Li-rich Mn-based Li1.2Mn0.54 Ni0.13Co0.13O2 with carbothermal reduction coated spinel heterogeneous layer to enhance the electrochemical performance

Abstract

High-capacity Li-rich Manganese-based cathode materials (LMCs) have been considered ideal cathodes for Li-ion batteries (LIBs) because of the Li2MnO3 phase with anion activity and the LiTMO2 phase (TM: transition metal) with cation activity. However, the LMCs suffer from oxygen and Li irreversible loss in the cycles, which results in voltage decline, capacity attenuation, and a low initial Coulomb efficiency (ICE). Herein, we report co-precipitation synthesis of Li1.2Mn0.54Ni0.13 Co0.13O2 (LMNCO) cathodes by citric acid pretreatment, followed by carbothermal reduction to obtain a heterogeneous spinel layer of LMNCO surface. Organic acid undergoes carbonation and thermal reduction during annealing in an Ar atmosphere, contributing to the heterogeneous spinel layer reconstruction and the Mn reduction. The heterogeneous spinel layer facilitates Li-ion transportation by providing 3D Li diffusion channels and avoids bulk-phase corrosion by the electrolyte, as a buffer layer. At 0.1C, the surface-modified LMNCO cathodes render discharge capacity reaches up to 303.7 mAh g−1, and the ICE is 85.6%. Furthermore, at a 1C current, the discharge capacity is found to be 248.4 mAh g−1, and after 100 cycles, the capacity retention is 84.6%. These consequences demonstrate that the heterogeneous spinel layer significantly improves the capacity, ICE, and cyclic stability of the surface-modified LMNCO cathodes. The current study presents a successful modification to enhance the LMCs electrochemical performance, which is of utmost significance for practical applications.