Improving electrochemical performance of spinel-type Ni/Mn-based high-voltage cathode material for lithium-ion batteries via La-F co-doping combined with in-situ integrated perovskite LaMnO3 coating layer

Spinel-type LiNi0.5Mn1.5O4 (LNMO) can provide high-voltage and high theoretical specific capacity as cathode material for lithium-ion batteries (LIBs), thereby LNMO is particularly suitable for electric/hybrid electric vehicles that require high power. Unfortunately, both serious structural deformation derived from the Jahn-Teller effect of Mn3+ and decomposition of electrolyte during repetitive charge/discharge processes at high operating potential result in fast capacity fade. In this work, lanthanum and fluorine co-doping LiNi0.5La0.01Mn1.49O3.97F0.03 (LF-LNMO) is proposed to eliminate its inherent defects. Fluorine can suppress Jahn-Teller effect of Mn3+ by reducing the generation of Mn3+; La3+ ions in LF-LNMO play a role in solidly riveting atoms together in the structure, and LaMnO3 coating layer acts as a physical protection barrier suppressing adverse side reactions that may damage battery performance. Thanks to the synergistic effect derived from structural modification of F−, the pinning effect of La3+ ions, and LaMnO3 surface coating interface reconstruction, the LF-LNMO cathode provides the best cycling performance and rate performance among all investigated electrode materials. Such as, LF-LNMO cathode can provide 64.02% capacity retention after the 1000th cycle at 500 mA g−1 and 30 °C, which is much higher than that (25.56%) of the undoped LiNi0.5Mn1.5O4 (P-LNMO). Besides, LF-LNMO electrode also behaves the excellent high-temperature cycling performance. This work provides a new strategy enhancing structural stability of spinel-type Ni/Mn-based oxide and would motivate us to further devise and prepare high power cathode materials for LIBs.