Study On The Influence Of Electrolyte Additives On The Performance Of Silicon-based Anodes

With the commercialization of lithium-ion batteries,silicon anodes have been the most promising next-generation anode materials,because their theoretical specific capacity is ten times higher than graphite.However,the silicon anode is broken and powdered owing to volume expansion during the cycle,which has become a bottleneck in the development of the commercialization of silicon anode.Adding electrolyte additives is the most economical and effective way to enhance the performance of lithium-ion batteries.Adding a little additive can improve electrode stability and alleviate the crush and pulverization.Therefore,this paper mainly studies three kinds of electrolyte additives(LiPO2F2,AS and PTSI)applied to two kinds of anode materials(Si/C and Si)to analyze its effect on electrode interface,and initially explored the effects of three additives on SEI film.The effect of LiPO2F2 as electrolyte additive on the electrochemical performance of Si/C and Si anodes was studied.The experimental results show that LiPO2F2 can effectively reduce the impedance and improve the cycle and rate performance of Si/C anode.After 100 cycles of 1000 mA/g current,the capacity retention ratio of Si/C anode in the electrolyte containing 1 wt.% LiPO2F2 was 40% higher than non-addition.When the current density is 2000 mA/g,the charge specific capacity increases by more than 55%,and when the current density is 5000 mA/g,the capacity increases by more than 100%.The effect of AS as electrolyte additive on the electrochemical properties of Si/C and Si anodes was studied.The results show that AS can improve the cycling performance of Si/C and Si anodes.After charging and discharging 100 times with a current of 1000 mA/g,the capacity retention rate of Si/C anodes in electrolyte containing 2 wt.% AS compared with non-addition,the capacity retention rate is increased by 27%,The capacity retention rate of the 1 wt.% AS electrolyte was 34% higher than that of the non-addition.The effect of PTSI as electrolyte additive on the electrochemical properties of Si/C and Si anodes was studied.The results show that PTSI can effectively reduce the impedance and improve the cycle and rate performance of Si/C and Si anodes.After 100 cycles of 1000 mA/g current,the capacity retention rate of Si/C anode in electrolyte containing 2 wt.% PTSI was increased by 79% compared with non-addition,the capacity retention rate of Si anode in electrolyte containing 1 wt.% PTSI was increased by 55% compared with non-addition.When the current density is 5000 mA/g,the capacity of Si anode in the electrolyte containing 2 wt.% PTSI increased by 221% compared with non-addition.