Improved Cycling of Li||NMC811 Batteries under Practical Conditions by a Localized High‐Concentration Electrolyte

Abstract Li||NMC811 battery, with lithium‐metal (high specific capacity and low redox potential) as anode and LiNi_0.8Co_0.1Mn_0.1O₂ (NMC811) as cathode, has been widely accepted to be a good candidate as one of the high‐energy‐density batteries. However, its cyclability needs improvement to fulfill the requirement for its future commercial use, especially under practical conditions. Electrolyte plays a key role in improving the cycling performance of Li||NMC811 batteries, where a high voltage/electrochemical window and good stability with the electrodes of the electrolyte are required. Herein, a localized high‐concentration electrolyte with an additive of lithium difluoro(oxalate)borate (LiDFOB) is reported that improves the cycling performance of Li||NMC811 cells under crucial conditions with Li foil thickness of 50 µm, cathode areal loading of 4 mAh cm⁻², the areal capacity ratio between the negative and positive electrodes (N/P ratio) of 2.6 and the electrolyte/cell capacity ratio (E/C ratio) of 3.0 g (Ah)⁻¹. These cells can maintain 80% of the capacity after 195 cycles.