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

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 LiNi_0.8Co_0.1Mn_0.1O₂/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.