Constructing heterostructured Li-Fe-Ni-Mn-O cathodes for lithium-ion batteries: effective improvement of ultrafast...

Surface modification is proved to be an effective strategy to improve the power density of lithium-ion batteries (LIBs) applied in electric vehicles. In this article, a protective modification layer (FeF₃/LiF) is successfully deposited onto the surface of a low-cost cathode material, Li_6/5[Fe_1/10Ni_3/20Mn_11/20]O₂, for realizing the improvement of ultrafast lithium storage. The reversible specific capacity and ultrahigh rate capability are effectively improved. The modified sample can achieve a higher reversible discharge specific capacity of 171.8 mA h g^-1 at 0.2C. A discharge specific capacity of 150.4 mA h g^-1 is delivered at 1C after 60 cycles. Even at 2C and 5C, the discharge specific capacities are still maintained at 135.7 and 124.5 mA h g^-1. Notably, when charged and discharged at 20C, a discharge specific capacity of 73.4 mA h g^-1 can be achieved after 200 cycles by the heterostructured Li-Fe-Ni-Mn-O cathode, almost twice that of the bare material. The good fast lithium storage capability can be ascribed to the effective suppression of interfacial side reactions, the conversion reaction from the FeF₃ phase, and the harmonious coexistence of layered and spinel phases. The triple benefits from the heterostructured cathode provide a promising route for constructing advanced LIBs.