Dual‐phase structure design of Mn‐site nickel doping <scp> Li <sub>2</sub> MnSiO <sub>4</sub> </scp> @C cathode material for improved electrochemical lithium storage performance
Zhan Yang, Qing Wang, Shaohua Luo, Si Li, Luoxuan Wang, Xin Liu, Yahui Zhang, Long‐Jiao Chang
Abstract
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 (Pmn21, and Pn) coexisting Li2Mn1−xNixSiO4@C is prepared successfully via a two-step calcination process to address the aforementioned problems. The orthorhombic Pmn21 and Pn phase are expected to bring well solid-state Li diffusion properties (DLi+) 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 DLi+ 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.