In situ transformation of a liquid electrolyte into a solid polymer electrolyte: influence of TMSP in a layered LiNi0.82Mn0.12Al0.06O2 cathode

Abstract

Herein, we successfully demonstrated a thermal polymerization technique for the in situ transformation of a commercial liquid electrolyte into a gel-solid polymer electrolyte (G-SPE). In addition, an attempt has been made to improve the interfacial contact and electrolyte stability by introducing a film-forming additive, tris(trimethylsilyl)phosphate (TMSP), and its influence on the electrochemical stability has been studied by varying its concentration and is denoted as G-SPE_TMSP (1–5 wt%). The electrochemical studies reveal enhanced ionic conductivity and transference number, when the TMSP concentration is increased from 1 to 5 wt%. The unique behavior originated from the increase in thickness of the cathode electrolyte interphase (CEI) layer formation. To demonstrate the feasibility of using G-SPE_TMSP in practical cells, a Li-battery has been made with LiNi_0.82Mn_0.12Al_0.06O₂ (NMA) as the cathode and Li metal as the anode. The galvanostatic charge–discharge studies exhibit an enhancement in the electrochemical performance as the concentration of TMSP is increased from 1 to 5 wt% due to an increase in the stability of the CEI–gel interface. The in operando analysis shows the absence of phase transition. Moreover, post-analysis of the electrode and electrolyte reveals the absence of parasitic side reactions between the electrode and electrolyte. Therefore, the G-SPE promotes excellent cycle stability and coulombic efficiency in the cell assembly.