Crosslinked Hetero-Chain Polymeric Interphase Enables the Stable Cycling of Li-Rich Mn-Based Lithium Metal Batteries

The lithium-rich manganese-based layered oxide (LRMO) cathode shows grar promise for high-energy density and environment-friendly batteries due to its cation and anion redox. However, it suffers from continuous electrolyte consumption and capacity decay, especially at high mass loadings (>10 mg cm⁻²). Conventional electrolyte/interphase strategies fail to address the structural characteristics of LRMO, limiting its practical application. Here, we reveal the specific requirements for cathode electrolyte interphase (CEI) of LRMO and accordingly design a non-fluorinated additive, 2,4,6-trivinyl-2,4,6-trimethylcyclotrisiloxane (TVTMS). TVTMS could form a crosslinked hetero-chain polymeric CEI (CHP-CEI) through ring-opening polymerization and ethylene group crosslinking, offering a unique balance of high robustness, flexibility, and mechanical energy dissipation, which could not be achieved by conventional additives. Therefore, the cracking of LRMO cathode, gas release and transition metal dissolution were effectively mitigated. It should be noted that, for the first time to our knowledge, we employed the single-particle aerosol mass spectrometry (SPAMS) to study CEI components, especially the organic/polymer species. The Li|LRMO cells based on CHP-CEI display a lifespan >825 cycles with remained capacity of 204 mAh g⁻¹ and the cells with high-loading cathode (12 mg cm⁻²) achieve stable cycling >145 cycles with 80% capacity retention, which surpasses the performance of previously reported electrolytes.