Lignin-derived hard carbon anode with a robust solid electrolyte interphase for boosted sodium storage performance

Hard carbon is regarded as a promising anode candidate for sodium-ion batteries due to its low cost,relatively low working voltage,and satisfactory specific capacity.However,it still remains a challenge to obtain a high-performance hard carbon anode from cost-effective carbon sources.In addition,the solid electrolyte interphase(SEI)is subjected to continuous rupture during battery cycling,leading to fast capacity decay.Herein,a lignin-based hard carbon with robust SEI is developed to address these issues,effectively killing two birds with one stone.An innovative gas-phase removal-assisted aqueous washing strategy is developed to remove excessive sodium in the precursor to upcycle industrial lignin into high-value hard carbon,which demonstrated an ultrahigh sodium storage capacity of 359 mAh g^(-1).It is found that the residual sodium components from lignin on hard carbon act as active sites that controllably regulate the composition and morphology of SEI and guide homogeneous SEI growth by a near-shore aggregation mechanism to form thin,dense,and organic-rich SEI.Benefiting from these merits,the as-developed SEI shows fast Na+transfer at the interphases and enhanced structural stability,thus preventing SEI rupture and reformation,and ultimately leading to a comprehensive improvement in sodium storage performance.

Comprehension-driven design of advanced multi-block single-ion conducting polymer electrolytes for high-performance lithium-metal batteries

The continuously growing importance of batteries for powering(hybrid)electric vehicles and storing renewable energy has prompted a renewed focus on lithium-metal batteries(LMBs)in recent years,as its high theoretical specific capacity of about 3860 mA h g^(-1) and very low redox potential(-3.04 V vs.the standard hydrogen electrode)promise substantially higher energy densities compared to current lithium-ion batteries(LIBs)[1].However,lithium metal electrodes face severe challenges associated with the risk of dendritic lithium deposition and the high reactivity with traditional organic liquid electrolytes,resulting in a continuous loss of electrochemically active lithium and a relatively low Coulombic efficiency[2].To address these challenges,solid inorganic and polymer electrolytes have emerged as a potentially saferalternative.

Insights into the hydrogen evolution reaction in vanadium redox flow batteries:A synchrotron radiation based X-ray imaging study

The parasitic hydrogen evolution reaction(HER)in the negative half-cell of vanadium redox flow batteries(VRFBs)causes severe efficiency losses.Thus,a deeper understanding of this process and the accompanying bubble formation is crucial.This benchmarking study locally analyzes the bubble distribution in thick,porous electrodes for the first time using deep learning-based image segmentation of synchrotron X-ray micro-tomograms.Each large three-dimensional data set was processed precisely in less than one minute while minimizing human errors and pointing out areas of increased HER activity in VRFBs.The study systematically varies the electrode potential and material,concluding that more negative electrode potentials of-200 m V vs.reversible hydrogen electrode(RHE)and lower cause more substantial bubble formation,resulting in bubble fractions of around 15%–20%in carbon felt electrodes.Contrarily,the bubble fractions stay only around 2%in an electrode combining carbon felt and carbon paper.The detected areas with high HER activity,such as the border subregion with more than 30%bubble fraction in carbon felt electrodes,the cutting edges,and preferential spots in the electrode bulk,are potential-independent and suggest that larger electrodes with a higher bulk-to-border ratio might reduce HER-related performance losses.The described combination of electrochemical measurements,local X-ray microtomography,AI-based segmentation,and 3D morphometric analysis is a powerful and novel approach for local bubble analysis in three-dimensional porous electrodes,providing an essential toolkit for a broad community working on bubble-generating electrochemical systems.

Stepwise optimization of single-ion conducting polymer electrolytes for high-performance lithium-metal batteries

Single-ion conducting polymer electrolytes(SIPEs)are promising candidates for high-energy and highsafety lithium-metal batteries(LMBs).However,their insufficient ionic conductivity and electrochemical stability hinder their practical application.Herein,three new SIPEs,i.e.,poly(1,4-phenylene ether ether sulfone)-Li(PEES-Li),polysulfone-Li(PSF-Li),and hexafluoropolysulfone-Li(6FPSF-Li),all containing covalently tethered perfluorinated ionic side chains,have been designed,synthesized,and compared to investigate the influence of the backbone chemistry and the concentration of the ionic group on their electrochemical properties and cell performance.Especially,the trifluoromethyl group in the backbone and the concentration of the ionic function appear to play an essential role for the charge transport and stability towards oxidation,and the combination of both yields the best-performing SIPE with high ionic conductivity of ca.2.5×10^(-4)S cm^(-1),anodic stability of more than 4.8 V,and the by far highest capacity retention in Li‖LiNi0.6Co0.2Mn0.2O2cells.

Electrochemical Kinetic Modulators in Lithium–Sulfur Batteries:From Defect-Rich Catalysts to Single Atomic Catalysts

Lithium–sulfur batteries exhibit unparalleled merits in theoretical energy density(2600 W h kg^(-1))among next-generation storage systems.However,the sluggish electrochemical kinetics of sulfur reduction reactions,sulfide oxidation reactions in the sulfur cathode,and the lithium dendrite growth resulted from uncontrollable lithium behaviors in lithium anode have inhibited high-rate conversions and uniform deposition to achieve high performances.Thanks to the“adsorption-catalysis”synergetic effects,the reaction kinetics of sulfur reduction reactions/sulfide oxidation reactions composed of the delithiation of Li_(2)S and the interconversions of sulfur species are propelled by lowering the delithiation/diffusion energy barriers,inhibiting polysulfide shuttling.Meanwhile,the anodic plating kinetic behaviors modulated by the catalysts tend to uniformize without dendrite growth.In this review,the various active catalysts in modulating lithium behaviors are summarized,especially for the defect-rich catalysts and single atomic catalysts.The working mechanisms of these highly active catalysts revealed from theoretical simulation to in situ/operando characterizations are also highlighted.Furthermore,the opportunities of future higher performance enhancement to realize practical applications of lithium–sulfur batteries are prospected,shedding light on the future practical development.

Perspective on ultramicroporous carbon as sulphur host for Li-S batteries

Lithium-sulphur(Li-S)batteries are currently considered as next-generation battery technology.Sulphur is an attractive positive electrode for lithium metal batteries,mainly due to its high capacity(1675 m Ah g^(-1))and high specific energy(2600 Wh kg^(-1)).The electrochemical reaction of lithium with sulphur in non-aqueous electrolytes results in the formation of electrolyte soluble intermediate lithium-polysulphides.The dissolved polysulphides shuttle to the anode and get reduced at the anode resulting in Li metal corrosion.The solubility of polysulphide gradually reduces the amount of sulphur in the cathode,thereby limiting the cycle life of Li-S batteries.Several strategies have been proposed to improve the cycling stability of Li-S batteries.A unique approach to eliminate the polysulphide shuttle is to use ultramicroporous carbon(UMC)as a host for sulphur.The pore size of UMC which is below 7A,is the bottleneck for carbonate solvents to access sulphur/polysulphides confined in the pores,thereby preventing the polysulphide dissolution.This perspective article will emphasise the role of UMC host in directing the lithiation mechanism of sulphur and in inhibiting polysulphide dissolution,including the resulting parasitic reaction on the lithium anode.Further,the challenges that need to be addressed by UMC-S based Li-S batteries,and the strategies to realise high power density,high Coulombic efficiency,and resilient Li-S batteries will be discussed.

Enhanced interfacial compatibility of FeS@N,S-C anode with ester-based electrolyte enables stable sodium-ion full cells

The development of sodium-ion full cells is seriously suppressed by the incompatibility between electrodes and electrolytes. Most representatively, high-voltage ester-based electrolytes required by the cathodes present poor interfacial compatibility with the anodes due to unstable solid electrode interphase(SEI). Herein, Fe S@N,S-C(spindle-like Fe S nanoparticles individually encapsulated in N,S-doped carbon) with excellent structural stability is synthesized as a potential sodium anode material. It exhibits exceptional interfacial stability in ester-based electrolyte(1 M NaClO_(4) in ethylene carbonate/propylene carbonate with 5% fluoroethylene carbonate) with long-cycling lifespan(294 days) in Na|Fe S@N,S-C coin cell and remarkable cyclability in pouch cell(capacity retention of 82.2% after 170 cycles at 0.2 A g^(-1)).DFT calculation reveals that N,S-doping on electrode surface could drive strong repulsion to solvated Na_(2) and preferential adsorption to ClO_(4)^(-) anion, guiding the anion-rich inner Helmholtz plane.Consequently, a robust SEI with rich inorganic species(NaCl and Na_(2)O) through the whole depth stabilizes the electrode–electrolyte interface and protects its integrity. This work brings new insight into the role of electrode’s surface properties in interfacial compatibility that can guide the design of more versatile electrodes for advanced rechargeable metal-ion batteries.

Oxygen-Containing Functional Groups Regulating the Carbon/Electrolyte Interfacial Properties Toward Enhanced K^(+)Storage

Oxygen-containing functional groups were found to e ectively boost the K^(+)storage performance of carbonaceous materials,however,the mechanism behind the performance enhancement remains unclear.Herein,we report higher rate capability and better long-term cycle performance employing oxygen-doped graphite oxide(GO)as the anode material for potassium ion batteries(PIBs),compared to the raw graphite.The in situ Raman spectroscopy elucidates the adsorption-intercalation hybrid K^(+)storage mechanism,assigning the capacity enhancement to be mainly correlated with reversible K^(+)adsorption/desorption at the newly introduced oxygen sites.It is unraveled that the C=O and COOH rather than C-O-C and OH groups contribute to the capacity enhancement.Based on in situ Fourier transform infrared(FT-IR)spectra and in situ electrochemical impedance spectroscopy(EIS),it is found that the oxygen-containing functional groups regulate the components of solid electrolyte interphase(SEI),leading to the formation of highly conductive,intact and robust SEI.Through the systematic investigations,we hereby uncover the K^(+)storage mechanism of GO-based PIB,and establish a clear relationship between the types/contents of oxygen functional groups and the regulated composition of SEI.

Solvation structure and dynamics of Li and LiO_(2)and their transformation in non-aqueous organic electrolyte solvents from first-principles simulations

Density functional theory calculations together with ab initio molecular dynamics(AIMD)simulations have been used to study the solvation,diffusion and transformation of Li^(+)and LiO_(2)upon O_(2)reduction in three organic electrolytes.These processes are critical for the performance of Li-air batteries.Apart from studying the structure of the solvation shells in detail,AIMD simulations have been used to derive the diffusivity and together with the Blue Moon ensemble approach to explore LiO_(2)formation from Li^(+)and O_(2)−and the subsequent disproportionation of 2LiO_(2)into Li_(2)O_(2)+O_(2).By comparing the results of the simulations to gas phase calculations,the impact of electrolytes on these reactions is assessed which turns out to be more pronounced for the ionic species involved in these reactions.

Understanding surface charge effects in electrocatalysis.Part 2:Hydrogen peroxide reactions at platinum

Electrocatalytic activity is influenced by the surface charge on the solid catalyst.Conventionally,our attention has been focused on how the surface charge shapes the electric potential and concentration of ionic reactant(s)in the local reaction zone.Taking H_(2)O_(2)redox reactions at Pt(111)as a model system,we reveal a peculiar surface charge effect using ab initio molecular dynamics simulations of electrified Pt(111)-water interfaces.In this scenario,the negative surface charge on Pt(111)repels the O-O bond of the reactant(H_(2)O_(2))farther away from the electrode surface.This leads to a higher activation barrier for breaking the O-O bond.Incorporating this microscopic mechanism into a microkinetic-double-layer model,we are able to semi-quantitatively interpret the pH-dependent activity of H_(2)O_(2)redox reactions at Pt(111),especially the anomalously suppressed activity of H_(2)O_(2)reduction with decreasing electrode potential.The relevance of the present surface charge effect is also examined in wider scenarios with different electrolyte cations,solution pHs,crystal facets of the catalyst,and model parameters.In contrast with previous mechanisms focusing on how surface charge influences the local reaction condition at a fixed reaction plane,the present work gives an example in which the location of the reaction plane is adjusted by the surface charge.

In operando study of orthorhombic V_(2)O_(5) as positive electrode materials for K-ion batteries

Herein, the electrochemical performance and the mechanism of potassium insertion/deinsertion in orthorhombic V_(2)O_(5) nanoparticles are studied. The V2O5 electrode displays an initial potassiation/depotassiation capacity of 200 mAh g^(−1)/217 mAh g^(−1) in the voltage range 1.5–4.0 V vs. K^(+)/K at C/12 rate, suggesting fast kinetics for potassium insertion/deinsertion. However, the capacity quickly fades during cycling, reaching 54 mAh g^(−1) at the 31st cycle. Afterwards, the capacity slowly increases up to 80 mAh g^(−1) at the 200th cycle. The storage mechanism upon K ions insertion into V2O5 is elucidated. In operando synchrotron diffraction reveals that V_(2)O_(5) first undergoes a solid solution to form K_(0.6)V_(2)O_(5) phase and then, upon further K ions insertion, it reveals coexistence of a solid solution and a two-phase reaction. During K ions deinsertion, the coexistence of solid solution and the two-phase reaction is identified together with an irreversible process. In operando XAS confirms the reduction/oxidation of vanadium during the K insertion/extraction with some irreversible contributions. This is consistent with the results obtained from synchrotron diffraction, ex situ Raman, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Moreover, ex situ XPS confirms the “cathode electrolyte interphase” (CEI) formation on the electrode and the decomposition of CEI film during cycling.

Towards an enhanced understanding of the particle size effect on conversion/alloying lithium-ion anodes

Conversion/alloying materials(CAMs)represent a potential alternative to graphite as a Li-ion anode active material,especially for high-power applications.So far,however,essentially all studies on CAMs have been dealing with nano-sized particles,leaving the question of how the performance(and the de-/lithiation mechanism in general)is affected by the particle size.Herein,we comparatively investigate four different samples of Zn_(0.9)Co_(0.1)O with a particle size ranging from about 30 nm to a few micrometers.The results show that electrodes made of larger particles are more susceptible to fading due to particle displacement and particle cracking.The results also show that the conversion-type reaction in particular is affected by an increasing particle size,becoming less reversible due to the formation of relatively large transition metal(TM)and alloying metal nanograins upon lithiation,thus hindering an efficient electron transport within the initial particle,while the alloying contribution remains essentially unaffected.The generality of these findings is confirmed by also investigating Sn_(0.9)Fe_(0.1)O_(2) as a second CAM with a substantially greater contribution of the alloying reaction and employing Fe instead of Co as a TM dopant.

Restraining growth of Zn dendrites by poly dimethyl diallyl ammonium cations in aqueous electrolytes

Metallic zinc is an excellent anode material for Zn-ion batteries,but the growth of Zn dendrite severely hinders its practical application.Herein,an efficient and economical cationic additive,poly dimethyl diallyl ammonium(PDDA) was reported,used in aqueous Zn-ion batteries electrolyte for stabilizing Zn anode.The growth of zinc dendrites can be significantly restrained by benefiting from the pronounced electrostatic shielding effect from PDDA on the Zn metal surface.Moreover,the PDDA is preferentially absorbed on Zn(002) plane,thus preventing unwanted side reactions on Zn anode.Owing to the introduction of a certain amount of PDDA additive into the common ZnSO_(4)-based electrolyte,the cycle life of assembled Zn‖Zn cells(1 mA·cm^(-2) and 1 mAh·cm^(-2)) is prolonged to more than 1100 h.In response to the perforation issue of Zn electrodes caused by PDDA additives,the problem can be solved by combining foamy copper with zinc foil.For real application,Zn-ion hybrid supercapacitors and MnO_(2)‖Zn cells were assembled,which exhibited excellent cycling stability with PDDA additives.This work provides a new solution and perspective to cope with the dendrite growth problem of Zn anode.

Electron delocalization-enhanced sulfur reduction kinetics on an MXene-derived heterostructured electrocatalyst

Lithium-sulfur(Li-S)batteries mainly rely on the reversible electrochemical reaction of between lithium ions(Li^(+))and sulfur species to achieve energy storage and conversion,therefore,increasing the number of free Li^(+)and improving the Li^(+)diffusion kinetics will effectively enhance the cell performance.Here,Mo-based MXene heterostructure(MoS_(2)@Mo_(2)C)was developed by partial vulcanization of Mo_(2)C MXene,in which the introduction of similar valence S into Mo-based MXene(Mo_(2)C)can create an electron delocalization effect.Through theoretical simulations and electrochemical characterisation,it is demonstrated that the MoS_(2)@Mo_(2)C heterojunction can effectively promote ion desolvation,increase the amount of free Li^(+),and accelerate Li^(+)transport for more efficient polysulfide conversion.In addition,the MoS_(2)@Mo_(2)C material is also capable of accelerating the oxidation and reduction of polysulfides through its sufficient defects and vacancies to further enhance the catalytic efficiency.Consequently,the Li-S battery with the designed MoS_(2)@Mo_(2)C electrocatalyst performed for 500 cycles at 1 C and still maintained the ideal capacity(664.7 mAh·g^(−1)),and excellent rate performance(567.6 mAh·g^(−1)at 5 C).Under the extreme conditions of high loading,the cell maintained an excellent capacity of 775.6 mAh·g^(−1)after 100 cycles.It also retained 838.4 mAh·g^(−1)for 70 cycles at a low temperature of 0℃,and demonstrated a low decay rate(0.063%).These results indicate that the delocalized electrons effectively accelerate the catalytic conversion of lithium polysulfide,which is more practical for enhancing the behaviour of Li-S batteries.

Fast interfacial electrocatalytic desolvation enabling lowtemperature and long-cycle-life aqueous Zn batteries

Low-temperature zinc batteries(LT-ZIBs)based on aqueous electrolytes show great promise for practical applications owing to their natural resource abundance and low cost.However,they suffer from sluggish kinetics with elevated energy barriers due to the dissociation of bulky Zn(H2O)62+solvation structure and free Zn2+diffusion,resulting in unsatisfactory lifespan and performance.Herein,dissimilar to solvation shell tuning or layer spacing enlargement engineering,delocalized electrons in cathode through constructing intrinsic defect engineering is proposed to achieve a rapid electrocatalytic desolvation to obtain free Zn2+for insertion/extraction.As revealed by density functional theory calculations and interfacial spectroscopic characterizations,the intrinsic delocalized electron distribution propels the Zn(H2O)62+dissociation,forming a reversible interphase and facilitating Zn2+diffusion across the electrolyte/cathode interface.The as-fabricated oxygen defect-rich V2O5 on hierarchical porous carbon(ODVO@HPC)electrode exhibits high capacity robustness from 25 to20℃.Operating at-20℃,the ODVO@HPC delivers 191 mAh g-1 at 50 A g-1 and lasts for 50000 cycles at 10 A g-1,significantly enhancing the power density and lifespan under low-temperature environments in comparison to previous reports.Even with areal mass loading of-13 mg cm2,both coin cells and pouch batteries maintain excellent stability and areal capacities,realizing practical high-performance LT-ZIBs.

Improving cycling performance of the NaNiO_(2)cathode in sodium-ion batteries by titanium substitution

O3-type layered oxide cathodes,such as NaNi_(0.5)Mn_(0.5)O_(2),have garnered significant attention due to their high theoretical specific capacity while using abundant and low-cost sodium as intercalation species.Unlike the lithium analog(LiNiO_(2)),NaNiO_(2)(NNO)exhibits poor electrochemical performance resulting from structural instability and inferior Coulomb efficiency.To enhance its cyclability for practical application,NNO was modified by titanium substitution to yield the O3-type NaNi_(0.9)Ti_(0.1)O_(2)(NNTO),which was successfully synthesized for the first time via a solid-state reaction.The mechanism behind its superior performance in comparison to that of similar materials is examined in detail using a variety of characterization techniques.NNTO delivers a specific discharge capacity of∼190 mAh g^(−1)and exhibits good reversibility,even in the presence of multiple phase transitions during cycling in a potential window of 2.0−4.2 V vs.Na^(+)/Na.This behavior can be attributed to the substituent,which helps maintain a larger interslab distance in the Na-deficient phases and to mitigate Jahn–Teller activity by reducing the average oxidation state of nickel.However,volume collapse at high potentials and irreversible lattice oxygen loss are still detrimental to the NNTO.Nevertheless,the performance can be further enhanced through coating and doping strategies.This not only positions NNTO as a promising next-generation cathode material,but also serves as inspiration for future research directions in the field of high-energy-density Na-ion batteries.

Manipulating dielectric property of polymer coatings toward highretention-rate lithium metal full batteries under harsh critical conditions

Lithium(Li)metal batteries(LMBs)can potentially deliver much higher energy density but remain plagued by uncontrollable Li plating with dendrite growth,unstable interfaces,and highly abundant excess Li(>50 mAh·cm^(-2)).Herein,different from the artificial layer or three-dimensional(3D)matrix host constructions,various dielectric polymers are initially well-comprehensively investigated from experimental characterizations to theoretical simulation to evaluate their functions in modulating Li ion distribution.As a proof of concept,a 3D interwoven high dielectric functional polymer(HDFP)nanofiber network with polar C-F dipole moments electrospun on copper(Cu)foil is designed,realizing uniform and controllable Li deposition capacity up to 5.0 mAh·cm^(-2),thereby enabling stable Li plating/stripping cycling over 1400 h at 1.0 mA·cm^(-2).More importantly,under the highcathode loading(~3.1 mAh·cm^(-2))and only 0.6×excess Li(N/P ratio of 1.6),the full cells retain capacity retention of 97.4%after 200 cycles at 3.36 mA·cm^(-2)and achieve high energy density(297.7 Wh·kg^(-1)at cell-level)under lean electrolyte conditions(15μL),much better than ever-reported literatures.Our work provides a new direction for designing high dielectric polymer coating toward high-retention-rate practical Li full batteries.

Interface engineering of MXene-based heterostructures for lithiumsulfur batteries

High energy density and low cost make lithium-sulfur(Li-S)batteries as one of the next generation's promising energy storage systems.However,the following problems need to be solved before commercialization:(i)the shuttling effect and sluggish redox kinetics of lithium polysulfides in sulfur cathode;(ii)the formation of lithium dendrites and the crack of solid electrolyte interphase;(iii)the large volume changes during charge and discharge processes.MXenes,as newly emerging two-dimensional transition metal carbides/nitrides/carbonitrides,have attracted widespread attention due to their abundant active surface terminals,adjustable vacancies,and high electrical conductivity.Designing MXene-based heterogeneous structures is expected to solve the stacking problem induced by hydrogen bonds or Van der Waals force and to provide other charming physiochemical properties.Herein,we generalize the design principles of MXene-based heterostructures and their functions,i.e.,adsorption and catalysis in advanced conversion-based Li-S batteries.Firstly,the physiochemical properties of MXene and MXene-based heterostructures are briefly introduced.Secondly,the catalytic functions of MXene-based heterostructures with the compositional constituents including carbon materials,metal compounds,organic frameworks,polymers,single atoms and special high-entropy MXenes are comprehensively summarized in sulfur cathodes and lithium anodes.Finally,the challenges of MXene-based heterostructure in current Li-S batteries are pointed out and we also provide some enlightenments for future developments in high-energy-density Li-S batteries.

Reasonable suppression of polysulfides/polyselenides shuttle based on MXene in Na-SeS_(2)batteries

Metal-sulfur/selenium batteries have become the focus of new-generation energy storage systems due to the advantages of low-cost and high energy density.However,it still suffers from the notorious shuttle of polysulfides/polyselenides,poor electronic conductivity and tremendous volume expansion.Herein,a dual defense system for polysulfides/polyselenides was proposed and constructed based on MXene.The nitrogen-doped porous carbon(NPC)decorated by Ti_(3)C_(2)T_(x)MXene(M@NPC)was employed as the SeS_(2)host(SeS_(2)@M@NPC).Particularly,Ti_(3)C_(2)T_(x)sheets wrapped on NPC guarantee the rapid ion diffusion and serve as the first barrier for SeS_(2)and dissolved sodium polysulfides/polyselenides.Meanwhile,the few-layered Ti_(3)C_(2)T_(x)sheets coated on glass fiber separators act as the second barrier for alleviating the shuttle of polysulfides/polyselenides through physical interception and chemical adsorption.With this elaborate design,the integrated Na-SeS_(2)battery achieves a high specific capacity of 1243 mAh·g^(-1)at 1.0C,revealing a distinct superiority over its counterparts(SeS_(2)@M@NPC,1083mAh·g^(-1)at 0.5C;and SeS_(2)@NPC,823 mAh·g^(-1)at 0.5C).The findings gained in this work provide a creative idea for the construction of durable room-temperature Na-SeS_(2)batteries based on MXenes and their derivative materials.

Beneficial impact of lithium bis(oxalato)borate as electrolyte additive for high-voltage nickel-rich lithium-battery cathodes

High-voltage nickel-rich layered cathodes possess the requisite,such as excellent discharge capacity and high energy density,to realize lithium batteries with higher energy density.However,such materials suffer from structural and interfacial instability at high voltages(>4.3 V).To reinforce the stability of these cathode materials at elevated voltages,lithium borate salts are investigated as electrolyte additives to generate a superior cathode-electrolyte interphase.Specifically,the use of lithium bis(oxalato)borate(LiBOB)leads to an enhanced cycling stability with a capacity retention of 81.7%.Importantly,almost no voltage hysteresis is detected after 200 cycles at 1C.This outstanding electrochemical performance is attributed to an enhanced structural and interfacial stability,which is attained by suppressing the generation of micro-cracks and the superficial structural degradation upon cycling.The improved stability stems from the formation of a fortified borate-containing interphase which protects the highly reactive cathode from parasitic reactions with the electrolyte.Finally,the decomposition process of LiBOB and the possible adsorption routes to the cathode surface are deduced and elucidated.