High performance layered LiNi0.8Co0.07Fe0.03Mn0.1O2 cathode materials for Li-ion battery

Ni/Li disordering often occurs in LiNixCoyMn1-x yO2 (NMC) layered materials and affects the electrochemical performance of Li-ion batteries (LIBs). Substituting partly Co with Fe in the Ni-rich cathode LiNi0.8Co0.10Mn0.1O2 (NCM811) provided a new cathode material (LiNi0.8Co0.07Fe0.03Mn0.1O2 (Fe3-NCM871)) with markedly enhanced electrochemical performance via a coprecipitation method. The Fe3-NCM871 cathode achieved an initial capacity of 207.5 mAh g(-1), while the NCM811 cathode has 188.7 mAh g(-1) between 2.8 and 4.3 V at the C/10 rate. Its rate capacity (145.8 mAh g 1), 25.7 mAh g(-1) higher than the NCM811 at a rate of 5C. Furthermore, it maintains better cycle stability performance and reaches 80% state-of-health (SOH) only after 400 cycles, which is higher than that of the NCM811 (nearly 200 cycles) at C/2 between 2.8 and 4.3 V. As confirmed from density functional theory (DFT) calculations, such high performance is due to linear Ni2+-O2--Fe3+ superexchange between layers because of the antisite Ni2+ is weak, thus the content of Ni/Li exchange is effectively reduced, which was consistent with the experimental findings.

Automated summary

By partially substituting Co with Fe, a new cathode material (Fe3-NCM871) with significantly enhanced electrochemical performance was developed. This material showed higher initial capacity, rate capacity, and cycle stability compared to the conventional cathode material NCM811. Density functional theory calculations confirmed that the improved performance was due to reduced Ni/Li exchange content and linear Ni2+-O2--Fe3+ superexchange between layers.