Alleviating Mn Ion Dissolution in LiMn2O4 by Activation of TiO2 Lewis Acid Sites in Electrospun PVA/TiO2 Quasi-Solid Polymer Electrolyte

Abstract

The primary concern of interest in high-voltage cathodes such as spinel LiMn₂O₄ is transition metal dissolution. Though several techniques and structural modifications are continuously under examination, a crucial factor that could make a significant impact is the careful evaluation of electrolyte properties. In this regard, a PVA/TiO₂ (PT) quasi-solid polymer electrolyte prepared using an electrospinning technique is employed to suppress HF scavengers, a main cause of manganese dissolution. Good electrochemical stability of 5.05 V, ionic conductivity of 0.26 × 10^–5 S cm^–1, stable plating–stripping, and t_Li⁺ of 0.82 are evidence for good electrolyte performance. Lewis acid sites of TiO₂ firmly hold the PF₆^– anions, and strong hydrogen bonding of carbonate solvents disrupts the cycle of electrolyte decomposition reactions. The capacity retention of 73% after 500 cycles at a 2C rate and post-mortem analysis of the LMO cathode provide evidence for the successful suppression of manganese dissolution using a PT electrolyte.