Cyclic Aminosilane-Based Additive Ensuring Stable Electrode-Electrolyte Interfaces in Li-Ion Batteries

Abstract

Ni-rich cathodes are considered feasible candidates for high-energy-density Li-ion batteries (LIBs). However, the structural degradation of Ni-rich cathodes on the micro- and nanoscale leads to severe capacity fading, thereby impeding their practical use in LIBs. Here, it is reported that 3-(trimethylsilyl)-2-oxazolidinone (TMS-ON) as a multifunctional additive promotes the dissociation of LiPF6, prevents the hydrolysis of ion-paired LiPF6 (which produces undesired acidic compounds including HF), and scavenges HF in the electrolyte. Further, the presence of 0.5 wt% TMS-ON helps maintain a stable solid-electrolyte interphase (SEI) at Ni-rich LiNi0.7Co0.15Mn0.15O2 (NCM) cathodes, thus mitigating the irreversible phase transformation from layered to rock-salt structures and enabling the long-term stability of the SEI at the graphite anode with low interfacial resistance. Notably, NCM/graphite full cells with TMS-ON, which exhibit an excellent discharge capacity retention of 80.4%, deliver a discharge capacity of 154.7 mAh g(-1) after 400 cycles at 45 degrees C.