Dual-phase structure design of Mn-site nickel doping Li2MnSiO4@C cathode material for improved electrochemical lithium storage performance

The lithium transition metal orthosilicates (Li2MnSiO4) compounds are considered key materials for the next-generation lithium-ion batteries (LIBs). However, they exhibit poor electronic conductivity and structural stability. Herein, the dual-phase (Pmn2(1,) and Pn) coexisting Li2Mn1-xNixSiO4@C is prepared successfully via a two-step calcination process to address the aforementioned problems. The orthorhombic Pmn2(1) and Pn phase are expected to bring well solid-state Li diffusion properties (D-Li(+)) and structural stability for electrode material, respectively. Also, the Ni doping and carbon coating are expected to raise electronic conductivity. Then, the electrochemical performance of LIBs utilizing LiMn0.995Ni0.005SiO4@C, LiMn0.985Ni0.015SiO4@C, and LiMn0.92Ni0.08SiO4@C (ZNi-02 to ZNi-04) as cathode materials are investigated and compared with that of the LiB using Li2MnSiO4@C (ZNi-01). The ZNi-04 sample-based LiB shows well D-Li(+) and a peak discharge capacity as high as 188.4 mAh g(-1). In addition, the ZNi-04 sample can still maintain a capacity of about 80 mAh g(-1) at rate of 8 C. Such excellent electrochemical performance is ascribed to the synergistic effect of the dual-phase coexistence, the proper amount of Ni doping, and surface coating of carbon, which enhances the electrical conductivity and structural stability. Thus, Li2Mn1-xNixSiO4@C has broad application chances as a high-performance LIBs electrode material.

Automated summary

The dual-phase Li2Mn1-xNixSiO4@C composite material prepared in this study successfully addresses the issues of poor electronic conductivity and structural stability by utilizing coexisting phases, Ni doping, and carbon coating. The LiB based on this composite material exhibits excellent electrochemical performance, showing promising prospects for broad applications.