Application of Artificial Interphase on Ni-Rich Cathode Materials Via Hybrid Ceramic-Polymer Electrolyte in All Solid State Batteries

Abstract

Among many cathode materials, nickel-rich LiNi0.83Co0.12Mn0.05O2 (NCM 831205) has been spotlighted as one of the most feasible candidates for next-generation LIBs because of its high discharge capacity (~200 mAh/g). However, NCM 831205 shows significant performance degradation, which is mostly attributed to cation mixing, surface side reactions, and intrinsic structural instability originating from the large volume changes during repeated cycling.Conventional lithium ion batteries (LIB) normally use flammable nonaqueous liquid electrolytes, resulting in a serious safety issue in use. In this respect, all-solid-state batteries (ASSB) are regarded as a fundamental solution to address the safety issue by using a solid state electrolyte in place of the conventional liquid one.This work employed lithium sulfonate (SO3Li) tethered polymer, obtained from sulfonation of commercial polymer, to serve as the artificial protective coating on the active NCM831205 of the cathode for ASSB based on hybrid PEO-ceramic solid electrolyte.The coating layer should prevent direct contact of electrolyte with the cathode, thus avoid the negative effects such as microcracks of NCM831205 and undesired CEI formation. The preparation of hybrid ceramic-polymer electrolyte through a solvent-free process. The hybrid electrolytes exhibit good flexibility and processability with respect to pure ceramic and pure PEO polymer electrolyte.It is demonstrated that the hybrid electrolytes can penetrate into cathode under 60°C, providing a good Li+ transfer channel inside the battery. Moreover, the sulfone based polymer protective coating could effectively improve the electrochemical stability of the NCM831205 without sacrificing the battery performance. Keywords: NCM831205, Artificial Polymer Coating, All-Solid-State Batteries