Tris(vinyl dimethylsilyl) phosphate: Enhancing interface stability in high-voltage Li-ion batteries at elevated...

High temperature will aggravate the breakdown of electrolyte as well as corrosion of electrodes in high-voltage lithium-ion batteries (LIBs), thus impairing their cycling and storage performance. Constructing a stable electrolyte/electrode interface is key to overcoming the above obstacle. Trimethylsilyl phosphate (TMSP), a common electrolyte additive, can form an ionic-conductive and high-voltage-resistant cathode electrolyte interface (CEI) film to boost the cycle life for high-voltage LIBs. However, this inorganic-rich interface film suffers from low density and poor adhesion, easily detaching at high temperatures and susceptible to HF corrosion. Moreover, the free radicals generated by the thermal decomposition of TMSP can intensify side reactions. This research designs a novel electrolyte additive, tris(vinyldimethylsilyl) phosphate (Vi-TMSP). Through vinyl polymerization, Vi-TMSP forms a dense and thermally stable organic framework. Combined with inorganic components derived from the oxidation of silicon and phosphate, it constructs a reinforced concrete-like organic-inorganic composite CEI film with superior thermal and high-voltage stability. Meanwhile, the generation of harmful radicals from additive decomposition is suppressed, thereby avoiding catalytic side effects. Thus, Vi-TMSP effectively enhances the electrode/electrolyte interface, improving the high-temperature cycling and storage performance of high-voltage NCM811/Graphite full batteries. The capacity retention remained at 93.27% after 300 cycles at 45 °C over 3.0-4.5 V. Moreover, the capacity retention and recovery ratio are 82.98% and 82.97%, respectively, after storage at 60 °C for 7 days, whereas those for the TMSP system are only 75.13% and 75.17%. This work inspires the design of film-forming electrolyte additives and high-performance LIBs.