The key to realize long-life high energy density lithium batteries is to exploit functional electrolytes capable of stabilizing both high voltage cathode and lithium anode.The emergence of localized high-concentration...The key to realize long-life high energy density lithium batteries is to exploit functional electrolytes capable of stabilizing both high voltage cathode and lithium anode.The emergence of localized high-concentration electrolytes(LHCEs)shows great promise for ameliorating the above-mentioned interfacial issues.In this work,a lithium difluoro(oxalate)borate(LiDFOB)based nonflammable dual-anion LHCE is designed and prepared.Dissolving in the mixture of trimethyl phosphate(TMP)/1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropylether(D_(2)),the continuously consumption of LiDFOB is suppressed by simply introducing lithium nitrate(LiNO_(3)).Meantime,as most of the TMP molecular are coordinated with Li^(+),the electrolyte does not show incompatibility issue between neither metal lithium nor graphite anode.Therefore,it demonstrates excellent capability in stabilizing the interface of Ni-rich cathode and regulating lithium deposition morphology.The Li||LiNi_(0.87)Co_(0.08)Mn_(0.05)O_(2)(NCM87)batteries exhibit high capacity retention of more than 90%after 200 cycles even under the high cutoff voltage of 4.5 V,1 C rate.This study offers a prospective method to develop safe electrolytes suitable for high voltage applications,thus providing higher energy densities.展开更多
With the increasing development of digital devices and electric vehicles,high energy-density rechargeable batteries are strongly required.As one of the most promising anode materials with an ultrahigh specific capacit...With the increasing development of digital devices and electric vehicles,high energy-density rechargeable batteries are strongly required.As one of the most promising anode materials with an ultrahigh specific capacity and extremely low electrode potential,lithium metal is greatly considered an ideal candidate for nextgeneration battery systems.Nevertheless,limited Coulombic efficiency and potential safety risks severely hinder the practical applications of lithium metal batteries due to the inevitable growth of lithium dendrites and poor interface stability.Tremendous efforts have been explored to address these challenges,mainly focusing on the design of novel electrolytes.Here,we provide an overview of the recent developments of localized high-concentration electrolytes in lithium metal batteries.Firstly,the solvation structures and physicochemical properties of localized high-concentration electrolytes are analyzed.Then,the developments of localized high-concentration electrolytes to suppress the formation of dendritic lithium,broaden the voltage window of electrolytes,enhance safety,and render low-temperature operation for robust lithium metal batteries are discussed.Lastly,the remaining challenges and further possible research directions for localized highconcentration electrolytes are outlined,which can promisingly render the practical applications of lithium metal batteries.展开更多
Although graphite anodes operated with representative de/intercalation patterns at low potentials are considered highly desirable for K-ion batteries,the severe capacity fading caused by consecutive reduction reaction...Although graphite anodes operated with representative de/intercalation patterns at low potentials are considered highly desirable for K-ion batteries,the severe capacity fading caused by consecutive reduction reactions on the aggressively reactive surface is inevitable given the scarcity of effective protecting layers.Herein,by introducing a flame-retardant localized high-concentration electrolyte with retentive solvation configuration and relatively weakened anion-coordination and non-solvating fluorinated ether,the rational solid electrolyte interphase characterized by well-balanced inorganic/organic components is tailored in situ.This effectively prevented solvents from excessively decomposing and simultaneously improved the resistance against K-ion transport.Consequently,the graphite anode retained a prolonged cycling capability of up to 1400 cycles(245 mA h g,remaining above 12 mon)with an excellent capacity retention of as high as 92.4%.This is superior to those of conventional and high-concentration electrolytes.Thus,the optimized electrolyte with moderate salt concentration is perfectly compatible with graphite,providing a potential application prospect for K-storage evolution.展开更多
Localized high-concentration electrolytes(LHCE) have shown good compatibility with high-voltage lithium(Li)-metal batteries, but their practicality is yet to be proved in terms of cost and safety. Here we develop a hy...Localized high-concentration electrolytes(LHCE) have shown good compatibility with high-voltage lithium(Li)-metal batteries, but their practicality is yet to be proved in terms of cost and safety. Here we develop a hybrid-LHCE with favorable integrated properties by combining the merits of two representative diluents, fluorobenzene(FB) and 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether(TFE). Specifically,the extremely cheap and lightweight FB significantly reduces the cost and density of electrolyte, while the fire-retardant TFE circumvents the flammable nature of FB and thus greatly improves the safety of electrolyte. Moreover, the FB–TFE mixture enhances the thermodynamic stability of hybrid-LHCE and renders a controllable defluorination of FB, contributing to the formation of a thin and durable inorganic-rich solid electrolyte interphase(SEI) with rapid ion-transport kinetics. Benefiting from the designed hybridLHCE, a Li|NCM523 battery demonstrates excellent cycling performance(215 cycles, 91% capacity retention) under challenging conditions of thin Li-anode(30 μm) and high cathode loading(3.5 m Ah/cm^(2)).展开更多
Although high salt concentration electrolyte(HCE)can construct effective Li F-rich interphase film and solve the interphasial instability issue of graphite anode,its high cost,high viscosity and poor wettability with ...Although high salt concentration electrolyte(HCE)can construct effective Li F-rich interphase film and solve the interphasial instability issue of graphite anode,its high cost,high viscosity and poor wettability with electrode materials limit its large-scale application.Generally,localized high concentration electrolyte(LHCE)is obtained by introducing an electrochemically inert diluent into HCE to avoid the above-mentioned problems while maintaining the high interphasial stability of HCE with graphite anode.Unlike traditional inert diluents,1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluropropyl ether(TTE)with electrochemical activity is introduced into propylene carbonate(PC)-based HCE to obtain LHCE-2(1 M LiPF_(6),PC:DMC:TTE=1:1:6.1)herein.Experimental and theoretical simulation results show that TTE participates in the oxidation decomposition and film-forming reaction at the NCM622 cathode surface,conducting a cathode electrolyte interphase(CEI)rich in organic fluorides with excellent electron insulation ability,high structural stability and low interphasial impedance.Thanks to the outstanding interphasial properties induced by LHCE-2,the graphite||NMC622 pouch cell reaches a capacity retention of 80%after 500 cycles at 1 C under room temperature.While at sub-zero temperatures,the capacity released by the cell with LHCE-2 electrolyte is significantly higher than that of HCE and conventional EC-based electrolytes.Meanwhile,the LHCE-2 electrolyte inherits the advantages of TTE flame-resistant,thus improving the safety of the battery.展开更多
Benefiting from the environmental friendliness of organic electrodes and the high security of aqueous electrolyte,an all-organic aqueous potassium dual-ion full battery(APDIB) was assembled with 21 M potassium bis(flu...Benefiting from the environmental friendliness of organic electrodes and the high security of aqueous electrolyte,an all-organic aqueous potassium dual-ion full battery(APDIB) was assembled with 21 M potassium bis(fluoroslufonyl)imide(KFSI) water-in-salt as the electrolyte.The APDIB could deliver a reversible capacity of around 50 mAh g^(-1) at 200 mA g^(-1)(based on the weight of total active materials),a long cycle stability over 900 cycles at 500 mA g^(-1) and a high coulombic efficiency of 98.5%.The reaction mechanism of APDIB during the charge/discharge processes is verified:the FSI-could associate/disassociate with the nitrogen atom in the polytriphenylamine(PTPAn) cathode,while the K^(+) could react with C=O bonds in the 3,4,9,10-perylenetetracarboxylic diimide(PTCDI) anode reversibly.Our work contributes toward the understanding the nature of water-into-salt electrolyte and successfully constructed all-organic APDIB.展开更多
The resourceful and inexpensive red phosphorus has emerged as a promising anode material of potassium-ion batteries(PIBs) for its large theoretical capacities and low redox potentials in the multielectron alloying/dea...The resourceful and inexpensive red phosphorus has emerged as a promising anode material of potassium-ion batteries(PIBs) for its large theoretical capacities and low redox potentials in the multielectron alloying/dealloying reactions,yet chronically suffering from the huge volume expansion/shrinkage with a sluggish reaction kinetics and an unsatisfactory interfacial stability against volatile electrolytes.Herein,we systematically developed a series of localized high-concentration electrolytes(LHCE) through diluting high-concentration ether electrolytes with a non-solvating fluorinated ether to regulate the formation/evolution of solid electrolyte interphases(SEI) on phosphorus/carbon(P/C) anodes for PIBs.Benefitting from the improved mechanical strength and structural stability of a robust/uniform SEI thin layer derived from a composition-optimized LHCE featured with a unique solvation structure and a superior K+migration capability,the P/C anode with noticeable pseudocapacitive behaviors could achieve a large reversible capacity of 760 mA h g^(-1)at 100 mA g^(-1),a remarkable capacity retention rate of 92.6% over 200 cycles at 800 mA g^(-1),and an exceptional rate capability of 334 mA h g^(-1)at8000 mA g^(-1).Critically,a suppressed reduction of ether solvents with a preferential decomposition of potassium salts in anion-derived interfacial reactions on P/C anode for LHCE could enable a rational construction of an outer organic-rich and inner inorganic-dominant SEI thin film with remarkable mechanical strength/flexibility to buffer huge volume variations and abundant K+diffusion channels to accelerate reaction kinetics.Additionally,the highly reversible/durable full PIBs coupling P/C anodes with annealed organic cathodes further verified an excellent practical applicability of LHCE.This encouraging work on electrolytes regulating SEI formation/evolution would advance the development of P/C anodes for high-performance PIBs.展开更多
Passivation by the inorganic-rich solid electrolyte interphase(SEI),especially the LiF-rich SEI,is highly desirable to guarantee the durable lifespan of Li metal batteries(LMBs).Here,we report a diluent with the capab...Passivation by the inorganic-rich solid electrolyte interphase(SEI),especially the LiF-rich SEI,is highly desirable to guarantee the durable lifespan of Li metal batteries(LMBs).Here,we report a diluent with the capability to facilitate the formation of LiF-rich SEI while avoiding the excess consumption of Li salts.Dissimilar to most of reported inert diluents,heptafluoro-l-methoxypropane(HM) is firstly demonstrated to cooperate with the decomposition of anions to generate LiF-rich SEI via releasing Fcontaining species near Li surface.The designed electrolyte consisting of 1.8 M LiFSI in the mixture of1,2-dimethoxyethane(DME)/HM(2:1 by vol.) achieves excellent compatibility with both Li metal anodes(Coulombic efficiency~99.8%) and high-voltage cathodes(4.4 V LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)(NMC811) and 4.5 V LiCoO_(2)(LCO) vs Li^(+)/Li).The 4.4 V Li(20μm)‖NMC811(2.5 mA h cm^(-2)) and 4.5 V Li(20μm)‖LCO(2.5 mA h cm^(-2)) cells achieve capacity retentions of 80% over 560 cycles and 80% over 505 cycles,respectively.Meanwhile,the anode-free pouch cell delivers an energy density of~293 W h kg^(-1)initially and retains 70% of capacity after 100 deep cycles.This work highlights the critical impact of diluent on the SEI formation,and opens up a new direction for designing desirable interfacial chemistries to enable high-performance LMBs.展开更多
Lithium metal anodes hold great potential for high-energy-density secondary batteries.However,the uncontrollable lithium dendrite growth causes poor cycling efficiency and severe safety concerns,hindering lithium meta...Lithium metal anodes hold great potential for high-energy-density secondary batteries.However,the uncontrollable lithium dendrite growth causes poor cycling efficiency and severe safety concerns,hindering lithium metal anode from practical application.Electrolyte components play important roles in suppressing lithium dendrite growth and improving the electrochemical performance of long-life lithium metal anode,and it is still challenging to effectively compromise the advantages of the conventional electrolyte(1 mol·L^(−1)salts)and high-concentration electrolyte(>3 mol·L^(−1)salts)for the optimizing electrochemical performance.Herein,we propose and design an interfacial high-concentration electrolyte induced by the nitrogen-and oxygen-doped carbon nanosheets(NO-CNS)for stable Li metal anodes.The NO-CNS with abundant surface negative charges not only creates an interfacial high-concentration of lithium ions near the electrode surface to promote chargetransfer kinetics but also enables a high ionic conductivity in the bulk electrolyte to improve ionic mass-transfer.Benefitting from the interfacial high-concentration electrolyte,the NO-CNS@Ni foam host presents outstanding electrochemical cycling performances over 600 cycles at 1 mA·cm^(−2) and an improved cycling lifespan of 1,500 h for symmetric cells.展开更多
By optimizing electrolyte formulation to inhibit the deposition of transition metal ions(TMIs) on the surface of the graphite anode is an effective way to improve the electrochemical performance of lithium-ion batteri...By optimizing electrolyte formulation to inhibit the deposition of transition metal ions(TMIs) on the surface of the graphite anode is an effective way to improve the electrochemical performance of lithium-ion batteries.At present,it is generally believed the formation of an effective interfacial film on the surface of the anode electrode is the leading factor in reducing the dissolution of TMIs and prevent TMIs from being embedded in the electrode.It ignores the influence of the solvation structures in the electrolyte system with different composition,and is not conducive to the design of the electrolyte formulation from the perspective of changing the concentration and the preferred solvent to inhibit the degradation of battery performance caused by TMIs deposition.In this work,by analyzing the special solvation structures of the high-concentra tion electrolyte,we study the main reason why high-concentration electrolyte inhibits the destructive effect of Mn(Ⅱ) on the electrochemical performance of LIBs.By combining the potentialresolved in-situ electrochemical impedance spectroscopy technology(PRIs-EIS) and density functional theory(DFT) calculation,we find that Mn(Ⅱ) mainly exists in the form of contact ions pairs(CIPs) and aggregates(AGGs) in high-concentration electrolyte.These solvation structures can reduce the destructive effect of Mn(Ⅱ) on battery performance from two aspects:on the one hand,it can rise the lowest unoccupied orbital(LUMO) value of the solvation structures of Mn(Ⅱ),thereby reducing the chance of its reduction;on the other hand,the decrease of Mn2+ions reduction can reduce the deposition of metallic manganese in the solid electrolyte interphase(SEI),thereby avoiding the continuous growth of the SEI.This study can be provided inspiration for the design of electrolytes to inhibit the destructive effect of TMls on LIBs.展开更多
Lithium(Li)metal is an ideal anode for the next generation high-energy-density batteries.However,it suffers from dendrite growth,side reactions,and infinite relative volume change.Effective strategies are using porous...Lithium(Li)metal is an ideal anode for the next generation high-energy-density batteries.However,it suffers from dendrite growth,side reactions,and infinite relative volume change.Effective strategies are using porous carbons or surface modification carbons to guide Li deposition into their pores.While the Li deposition behavior is still ambiguous.Here,we systematically determine their deposition behavior in various surface-modified carbons and in different electrolytes via optical microscopy and scanning electron microscopy study.It is found that Li will not spontaneously deposit into the carbon pores,which is significantly dependent on the carbon surface,current density,areal capacity,and electrolyte.Thus,a“lithiophilic”modified commercial hard carbon with Ag is developed as a stable“host”and efficient surface protection derived from the localized high-concentration electrolyte exhibits a pretty low volume change(5.3%)during cycling at a current density of 2 mA·cm^(−2)and an areal capacity of 2 mAh·cm^(−2).This strategy addresses the volume change and dendrite problems by rationally designed host and electrolyte,providing a broad perspective for realizing Li-metal anode.展开更多
基金financially supported by National Key Research and Development Program of China(No.2019YFA0705603)National Natural Science Foundation of China(No.22078341,No.21808228 and No.21776290)+1 种基金Science Fund for Creative Research Groups of the National Natural Science Foundation of China(No.21921005)S&T Program of Hebei(No.B2020103028).
文摘The key to realize long-life high energy density lithium batteries is to exploit functional electrolytes capable of stabilizing both high voltage cathode and lithium anode.The emergence of localized high-concentration electrolytes(LHCEs)shows great promise for ameliorating the above-mentioned interfacial issues.In this work,a lithium difluoro(oxalate)borate(LiDFOB)based nonflammable dual-anion LHCE is designed and prepared.Dissolving in the mixture of trimethyl phosphate(TMP)/1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropylether(D_(2)),the continuously consumption of LiDFOB is suppressed by simply introducing lithium nitrate(LiNO_(3)).Meantime,as most of the TMP molecular are coordinated with Li^(+),the electrolyte does not show incompatibility issue between neither metal lithium nor graphite anode.Therefore,it demonstrates excellent capability in stabilizing the interface of Ni-rich cathode and regulating lithium deposition morphology.The Li||LiNi_(0.87)Co_(0.08)Mn_(0.05)O_(2)(NCM87)batteries exhibit high capacity retention of more than 90%after 200 cycles even under the high cutoff voltage of 4.5 V,1 C rate.This study offers a prospective method to develop safe electrolytes suitable for high voltage applications,thus providing higher energy densities.
基金supported by the National Key R&D Program of China(Grant No.2021YFB2400400)the National Natural Science Foundation of China(Grant Nos.22179070,U1932220)+2 种基金the Natural Science Foundation of Jiangsu Province(Grant No.BK20220073)the Project on Carbon Emission Peak and Neutrality of Jiangsu Province(Grant No.BE2022031-4)the Fundamental Research Funds for the Central Universities(Grant No.2242022R10082).
文摘With the increasing development of digital devices and electric vehicles,high energy-density rechargeable batteries are strongly required.As one of the most promising anode materials with an ultrahigh specific capacity and extremely low electrode potential,lithium metal is greatly considered an ideal candidate for nextgeneration battery systems.Nevertheless,limited Coulombic efficiency and potential safety risks severely hinder the practical applications of lithium metal batteries due to the inevitable growth of lithium dendrites and poor interface stability.Tremendous efforts have been explored to address these challenges,mainly focusing on the design of novel electrolytes.Here,we provide an overview of the recent developments of localized high-concentration electrolytes in lithium metal batteries.Firstly,the solvation structures and physicochemical properties of localized high-concentration electrolytes are analyzed.Then,the developments of localized high-concentration electrolytes to suppress the formation of dendritic lithium,broaden the voltage window of electrolytes,enhance safety,and render low-temperature operation for robust lithium metal batteries are discussed.Lastly,the remaining challenges and further possible research directions for localized highconcentration electrolytes are outlined,which can promisingly render the practical applications of lithium metal batteries.
基金supported by the National Natural Science Foundation of China(91963118 and 52173246)Science Technology Program of Jilin Province(20200201066JC)the 111 Project(B13013)。
文摘Although graphite anodes operated with representative de/intercalation patterns at low potentials are considered highly desirable for K-ion batteries,the severe capacity fading caused by consecutive reduction reactions on the aggressively reactive surface is inevitable given the scarcity of effective protecting layers.Herein,by introducing a flame-retardant localized high-concentration electrolyte with retentive solvation configuration and relatively weakened anion-coordination and non-solvating fluorinated ether,the rational solid electrolyte interphase characterized by well-balanced inorganic/organic components is tailored in situ.This effectively prevented solvents from excessively decomposing and simultaneously improved the resistance against K-ion transport.Consequently,the graphite anode retained a prolonged cycling capability of up to 1400 cycles(245 mA h g,remaining above 12 mon)with an excellent capacity retention of as high as 92.4%.This is superior to those of conventional and high-concentration electrolytes.Thus,the optimized electrolyte with moderate salt concentration is perfectly compatible with graphite,providing a potential application prospect for K-storage evolution.
基金supported by the National Natural Science Foundation of China (No. 21808125)China Postdoctoral Science Foundation (No. 2020M672805)supported by Tsinghua National Laboratory for Information Science and Technology。
文摘Localized high-concentration electrolytes(LHCE) have shown good compatibility with high-voltage lithium(Li)-metal batteries, but their practicality is yet to be proved in terms of cost and safety. Here we develop a hybrid-LHCE with favorable integrated properties by combining the merits of two representative diluents, fluorobenzene(FB) and 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether(TFE). Specifically,the extremely cheap and lightweight FB significantly reduces the cost and density of electrolyte, while the fire-retardant TFE circumvents the flammable nature of FB and thus greatly improves the safety of electrolyte. Moreover, the FB–TFE mixture enhances the thermodynamic stability of hybrid-LHCE and renders a controllable defluorination of FB, contributing to the formation of a thin and durable inorganic-rich solid electrolyte interphase(SEI) with rapid ion-transport kinetics. Benefiting from the designed hybridLHCE, a Li|NCM523 battery demonstrates excellent cycling performance(215 cycles, 91% capacity retention) under challenging conditions of thin Li-anode(30 μm) and high cathode loading(3.5 m Ah/cm^(2)).
基金supported by the National Natural Science Foundation of China (No.21972049)the Guangdong-Hong KongMacao Greater Bay Area Exchange Programs of SCNU (2022)。
文摘Although high salt concentration electrolyte(HCE)can construct effective Li F-rich interphase film and solve the interphasial instability issue of graphite anode,its high cost,high viscosity and poor wettability with electrode materials limit its large-scale application.Generally,localized high concentration electrolyte(LHCE)is obtained by introducing an electrochemically inert diluent into HCE to avoid the above-mentioned problems while maintaining the high interphasial stability of HCE with graphite anode.Unlike traditional inert diluents,1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluropropyl ether(TTE)with electrochemical activity is introduced into propylene carbonate(PC)-based HCE to obtain LHCE-2(1 M LiPF_(6),PC:DMC:TTE=1:1:6.1)herein.Experimental and theoretical simulation results show that TTE participates in the oxidation decomposition and film-forming reaction at the NCM622 cathode surface,conducting a cathode electrolyte interphase(CEI)rich in organic fluorides with excellent electron insulation ability,high structural stability and low interphasial impedance.Thanks to the outstanding interphasial properties induced by LHCE-2,the graphite||NMC622 pouch cell reaches a capacity retention of 80%after 500 cycles at 1 C under room temperature.While at sub-zero temperatures,the capacity released by the cell with LHCE-2 electrolyte is significantly higher than that of HCE and conventional EC-based electrolytes.Meanwhile,the LHCE-2 electrolyte inherits the advantages of TTE flame-resistant,thus improving the safety of the battery.
基金financially supported by the National Natural Science Foundation of China (Nos.51922038 and 51672078)the Hunan Outstanding Youth Talents(No.2019JJ20005)+1 种基金Hunan Provincial Natural Science Foundation of China(2019JJ40031)the Fundamental Research Funds for the Central Universities(531119200156)。
文摘Benefiting from the environmental friendliness of organic electrodes and the high security of aqueous electrolyte,an all-organic aqueous potassium dual-ion full battery(APDIB) was assembled with 21 M potassium bis(fluoroslufonyl)imide(KFSI) water-in-salt as the electrolyte.The APDIB could deliver a reversible capacity of around 50 mAh g^(-1) at 200 mA g^(-1)(based on the weight of total active materials),a long cycle stability over 900 cycles at 500 mA g^(-1) and a high coulombic efficiency of 98.5%.The reaction mechanism of APDIB during the charge/discharge processes is verified:the FSI-could associate/disassociate with the nitrogen atom in the polytriphenylamine(PTPAn) cathode,while the K^(+) could react with C=O bonds in the 3,4,9,10-perylenetetracarboxylic diimide(PTCDI) anode reversibly.Our work contributes toward the understanding the nature of water-into-salt electrolyte and successfully constructed all-organic APDIB.
基金supported by the National Key Research and Development Program of China(2021YFB2400200)the National Natural Science Foundation of China(52104313,22172117,52072298)the Scientific Research Program of Shaanxi Provincial Education Department(21JK0808)。
文摘The resourceful and inexpensive red phosphorus has emerged as a promising anode material of potassium-ion batteries(PIBs) for its large theoretical capacities and low redox potentials in the multielectron alloying/dealloying reactions,yet chronically suffering from the huge volume expansion/shrinkage with a sluggish reaction kinetics and an unsatisfactory interfacial stability against volatile electrolytes.Herein,we systematically developed a series of localized high-concentration electrolytes(LHCE) through diluting high-concentration ether electrolytes with a non-solvating fluorinated ether to regulate the formation/evolution of solid electrolyte interphases(SEI) on phosphorus/carbon(P/C) anodes for PIBs.Benefitting from the improved mechanical strength and structural stability of a robust/uniform SEI thin layer derived from a composition-optimized LHCE featured with a unique solvation structure and a superior K+migration capability,the P/C anode with noticeable pseudocapacitive behaviors could achieve a large reversible capacity of 760 mA h g^(-1)at 100 mA g^(-1),a remarkable capacity retention rate of 92.6% over 200 cycles at 800 mA g^(-1),and an exceptional rate capability of 334 mA h g^(-1)at8000 mA g^(-1).Critically,a suppressed reduction of ether solvents with a preferential decomposition of potassium salts in anion-derived interfacial reactions on P/C anode for LHCE could enable a rational construction of an outer organic-rich and inner inorganic-dominant SEI thin film with remarkable mechanical strength/flexibility to buffer huge volume variations and abundant K+diffusion channels to accelerate reaction kinetics.Additionally,the highly reversible/durable full PIBs coupling P/C anodes with annealed organic cathodes further verified an excellent practical applicability of LHCE.This encouraging work on electrolytes regulating SEI formation/evolution would advance the development of P/C anodes for high-performance PIBs.
基金supported by the National Natural Science Foundation of China(22072134,22161142017,and U21A2081)the Natural Science Foundation of Zhejiang Province(LZ21B030002)+2 种基金the Fundamental Research Funds for the Zhejiang Provincial Universities(2021XZZX010)the Fundamental Research Funds for the Central Universities(2021FZZX001-09)“Hundred Talents Program” of Zhejiang University。
文摘Passivation by the inorganic-rich solid electrolyte interphase(SEI),especially the LiF-rich SEI,is highly desirable to guarantee the durable lifespan of Li metal batteries(LMBs).Here,we report a diluent with the capability to facilitate the formation of LiF-rich SEI while avoiding the excess consumption of Li salts.Dissimilar to most of reported inert diluents,heptafluoro-l-methoxypropane(HM) is firstly demonstrated to cooperate with the decomposition of anions to generate LiF-rich SEI via releasing Fcontaining species near Li surface.The designed electrolyte consisting of 1.8 M LiFSI in the mixture of1,2-dimethoxyethane(DME)/HM(2:1 by vol.) achieves excellent compatibility with both Li metal anodes(Coulombic efficiency~99.8%) and high-voltage cathodes(4.4 V LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)(NMC811) and 4.5 V LiCoO_(2)(LCO) vs Li^(+)/Li).The 4.4 V Li(20μm)‖NMC811(2.5 mA h cm^(-2)) and 4.5 V Li(20μm)‖LCO(2.5 mA h cm^(-2)) cells achieve capacity retentions of 80% over 560 cycles and 80% over 505 cycles,respectively.Meanwhile,the anode-free pouch cell delivers an energy density of~293 W h kg^(-1)initially and retains 70% of capacity after 100 deep cycles.This work highlights the critical impact of diluent on the SEI formation,and opens up a new direction for designing desirable interfacial chemistries to enable high-performance LMBs.
基金supported by the National Key Research and Development Program of China(No.2021YFF0500600)the Haihe Laboratory of Sustainable Chemical Transformations,and the Fundamental Research Funds for the Central Universities.
文摘Lithium metal anodes hold great potential for high-energy-density secondary batteries.However,the uncontrollable lithium dendrite growth causes poor cycling efficiency and severe safety concerns,hindering lithium metal anode from practical application.Electrolyte components play important roles in suppressing lithium dendrite growth and improving the electrochemical performance of long-life lithium metal anode,and it is still challenging to effectively compromise the advantages of the conventional electrolyte(1 mol·L^(−1)salts)and high-concentration electrolyte(>3 mol·L^(−1)salts)for the optimizing electrochemical performance.Herein,we propose and design an interfacial high-concentration electrolyte induced by the nitrogen-and oxygen-doped carbon nanosheets(NO-CNS)for stable Li metal anodes.The NO-CNS with abundant surface negative charges not only creates an interfacial high-concentration of lithium ions near the electrode surface to promote chargetransfer kinetics but also enables a high ionic conductivity in the bulk electrolyte to improve ionic mass-transfer.Benefitting from the interfacial high-concentration electrolyte,the NO-CNS@Ni foam host presents outstanding electrochemical cycling performances over 600 cycles at 1 mA·cm^(−2) and an improved cycling lifespan of 1,500 h for symmetric cells.
基金supported by the Natural Science Foundation of Gansu Province for Youths(21JR7RA254)the Gansu Provincial Department of Education: Innovation Fund Project(2022A-029)+1 种基金the Major Special Fund of Gansu Province(21ZD4GA031)the Lanzhou University of Technology Hongliu First-class Discipline Construction Program and Gansu Province Central Government Guided Local Science and Technology Development Fund ProjectIndustrialization of Automotive Low-Temperature Lithium-ion Battery Manufacturing Technology Achievements。
文摘By optimizing electrolyte formulation to inhibit the deposition of transition metal ions(TMIs) on the surface of the graphite anode is an effective way to improve the electrochemical performance of lithium-ion batteries.At present,it is generally believed the formation of an effective interfacial film on the surface of the anode electrode is the leading factor in reducing the dissolution of TMIs and prevent TMIs from being embedded in the electrode.It ignores the influence of the solvation structures in the electrolyte system with different composition,and is not conducive to the design of the electrolyte formulation from the perspective of changing the concentration and the preferred solvent to inhibit the degradation of battery performance caused by TMIs deposition.In this work,by analyzing the special solvation structures of the high-concentra tion electrolyte,we study the main reason why high-concentration electrolyte inhibits the destructive effect of Mn(Ⅱ) on the electrochemical performance of LIBs.By combining the potentialresolved in-situ electrochemical impedance spectroscopy technology(PRIs-EIS) and density functional theory(DFT) calculation,we find that Mn(Ⅱ) mainly exists in the form of contact ions pairs(CIPs) and aggregates(AGGs) in high-concentration electrolyte.These solvation structures can reduce the destructive effect of Mn(Ⅱ) on battery performance from two aspects:on the one hand,it can rise the lowest unoccupied orbital(LUMO) value of the solvation structures of Mn(Ⅱ),thereby reducing the chance of its reduction;on the other hand,the decrease of Mn2+ions reduction can reduce the deposition of metallic manganese in the solid electrolyte interphase(SEI),thereby avoiding the continuous growth of the SEI.This study can be provided inspiration for the design of electrolytes to inhibit the destructive effect of TMls on LIBs.
基金supported by the National Natural Science Foundation of China(No.52072061)the Fundamental Research Funds for the Central Universities,China(No.ZYGX2019Z008)the China Postdoctoral Science Foundation Funded Project(No.2019M661941).
文摘Lithium(Li)metal is an ideal anode for the next generation high-energy-density batteries.However,it suffers from dendrite growth,side reactions,and infinite relative volume change.Effective strategies are using porous carbons or surface modification carbons to guide Li deposition into their pores.While the Li deposition behavior is still ambiguous.Here,we systematically determine their deposition behavior in various surface-modified carbons and in different electrolytes via optical microscopy and scanning electron microscopy study.It is found that Li will not spontaneously deposit into the carbon pores,which is significantly dependent on the carbon surface,current density,areal capacity,and electrolyte.Thus,a“lithiophilic”modified commercial hard carbon with Ag is developed as a stable“host”and efficient surface protection derived from the localized high-concentration electrolyte exhibits a pretty low volume change(5.3%)during cycling at a current density of 2 mA·cm^(−2)and an areal capacity of 2 mAh·cm^(−2).This strategy addresses the volume change and dendrite problems by rationally designed host and electrolyte,providing a broad perspective for realizing Li-metal anode.
