Optimizing solution combustion method fuel ratios for enhanced electrochemical performance of LiNi0.5Mn1.5O4 cathode materials

Abstract

LiNi0.5Mn1.5O4 (LNMO) is a promising high-performance lithium-ion battery cathode material. We synthesized various structures of LNMO precursors based on two calculations, using the solution combustion method with different fuel ratios. The precursors were annealed for a short time under ambient atmospheric conditions, and various polyhedral structures of LNMO samples were formed through natural oxygen absorption. The results reveal that lower fuel ratios (0.2) cause the samples having incomplete crystal structures and severe particle aggregation, resulting in higher polarization and poorer electrochemical performance. Samples with higher fuel ratios (0.8) exhibit complete crystal structures, lower polarization, and excellent rate performance. At 20 C, the electrochemical capacity of sample with fuel ratios (0.8) can reach 90.47 mAh/g. Samples with theoretical fuel ratios (0.5) show the best electrochemical cycling performance, capacity retention, and cycling stability. After 200 cycles at 1 C, the electrochemical capacity still maintains 123.08 mAh/g, with a capacity retention rate of 96.5%. The results indicate that the formation of the precursor, oxygen absorption during annealing, polyhedral structures, different redox couples, and stability of the electrode/electrolyte interface have significant effects on the electrochemical performance. In summary, our research provides insights into the solution combustion synthesis of high-performance LNMO cathode materials, emphasizing the importance of accurate calculation of synthesis parameters to achieve optimal electrochemical performance.