Stabilizing the Interphasial Layer of Ni-rich Cathode and Graphite Anode for Lithium Ion Battery with Multifunctional Additive

As a promising cathode candidate in high energy density lithium-ion batteries, Nickel-rich cathode LiNi0.8Co0.15Al0.05O2 (LNCAO) has received extensive attention for its high specific capacity and low cost, while it is subject to fast capacity fading due to the inferior interphasial stability. This work aims to improve the cyclic stability of LNCAO cathode by using a multifunctional electrolyte additive, p-toluenesulfonylmethyl isocyanide (TOSMIC). DFT calculation shows that the high reduction activity of TOSMIC additive is mainly contributed by its sulfone group, while the high oxidation activity is primarily caused by its phenyl group. The obtained experimental results indicate that TOSMIC simultaneously generates effective cathode electrolyte interphase and solid electrolyte interphase layer on LNCAO and graphite surface, respectively, leading to greatly enhanced cyclic stability of LNCAO cathode and increased rate performance of graphite anode. On the other hand, application of TOSMIC could suppress the hydrolyzation reaction of LiPF6, and therefore, hindering the generation of harmful product HF and dissolution of transition metal from LNCAO cathode during cycling. Application of such multifunctional electrolyte additive significantly improves the cycle life of the LNCAO/graphite full cell.