Suppressing Nickel Dissolution in Ni‐rich Layered Oxide Cathodes Using NiF2 as Electrolyte Additive

Abstract The dissolution of transition metals is the main reason for the capacity fading and structural degradation of Ni‐rich cathode materials. In this work, NiF 2 is used as functional electrolyte additive for the first time to improve the performance of LiNi 0.6 Co 0.2 Mn 0.2 O 2 cathodes by the chemical‐equilibrium principle. The suppression of transition‐metal dissolution, especially Ni, is proved by energy disperse spectroscopy and inductively coupled plasma analyses. The NiF 2 additive can stabilize the cathode structure by relieving the dissolution of transition metals, which is confirmed by morphology and structure analyses. Moreover, the NiF 2 additive also reduces side reactions of the cell, which is verified by self‐discharge tests and coulombic efficiency analysis. As a result, the addition of 100 ppm NiF 2 elevates the capacity retention of the Li/NCM622 half‐cell from 69.53 to 79.67 % after 100 cycles, and the 100 ppm NiF 2 ‐containing cathode delivers an initial capacity of 174.0 mAh g −1 even at 8 C after 50 cycles.