Phosphorus-silicon-integrated electrolyte additive boosts cycling performance and safety of high-voltage lithium-ion batteries

Safety and energy density are significant for lithium-ion batteries (LIBs), and the flammable organic electrolyte is one of the most critical causes of the safety problem of LIBs. Although LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode with high capacity can improve the energy density, the interface stability between NCM811 cathode and electrolytes needs to be improved. Herein, we report a multifunctional additive, diethyl (2-(triethoxysilyl) ethyl) phosphonate (DETSP), which can suppress the flammability of the electrolyte and enhance the cycling stability of NCM811 cathode with a capacity retention of 89.9% after 400 cycles at 1 C, while that of the blank electrolyte is merely 61.3%. In addition, DETSP is compatible well with the graphite anode without impairing the electrochemical performances. Significantly, the performance and safety of NCM811/graphite full cells are also improved. Experimental and theoretical results demonstrate that DETSP can scavenge acidic byproducts and is beneficial to form a stable cathode-electrolyte interface (CEI). Accordingly, DETSP can potentially be an effective solution to ameliorating the safety of the commercial electrolyte and improving the stability of high-voltage cathodes.