Alleviating Mn Ion Dissolution in LiMn<sub>2</sub>O<sub>4</sub> by Activation of TiO<sub>2</sub> Lewis Acid Sites in Electrospun PVA/TiO<sub>2</sub> Quasi-Solid Polymer Electrolyte.

Johnson, Jenny; Sasirajan Littleflower, Sajan Raj; Vediappan, Kumaran; Annal Therese, Helen · Nano Lett · 2025

basic_science · Level V

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Abstract

The primary concern of interest in high-voltage cathodes such as spinel LiMn<sub>2</sub>O<sub>4</sub> 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/TiO<sub>2</sub> (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<sup>-5</sup> S cm<sup>-1</sup>, stable plating-stripping, and <i>t</i><sub>Li</sub><sup>+</sup> of 0.82 are evidence for good electrolyte performance. Lewis acid sites of TiO<sub>2</sub> firmly hold the PF<sub>6</sub><sup>-</sup> 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.