Effects of LiFSi and LMO-Coated NCM on Capacity and Cycle Characteristics of All-Solid Lithium Batteries

Abstract

The initial capacity and cycle retention properties of all-solid lithium batteries (ASLBs) were greatly improved by utilizing polyethylene oxide (PEO)/lithium salts in conjunction with LiFSi, and coating the nickel manganese cobalt oxide (NCM) cathode component with lithium manganese oxide (LMO). That is, composite cathodes for ASLBs were fabricated by using lithium salts (LiClO4/LiFSi (8:2)) with PEO, Al-LLZO powder, Super-P, and LMO-coated NCM-424/622, respectively (Al-LLZO = Li6.25Al0.25La3Zr2O12). LiFSi was added to a solution of PEO/LiClO4 ([EO]:[Li] = 13:1) to generate a composite cathode and composite solid electrolyte (CSE) sheet. The initial capacity and cycle retention of the resulting cells were improved by controlling the side reactions and the improving kinetic characteristics. Moreover, NCM-424 and NCM-622 were coated with LMO; the optimum LMO coating amount (1 wt%) and NCM-424/622 ratio (9:1) for simultaneously improving the capacity and cycle retention were explored. Overall, the initial capacity of the ASLBs reached 152 mAh g−1, with a capacity retention rate of 92% at the 100th cycle.

Preparation and electrochemical investigation of single-crystal LiNi0.6Co0.2Mn0.2O2 for high-performance lithium-ion batteries

“…This secondary particle structure is prone to grain boundary fracture, especially during high voltage operation and long-term cycling, greatly increasing the electrode/electrolyte interphase area, exposing new surfaces connected to the electrolyte, which accelerates the cathode–electrolyte side reactions and phase transformation. 11,12 Many efforts have been made to overcome these problems, such as doping, 13–18 surface modification 19–25 and using a core–shell structure.…”

Adaptive protection for PEO-based solid electrolyte with chelation of triphenyl phosphite and LiNi0.8Co0.1Mn0.1O2

“…There are two reasons for the capacity degradation of NCM. 5 (i) Under a high charge state, Ni 4+ with the strongly oxidizing oxidizes the electrolyte, leading to decomposition of the electrolyte and the occurrence of side reactions at the electrode/electrolyte interface. (ii) The Ni 2+ and Li + radii are very similar, and Ni/Li cationic disordering is prone to occur in high-nickel NCM, resulting in a decrease in the lattice constant, a decrease in the Li + diffusion rate, and the occurrence of cracks in the material particles.…”