To enhance the capacity of Li-rich layered oxides by surface modification with metal–organic frameworks (MOFs) as cathodes for advanced lithium-ion batteries

Abstract

Li-rich layered oxides with a large discharge capacity have attracted considerable attention as cathodes for high energy lithium-ion batteries. To further enhance the discharge capacity and thermal stability of these Li-rich layered oxides, Mn-based metal–organic frameworks (MOFs) with high surface areas, large pore sizes, and stable architectures are employed as the active coating material. Herein, Mn-based MOFs can partially absorb or store oxygen gas originating from the oxidation of oxygen anions from the host lattice of Li-rich layered oxides in the initial charging stage to above 4.5 V (vs. Li/Li⁺). Moreover, the structure of the Li-rich layered oxide could be strengthened by the interconnection frameworks between the metal cations and organic ligands. As expected, the Li-rich layered Li(Li_0.17Ni_0.20Co_0.05Mn_0.58)O₂ oxide modified with a MOF exhibits a large discharge capacity (323.8 mA h g⁻¹ at 0.1C rate), high initial coulombic efficiency (91.1%), and good thermal stability without harming the cycle stability and high-rate capability. Surface modification with MOFs offers a new insight for further enhancing the discharge capacity of Li-rich layered oxides as cathodes for advanced lithium-ion batteries.