Quantum chemical design and experimental validation of a multifunctional additive for improved performance of high-nickel lithium-ion batteries

Abstract

LiPF6 undergoes chemical decomposition, including hydrolysis, in high-nickel lithium-ion battery systems and generates highly reactive HF and PF5. These highly reactive species cause corrosion on the surface of high-nickel cathodes, leading to the dissolution of transition metals and subsequent fading of the battery cycle performance. Consequently, the development of additives that can scavenge HF and stabilize PF5 has garnered significant attention in materials research for high-nickel cathodes to address this issue. This study uses quantum chemical calculations to design a multifunctional additive suitable for high-nickel systems and experimentally validates its performance. Theoretical calculations suggest that N-trimethylsilylimino triphenylphosphorane (TMSiTPP) is a chemically stable additive under both oxidation and reduction conditions owing to its triphenylphosphoranyl functional group. The PF5 binding energy and HF scavenging reaction calculations indicate that TMSiTPP functions as a multifunctional additive capable of both PF5 stabilization and HF scavenging in high-nickel cathode systems. Exposure of TMSiTPP to a water-containing standard electrolyte causes no color change, even in the presence of water after storage tests, confirming the stabilization of PF5, in agreement with nuclear magnetic resonance analyses. The electrochemical performance of a LiNi0.8Co0.1Mn0.1O2/graphite full cell containing 1% TMSiTPP is outstanding, showing a capacity retention rate of 86.1% over 150 cycles. This study demonstrates an efficient method for developing electrolyte additives by designing materials using quantum chemical calculation results and later experimentally verifying the designed materials.