High-Rate and Long-Life Cycle of Nano-LiMn2O4 Under High Cut-Off Potential

Abstract Nano-LiMn2O4 was successfully synthesized by a low-temperature hydrothermal route with the absence of post-calcination treatment. Employing ethanol as an organic reagent triggers the formation of nanostructured particles approximately 30.39 nm in diameter, associated with 0.007 lattice strain. The pure phase of nano-LiMn2O4/Li displays outstanding electrochemical performances. Under 4.6 V versus Li+/Li cut-off potential, 74.3% of capacity is reserved when C-rate is increased by 50 times, while excellent capacity restoration of 96.9% after cycled again at 1 C. After 331 cycles, a capacity retention of 84.3% is harvested by nano-LiMn2O4/Li, implying the absence of phase transformations in spinel structures under such abuse conditions. This remarkable structural stability can be attributed to the small lattice strain, associated with high Li+ diffusion coefficient, which is estimated to be 10−9.76 cm2 s−1 by the EIS technique. Additionally, Li+ extraction is more favorable when nano-LiMn2O4/Li is charged up to 4.6 V versus Li+/Li, interpreted by the polarization resistance (Rp) of the cell.