Enhancing Electrochemical Performance of High Entropy Spinel Oxide via Optimization of Binder and Electrolyte Additive for Lithium-Ion Batteries

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High-entropy oxide (HEO) materials have emerged as promising anodes for lithium-ion batteries (LIBs). This study investigates the effects of binders and fluoroethylene carbonate (FEC) electrolyte additive on the electrochemical performance of (CrMnFeNiCu)₃O₄ HEO anodes. Various binders, including organic-solvent-soluble polyvinylidene fluoride (PVDF) and water-soluble polyvinyl formamide, sodium carboxymethyl cellulose, sodium alginate, and sodium polyacrylate (NaPAA), are examined. Notably, the NaPAA binder significantly enhances HEO performance by improving charge-discharge Coulombic efficiency, rate capability, and mitigating electrode degradation during cycling. The thermal reactivity of the lithiated electrodes is assessed using differential scanning calorimetry, revealing the impact of binders on the exothermic onset temperature and total heat released. These findings offer valuable insights into the safety of HEO anodes for LIBs. Furthermore, this study explores the influence of the FEC electrolyte additive on HEO anode performance. The charge-discharge performance of the (CrMnFeNiCu)₃O₄ anode is strongly influenced by the properties of solid-electrolyte interphase (SEI), with different FEC concentrations yielding distinct SEI compositions. The electrode cycled with FEC-free electrolyte shows poor passivation, resulting in a thick, non-uniform SEI and low cycling stability. Of note, 10 wt% FEC optimally forms a thin, continuous SEI, improving electrode rate capability and cycling stability. Excessive FEC (15 wt%) leads to brittle SEI and degraded performance. These results highlight the critical role of binder and FEC optimization in enhancing HEO anode performance.

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