Study on the application of TPP additive to improve high temperature gas production of high nickel and high silicon soft pack batteries
High nickel/high silicon soft pack batteries have the problems of poor calendar life and high temperature storage gas production.The electrochemical stability analysis between the positive and negative electrodes and the electrolyte in full charge state shows that the main source of gas pro-duction is the oxidation decomposition of the solvent on the positive electrode side.The research shows that:when 0.5％TPP is added to the electrolyte,the gas production rate of the battery is rap-idly reduced from 132％to 6％after being stored at 60 ℃ for 7 days,which is attributed to the fact that TPP additives can build a CEI film with high thermal stability at the positive electrode interface and inhibit solvent oxidation.At the same time,TPP,because it contains 3 unsaturated alkynyl func-tional groups,co-participates in film formation with FEC on the silicon negative electrode surface,en-hancing the toughness of SEI film.The interface impedance of the negative electrode is reduced from 9.45 Ω to 1.19 Ω by 87％.In addition,TPP additive has a significant effect on the high temperature cycle of silicon-based batteries,and the capacity retention rate of 1 000 cycles of 1 C at 45 ℃ in-creased from 82.3％to 86.9％.Therefore,because of its excellent high-temperature film forming sta-bility,TPP is expected to solve the problem of insufficient calendar life faced by the commercializa-tion of high nickel/high silicon systems,and accelerate the rapid landing of the next generation of high specific energy silicon-based battery products.
high Ni/high Si systemhigh temperature storage performancetripropyl phosphate(TPP)calendar lifeinterface stabilization technology
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