2D Nanospace Confined Synthesis of Pseudocapacitance‐Dominated MoS2‐in‐Ti3C2 Superstructure for Ultrafast and Stable Li/Na‐Ion Batteries

Exploring a universal strategy to implement the precise control of 2D nanomaterials in size and layer number is a big challenge for achieving ultrafast and stable Li/Na‐ion batteries. Herein, the confined synthesis of 1–3 layered MoS₂ nanocrystals into 2D Ti₃C₂ interlayer nanospace with the help of electrostatic attraction and subsequent cetyltrimethyl ammonium bromide (CTAB) directed growth is reported. The MoS₂ nanocrystals are tightly anchored into the interlayer by 2D confinement effect and strong Mo? C covalent bond. Impressively, the disappearance of Li⁺ intercalated into MoS₂ reduction peak is successfully observed for the first time in the experiment, showing in a typical surface‐controlled charge storage behavior. The pseudocapacitance‐dominated contribution guarantees a much faster and more stable Li/Na storage performance. As predicted, this electrode exhibits a very high Li⁺ storage capacity of 340 mAh g^?1 even at 20 A g^?1 and a long cycle life (>1000 times). It also shows an excellent Na⁺ storage capacity of 310 mAh g^?1 at 1 A g^?1 with a 1600 times high‐rate cycling. Such impressive confined synthesis strategy can be extended to the precise control of other 2D nanomaterials.     

Self‐Assembly of Flexible Free‐Standing 3D Porous MoS2‐Reduced Graphene Oxide Structure for High‐Performance Lithium‐Ion Batteries

Flexible freestanding electrodes are highly desired to realize wearable/flexible batteries as required for the design and production of flexible electronic devices. Here, the excellent electrochemical performance and inherent flexibility of atomically thin 2D MoS₂ along with the self‐assembly properties of liquid crystalline graphene oxide (LCGO) dispersion are exploited to fabricate a porous anode for high‐performance lithium ion batteries. Flexible, free‐standing MoS₂–reduced graphene oxide (MG) film with a 3D porous structure is fabricated via a facile spontaneous self‐assembly process and subsequent freeze‐drying. This is the first report of a one‐pot self‐assembly, gelation, and subsequent reduction of MoS₂/LCGO composite to form a flexible, high performance electrode for charge storage. The gelation process occurs directly in the mixed dispersion of MoS₂ and LCGO nanosheets at a low temperature (70 °C) and normal atmosphere (1 atm). The MG film with 75 wt% of MoS₂ exhibits a high reversible capacity of 800 mAh g^?1 at a current density of 100 mA g^?1. It also demonstrates excellent rate capability, and excellent cycling stability with no capacity drop over 500 charge/discharge cycles at a current density of 400 mA g^?1.     

MoS2/Graphene Composite Anodes with Enhanced Performance for Sodium‐Ion Batteries: The Role of the Two‐Dimensional Heterointerface

Graphene has been widely used as conformal nanobuilding blocks to improve the electrochemical performance of layered metal sulfides (MoS₂, WS₂, SnS, and SnS₂) as anode materials for sodium‐ion batteries. However, it still lacks in‐depth understanding of the synergistic effect between these layered sulfides and graphene, which contributes to the enhanced electroactivity for sodium‐ion batteries. Here, MoS₂/reduced graphene oxide (RGO) nanocomposites with intimate two‐dimensional heterointerfaces are prepared by a facile one‐pot hydrothermal method. The heterointerfacial area can be effectively tuned by changing the ratio of MoS₂ to RGO. When used as anode materials for sodium‐ion batteries, the synergistic effect contributing to the enhanced reversible capacity of MoS₂/RGO nanocomposites is closely related with the heterointerfacial area. The computational results demonstrate that Na prefers to be adsorbed on MoS₂ in the MoS₂/RGO heterostructure rather than intercalate into the MoS₂/RGO heterointerface. Interestingly, the MoS₂/RGO heterointerfaces can significantly increase the electronic conductivity of MoS₂, store more Na ions, while maintaining the high diffusion mobility of Na atoms on MoS₂ surface and high electron transfer efficiency from Na to MoS₂. It is expected that the efforts to establish the correlation between the two‐dimensional heterointerface and the electrochemical sodium‐ion storage performance offer fundamental understanding for the rational design of layered metal sulfides/graphene composites as high‐performance electrode materials for sodium‐ion batteries.     

Novel Designed MnS-MoS2 Heterostructure for Fast and Stable Li/Na Storage:Insights into the Advanced Mechanism Attributed to Phase Engineering

Combining 2D MoS₂ with other transition metal sulfide is a promising strategy to elevate its electrochemical performances. Herein, heterostructures constructed using MnS nanoparticles embedded in MoS₂ nanosheets (denoted as MnS-MoS₂) are designed and synthesized as anode materials for lithium/sodium-ion batteries via a facile one-step hydrothermal method. Phase transition and built-in electric field brought by the heterostructure enhance the Li/Na ion intercalation kinetics, elevate the charge transport, and accommodate the volume expansion. The sequential phase transitions from 2H to 3R of MoS₂ and α to γ of MnS are revealed for the first time. As a result, the MnS-MoS₂ electrode delivers outstanding specific capacity (1246.2 mAh g⁻¹ at 1 A g⁻¹), excellent rate, and stable long-term cycling stability (397.2 mAh g⁻¹ maintained after 3000 cycles at 20 A g⁻¹) in Li-ion half-cells. Superior cycling and rate performance are also presented in sodium half-cells and Li/Na full cells, demonstrating a promising practical application of the MnS-MoS₂ electrode. This work is anticipated to afford an in-depth comprehension of the heterostructure contribution in energy storage and illuminate a new perspective to construct binary transition metal sulfide anodes.     

3D Interconnected Porous Carbon Aerogels as Sulfur Immobilizers for Sulfur Impregnation for Lithium‐Sulfur Batteries with High Rate Capability and Cycling Stability

To eliminate capacity‐fading effects due to the loss of sulfur cathode materials as a result of polysulfide dissolution in lithium–sulfur (Li–S) cells, 3D carbon aerogel (CA) materials with abundant narrow micropores can be utilized as an immobilizer host for sulfur impregnation. The effects of S incorporation on microstructure, surface area, pore size distribution, and pore volume of the S/CA hybrids are studied. The electrochemical performance of the S/CA hybrids is investigated using electrochemical impedance spectroscopy, galvanostatical charge–discharge, and cyclic voltammetry techniques. The 3D porous S/CA hybrids exhibit significantly improved reversible capacity, high‐rate capability, and excellent cycling performance as a cathode electrode for Li–S batteries. The S/CA hybrid with an optimal incorporating content of 27% S shows an excellent reversible capacity of 820 mAhg^?1 after 50 cycles at a current density of 100 mAg^?1. Even at a current density of 3.2C (5280 mAg^?1), the reversible capacity of 27%S/CA hybrid can still maintain at 521 mAhg^?1 after 50 cycles. This strategy for the S/CA hybrids as cathode materials to utilize the abundant micropores for sulfur immobilizers for sulfur impregnation for Li–S battery offers a new way to solve the long‐term reversibility obstacle and provides guidelines for designing cathode electrode architectures.     

Excellent Cycling Stability of Sodium Anode Enabled by a Stable Solid Electrolyte Interphase Formed in Ether‐Based Electrolytes

Sodium‐ion batteries have been considered one of the most promising power sources beyond Li‐ion batteries. Although the Na metal anode exhibits a high theoretical capacity of 1165 mAh g^?1, its application in Na batteries is largely hindered by dendrite growth and low coulombic efficiency. Herein, it is demonstrated that an electrolyte consisting of 1 m sodium tetrafluoroborate in tetraglyme can enable excellent cycling efficiency (99.9%) of a Na metal anode for more than 1000 cycles. This high reversibility of a Na anode can be attributed to a stable solid electrolyte interphase formed on the Na surface, as revealed by cryogenic transmission electron microscopy and X‐ray photoelectron spectroscopy (XPS). These electrolytes also enable excellent cycling stability of Na||hard‐carbon cells and Na||Na_2/3Co_1/3Mn_2/3O₂ cells at high rates with very high coulombic efficiencies.     

Approaching the Downsizing Limit of Maricite NaFePO4 toward High‐Performance Cathode for Sodium‐Ion Batteries

Maricite NaFePO₄ nanodots with minimized sizes (≈1.6 nm) uniformly embedded in porous N‐doped carbon nanofibers (designated as NaFePO₄@C) are first prepared by electrospinning for maximized Na‐storage performance. The obtained flexible NaFePO₄@C fiber membrane adherent on aluminum foil is directly used as binder‐free cathode for sodium‐ion batteries, revealing that the ultrasmall nanosize effect as well as a high‐potential desodiation process can transform the generally perceived electrochemically inactive maricite NaFePO₄ into a highly active amorphous phase; meanwhile, remarkable electrochemical performance in terms of high reversible capacity (145 mA h g^?1 at 0.2 C), high rate capability (61 mA h g^?1 at 50 C), and unprecedentedly high cyclic stability (≈89% capacity retention over 6300 cycles) is achieved. Furthermore, the soft package Na‐ion full battery constructed by the NaFePO₄@C nanofibers cathode and the pure carbon nanofibers anode displays a promising energy density of 168.1 Wh kg^?1 and a notable capacity retention of 87% after 200 cycles. The distinctive 3D network structure of very fine NaFePO₄ nanoparticles homogeneously encapsulated in interconnected porous N‐doped carbon nanofibers, can effectively improve the active materials' utilization rate, facilitate the electrons/Na⁺ ions transport, and strengthen the electrode stability upon prolonged cycling, leading to the fascinating Na‐storage performance.     

A Composite of Carbon‐Wrapped Mo2C Nanoparticle and Carbon Nanotube Formed Directly on Ni Foam as a High‐Performance Binder‐Free Cathode for Li‐O2 Batteries

Cathode design is indispensable for building Li‐O₂ batteries with long cycle life. A composite of carbon‐wrapped Mo₂C nanoparticles and carbon nanotubes is prepared on Ni foam by direct hydrolysis and carbonization of a gel composed of ammonium heptamolybdate tetrahydrate and hydroquinone resin. The Mo₂C nanoparticles with well‐controlled particle size act as a highly active oxygen reduction reactions/oxygen evolution reactions (ORR/OER) catalyst. The carbon coating can prevent the aggregation of the Mo₂C nanoparticles. The even distribution of Mo₂C nanoparticles results in the homogenous formation of discharge products. The skeleton of porous carbon with carbon nanotubes protrudes from the composite, resulting in extra voids when applied as a cathode for Li‐O₂ batteries. The batteries deliver a high discharge capacity of ≈10 400 mAh g^?1 and a low average charge voltage of ≈4.0 V at 200 mA g^?1. With a cutoff capacity of 1000 mAh g^?1, the Li‐O₂ batteries exhibit excellent charge–discharge cycling stability for over 300 cycles. The average potential polarization of discharge/charge gaps is only ≈0.9 V, demonstrating the high ORR and OER activities of these Mo₂C nanoparticles. The excellent cycling stability and low potential polarization provide new insights into the design of highly reversible and efficient cathode materials for Li‐O₂ batteries.     

3D MoS2–Graphene Microspheres Consisting of Multiple Nanospheres with Superior Sodium Ion Storage Properties

A novel anode material for sodium‐ion batteries consisting of 3D graphene microspheres divided into several tens of uniform nanospheres coated with few‐layered MoS₂ by a one‐pot spray pyrolysis process is prepared. The first discharge/charge capacities of the composite microspheres are 797 and 573 mA h g^?1 at a current density of 0.2 A g^?1. The 600th discharge capacity of the composite microspheres at a current density of 1.5 A g^?1 is 322 mA h g^?1. The Coulombic efficiency during the 600 cycles is as high as 99.98%. The outstanding Na ion storage properties of the 3D MoS₂–graphene composite microspheres may be attributed to the reduced stacking of the MoS₂ layers and to the 3D structure of the porous graphene microspheres. The reduced stacking of the MoS₂ layers relaxes the strain and lowers the barrier for Na⁺ insertion. The empty nanospheres of the graphene offer voids for volume expansion and pathways for fast electron transfer during repeated cycling.     

Enhancing Ultrafast Lithium Ion Storage of Li4Ti5O12 by Tailored TiC/C Core/Shell Skeleton Plus Nitrogen Doping

It is of great importance to reinforce electronic and ionic conductivity of Li₄Ti₅O₁₂ electrodes to achieve fast reaction kinetics and good high‐power capability. Herein, for the first time, a dual strategy of combing N‐doped Li₄Ti₅O₁₂ (N‐LTO) with highly conductive TiC/C skeleton to realize enhanced ultrafast Li ion storage is reported. Interlinked hydrothermal‐synthesized N‐LTO nanosheets are homogeneously decorated on the chemical vapor deposition (CVD) derived TiC/C nanowires forming binder‐free N‐LTO@TiC/C core–branch arrays. Positive advantages including large surface area, strong mechanical stability, and enhanced electronic/ionic conductivity are obtained in the designed integrated arrays and rooted upon synergistic TiC/C matrix and N doping. The above appealing features can effectively boost kinetic properties throughout the N‐LTO@TiC/C electrodes to realize outstanding high‐rate capability at different working temperatures (143 mAh g^?1/10 C at 25 °C and 122 mAh g^?1/50 C at 50 °C) and notable cycling stability with a capacity retention of 99.3% after 10 000 cycles at 10 C. Moreover, superior high‐rate cycling life is also demonstrated for the full cells with N‐LTO@TiC/C anode and LiFePO₄ cathode. The dual strategy may provoke wide interests in fast energy storage areas and motivate the further performance improvement of power‐type lithium ion batteries (LIBs).     

Highly Surface‐Wrinkled and N‐Doped CNTs Anchored on Metal Wire: A Novel Fiber‐Shaped Cathode toward High‐Performance Flexible Li–CO2 Batteries

Li–CO₂ batteries are regarded as a promising candidate for the next‐generation high‐performance electrochemical energy storage system owing to their ultrahigh theoretical energy density and environmentally friendly CO₂ fixation ability. Until now, the majority of reported catalysts for Li–CO₂ batteries are in the powder state. Thus, the air electrodes are produced in 2D rigid bulk structure and their electrochemical properties are negatively influenced by binder. The nondeformable feature and unsatisfactory performance of the cathode have already become the main obstacles that hinder Li–CO₂ batteries toward ubiquity for wearable electronics. In this work, for the first time, a flexible hybrid fiber is reported comprising highly surface‐wrinkled and N‐doped carbon nanotube (CNT) networks anchored on metal wire as the cathode integrated with high performance and high flexibility for fiber‐shaped Li–CO₂ battery. It exhibits a large discharge capacity as high as 9292.3 mAh g^?1, an improved cycling performance of 45 cycles, and a decent rate capability. A quasi‐solid‐state flexible fiber‐shaped Li–CO₂ battery is constructed to illustrate the advantages on mechanical flexibility of this fiber‐shaped cathode. Experiments and theoretical simulations prove that those doped pyridinic nitrogen atoms play a critical role in facilitating the kinetics of CO₂ reduction and evolution reaction, thereby enabling distinctly enhanced electrochemical performance.     

In Situ Formation of Copper‐Based Hosts Embedded within 3D N‐Doped Hierarchically Porous Carbon Networks for Ultralong Cycle Lithium–Sulfur Batteries

Lithium–sulfur (Li–S) batteries are promising energy storage systems due to their large theoretical energy density of 2600 Wh kg^?1 and cost effectiveness. However, the severe shuttle effect of soluble lithium polysulfide intermediates (LiPSs) and sluggish redox kinetics during the cycling process cause low sulfur utilization, rapid capacity fading, and a low coulombic efficiency. Here, a 3D copper, nitrogen co‐doped hierarchically porous graphitic carbon network developed through a freeze‐drying method (denoted as 3D Cu@NC‐F) is prepared, and it possesses strong chemical absorption and electrocatalytic conversion activity for LiPSs as highly efficient sulfur host materials in Li–S batteries. The porous carbon network consisting of 2D cross‐linked ultrathin carbon nanosheets provides void space to accommodate volumetric expansion upon lithiation, while the Cu, N‐doping effect plays a critical role for the confinement of polysulfides through chemical bonding. In addition, after sulfuration of Cu@NC‐F network, the in situ grown copper sulfide (Cu_xS) embedded within Cu_xS@NC/S‐F composite catalyzes LiPSs conversion during reversible cycling, resulting in low polarization and fast redox reaction kinetics. At a current density of 0.1 C, the Cu_xS@NC/S‐F composites' electrode exhibits an initial capacity of 1432 mAh g^?1 and maintains 1169 mAh g^?1 after 120 cycles, with a coulombic efficiency of nearly 100%.     

GeO2 Encapsulated Ge Nanostructure with Enhanced Lithium‐Storage Properties

Germanium (Ge)‐based nanostructures, especially those with germanium dioxide (GeO₂), have drawn great interest for applications in lithium (Li)‐ion batteries due to their ultrahigh theoretical Li⁺ storage capability (8.4 Li/Ge). However, GeO₂ in conventional Ge(s)/GeO₂(c) (where (c) means the core and (s) means the shell) composite anodes with Ge shell outside GeO₂ undergoes an irreversible conversion reaction, which restricts the maximum capacity of such batteries to 1126 mAhg^?1 (the equivalent of storing 4.4 Li⁺). In this work, a porous GeO₂(s)/Ge(c) nanostructure with GeO₂ shell outside Ge cores are successfully fabricated utilizing the Kirkendall effect and used as a lithium‐ion battery anode, giving a substantially improved capacity of 1333.5 mAhg^?1 at a current density of 0.1 Ag^?1 after 30 cycles and a stable long‐time cycle performance after 100 cycles at a current density of 0.5 A g^?1. The enhanced battery performance is attributed to the improved reversibility of GeO₂ lithiation/delithiation processes catalyzed by Ge in the properly structured porous GeO₂(s)/Ge(c) nanostructure.     

Ultrathin MoS2 Nanosheets@Metal Organic Framework‐Derived N‐Doped Carbon Nanowall Arrays as Sodium Ion Battery Anode with Superior Cycling Life and Rate Capability

This study reports the design and fabrication of ultrathin MoS₂ nanosheets@metal organic framework‐derived N‐doped carbon nanowall array hybrids on flexible carbon cloth (CC@CN@MoS₂) as a free‐standing anode for high‐performance sodium ion batteries. When evaluated as an anode for sodium ion battery, the as‐fabricated CC@CN@MoS₂ electrode exhibits a high capacity (653.9 mA h g^?1 of the second cycle and 619.2 mA h g^?1 after 100 cycles at 200 mA g^?1), excellent rate capability, and long cycling life stability (265 mA h g^?1 at 1 A g^?1 after 1000 cycles). The excellent electrochemical performance can be attributed to the unique 2D hybrid structures, in which the ultrathin MoS₂ nanosheets with expanded interlayers can provide shortened ion diffusion paths and favorable Na⁺ insertion/extraction space, and the porous N‐doped carbon nanowall arrays on flexible carbon cloth are able to improve the conductivity and maintain the structural integrity. Moreover, the N‐doping‐induced defects also make them favorable for the effective storage of sodium ions, which enables the enhanced capacity and rate performance of MoS₂.     

Few‐Layered SnS2 on Few‐Layered Reduced Graphene Oxide as Na‐Ion Battery Anode with Ultralong Cycle Life and Superior Rate Capability

Na‐ion Batteries have been considered as promising alternatives to Li‐ion batteries due to the natural abundance of sodium resources. Searching for high‐performance anode materials currently becomes a hot topic and also a great challenge for developing Na‐ion batteries. In this work, a novel hybrid anode is synthesized consisting of ultrafine, few‐layered SnS₂ anchored on few‐layered reduced graphene oxide (rGO) by a facile solvothermal route. The SnS₂/rGO hybrid exhibits a high capacity, ultralong cycle life, and superior rate capability. The hybrid can deliver a high charge capacity of 649 mAh g^?1 at 100 mA g^?1. At 800 mA g^?1 (1.8 C), it can yield an initial charge capacity of 469 mAh g^?1, which can be maintained at 89% and 61%, respectively, after 400 and 1000 cycles. The hybrid can also sustain a current density up to 12.8 A g^?1 (≈28 C) where the charge process can be completed in only 1.3 min while still delivering a charge capacity of 337 mAh g^?1. The fast and stable Na‐storage ability of SnS₂/rGO makes it a promising anode for Na‐ion batteries.     

Intercalated Electrolyte with High Transference Number for Dendrite‐Free Solid‐State Lithium Batteries

Solid‐state lithium (Li) batteries using solid electrolytes and Li anodes are highly desirable because of their high energy densities and intrinsic safety. However, low ambient‐temperature conductivity and poor interface compatibility of solid electrolytes as well as Li dendrite formation cause large polarization and poor cycling stability. Herein, a high transference number intercalated composite solid electrolyte (CSE) is prepared by the combination of a solution‐casting and hot‐pressing method using layered lithium montmorillonite, poly(ethylene carbonate), lithium bis(fluorosulfonyl)imide, high‐voltage fluoroethylene carbonate additive, and poly(tetrafluoroethylene) binder. The electrolyte presents high ionic conductivity (3.5 × 10^?4 S cm^?1), a wide electrochemical window (4.6 V vs Li⁺/Li), and high ionic transference number (0.83) at 25 °C. In addition, a 3D Li anode is also fabricated via a facile thermal infusion strategy. The synergistic effect of high transference number intercalated electrolyte and 3D Li anode is more favorable to suppress Li dendrites in a working battery. The solid‐state batteries based on LiFePO₄ (Al₂O₃ @ LiNi_0.5Co_0.2Mn_0.3O₂), CSE, and 3D Li deliver admirable cycling stability with discharge capacity 145.9 mAh g^?1 (150.7 mAh g^?1) and capacity retention 91.9% after 200 cycles at 0.5 C (92.0% after 100 cycles at 0.2 C) at 25 °C. This work affords a splendid strategy for high‐performance solid‐state battery.     

3D Porous Cu Current Collector/Li‐Metal Composite Anode for Stable Lithium‐Metal Batteries

Lithium‐metal batteries are of particular interest for next‐generation electrical energy storage because of their high energy density on both volumetric and gravimetric bases. Effective strategies to stabilize the Li‐metal anode are the prerequisite for the progress of these exceptional storage technologies, such as Li–S and Li–O₂ batteries. Various challenges, such as uneven Li electrodeposition, anode volume expansion, and dendrite‐induced short‐circuit have hindered the practical application of rechargeable Li‐metal batteries. Herein, a one‐step facile and cost‐effective strategy for stabilizing lithium‐metal batteries via 3D porous Cu current collector/Li‐metal composite anode is reported. The porous structure of the composite electrode provides a “cage” for the redeposition of “hostless” lithium and accommodates the anode volume expansion during cycling. Compared with planar Cu foil, its high specific surface area favors the electrochemical reaction kinetics and lowers the local current density along the anode. It leads to low interfacial resistance and stabilizes the Li electrodeposition. On this basis, galvanostatic measurements are performed on both symmetric cells and Li/Li₄Ti₅O₁₂ cells and it is found that the electrodes exhibit exceptional abilities of promoting cell lifetime and stabilizing the cycling behavior. Although this work focuses on lithium metal, this novel tactic is easy to generalize to other metal electrodes.     

Platinum‐Coated Hollow Graphene Nanocages as Cathode Used in Lithium‐Oxygen Batteries

One of the formidable challenges facing aprotic lithium‐oxygen (Li‐O₂) batteries is the high charge overpotential, which induces the formation of byproducts, loss in efficiency, and poor cycling performance. Herein, the synthesis of the ultrasmall Pt‐coated hollow graphene nanocages as cathode in Li‐O₂ batteries is reported. The charge voltage plateau can reduce to 3.2 V at the current density of 100 mA g^?1, even maintain below 3.5 V when the current density increased to 500 mA g^?1. The unique hollow graphene nanocages matrix can not only provide numerous nanoscale tri‐phase regions as active sites for efficient oxygen reduction, but also offer sufficient amount of mesoscale pores for rapid oxygen diffusion. Furthermore, with strong atomic‐level oxygen absorption into its subsurface, ultrasmall Pt catalytically serves as the nucleation site for Li₂O₂ growth. The Li₂O₂ is subsequently induced into a favorable form with small size and amorphous state, decomposed more easily during recharge. Meanwhile, the conductive hollow graphene substrate can enhance the catalytic activity of noble metal Pt catalysts due to the graphene‐metal interfacial interaction. Benefiting from the above synergistic effects between the hollow graphene nanocages and the nanosized Pt catalysts, the ultrasmall Pt‐decorated graphene nanocage cathode exhibits enhanced electrochemical performances.     

Engineering Wavy‐Nanostructured Anode Interphases with Fast Ion Transfer Kinetics: Toward Practical Li‐Metal Full Batteries

Fast Li‐metal depletion and severe anode pulverization are the most critical obstacles for the energy‐dense Li‐metal full batteries using thin Li‐metal anodes (<50 µm). Here, a wavy‐nanostructured solid electrolyte interphase (SEI) with fast ion transfer kinetics is reported, which can promote high‐efficiency Li‐metal plating/stripping (>98% at 4 mAh cm^?2) in conventional carbonate electrolyte. Cryogenic transmission electron microscopy (cryo‐TEM) further reveals the fundamental relationship between wavy‐nanostructured SEI, function, and the electrochemical performance. The wavy SEI with greatly decreased surface diffusion resistance can realize grain coarsening of Li‐metal deposition and exhaustive dissolution of active Li‐metal during the stripping process, which can effectively alleviate “dead Li” accumulation and anode pulverization problems in practical full cells. Under highly challenging conditions (45 µm Li‐metal anodes, 4.3 mAh cm^?2 high capacity LiNi_0.8Mn_0.1Co_0.1O₂ cathodes), full cells exhibit significantly improved cycling lifespan (170 cycles; 20 cycles for control cells) via the application of wavy SEI.     

Highly Improved Rate Capability for a Lithium‐Ion Battery Nano‐Li4Ti5O12 Negative Electrode via Carbon‐Coated Mesoporous Uniform Pores with a Simple Self‐Assembly Method

A mesostructured spinel Li₄Ti₅O₁₂ (LTO)‐carbon nanocomposite (denoted as Meso‐LTO‐C) with large (>15 nm) and uniform pores is simply synthesized via block copolymer self‐assembly. Exceptionally high rate capability is then demonstrated for Li‐ion battery (LIB) negative electrodes. Polyisoprene‐block‐poly(ethylene oxide) (PI‐b‐PEO) with a sp²‐hybridized carbon‐containing hydrophobic block is employed as a structure‐directing agent. Then the assembled composite material is crystallized at 700 °C enabling conversion to the spinel LTO structure without loss of structural integrity. Part of the PI is converted to a conductive carbon that coats the pores of the Meso‐LTO‐C. The in situ pyrolyzed carbon not only maintains the porous mesostructure as the LTO is crystallized, but also improves the electronic conductivity. A Meso‐LTO‐C/Li cell then cycles stably at 10 C‐rate, corresponding to only 6 min for complete charge and discharge, with a reversible capacity of 115 mA h g^?1 with 90% capacity retention after 500 cycles. In sharp contrast, a Bulk‐LTO/Li cell exhibits only 69 mA h g^?1 at 10 C‐rate. Electrochemical impedance spectroscopy (EIS) with symmetric LTO/LTO cells prepared from Bulk‐LTO and Meso‐LTO‐C cycled in different potential ranges reveals the factors contributing to the vast difference between the rate‐capabilities. The carbon‐coated mesoporous structure enables highly improved electronic conductivity and significantly reduced charge transfer resistance, and a much smaller overall resistance is observed compared to Bulk‐LTO. Also, the solid electrolyte interphase (SEI)‐free surface due to the limited voltage window (>1 V versus Li/Li⁺) contributes to dramatically reduced resistance.