Crucial Role of Solvent and Additive During the Transformation of Liquid to Solid Polymer Electrolyte for Stabilizing 4.8 V Class LiCo _0.9 Fe _0.1 PO ₄ Cathode in Anode and Anodeless Assemblies

Here, a new class of solid electrolyte is successfully demonstrated, the so-called gel-solid polymer electrolyte (G-SPE), for the stabilization of high-voltage cathodes. This work aims to optimize the suitable G-SPE configuration, wherein different electrolyte combinations have been experimented with by varying the solvent and introducing additives. Further, the study has been extended for the stabilization of high-voltage cathodes like solid-state synthesized LiCo_0.9Fe_0.1PO₄ (LCFP) and commercial LiNi_0.5Mn_1.5O₄ (LNMO), wherein the electrolyte combinations of G-SPE_B-EL_LIDFOB and G-SPE_B-EL_FEC show excellent electrochemical performance. The in situ impedance analysis has been carried out to analyze the stability of the gel-polymer interface, wherein RCT exhibits a stable magnitude even as the cycling progresses to the 50^th and 100^th cycle. The post-XPS analysis of the electrode shows a stable LiF-rich solid electrolyte interphase layer on the electrode surface, showing the formation of a stable and robust layer enabled by LIDFOB along with the gel. In addition, the optimized G-SPE_B-EL_LIDFOB electrolyte combination has been further utilized for the fabrication of full- and anode-less cell configurations against Li₄Ti₅O₁₂ (LTO) and Cu as counter electrodes, respectively.