Compared with the extensively used ester‐based electrolyte,the hard carbon(HC)electrode is more compatible with the ether‐based counterpart in sodium‐ion batteries,which can lead to improved cycling stability and r...Compared with the extensively used ester‐based electrolyte,the hard carbon(HC)electrode is more compatible with the ether‐based counterpart in sodium‐ion batteries,which can lead to improved cycling stability and robust rate capability.However,the impact of salt anion on the electrochemical performance of HC electrodes has yet to be fully understood.In this study,the anionic chemistry in regulating the stability of electrolytes and the performance of sodium‐ion batteries have been systematically investigated.This work shows discrepancies in the reductive stability of the anionic group,redox kinetics,and component/structure of solid electrolyte interface(SEI)with different salts(NaBF_(4),NaPF_(6),and NaSO_(3)CF_(3))in the typical ether solvent(diglyme).Particularly,the density functional theory calculation manifests the preferred decomposition of PF_(6)−due to the reduced reductive stability of anions in the solvation structure,thus leading to the formation of NaF‐rich SEI.Further investigation on redox kinetics reveals that the NaPF_(6)/diglyme can induce the fast ionic diffusion dynamic and low charge transfer barrier for HC electrode,thus resulting in superior sodium storage performance in terms of rate capability and cycling life,which outperforms those of NaBF_(4)/diglyme and NaSO_(3)CF_(3)/diglyme.Importantly,this work offers valuable insights for optimizing the electrochemical behaviors of electrode materials by regulating the anionic group in the electrolyte.展开更多
Hard carbon(HC)remains the most commercially viable anode for sodium-ion batteries,yet its low initial Coulombic efficiency and unstable solid electrolyte interphase(SEI)hinder long-term performance.Electrolyte engine...Hard carbon(HC)remains the most commercially viable anode for sodium-ion batteries,yet its low initial Coulombic efficiency and unstable solid electrolyte interphase(SEI)hinder long-term performance.Electrolyte engineering offers a promising strategy to regulate SEI chemistry,enhancing interfacial Na^(+)transport and interphase stability.However,the respective roles of solvents and anions in tailoring the SEI on HC remain elusive.Here we propose a“revitalization”strategy to clarify the synergistic influence of solvent and anion chemistry by systematically evaluating three electrolytes:1.0 M NaPF_(6)in EC/DMC,1.0 M NaPF_(6)in diethylene glycol dimethyl ether(Na PF_(6)-G2),and 1.0 M sodium trifluoromethanesulfonate in G2(NaOTF-G2).Combined experimental and theoretical analyses reveal that weak Na^(+)-G2 interactions permit more anions to enter the primary solvation shell,facilitating the formation of an inorganic-rich SEI that promotes high ionic conductivity and redox kinetics.Additionally,the preferential decomposition of OTF^(-)-anions results in a uniform and robust SEI.As a result,HC anodes cycled in NaOTF-G2 deliver a reversible specific capacity of~200 mAh g^(-1)over 3000 cycles.Furthermore,a Na_(3)V_(2)(PO_(4))_(3)||HC pouch cell incorporating this optimized electrolyte achieves a capacity retention of 81%at-40℃.This work provides molecular-level insights into electrolyte design principles and highlights the critical role of solvation structure in enabling durable low-temperature sodium storage.展开更多
基金Australian Research Council,Grant/Award Numbers:DP200101249,DP210101389,IH180100020Natural Science Foundation of Jiangsu Province,Grant/Award Number:BK20210821National Natural Science Foundation of China,Grant/Award Number:22102141。
文摘Compared with the extensively used ester‐based electrolyte,the hard carbon(HC)electrode is more compatible with the ether‐based counterpart in sodium‐ion batteries,which can lead to improved cycling stability and robust rate capability.However,the impact of salt anion on the electrochemical performance of HC electrodes has yet to be fully understood.In this study,the anionic chemistry in regulating the stability of electrolytes and the performance of sodium‐ion batteries have been systematically investigated.This work shows discrepancies in the reductive stability of the anionic group,redox kinetics,and component/structure of solid electrolyte interface(SEI)with different salts(NaBF_(4),NaPF_(6),and NaSO_(3)CF_(3))in the typical ether solvent(diglyme).Particularly,the density functional theory calculation manifests the preferred decomposition of PF_(6)−due to the reduced reductive stability of anions in the solvation structure,thus leading to the formation of NaF‐rich SEI.Further investigation on redox kinetics reveals that the NaPF_(6)/diglyme can induce the fast ionic diffusion dynamic and low charge transfer barrier for HC electrode,thus resulting in superior sodium storage performance in terms of rate capability and cycling life,which outperforms those of NaBF_(4)/diglyme and NaSO_(3)CF_(3)/diglyme.Importantly,this work offers valuable insights for optimizing the electrochemical behaviors of electrode materials by regulating the anionic group in the electrolyte.
基金supported by the National Natural Science Foundation of China(52271222,52301245,52171218)the Shanghai Municipal Science and Technology Commission(23DZ1202500)+3 种基金the Shanghai Rising-Star Program(Yangfan Special Project,23YF1428900)the China Postdoctoral Science Foundation Funded Project(2023M742369)the China Postdoctoral Science Foundation,No.17 Special Fund(In-Station)(2024T170572)the Shanghai Super Postdoctoral Fellowships(2022475)。
文摘Hard carbon(HC)remains the most commercially viable anode for sodium-ion batteries,yet its low initial Coulombic efficiency and unstable solid electrolyte interphase(SEI)hinder long-term performance.Electrolyte engineering offers a promising strategy to regulate SEI chemistry,enhancing interfacial Na^(+)transport and interphase stability.However,the respective roles of solvents and anions in tailoring the SEI on HC remain elusive.Here we propose a“revitalization”strategy to clarify the synergistic influence of solvent and anion chemistry by systematically evaluating three electrolytes:1.0 M NaPF_(6)in EC/DMC,1.0 M NaPF_(6)in diethylene glycol dimethyl ether(Na PF_(6)-G2),and 1.0 M sodium trifluoromethanesulfonate in G2(NaOTF-G2).Combined experimental and theoretical analyses reveal that weak Na^(+)-G2 interactions permit more anions to enter the primary solvation shell,facilitating the formation of an inorganic-rich SEI that promotes high ionic conductivity and redox kinetics.Additionally,the preferential decomposition of OTF^(-)-anions results in a uniform and robust SEI.As a result,HC anodes cycled in NaOTF-G2 deliver a reversible specific capacity of~200 mAh g^(-1)over 3000 cycles.Furthermore,a Na_(3)V_(2)(PO_(4))_(3)||HC pouch cell incorporating this optimized electrolyte achieves a capacity retention of 81%at-40℃.This work provides molecular-level insights into electrolyte design principles and highlights the critical role of solvation structure in enabling durable low-temperature sodium storage.
