A special enabler for boosting cyclic life and rate capability of LiNi0.8Co0.1Mn0.1O2: Green and simple additive

LiNi0.8Co0.1Mn0.1O2 (NCM811) is widely known for its extremely high specific capacity and relatively low cost, which draws extensive attention worldwide. However, poor cycling performance and rate capability impose restrictions on its large-scale practical application. Here we report that succinic anhydride (SA) as an additive in carbonate electrolyte significantly enhances the cycling performance and rate capability of Li/NCM811 cells. Capacity retention can reach 93.8% after 400 cycles at 1C rate by adding 3 wt% SA, while the pristine one cannot even endure 100 cycles. Moreover, rate capability can also be optimized to 82.4% of 5C/0.5C capacity ratio. The improvement of electrochemical performance was attributed to the formation of a uniform conductive cathode electrolyte interphase (CEI) layer upon particles. Our results confirm that firstly, the CEI formed by SA can protect active sites on the surface of NCM811 from side reactions. Secondly, the uniform conductive CEI plays a part in inhibiting severe polarization and local overcharge during long cycles. Moreover, the robust CEI layer can suppress the internal cracks, prohibit the irreversible phase transformation and nickel element migration of NCM811.