Uniform nanoplating of metallic magnesium film on titanium dioxide nanotubes as a skeleton for reversible Na metal anode

To meet the low-cost concept advocated by the sodium metal anode,this paper reports the use of a pulsed electrodeposition technology with ionic liquids as electrolytes to achieve uniform nanoplating of metallic magnesium films at around 20 nm on spaced titanium dioxide(TiO_(2))nanotubes(STNA-Mg).First,the sodiophilic magnesium metal coating can effectively reduce the nucleation overpotential of sodium metal.Moreover,three-dimensional STNA can limit the volume expansion during sodium metal plating and stripping to achieve the ultrastable deposition and stripping of sodium metals with a high Coulombic efficiency of up to 99.5%and a small voltage polarization of 5 mV in symmetric Na||Na batteries.In addition,the comparative study of sodium metal deposition behavior of STNA-Mg and STNA-Cu prepared by the same route further confirmed the advantage of magnesium metal to guide sodium metal growth.Finally,the prepared STNA-Mg-Na metal anode and commercial sodium vanadium phosphate cathode were assembled into a full cell,delivering a discharge capacity of 110.2 mAh·g^(-1)with a retention rate of 95.6%after 110 cycles at 1C rate.

Carbon-based interface engineering and architecture design for high-performance lithium metal anodes

Metallic lithium(Li)is considered the“Holy Grail”anode material for the nextgeneration of Li batteries with high energy density owing to the extraordinary theoretical specific capacity and the lowest negative electrochemical potential.However,owing to inhomogeneous Li-ion flux,Li anodes undergo uncontrollable Li deposition,leading to limited power output and practical applications.Carbon materials and their composites with controllable structures and properties have received extensive attention to guide the homogeneous growth of Li to achieve high-performance Li anodes.In this review,the correlation between the behavior of Li anode and the properties of carbon materials is proposed.Subsequently,we review emerging strategies for rationally designing high-performance Li anodes with carbon materials,including interface engineering(stabilizing solid electrolyte interphase layer and other functionalized interfacial layer)and architecture design of host carbon(constructing three-dimension structure,preparing hollow structure,introducing lithiophilic sites,optimizing geometric effects,and compositing with Li).Based on the insights,some prospects on critical challenges and possible future research directions in this field are concluded.It is anticipated that further innovative works on the fundamental chemistry and theoretical research of Li anodes are needed.

Achieving an ion-homogenizing and corrosion-resisting interface through nitro-coordination chemistry for stable zinc metal anodes

Suppression of uncontrollable dendrite growth and water-induced side reactions of Zn metal anodes is crucial for achieving long-lasting cycling stability and facilitating the practical implementations of aqueous Zn-metal batteries.To address these challenges,we report in this study a functional nitro-cellulose interfacial layer(NCIL)on the surface of Zn anodes enlightened by a nitro-coordination chemistry strategy.The NCIL exhibits strong zincophilicity and superior coordination capability with Zn^(2+)due to the highly electronegative and highly nucleophilic nature of the nitro functional group.This characteristic facilitates a rapid Zn-ion desolvation process and homogeneous Zn plating,effectively preventing H_(2) evolution and dendrite formation.Additionally,the negatively charged surface of NCIL acts as a shield,repelling SO_(4)^(2-)anions and inhibiting corrosive reactions on the Zn surface.Remarkably,reversible and stable Zn plating/stripping is achieved for over 5100 h at a current density of 1 mA cm^(-2),which is nearly 30 times longer than that of bare Zn anodes.Furthermore,the Zn/V_(2)O_(5) full cells with the functional interface layer deliver a high-capacity retention of 80.3%for over 10,000 cycles at 5 A g^(-1).This research offers valuable insights for the rational development of advanced protective interface layers in order to achieve ultra-long-lifeZnmetal batteries.

Bilayer separator enabling dendrite-free zinc anode with ultralong lifespan >5000 h

Aqueous zinc(Zn)batteries with Zn metal anodes are promising clean energy storage devices with intrinsic safety and low cost.However,Zn dendrite growth severely restricts the use of Zn anodes.To effectively suppress Zn dendrite growth,we propose a bilayer separator consisting of commercial butter paper and glassfiber membrane.The dense cellulose-based butter paper(BP)with low zincophilicity and high mechanical properties prevents the pore-filling behavior of deposited Zn and related separator piercing,effectively suppressing the Zn dendrite growth.As a result,the bilayer separators endow the ZnjjZn symmetrical batteries with a superlong cycling life of Zn anodes(over 5000 h)at 0.5 mA cm^(-2) and the full batteries enhanced capacity retention,demonstrating the advancement of the bilayer separator to afford excellent cyclability of aqueous metal batteries.

Towards advanced zinc anodes by interfacial modification strategies for efficient aqueous zinc metal batteries

Developing sustainable and clean energy sources(e.g.,solar,wind,and tide energy)is essential to achieve the goal of carbon neutrality.Due to the discontinuous and inco nsistent nature of common clean energy sources,high-performance energy storage technologies are a critical part of achieving this target.Aqueous zinc metal batteries(AZMBs)with inherent safety,low cost,and competitive performance are regarded as one of the promising candidates for grid-scale energy storage.However,zinc metal anodes(ZMAs)with irreversible problems of dendrite growth,hydrogen evolution reaction,self-corrosio n,and other side reactions have seriously hindered the development and commercialization of AZMBs.An increasing number of researchers are focusing on the stability of ZMAs,so assessing the effectiveness of existing research strategies is critical to the development of AZMBs.This review aims to provide a comprehensive overview of the fundamentals and challenges of AZMBs.Resea rch strategies for interfacial modification of ZMAs are systematically presented.The features of artificial interfacial coating and in-situ interfacial coating of ZMAs are compared and discussed in detail,as well as the effect of modified interfacial ZMA on the full-battery performance.Finally,perspectives are provided on the problems and challenges of ZMAs.This review is expected to offer a constructive reference for the further development and commercialization of AZMBs.

A layered multifunctional framework based on polyacrylonitrile and MOF derivatives for stable lithium metal anode

Composite Li metal anodes based on three-dimensional(3D) porous frameworks have been considered as an effective material for achieving stable Li metal batteries with high energy density.However,uneven Li deposition behavior still occurs at the top of 3D frameworks owing to the local accumulation of Li ions.To promote uniform Li deposition without top dendrite growth,herein,a layered multifunctional framework based on oxidation-treated polyacrylonitrile(OPAN) and metal-organic framework(MOF) derivatives was proposed for rationally regulating the distribution of Li ions flux,nucleation sites,and electrical conductivity.Profiting from these merits,the OPAN/carbon nano fiber-MOF(CMOF) composite framework demonstrated a reversible Li plating/stripping behavior for 500 cycles with a stable Coulombic efficiency of around 99.0% at the current density of 2 mA/cm~2.Besides,such a Li composite anode exhibited a superior cycle lifespan of over 1300 h under a low polarized voltage of 18 mV in symmetrical cells.When the Li composite anode was paired with LiFePO_(4)(LFP) cathode,the obtained full cell exhibited a stable cycling over 500 cycles.Moreover,the COMSOL Multiphysics simulation was conducted to reveal the effects on homogeneous Li ions distribution derived from the above-mentioned OPAN/CMOF framework and electrical insulation/conduction design.These electrochemical and simulated results shed light on the difficulties of designing stable and safe Li metal anode via optimizing the 3D frameworks.

Surface Patterning of Metal Zinc Electrode with an In‑Region Zincophilic Interface for High‑Rate and Long‑Cycle‑Life Zinc Metal Anode

The undesirable dendrite growth induced by non-planar zinc(Zn)deposition and low Coulombic efficiency resulting from severe side reactions have been long-standing challenges for metallic Zn anodes and substantially impede the practical application of rechargeable aqueous Zn metal batteries(ZMBs).Herein,we present a strategy for achieving a high-rate and long-cycle-life Zn metal anode by patterning Zn foil surfaces and endowing a Zn-Indium(Zn-In)interface in the microchannels.The accumulation of electrons in the microchannel and the zincophilicity of the Zn-In interface promote preferential heteroepitaxial Zn deposition in the microchannel region and enhance the tolerance of the electrode at high current densities.Meanwhile,electron aggregation accelerates the dissolution of non-(002)plane Zn atoms on the array surface,thereby directing the subsequent homoepitaxial Zn deposition on the array surface.Consequently,the planar dendrite-free Zn deposition and long-term cycling stability are achieved(5,050 h at 10.0 mA cm^(−2) and 27,000 cycles at 20.0 mA cm^(−2)).Furthermore,a Zn/I_(2) full cell assembled by pairing with such an anode can maintain good stability for 3,500 cycles at 5.0 C,demonstrating the application potential of the as-prepared ZnIn anode for high-performance aqueous ZMBs.

Hard-carbon hybrid Li-ion/metal anode enabled by preferred mesoporous uniform lithium growth mechanism

To achieve high energy density in lithium batteries,the construction of lithium-ion/metal hybrid anodes is a promising strategy.In particular,because of the anisotropy of graphite,hybrid anode formed by graphite/Li metal has low transport kinetics and is easy to causes the growth of lithium dendrites and accumulation of dead Li,which seriously affects the cycle life of batteries and even causes safety problems.Here,by comparing graphite with two types of hard carbon,it was found that hybrid anode formed by hard carbon and lithium metal,possessing more disordered mesoporous structure and lithophilic groups,presents better performance.Results indicate that the mesoporous structure provides abundant active site and storage space for dead lithium.With the synergistic effect of this structure and lithophilic functional groups(–COOH),the reversibility of hard carbon/lithium metal hybrid anode is maintained,promoting uniform deposition of lithium metal and alleviating formation of lithium dendrites.The hybrid anode maintains a 99.5%Coulombic efficiency(CE)after 260 cycles at a specific capacity of 500 m Ah/g.This work provides new insights into the hybrid anodes formed by carbon-based materials and lithium metal with high specific energy and fast charging ability.

Gas treatment protection of metallic lithium anode

The effects of different coating layers on lithium metal anode formed by reacting with different controlled atmospheres（argon,CO_2–O_2（2：1）,N_2,and CO_2–O_2–N_2（2：1：3））have been investigated.The obtained XRD,second ion mass spectroscopy（SIMS）,and scanning probe microscope（SPM）results demonstrate the formation of coating layers composed of Li_2CO_3,Li_3N,and the mixture of them on lithium tablets,respectively.The Li/Li symmetrical cell and Li/S cell are assembled to prove the advantages of the protected lithium tablet on electrochemical performance.The comparison of SEM and SIMS characterizations before/after cycles clarifies that an SEI-like composition formed on the lithium tablets could modulate the interfacial stabilization between the lithium foil and the ether electrolyte.

In situ generation of Li_(3)N concentration gradient in 3D carbon-based lithium anodes towards highly-stable lithium metal batteries

The uncontrolled dendrite growth of lithium metal anodes(LMAs)caused by unstable anode/electrolyte interface and uneven lithium deposition have impeded the practical applications of lithium metal batteries(LMBs).Constructing a robust artificial solid electrolyte interphase(SEI)and regulating the lithium deposition behavior is an effective strategy to address these issues.Herein,a three-dimensional(3D)lithium anode with gradient Li_(3)N has been in-situ fabricated on carbon-based framework by thermal diffusion method(denoted as CC/Li/Li_(3)N).Density functional theory(DFT)calculations reveal that Li_(3)N can effectively promote the transport of Li^(+)due to the low energy barrier of Li^(+)diffusion.As expected,the Li_(3)N-rich conformal artificial SEI film can not only effectively stabilize the interface and avoid parasitic reactions,but also facilitate fast Li^(+)transport across the SEI layer.The anode matrix with uniformly distributed Li3N can enable homogenous deposition of Li,thus preventing Li dendrite propagation.Benefiting from these merits,the CC/Li/Li_(3)N anode achieves ultralong-term cycling for>1000 h at a current density of 2 m A cm^(-2)and dendrite-free Li deposition at an ultrahigh rate of 20 m A cm^(-2).Moreover,the full cells coupled with LiFePO4cathodes show extraordinary cycling stability for>300 cycles in liquidelectrolyte-based batteries and display a high-capacity retention of 96.7%after 100 cycles in solid-state cells,demonstrating the promising prospects for the practical applications of LMBs.

3D Artificial Array Interface Engineering Enabling Dendrite-Free Stable Zn Metal Anode

The ripple effect induced by uncontrollable Zn deposition is considered as the Achilles heel for developing high-performance aqueous Zn-ion batteries.For this problem,this work reports a design concept of 3D artificial array interface engineering to achieve volume stress elimination,preferred orientation growth and dendrite-free stable Zn metal anode.The mechanism of MXene array interface on modulating the growth kinetics and deposition behavior of Zn atoms were firstly disclosed on the multi-scale level,including the in-situ optical microscopy and transient simulation at the mesoscopic scale,in-situ Raman spectroscopy and in-situ X-ray diffraction at the microscopic scale,as well as density functional theory calculation at the atomic scale.As indicated by the electrochemical performance tests,such engineered electrode exhibits the comprehensive enhancements not only in the resistance of corrosion and hydrogen evolution,but also the rate capability and cyclic stability.High-rate performance(20 mA cm^(-2))and durable cycle lifespan(1350 h at 0.5 mA cm^(-2),1500 h at 1 mA cm^(-2)and 800 h at 5 mA cm^(-2))can be realized.Moreover,the improvement of rate capability(214.1 mAh g^(-1)obtained at 10 A g^(-1))and cyclic stability also can be demonstrated in the case of 3D MXene array@Zn/VO2battery.Beyond the previous 2D closed interface engineering,this research offers a unique 3D open array interface engineering to stabilize Zn metal anode,the controllable Zn deposition mechanism revealed is also expected to deepen the fundamental of rechargeable batteries including but not limited to aqueous Zn metal batteries.

Lithiophilicity: The key to efficient lithium metal anodes for lithium batteries

Lithium metal anode of lithium batteries,including lithium-ion batteries,has been considered the anode for next-generation batteries with desired high energy densities due to its high theoretical specific capacity(3860 mA h g^(-1))and low standards electrode potential(-3.04 V vs.SHE).However,the highly reactive nature of metallic lithium and its direct contact with the electrolyte could lead to severe chemical reactions,leading to the continuous consumption of the electrolyte and a reduction in the cycle life and Coulombic efficiency.In addition,the solid electrolyte interface formed during battery cycling is mainly inorganic,which is too fragile to withstand the extreme volume change during the plating and stripping of lithium.The uneven flux of lithium ions could lead to excessive lithium deposition at local points,resulting in needle-like lithium dendrites,which could pierce the separator and cause short circuits,battery failure,and safety issues.In the last five years,tremendous efforts have been dedicated to addressing these issues,and the most successful improvements have been related to lithiophilicity optimizations.Thus,this paper comprehensively reviewed the lithiophilicity regulation in lithium metal anode modifications and highlighted the vital effect of lithiophilicity.The remaining challenges faced by the lithiophilicity optimization for lithium metal anodes are discussed with the proposed research directions for overcoming the technical challenges in this subject.

Recent advanced development of stabilizing sodium metal anodes

As the application of next-generation energy storage systems continues to expand,rechargeable secondary batteries with enhanced energy density and safety are imperative for energy iteration.Sodium-ion batteries(SIBs)have attracted extensive attention and are recognized as ideal candidates for large-scale energy storage due to the abundant sodium resources and low cost.Sodium metal anodes(SMAs)have been considered as one of the most attractive anode materials for SIBs owing to their high specific capacity(1166 mAh g^(-1)),low redox potential,and abundant natural resources.However,the uncontrollable dendrite growth and inevitable side reactions on SMA lead to the continuous deterioration of the electrochemical performance,causing serious safety concerns and limiting their practical application in the future.Therefore,the construction of stable dendrite-free SMAs is a pressing problem for advanced sodium metal batteries(SMBs).In this review,we comprehensively summarize the research progress in suppressing the formation of sodium dendrite,including artificial solid electrolyte interphase(SEI),liquid electrolyte modification,three-dimensional(3D)host materials,and solid-state electrolyte.Additionally,key aspects and prospects of future research directions for SMAs are highlighted.We hope that this timely review can provide an overall picture of sodium protection strategies and stimulate more research in the future.

In Situ Reaction Fabrication of a Mixed-Ion/Electron-Conducting Skeleton Toward Stable Lithium Metal Anodes

Lithium metal batteries are emerging as a strong candidate in the future energy storage market due to its extremely high energy density.However,the uncontrollable lithium dendrites and volume change of lithium metal anodes severely hinder its application.In this work,the porous Cu skeleton modified with Cu_(6)Sn_(5)layer is prepared via dealloying brass foil following a facile electroless process.The porous Cu skeleton with large specific surface area and high electronic conductivity effectively reduces the local current density.The Cu_(6)Sn_(5)can react with lithium during the discharge process to form lithiophilic Li_(7)Sn_(2)in situ to promote Li-ions transport and reduce the nucleation energy barrier of lithium to guide the uniform lithium deposition.Therefore,more than 300 cycles at 1 mA cm^(−2)are achieved in the half-cell with an average Coulombic efficiency of 97.5%.The symmetric cell shows a superior cycle life of more than 1000 h at 1 mA cm^(−2)with a small average hysteresis voltage of 16 mV.When coupled with LiFePO_(4)cathode,the full cell also maintains excellent cycling and rate performance.

Review on lithium metal anodes towards high energy density batteries

Lithium metal anode(LMA) is a promising candidate for achieving next-generation high-energy-density batteries due to its ultrahigh theoretical capacity and most negative electrochemical potential. However, the practical application of lithium metal battery(LMB) is largely retarded by the instable interfaces, uncontrolled dendrites, and rapid capacity deterioration. Herein, we present a comprehensive overview towards the working principles and inherent challenges of LMAs. Firstly, we diligently summarize the intrinsic mechanism of Li stripping and plating process. The recent advances in atomic and mesoscale simulations which are crucial in guiding mechanism study and material design are also summarized. Furthermore, the advanced engineering strategies which have been proved effective in protecting LMAs are systematically reviewed, including electrolyte optimization, artificial interface, composite/alloy anodes and so on. Finally, we highlight the current limitations and promising research directions of LMAs. This review sheds new lights on deeply understanding the intrinsic mechanism of LMAs, and calls for more endeavors to realize practical Li metal batteries.

Elucidating the suppression of lithium dendrite growth with a void-reduced anti-perovskite solid-state electrolyte pellet for stable lithium metal anodes

Solid-state lithium-metal batteries,with their high theoretical energy density and safety,are highly promising as a next-generation battery contender.Among the alternatives proposed as solid-state electrolyte,lithium-rich anti-perovskite(Li RAP)materials have drawn the most interest because of high theoretical Li^(+)conductivity,low cost and easy processing.Although solid-state electrolytes are believed to have the potential to physically inhibit the lithium dendrite growth,lithium-metal batteries still suffer from the lithium dendrite growth and thereafter the short circuiting.The voids in practical Li RAP pellets are considered as the root cause.Herein,we show that reducing the voids can effectively suppress the lithium dendrite growth.The voids in the pellet resulted in an irregular Li^(+)flux distribution and a poor interfacial contact with lithium metal anode;and hence the ununiform lithium dendrites.Consequently,the lithium-metal symmetric cell with void-reduced Li_(2)OHCl-HT pellet was able to display excellent cycling performance(750 h at 0.4 m A cm^(-2))and stability at high current density(0.8 m A cm^(-2)for 120 h).This study provides not only experimental evidence for the impact of the voids in Li RAP pellets on the lithium dendrite growth,but also a rational pellet fabrication approach to suppress the lithium dendrite growth.

Reinforced interface endows the lithium anode with stable cycle at high-temperature of 80℃

Embracing ultrahigh theoretical capacity of 3860 mA h g^(-1)and the lowest reduction potential of-3.04 V(versus standard hydrogen electrode),lithium(Li) is considered as the "holy grail" material for pursuing higher energy density,of which application has been challenged due to the unstable interface caused by the non-uniform electrodeposition as well as high chemical activity.Operating at higher temperature can be recommended to uniform electrodeposition of Li metal.Nevertheless,the intrinsic side-reaction between Li metal anode and electrolyte is inevitably aggravated and thus fosters the failure of Li metal anode rapidly with uneven electrodeposition.Here,a kind of temperature-tolerated ionic liquid(1-methyl-3-ethylimidazole bis(fluorosulfo nyl)imide/lithium bis(trifluoromethylsulfo nyl)imide,EF/LT)based electrolyte that matrixed with poly(vinylidene fluoride-hexafluoropropylene) was designed to maintain the interfacial stabilization of Li metal due to the weak interfacial reaction and uniform electrodeposition at high temperature of 80℃.It is the matter that the 660-h cycle with lower polarization is achieved with EF/LT-based electrolyte at temperature of 80 ℃ and the full cell embraces outstanding cyclic performance,without capacity fading within 100 cycles.Delighting,a door for practical application of Li metal anode for higher energy density as the carbon neutrality progresses in the blooming human society has been opened gradually.

Full-chain enhanced ion transport toward stable lithium metal anodes

The dendrite growth that results from the slow electrode process kinetics prevents the lithium(Li) metal anode from being used in practical applications. Here, full-chain enhanced ion transport for stabilizing Li metal anodes is proposed. Experimental and theoretical studies confirm that full-chain enhanced ion transport(electrocrystallization, mass transport in the electrolyte and diffusion in solid electrolyte interphase) under magnetoelectrochemistry contributes to a homogeneous, dense, and dendrite-free morphology. Specifically, the enhanced electrocrystallization behavior promotes the Li nucleation;the enhanced mass transport in the electrolyte alleviates the ion concentration gradient at the electrode surface, which helps to inhibit dendrite growth;and the enhanced diffusion in the solid electrolyte interphase further homogenizes the Li deposition behavior, obtaining regular and uniform Li particles.Consequently, the Li metal anode has exceptional cycling stability in both symmetric and full cells,and the pouch cell performs long cycles(170 cycles) in practice evaluation. This work advances fundamental knowledge of the magneto-dendrite effect and offers a new perspective on stabilizing metal anodes.

Unraveling the heterogeneity of solid electrolyte interphase kinetically affecting lithium electrodeposition on lithium metal anode

The stability and uniformity of solid electrolyte interphase(SEI)are critical for clarifying the origin of capacity fade and safety issues for lithium metal anodes(LMA).However,understanding the interplay of SEI heterogeneity and Li electrodeposition is limited by the coupling of complex electrochemistry and mechanics processes.Herein,the correlation between the SEI failure behavior and Li deposition morphology is investigated through a quantitative electrochemical-mechanical model.The local deformation and stress of SEI during Li electrodeposition identify that the heterogeneous interface between different components first fails.Compared with the well-known mechanical strength,component uniformity plays the most important role in the initial SEI failure and uneven Li deposition,and a relative component uniformity(p>0.01)represents a proper balance to ensure the stability of the naturally heterogeneous SEI.Furthermore,the component regulation of SEI via the designed electrolyte experimentally demonstrates that improving component uniformity benefits SEI stability and the uniform Li electrodeposition for LMA,thereby increasing the capacity by~20%after 300 cycles.These fundamental understandings and proposed strategy can be not only used to guide the SEI optimization via the electrolyte regulation,but also extended to the rational designs of artificial SEI for high-performance LMA.

Sulfur-doped hard carbon hybrid anodes with dual lithium-ion/metal storage bifunctionality for high-energy-density lithium-ion batteries

Bifunctional hybrid anodes(BHAs),which are both a high-performance active host material for lithium-ion storage as well as a guiding agent for homogeneous lithium metal nucleation and growth,exhibit significant potential as anodes for next-generation high-energy-density lithium-ion batteries(LIBs).In this study,sulfur-doped hard carbon nanosphere assemblies(S-HCNAs)were prepared through a hydrothermal treatment of a liquid organic precursor,followed by high-temperature thermal annealing with elemental sulfur for application as BHAs for LIBs.In a carbonate-based electrolyte containing fluoroethylene carbonate additive,the S-HCNAs showed high lithium-ion storage capacities in sloping as well as plateau voltage sections,good rate capabilities,and stable cyclabilities.In addition,high average Coulombic efficiencies(CEs)of~96.9%were achieved for dual lithium-ion and lithium metal storage cycles.In the LIB full-cell tests with typical NCM811 cathodes,the S-HCNA-based BHAs containing~400 mA h g^(−1) of excess lithium led to high energy and power densities of~500Wh kg^(−1) and~1695Wkg^(−1),respectively,and a stable cycling performance with~100%CEs was achieved.