Effects of Structure and Magnetism on the Electrochemistry of the Layered Li<sub>1+<i>x</i></sub>(Ni<sub>0.5</sub>Mn<sub>0.5</sub>)<sub>1–<i>x</i></sub>O<sub>2</sub> Cathode Material
Xiaofei Bian, Rongyu Zhang, Xu Yang
Abstract
We have synthesized a series of Li1+x(Ni0.5Mn0.5)1–xO2 (LNMO) materials to study the influence of excess lithium ions on the structure and electrochemical behaviors of nickel–manganese-based layered compounds. The increasing content of Li+ ions in the transition-metal (TM) layer leads to the departure of the follower-like clusters to Ni-rich and Mn-rich clusters. The Ni2+ ions in the Li layer couple with adjacent transition-metal ions via strong 180° exchange interactions and moderate the local structure, which leads to magnetic clusters with finite size. Electrochemical performance shows that appropriate Ni2+ ions could improve the cycle stability without decreasing the rate capability. Among them, Li1.1Ni0.45Mn0.45O2 shows a rate capability of 76 mAh g–1 at 1000 mA g–1 and a lifespan of 300 cycles at 200 mA g–1. This work shows that structure moderation has an essential impact on its electrochemical performance. Besides this, the crystal and magnetic combined methods we use could offer a better way of studying cathode materials.