.7 mA h g^?1 at 0.1 A g^?1, the best MXene‐based Li⁺‐storage capacity reported so far. Further, cobalt ions are stably intercalated into the interlayer of V₂C MXene to form a new interlayer‐expanded structure via strong V–O–Co bonding. The intercalated V₂C MXene electrodes not only exhibit superior capacity up to 1117.3 mA h g^?1 at 0.1 A g^?1, but also deliver a significantly ultralong cycling stability over 15 000 cycles. These results clearly suggest that MXene materials with an engineered interlayer distance will be a rational route for realizing them as superstable and high‐performance Li⁺ capacitor electrodes.     

Synthesis Process of CoSeO3 Microspheres for Unordinary Li‐ion Storage Performances and Mechanism of Their Conversion Reaction with Li ions

Multicomponent materials with various double cations have been studied as anode materials of lithium‐ion batteries (LIBs). Heterostructures formed by coupling different‐bandgap nanocrystals enhance the surface reaction kinetics and facilitate charge transport because of the internal electric field at the heterointerface. Accordingly, metal selenites can be considered efficient anode materials of LIBs because they transform into metal selenide and oxide nanocrystals in the first cycle. However, few studies have reported synthesis of uniquely structured metal selenite microspheres. Herein, synthesis of high‐porosity CoSeO₃ microspheres is reported. Through one‐pot oxidation at 400 °C, CoSe_x–C microspheres formed by spray pyrolysis transform into CoSeO₃ microspheres showing unordinary cycling and rate performances. The conversion mechanism of CoSeO₃ microspheres for lithium‐ion storage is systematically studied by cyclic voltammetry, in situ X‐ray diffraction and electrochemical impedance spectroscopy, and transmission electron microscopy. The reversible reaction mechanism of the CoSeO₃ phase from the second cycle onward is evaluated as CoO + xSeO₂ + (1 ? x)Se + 4(x + 1)Li⁺+ 4( x + 1)e^? ? Co + (2x + 1)Li₂O + Li₂Se. The CoSeO₃ microspheres show a high reversible capacity of 709 mA h g^?1 for the 1400th cycle at a current density of 3 A g^?1 and a high reversible capacity of 526 mA h g^?1 even at an extremely high current density of 30 A g^?1.     

Flexible 3D Porous MXene Foam for High‐Performance Lithium‐Ion Batteries

2D transition‐metal carbides and nitrides, named MXenes, are promising materials for energy storage, but suffer from aggregation and restacking of the 2D nanosheets, which limits their electrochemical performance. In order to overcome this problem and realize the full potential of MXene nanosheets, a 3D MXene foam with developed porous structure is established via a simple sulfur‐template method, which is freestanding, flexible, and highly conductive, and can be directly used as the electrode in lithium‐ion batteries. The 3D porous architecture of the MXene foam offers massive active sites to enhance the lithium storage capacity. Moreover, its foam structure facilitates electrolyte infiltration for fast Li⁺ transfer. As a result, this flexible 3D porous MXene foam exhibits significantly enhanced capacity of 455.5 mAh g^?1 at 50 mA g^?1, excellent rate performance (101 mAh g^?1 at 18 A g^?1), and superior ultralong‐term cycle stability (220 mAh g^?1 at 1 A g^?1 after 3500 cycles). This work not only demonstrates the great superiority of the 3D porous MXene foam but also proposes the sulfur‐template method for controllable constructing of the 3D foam from 2D nanosheets at a relatively low temperature.     

Construction of 3D Electronic/Ionic Conduction Networks for All‐Solid‐State Lithium Batteries

High and balanced electronic and ionic transportation networks with nanoscale distribution in solid‐state cathodes are crucial to realize high‐performance all‐solid‐state lithium batteries. Using Cu₂SnS₃ as a model active material, such a kind of solid‐state Cu₂SnS₃@graphene‐Li₇P₃S₁₁ nanocomposite cathodes are synthesized, where 5–10 nm Cu₂SnS₃ nanoparticles homogenously anchor on the graphene nanosheets, while the Li₇P₃S₁₁ electrolytes uniformly coat on the surface of Cu₂SnS₃@graphene composite forming nanoscaled electron/ion transportation networks. The large amount of nanoscaled triple‐phase boundary in cathode ensures high power density due to high ionic/electronic conductions and long cycle life due to uniform and reduced volume change of nano‐Cu₂SnS_3. The Cu₂SnS₃@graphene‐Li₇P₃S₁₁ cathode layer with 2.0 mg cm^?2 loading in all‐solid‐state lithium batteries demonstrates a high reversible discharge specific capacity of 813.2 mAh g^?1 at 100 mA g^?1 and retains 732.0 mAh g^?1 after 60 cycles, corresponding to a high energy density of 410.4 Wh kg^?1 based on the total mass of Cu₂SnS₃@graphene‐Li₇P₃S₁₁ composite based cathode. Moreover, it exhibits excellent rate capability and high‐rate cycling stability, showing reversible capacity of 363.5 mAh g^?1 at 500 mA g^?1 after 200 cycles. The study provides a new insight into constructing both electronic and ionic conduction networks for all‐solid‐state lithium batteries.     

S‐Doped Carbon Fibers Uniformly Embedded with Ultrasmall TiO2 for Na+/Li+ Storage with High Capacity and Long‐Time Stability

Building a rechargeable battery with high capacity, high energy density, and long lifetime contributes to the development of novel energy storage devices in the future. Although carbon materials are very attractive anode materials for lithium‐ion batteries (LIBs), they present several deficiencies when used in sodium‐ion batteries (SIBs). The choice of an appropriate structural design and heteroatom doping are critical steps to improve the capacity and stability. Here, carbon‐based nanofibers are produced by sulfur doping and via the introduction of ultrasmall TiO₂ nanoparticles into the carbon fibers (CNF‐S@TiO₂). It is discovered that the introduction of TiO₂ into carbon nanofibers can significantly improve the specific surface area and microporous volume for carbon materials. The TiO₂ content is controlled to obtain CNF‐S@TiO₂‐5 to use as the anode material for SIBs/LIBs with enhanced electrochemical performance in Na⁺/Li⁺ storage. During the charge/discharge process, the S‐doping and the incorporation of TiO₂ nanoparticles into carbon fibers promote the insertion/extraction of the ions and enhance the capacity and cycle life. The capacity of CNF‐S@TiO₂‐5 can be maintained at ≈300 mAh g^?1 over 600 cycles at 2 A g^?1 in SIBs. Moreover, the capacity retention of such devices is 94%, showing high capacity and good stability.     

Birnessite Nanosheet Arrays with High K Content as a High‐Capacity and Ultrastable Cathode for K‐Ion Batteries

Potassium‐ion batteries (PIBs) are one of the emerging energy‐storage technologies due to the low cost of potassium and theoretically high energy density. However, the development of PIBs is hindered by the poor K⁺ transport kinetics and the structural instability of the cathode materials during K⁺ intercalation/deintercalation. In this work, birnessite nanosheet arrays with high K content (K_0.77MnO₂?0.23H₂O) are prepared by “hydrothermal potassiation” as a potential cathode for PIBs, demonstrating ultrahigh reversible specific capacity of about 134 mAh g^?1 at a current density of 100 mA g^?1, as well as great rate capability (77 mAh g^?1 at 1000 mA g^?1) and superior cycling stability (80.5% capacity retention after 1000 cycles at 1000 mA g^?1). With the introduction of adequate K⁺ ions in the interlayer, the K‐birnessite exhibits highly stabilized layered structure with highly reversible structure variation upon K⁺ intercalation/deintercalation. The practical feasibility of the K‐birnessite cathode in PIBs is further demonstrated by constructing full cells with a hard–soft composite carbon anode. This study highlights effective K⁺‐intercalation for birnessite to achieve superior K‐storage performance for PIBs, making it a general strategy for developing high‐performance cathodes in rechargeable batteries beyond lithium‐ion batteries.     

Self‐Formed Electronic/Ionic Conductive Fe3S4 @ S @ 0.9Na3SbS4⋅0.1NaI Composite for High‐Performance Room‐Temperature All‐Solid‐State Sodium–Sulfur Battery

Fe₃S₄ @ S @ 0.9Na₃SbS₄?0.1NaI composite cathode is prepared through one‐step wet‐mechanochemical milling procedure. During milling process, ionic conduction pathway is self‐formed in the composite due to the formation of 0.9Na₃SbS₄?0.1NaI electrolyte without further annealing treatment. Meanwhile, the introduction of Fe₃S₄ can increase the electronic conductivity of the composite cathode by one order of magnitude and nearly double enhance the ionic conductivities. Besides, the aggregation of sulfur is effectively suppressed in the obtained Fe₃S₄ @ S @ 0.9Na₃SbS₄?0.1NaI composite, which will enhance the contact between sulfur and 0.9Na₃SbS₄?0.1NaI electrolyte, leading to a decreased interfacial resistance and improving the electrochemical kinetics of sulfur. Therefore, the resultant all‐solid‐state sodium–sulfur battery employing Fe₃S₄ @ S @ 0.9Na₃SbS₄?0.1NaI composite cathode shows discharge capacity of 808.7 mAh g^?1 based on Fe₃S₄@S and a normalized discharge capacity of 1040.5 mAh g^?1 for element S at 100 mA g^?1 for 30 cycles at room temperature. Moreover, the battery also exhibits excellent cycling stability with a reversible capacity of 410 mAh g^?1 at 500 mA g^?1 for 50 cycles, and superior rate capability with capacities of 952.4, 796.7, 513.7, and 445.6 mAh g^?1 at 50, 100, 200, and 500 mA g^?1, respectively. This facile strategy for sulfur‐based composite cathode is attractive for achieving room‐temperature sodium–sulfur batteries with superior electrochemical performance.     

Novel 2D Layered Molybdenum Ditelluride Encapsulated in Few‐Layer Graphene as High‐Performance Anode for Lithium‐Ion Batteries

Molybdenum ditelluride nanosheets encapsulated in few‐layer graphene (MoTe₂/FLG) are synthesized by a simple heating method using Te and Mo powder and subsequent ball milling with graphite. The as‐prepared MoTe₂/FLG nanocomposites as anode materials for lithium‐ion batteries exhibit excellent electrochemical performance with a highly reversible capacity of 596.5 mAh g^?1 at 100 mA g^?1, a high rate capability (334.5 mAh g^?1 at 2 A g^?1), and superior cycling stability (capacity retention of 99.5% over 400 cycles at 0.5 A g^?1). Ex situ X‐ray diffraction and transmission electron microscopy are used to explore the lithium storage mechanism of MoTe₂. Moreover, the electrochemical performance of a MoTe₂/FLG//0.35Li₂MnO₃·0.65LiMn_0.5Ni_0.5O₂ full cell is investigated, which displays a reversible capacity of 499 mAh g^?1 (based on the MoTe₂/FLG mass) at 100 mA g^?1 and a capacity retention of 78% over 50 cycles, suggesting the promising application of MoTe₂/FLG for lithium‐ion storage. First‐principles calculations exhibit that the lowest diffusion barrier (0.18 eV) for lithium ions along pathway III in the MoTe₂ layered structure is beneficial for improving the Li intercalation/deintercalation property.     

Electrostatically Assembling 2D Nanosheets of MXene and MOF‐Derivatives into 3D Hollow Frameworks for Enhanced Lithium Storage

As an essential member of 2D materials, MXene (e.g., Ti₃C₂T_x) is highly preferred for energy storage owing to a high surface‐to‐volume ratio, shortened ion diffusion pathway, superior electronic conductivity, and neglectable volume change, which are beneficial for electrochemical kinetics. However, the low theoretical capacitance and restacking issues of MXene severely limit its practical application in lithium‐ion batteries (LIBs). Herein, a facile and controllable method is developed to engineer 2D nanosheets of negatively charged MXene and positively charged layered double hydroxides derived from ZIF‐67 polyhedrons into 3D hollow frameworks via electrostatic self‐assembling. After thermal annealing, transition metal oxides (TMOs)@MXene (CoO/Co₂Mo₃O₈@MXene) hollow frameworks are obtained and used as anode materials for LIBs. CoO/Co₂Mo₃O₈ nanosheets prevent MXene from aggregation and contribute remarkable lithium storage capacity, while MXene nanosheets provide a 3D conductive network and mechanical robustness to facilitate rapid charge transfer at the interface, and accommodate the volume expansion of the internal CoO/Co₂Mo₃O₈. Such hollow frameworks present a high reversible capacity of 947.4 mAh g^?1 at 0.1 A g^?1, an impressive rate behavior with 435.8 mAh g^?1 retained at 5 A g^?1, and good stability over 1200 cycles (545 mAh g^?1 at 2 A g^?1).     

α‐Fe2O3 Nanoparticles Decorated C@MoS2 Nanosheet Arrays with Expanded Spacing of (002) Plane for Ultrafast and High Li/Na‐Ion Storage

MoS₂ nanosheets as a promising 2D nanomaterial have extensive applications in energy storage and conversion, but their electrochemical performance is still unsatisfactory as an anode for efficient Li⁺/Na⁺ storage. In this work, the design and synthesis of vertically grown MoS₂ nanosheet arrays, decorated with graphite carbon and Fe₂O₃ nanoparticles, on flexible carbon fiber cloth (denoted as Fe₂O₃@C@MoS₂/CFC) is reported. When evaluated as an anode for lithium‐ion batteries, the Fe₂O₃@C@MoS₂/CFC electrode manifests an outstanding electrochemical performance with a high discharge capacity of 1541.2 mAh g^?1 at 0.1 A g^?1 and a good capacity retention of 80.1% at 1.0 A g^?1 after 500 cycles. As for sodium‐ion batteries, it retains a high reversible capacity of 889.4 mAh g^?1 at 0.5 A g^?1 over 200 cycles. The superior electrochemical performance mainly results from the unique 3D ordered Fe₂O₃@C@MoS₂ array‐type nanostructures and the synergistic effect between the C@MoS₂ nanosheet arrays and Fe₂O₃ nanoparticles. The Fe₂O₃ nanoparticles act as spacers to steady the structure, and the graphite carbon could be incorporated into MoS₂ nanosheets to improve the conductivity of the whole electrode and strengthen the integration of MoS₂ nanosheets and CFC by the adhesive role, together ensuring high conductivity and mechanical stability.