Tailoring the Spatial Distribution and Content of Inorganic Nitrides in Solid-Electrolyte Interphases for the Stable Li Anode in Li-S Batteries

Among the alternatives to lithium-ion batteries,lithium-sulfur(Li-S)batteries are considered as an attractive option because of their high theoretical energy density of 2570 Wh kg^(−1).However,the application of the Li-S battery has been plagued by the rapid failure of the Li anode due to the Li dendrite growth and severe parasitic reactions between Li and lithium polysulfides.The physicochemical properties of the solid-electrolyte interphase have a profound impact on the performance of the Li anode.Herein,a lithium polyacrylic acid/lithium nitrate(LPL)-protective layer is developed to inhibit the dendrite Li growth and parasitic reactions by tailoring the spatial distribution and content of LiN_(x)O_(y) and Li_(3)N at the SEI.The modified SEI is thoroughly investigated for compositions,ion transport properties,and Li plating/stripping kinetics.Consequently,the Li-S cell with a high S loading cathode(5.0 mg cm^(−2)),LPL layer-protected thin Li anode(50μm),and 40μL electrolyte shows a long life span of 120 cycles.This work evokes the avenue for regulating the spatial distribution of inorganic nitride at the SEI to suppress the formation of Li dendrites and parasitic reactions in Li-S batteries and perhaps guiding the design of analogous battery systems.

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.

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.

Facile construction of a water-defendable Li anode protection enables rechargeable Li-O_(2) battery operating in humid atmosphere

The rechargeable Li-O_(2) battery endowed with high theoretical specific energy density has sparked intense research interest as a promising energy storage system. However, the intrinsic high activity of Li anode,especially to moisture, usually leads to inferior electrochemical performance of Li-O_(2) battery in humid environments, hindering its widespread application. To settle the trouble of poor moisture tolerance, fabricating a water-proof layer on the Li-metal anode could be an effective tactic. Herein, a facile strategy for constructing an ibuprofen-based protective layer on the Li anode has been proposed to realize highly rechargeable Li-O_(2) battery in humid atmosphere. Due to the in-situ reaction between ibuprofen reagent and metallic Li, the protective layer with a thickness of ~30 μm has been uniformly deposited on the surface of Li anode. Particularly, the protective layer, consisting of a large amount of hydrophobic alkyl group and benzene ring, can significantly resist water ingress and enhance the electrochemical stability of Li anode. As a result, the Li-O_(2) battery based on the protected Li anode achieves a long cycle life of 210 h(21 cycles at 1000 m Ah/g, 200 m A/g) in highly moist atmosphere with relative humidity(RH) of68%. This convenient and efficient strategy offers novel design concept of water-resistant metal anode,and paves the way to the promising future prospect for the high-energy Li-O_(2) battery implementing in the ambient atmosphere.

A 10-μm Ultrathin Lithium Metal Composite Anodes with Superior Electrochemical Kinetics and Cycling Stability

Lithium metal is a promising candidate for the promotion of the next generation high energy density batteries.The employment of ultrathin Li metal anode with controllable thickness could enable a higher efficiency of Li utilization.Herein,a simple method to fabricate free-standing 10μm ultrathin Li metal anode is developed in this work.A three-dimensional MnO_(x)-coated CNT framework is constructed through a facile hydrothermal process,utilizing as a host for molten Li infusion,which could not only put forward a simple strategy to modulate the thickness of Li metal film but also restricts the volume expansion.The abundant MnO_(x)nanoparticles acting as lithiophilic sites reduce the Li nucleation barrier and optimize the electrochemical kinetics at the anode/electrolyte interface.As a result,the ultrathin Li composite anode exhibits a superior lifespan expanded to 2000 cycles in a symmetric cell,as well as a better capacity and rate capability than that of bare Li anode in full cell,fulfilling the requirements of high energy density and stable cycling life.Furthermore,a wave-shaped Li metal pouch cell based on the ultrathin Li composite anode is assembled that exhibits remarkable mechanical bending toleration and cyclic stability,demonstrating large potential application in the field of flexible wearable devices.

Revealing the importance of suppressing formation of lithium hydride and hydrogen in Li anode protection

The reviving of the“Holy Grail”lithium metal batteries(LMBs)is greatly hindered by severe parasitic reactions between Li anode and electrolytes.Herein,first,we comprehensively summarize the failure mechanisms and protection principles of the Li anode.Wherein,despite being in dispute,the formation of lithium hydride(LiH)is demonstrated to be one of the most critical factors for Li anode pulverization.Secondly,we trace the research history of LiH at electrodes of lithium batteries.In LMBs,LiH formation is suggested to be greatly associated with the generation of H_(2)from Li/electrolyte intrinsic parasitic reactions,and these intrinsic reactions are still not fully understood.Finally,density functional theory calculations reveal that H_(2)adsorption ability of representative Li anode protective species(such as LiF,Li_(3)N,BN,Li_(2)O,and graphene)is much higher than that of Li and LiH.Therefore,as an important supplement of well-known lithiophilicity theory/high interfacial energy theory and three key principles(mechanical stability,uniform ion transport,and chemical passivation),we propose that constructing an artificial solid electrolyte interphase layer enriched of components with much higher H_(2)adsorption ability than Li will serve as an effective principle for Li anode protection.In summary,suppressing formation of LiH and H_(2)will be very important for cycle life enhancement of practical LMBs.

NbN quantum dots anchored hollow carbon nanorods as efficient polysulfide immobilizer and lithium stabilizer for Li-S full batteries

The shuttle effect of lithium polysulfides(LiPSs)and uncontrollable lithium dendrite growth seriously hinder the practical application of lithium-sulfur(Li-S)batteries.To simultaneously address such issues,monodispersed Nb N quantum dots anchored on nitrogen-doped hollow carbon nanorods(NbN@NHCR)are elaborately developed as efficient Li PSs immobilizer and Li stabilizer for high-performance Li-S full batteries.Density functional theory(DFT)calculations and experimental characterizations demonstrate that the sulfiphilic and lithiophilic NbN@NHCR hybrid can not only efficiently immobilize the soluble Li PSs and facilitate diffusion-conversion kinetics for alleviating the shuttling effect,but also homogenize the distribution of Li+ions and regulate uniform Li deposition for suppressing Li-dendrite growth.As a result,the assembled Li-S full batteries(NbN@NHCR-S||Nb N@NHCR-Li)deliver excellent long-term cycling stability with a low decay rate of 0.031%per cycle over 1000 cycles at high rate of 2 C.Even at a high S loading of 5.8 mg cm^(-2)and a low electrolyte/sulfur ratio of 5.2μL mg^(-1),a large areal capacity of 6.2 mA h cm^(-2)can be achieved in Li-S pouch cell at 0.1 C.This study provides a new perspective via designing a dual-functional sulfiphilic and lithiophilic hybrid to address serious issues of the shuttle effect of S cathode and dendrite growth of Li anode.

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.

Fast capture and stabilization of Li‐ions via physicochemical dual effects for an ultra‐stable self‐supporting Li metal anode

Lithium(Li)metal is regarded as one of the most promising anode candidates for next-generation batteries due to its extremely high specific capacity and low redox potential.However,its application is still hindered by the uncontrolled growth of dendritic Li and huge volume fluctuation during cycles.To address these issues,flexible and self-supporting three-dimensional(3D)interlaced Ndoped carbon nanofibers(NCNFs)coated with uniformly distributed 2D ultrathin NiCo_(2)S_(4)nanosheets(denoted CNCS)were designed to eliminate the intrinsic hotspots for Li deposition.Physicochemical dual effects of CNCS arise from limited surface Li diffusivity with a higher Li affinity,leading to uniform Li nucleation and less random accumulation of Li,as confirmed by ab initio molecular dynamics simulations.Due to the unique structure,exchange current density is reduced significantly and metallic Li is further contained within the interspace between the NCNF and NiCo_(2)S_(4)nanosheets,preventing the formation of dendritic Li.The symmetric cell with a Li/CNCS composite anode shows a long-running lifespan for almost 1200 h,with an exceptionally low and stable overpotential under 1mA cm^(-2)/1 mAh cm^(-2).A full cell coupled with a LiFePO4 cathode at a low N/P ratio of 2.45 shows typical voltage profiles but more significantly enhanced performance than that of a LiFePO4 cathode coupled with a bare Li anode.

Stable lithium metal anode enabled by a robust artificial fluorinated hybrid interphase

One of the key challenges for achieving stable lithium(Li) metal anode is the construction of the rational solid electrolyte interphase(SEI),but its realization still faces enormous challenges.In this work,a robust artificial fluorinated hybrid interphase consisting of lithium-bismuth(Li3Bi) alloy and lithium-fluoride(LiF) was designed to regulate Li deposition without Li dendrite growth.The obtained hybrid interphase showed the high Li+diffusion rate(3.5 × 10^(-4)S cm^(-1)),high electron resistivity(9.04 × 10^(4)Ω cm),and high mechanical strength(1348 MPa),thus enabling the uniform Li deposition at the Li/SEI interface.Specifically,Li3Bi alloy,as a superionic conductor,accelerated the Li+transport and stabilized the hybrid interphase.Meanwhile,LiF was identified as a superior electron-blocker to inhibit the electron tunneling from the Li anode into the SEI.As a result,the modified Li anode showed the stable Li plating/stripping behaviors over 1000 cycles even at 20 mA cm^(-2).Moreover,it also enabled the Li(50 μm)‖LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(4.4 mA h cm^(-2)) full cell to achieve an average Coulombic efficiency(CE) of 99.6%and a high-capacity retention of 79.2% after 100 cycles,whereas the bare Li anode only exhibited a low-capacity retention of 8.0%.This work sheds light on the internal mechanism of Li+transport within the hybrid interface and provides an effective approach to stabilize the interface of Li metal anode.

High-Performance 3D Li-B-C-Al Alloy Anode and its Twofold Li Electrostripping and Plating Mechanism Revealed by Synchrotron X-Ray Tomography

The uncontrollable Li electrostripping and plating process that results in dendritic Li growth and huge volume change of Li anode limits the practicality of Li metal batteries(LMBs).To simultaneously address these issues,designing three-dimensional(3D),lithiophilic and mechanically robust electrodes seems to be one of the cost-effective strategies.Herein,a new 3D Li-B-C-Al alloy anode is designed and fabricated.The prepared 3D alloy anode exhibits not only superior lithiophilicity that facilitates uniform Li nucleation and growth but also sufficient mechanical stability that maintains its structural integrity.Superior performance of the prepared 3D alloy is demonstrated through comprehensive electrochemical tests.In addition,non-destructive and 3D synchrotron X-ray computed tomography(SX-CT)technique is employed to investigate the underlying working mechanisms of the prepared alloy anode.A unique twofold Li electrostripping and plating mechanism under different electrochemical cycling conditions is revealed.Lastly,improved performance of the full cells built with the 3D alloy anode and LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)cathode corroborate its potential application capability.Overall,the current work not only showcases the superiority of the 3D alloy as potential anode material for LMBs but also provides fundamental insights into its underlying working mechanisms that may further propel its research and development.

Tuning Lithiophilicity and Stability of 3D Conductive Scaffold via Covalent Ag-S Bond for High-Performance Lithium Metal Anode

Li metal anode holds great promise to realize high-energy battery systems.However,the safety issue and limited lifetime caused by the uncontrollable growth of Li dendrites hinder its commercial application.Herein,an interlayer-bridged 3D lithiophilic rGO-Ag-S-CNT composite is proposed to guide uniform and stable Li plating/stripping.The 3D lithiophilic rGO-Ag-S-CNT host is fabricated by incorporating Ag-modified reduced graphene oxide(rGO)with S-doped carbon nanotube(CNT),where the rGO and CNT are closely connected via robust Ag-S covalent bond.This strong Ag-S bond could enhance the structural stability and electrical connection between rGO and CNT,significantly improving the electrochemical kinetics and uniformity of current distribution.Moreover,density functional theory calculation indicates that the introduction of Ag-S bond could further boost the binding energy between Ag and Li,which promotes homogeneous Li nucleation and growth.Consequently,the rGO-Ag-S-CNT-based anode achieves a lower overpotential(7.3 mV at 0.5 mA cm^(−2)),higher Coulombic efficiency(98.1%at 0.5 mA cm^(−2)),and superior long cycling performance(over 500 cycles at 2 mA cm−2)as compared with the rGO-Ag-CNT-and rGO-CNT-based anodes.This work provides a universal avenue and guidance to build a robust Li metal host via constructing a strong covalent bond,effectively suppressing the Li dendrites growth to prompt the development of Li metal battery.

Vesicle-shaped ZIF-8 shell shielded in 3D carbon cloth for uniform nucleation and growth towards long-life lithium metal anode

Lithium metal has aroused extensive research interests as the anode for next-generation rechargeable batteries.However,the well-known dendritic Li growth and consequent safety issues still impair the long-term cycling performance.Herein,a hybrid structure composed of 3 D carbon cloth and vesicleshaped hollow ZIF-8 modification shell(HZS@CC)was prepared as a smart host for guiding uniform Li deposition.The long-range interconnected 3 D carbon fiber network enables the reduced local current density with homogeneous electrons distribution.Synergistically,abundant surface polar groups and the ultrastructure on ZIF-8 particles effectively guide a well-distributed Li-ions flow to promote the uniform Li nucleation and growth.As a result,stable Li plating/stripping for 2000 h with a low overpotential(≈15 mV)at 1 mA cm^(-2) were achieved in symmetric cells.Coupling with LiFePO_(4) cathode,the full cell delivered long life over 1200 cycles at 6 C.This research demonstrated that a homogenization guiding of Li-ions is of great importance to better make use of the structural advantage of 3 D hosts and achieve improved electrochemical performance.

Dual-Functional Lithiophilic/Sulfiphilic Binary-Metal Selenide Quantum Dots Toward High-Performance Li-S Full Batteries

The commercial viability of lithium-sulfur batteries is still challenged by the notorious lithium polysulfides(Li PSs)shuttle effect on the sulfur cathode and uncontrollable Li dendrites growth on the Li anode.Herein,a bi-service host with Co-Fe binary-metal selenide quantum dots embedded in three-dimensional inverse opal structured nitrogen-doped carbon skeleton(3DIO FCSe-QDs@NC)is elaborately designed for both sulfur cathode and Li metal anode.The highly dispersed FCSe-QDs with superb adsorptive-catalytic properties can effectively immobilize the soluble Li PSs and improve diffusion-conversion kinetics to mitigate the polysulfide-shutting behaviors.Simultaneously,the 3D-ordered porous networks integrated with abundant lithophilic sites can accomplish uniform Li deposition and homogeneous Li-ion flux for suppressing the growth of dendrites.Taking advantage of these merits,the assembled Li-S full batteries with 3DIO FCSe-QDs@NC host exhibit excellent rate performance and stable cycling ability(a low decay rate of 0.014%over 2,000 cycles at 2C).Remarkably,a promising areal capacity of 8.41 mAh cm^(-2)can be achieved at the sulfur loading up to 8.50 mg cm^(-2)with an ultra-low electrolyte/sulfur ratio of 4.1μL mg^(-1).This work paves the bi-serve host design from systematic experimental and theoretical analysis,which provides a viable avenue to solve the challenges of both sulfur and Li electrodes for practical Li-S full batteries.

Dual-Functional Organotelluride Additive for Highly Efficient Sulfur Redox Kinetics and Lithium Regulation in Lithium–Sulfur Batteries

High energy density and low cost made lithium–sulfur(Li–S)batteries appealing for the next-generation energy storage devices.However,their commercial viability is seriously challenged by serious polysulfide shuttle effect,sluggish sulfur kinetics,and uncontrollable dendritic Li growth.Herein,a dual-functional electrolyte additive,diphenyl ditelluride(DPDTe)is reported for Li–S battery.For sulfur cathodes,DPDTe works as a redox mediator to accelerate redox kinetics of sulfur,in which Te radical-mediated catalytic cycle at the solid–liquid interface contributes significantly to the whole process.For lithium anodes,DPDTe can react with lithium metal to form a smooth and stable organic–inorganic hybrid solid-electrolyte interphase(SEI),enabling homogeneous lithium deposition for suppressing dendrite growth.Consequently,the Li–S battery with DPDTe exhibits remarkable cycling stability and superb rate capability,with a high capacity up to 1227.3 mAh g^(-1)and stable cycling over 300 cycles.Moreover,a Li–S pouch cell with DPDTe is evaluated as the proof of concept.This work demonstrates that organotelluride compounds can be used as functional electrolyte additives and offers new insights and opportunities for practical Li–S batteries.

Carbon materials for stable Li metal anodes: Challenges, solutions, and outlook

Lithium(Li)metal is regarded as the ultimate anode for next-generation Li-ion batteries due to its highest specific capacity and lowest electrochemical potential.However,the Li metal anode has limitations,including virtually infinite volume change,nonuniform Li deposition,and an unstable electrode-electrolyte interface,which lead to rapid capacity degradation and poor cycling stability,significantly hindering its practical application.To address these issues,intensive efforts have been devoted toward accommodating and guiding Li deposition as well as stabilizing the interface using various carbon materials,which have demonstrated excellent effectiveness,benefiting from their vast variety and excellent tunability of the structure-property relationship.This review is intended as a guide through the fundamental challenges of Li metal anodes to the corresponding solutions utilizing carbon materials.The specific functionalities and mechanisms of carbon materials for stabilizing Li metal anodes in these solutions are discussed in detail.Apart from the stabilization of the Li metal anode in liquid electrolytes,attention has also been paid to the review of anode-free Li metal batteries and solid-state batteries enabled by strategies based on carbon materials.Furthermore,we have reviewed the unresolved challenges and presented our outlook on the implementation of carbon materials for stabilizing Li metal anodes in practical applications.

Designer uniform Li plating/stripping through lithium–cobalt alloying hierarchical scaffolds for scalable high-performance lithium-metal anodes

Lithium metal anodes are of great interest for advanced high-energy density batteries such as lithiumair, lithium-sulfur and solid-state batteries, due to their low electrode potential and ultra-high theoretical capacity. There are, however, several challenges limiting their practical applications, which include low coulombic efficiency, the uncontrollable growth of dendrites and poor rate capability. Here, a rational design of 3D structured lithium metal anodes comprising of in-situ growth of cobalt-decorated nitrogen-doped carbon nanotubes on continuous carbon nanofibers is demonstrated via electrospinning.The porous and free-standing scaffold can enhance the tolerance to stresses resulting from the intrinsic volume change during Li plating/stripping, delivering a significant boost in both charge/discharge rates and stable cycling performance. A binary Co-Li alloying phase was generated at the initial discharge process, creating more active sites for the Li nucleation and uniform deposition. Characterization and density functional theory calculations show that the conductive and uniformly distributed cobalt-decorated carbon nanotubes with hierarchical structure can effectively reduce the local current density and more easily absorb Li atoms, leading to more uniform Li nucleation during plating. The current work presents an advance on scalable and cost-effective strategies for novel electrode materials with 3D hierarchical microstructures and mechanical flexibility for lithium metal anodes.

Revisiting the Role of Physical Confinement and Chemical Regulation of 3D Hosts for Dendrite-Free Li Metal Anode

Lithium metal anode has been demonstrated as the most promising anode for lithium batteries because of its high theoretical capacity,but infinite volume change and dendritic growth during Li electrodeposition have prevented its practical applications.Both physical morphology confinement and chemical adsorption/diffusion regulation are two crucial approaches to designing lithiophilic materials to alleviate dendrite of Li metal anode.However,their roles in suppressing dendrite growth for long-life Li anode are not fully understood yet.Herein,three different Ni-based nanosheet arrays(NiO-NS,Ni_(3)N-NS,and Ni_(5)P_(4)-NS)on carbon cloth as proof-of-concept lithiophilic frame-works are proposed for Li metal anodes.The two-dimensional nanoarray is more promising to facilitate uniform Li^(+)flow and electric field.Compared with the NiO-NS and the Ni_(5)P_(4)-NS,the Ni_(3)N-NS on carbon cloth after reacting with molten Li(Li-Ni/Li_(3)N-NS@CC)can afford the strongest adsorption to Li+and the most rapid Li+diffusion path.Therefore,the Li-Ni/Li_(3)N-NS@CC electrode realizes the lowest overpotential and the most excellent electrochemical performance(60 mA cm^(−2)and 60 mAh cm^(−2)for 1000 h).Furthermore,a remarkable full battery(LiFePO_(4)||Li-Ni/Li_(3)N-NS@CC)reaches 300 cycles at 2C.This research provides valuable insight into designing dendrite-free alkali metal batteries.

Synergistic effect of lithiophilic Zn nanoparticles and N-doping for stable Li metal anodes

Li metal is the most ideal anode material for next-generation high energy lithium-ion batteries.The uncontrollable growth of Li dendrites,however,hinders its practical application.Herein,we propose the adoption of Zn nanoparticles uniformly embedded in N-doped carbon polyhedra homogeneously built on carbon cloth(Zn@NC@CC)to prevent the formation of Li dendrites.Based on theoretical calculation and experimental observation,lithiophilic Zn nanoparticles and N-doping inside of the assynthesized Zn@NC play a synergistic role in enhancing the adsorption capacity with Li,thus resulting in uniform Li deposition and complete suppression of Li dendrites.Moreover,the porous N-doped carbon polyhedras uniformly distributed on carbon cloth effectively relieves the volume change of Li upon repeated Li stripping/plating process,which contributes to preserving the structural integrity of the whole electrode and hence enhancing its long-term cycling stability.Benefiting from these synergistic effects,the Li-Zn@NC@CC electrode delivers a prolonged lifespan of over 1200 h at 1 mA cm^(-2) with an areal capacity of 1 mA h cm^(-2) in symmetric cells and high Coulombic efficiencies of 95.4%under an ultrahigh capacity of 12 mA h cm^(-2).Remarkably,Li-Zn@NC@CC//LiFePO_(4) full cells deliver a high reversible capacity of 110.2 mA h g^(-1) at 1 C over 200 cycles.

Constructing a uniform lithium iodide layer for stabilizing lithium metal anode

The metallic lithium(Li)is the ultimate option in the development of anodes for high-energy secondary batteries.Unfortunately,inferior cycling reversibility and Li dendrites growth of Li metal as anode enormously impede its commercialization.Here,a uniform Li I protective layer is constructed on Li metal anode via a facile and direct solid-gas reaction of Li metal with iodine vapor.The pre-constructed Li I layer possesses more steadily and faster Li ion transport than the conventional SEI layer and contributes to a steady interface for the Li metal anode,which affords a smooth Li deposition morphology without Li dendrites formation.The symmetrical cell with the Li metal anode protected by Li I layer exhibits a longer cycling lifetime of over 700 h at a current density of 1 m A cm^(-2) with Li plating capacity of 1 m Ah cm^(-2).Moreover,the Li I layer protected Li metal anode can still remain high capacity retention of 74.6%after 500 cycles in the full cell paired with NCM523 cathode.The work proposes an easy and effective method to fabricate a uniform and stable protective layer on the Li metal anode and offers a practicable thinking for the commercial implementation of Li metal batteries.