Simultaneous Interphase Optimizations on Large-area Anode and Cathode of High-energy-density Lithium-ion Pouch Cells by a Multiple Additives Strategy.

Prior to the maturation of next-generation energy storage devices, the actual lithium-ion batteries for commercial purposes are still expected to fulfill some critical requirements, among which the high energy density, wide operating temperature range and related long-term cycling stability are the most challenging issues. Herein a multiple additives strategy is employed to simultaneously optimize the solid electrolyte interphase on large-area anode and cathode in a 2 Ah artificial graphite (AGr)/LiNi0.5Co0.2Mn0.3O2 (NCM523) pouch cells with high gravimetric (> 260 Wh Kg-1) and volumetric (> 630 Wh L-1) energy density. By introducing a rational mixture of electrolyte additives, a highly sulfurized surface layer and an uniform and thin passivation layer are separately formed on the anode and cathode of the AGr/NCM523 pouch cell, exhibiting high storage stability at 60 °C, much improved discharge capacity at ‒10 and ‒20 °C, high anodic stability at high voltage of 4.4 V, and stable cyclic performance with a capacity retention of 85.5% after 500 cycles, significantly outperforming the value of 75.7% after only 200 cycles of the cell without additional additives. These results demonstrate the critical effect of simultaneous optimizations of anode and cathode interphase layers to construct stable high-energy-density lithium-ion pouch cells.