Regulation of morphology and particle size of spinel LiMn2O4 induced by Fe-B co-doping for high-power lithium ion batteries

The spinel LiMn2O4 cathode material shows severe capacity degradation due to Jahn–Teller distortion and dissolution of Mn during the charge-discharge process. Herein, a series of single crystal truncated octahedral of LiFe0.03BxMn1.97−xO4 (0≤x≤0.10) were synthesized by simple solid-state combustion combined with Fe-B co-doping, morphology and particle size controlling strategy. Through Fe-B co-doping, not only the LiFe0.03Mn1.97O4 containing {111}, {100} and {110} planes are successfully controlled to the particles containing only {111} and {100} planes, but also the near-nanometer particles are controlled to bigger submicron sizes. It is found that Fe-B co-doping can enhance the stability of the crystal structure, inhibit Jahn-Teller distortion and reduce the dissolution of Mn. Among them, the optimized LiFe0.03B0.08Mn1.89O4 forms a truncated octahedral single crystal particle with good crystallization and only {111} and {100} crystal faces, and the particle size is around 349.3 nm, showing exceptional high rate capacity and long cycle life. The LiFe0.03B0.08Mn1.89O4 releases a high initial discharge capacity of 107.1 mAh/g with a capacity retention of 77.7% after 1000 cycles at 10 C, which is higher than that of the LiFe0.03Mn1.97O4 (58.8%). Even at 20 C, LiFe0.03B0.08Mn1.89O4 still achieves a high reversible specific capacity (90.4 mAh/g) and outstanding long-cycle stability (81.3%, 1000th). This work provides a scientific basis for the crystal surface control and particle size control of spinel LiMn2O4, which is of great significance for the development of the next generation of high-power lithium-ion batteries.