Ionics | 2021
Synthesizing kinetics and characteristics of high-capacity Li1.16(Ni0.25Mn0.75)0.84O2 cathode materials for lithium-ion batteries
Abstract
The reaction mechanism and kinetics of synthesis Li1.16(Ni0.25Mn0.75)0.84O2 were studied at different heating rates with the thermal analysis (TG-DTA) and non-isothermal kinetic analysis. The average activation energies were 167.40 kJ·mol−1 and 139.69 kJ·mol−1 between 200 and 450 °C (peak 2), and 450 and 560 °C (peak 3) as calculated by the Flynn-Wall-Ozawa and Kissinger methods. The reaction order, frequency factor, and kinetic equation of peak 2 and peak 3 were determined by the Kissinger method. Based on the results of the mechanism and dynamic study, the Li-rich and Mn-based cathode materials Li1.16(Ni0.25Mn0.75)0.84O2 were synthesized by an optimized two-step sintering process. The study results show that the materials show a layer structure with high crystallinity and superior electrochemical performance. Notably, the sample exhibits the discharge capacity of 225.4 mAhg−1, 92.7% of the initial discharge capacity after 300 cycles, accompanying with a high energy density retention of 140 Whkg−1.