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 LiNi0.8 Co0.1 Mn0.1 O2 (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 50µm, cathode areal loading of 4mAhcm-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 3.0g(Ah)-1 . These cells can maintain 80% of the capacity after 195 cycles.