Interphase engineering via a synergistic dual-additive electrolyte strategy for high-voltage LiNi0.6Co0.2Mn0.2O2 cathode materials with enhanced cycling stability

The pursuit of high-voltage nickel-based layered terminal oxide materials (NCM) has gained significant research momentum owing to their compelling combination of cost-effectiveness and high energy density. However, critical challenges persist in mitigating parasitic interfacial reactions, electrolyte oxidative decomposition, and structural degradation mechanisms under elevated operating voltages (>4.3 V vs. Li/Li + ). Here, we propose a synergistic dual-additive electrolyte strategy by adding tris(pentafluorophenyl)borane (TPFPB) and lithium difluoro(oxalato)borate (LiDFOB) to a conventional carbonate-based electrolyte, aiming to enhance the performance of high-voltage LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622). Theoretical and experimental analyses show that LiDFOB reduces harmful side products (e.g., HF, PF 5 ) by inhibiting LiPF 6 decomposition, while TPFPB's rigid structure promotes a uniform and dense cathode electrolyte interface (CEI) film on the cathode. The two additives work synergistically to enabling the Li/NCM622 half-cells to maintain a capacity retention of up to 76.8 % after 500 cycles at 1C under 4.5 V high voltage, while the cell prepared with an electrolyte without any additives only retained 7.6 % capacity after cycling. The synergistic strategy employing TPFPB and LiDFOB to enhance the high-voltage cycling stability provides a promising practical feasibility of high-voltage batteries for industrial application.