Cation-Doped Lini0.8co0.1mn0.1o2 Cathode with High Rate Performance

Abstract

The nickel-rich layered cathode material LiNi0.8Co0.1Mn0.1O2(NCM811) has high energy density and lower cost and is a promising cathode material currently under development. However, its electrochemical and structural stability is poor during cycling. Among the many modification methods, cationic doped modification has been consistently proven to be an effective strategy for enhancing electrochemical performance. Herein, the NCM811 cathode material was modified by solid-phase reactions with Mg and Al doped, respectively. In addition, the corresponding mechanism of NCM811 cathode material doped modification is explored by density functional theory (DFT) calculations. And we have extended this approach to other ternary cathode materials with different ratios and obtained universal laws. Combined with XRD, SEM, TEM, and DFT calculations, the results show that Mg2+ occupies the Li+ site and reduces the degree of Li/Ni mixture; Al3+ acts as a structural support during charging and discharging to prevent structural collapse. The electrochemical properties were tested by an electrochemical workstation and the LAND system and the results showed that the capacity retention rate increased to varying degrees from 63.66% to 69.87% and 89.05% for NCM811-Mg and NCM811-Al at room temperature after 300 cycles, respectively. This study provides a theoretical basis and design strategy for commercializing cationic doped modification of nickel-rich cathode materials.

Keywords: Li-ion battery, cathode material, doped, electrochemical properties, DFT calculation