摘要
Carbonate electrolytes have been widely applied in sodium-ion batteries(SIBs);however,the strong Na^(+) -solvent coordination induces sluggish desolvation kinetics and severe parasitic reactions at hard carbon(HC)anodes.Herein,tris(2,2,2-trifluoroethyl)phosphite(TFEPi)is introduced into a propylene carbonate/diethyl carbonate electrolyte(PDT,PC/DEC/TFEPi in a volume ratio of 5:4:1)to enhance the coordination of Na^(+)-PF_(6)^(-)for fast-charging SIBs.The electron-withdrawing CF_(3)groups in TFEPi reduce the electrondonating ability of carbonate solvents to weaken Na^(+) -solvent interactions and enrich PF_(6)^(-)in the first solvation sheath.This lowers Na^(+) desolvation energy from 68.1 kJ mol^(-1)in PC/DEC with a volume ratio of 5:5 to 54.1 kJ mol^(-1)in PDT.The anion-dominated solvation structure of PDT promotes its preferential adsorption on the HC anode,forming a NaF/Na_(3)PO_(4)-rich solid electrolyte interphase with enhanced Na^(+) transport and mechanical stability.Moreover,the phosphite group of TFEPi scavenges H/OH radicals to suppress combustion chain reactions,endowing PDT with exceptional flame retardancy with selfextinguishing time<1 s g^(-1).It is demonstrated that Na//HC half cell retains 80.6%and 61.7%of HC capacity at 200 and 500 mA g^(-1),respectively,and HC//Na_(3)V_(2)(PO_(4))_(2)F_(3)(NVPF)full cell shows 80%charge capacity of NVPF within 5 min at 1000 mA g^(-1)at 25℃ and maintains stable operation from -20 to 60℃.This work provides new insights into electrolyte solvation engineering for high chargeability and safety of SIBs.
基金
supported by the National Natural Science Foundation of China(W2412060 and 22325902)
the Natural Science Foundation of Tianjin City(24ZXZSSS00310 and 24JCZXJC00170)
the NCC Fund(NCC2022FH03)。
