A Dual-Function Electrolyte Additive Suppresses Mn Crosstalk for Durable High-Temperature Graphite/LiMn2O4 Batteries

Mn crosstalk accelerates the degradation of graphite/LiMn2O4 (LMO) batteries, particularly at elevated temperatures, through the migration and deposition of dissolved Mn species on the graphite anode, which destabilizes the anode interphase. Here, tris(trimethylsilyl) phosphate (TMSP) suppresses this cross-electrode degradation pathway by regulating both the bulk electrolyte chemistry and the LMO/electrolyte interface. In the bulk electrolyte, the Si-O groups of TMSP consume HF and suppress continued HF generation through LiPF6 hydrolysis, thereby weakening acid-induced LMO corrosion. At the cathode interface, preferential adsorption and oxidation of TMSP promote the formation of a thin (∼3 nm) Li3PO4-rich cathode-electrolyte interphase (CEI), which limits electrolyte decomposition and Mn dissolution. These complementary effects reduce Mn dissolution and deposition on the graphite anode, thereby limiting Mn-associated SEI growth and resistance increase. In 1.6 Ah graphite/LMO 18650 cells, 2.1 wt % TMSP reduces Mn deposition on the anode by 95.2% and increases capacity recovery from 90.5% to 95.1% after storage at 60 °C for 7 days. The cells also retain 80.2% of their initial capacity after 500 cycles at 1 C and 45 °C. These results establish the suppression of Mn crosstalk as an effective strategy for improving the high-temperature durability of graphite/LMO batteries.