Multi-doping induces truncated octahedral structure formation in lithium manganate cathode material

[Display omitted] •The critical electrochemical properties of LiMn2O4 depend heavily on its surface orientation.•Through the modulation of Mg-Al-Ti ternary co-doping, the prepared truncated octahedral LiMn2O4 material maintained a discharge specific capacity of 94.0 mAh/g after 500 cycles.•The truncated octahedral morphology with a large exposure of the highly reactive surface that inhibits Mn dissolution and a part of the truncated surface that promotes Li+ diffusion slows down the intensification of Mn dissolution due to the over-exposure of {110} crystal surfaces. The surface anisotropy of spinel LiMn2O4 crystals exerts a profound influence on the electrochemical performance of the material. The truncated octahedral structure consists of various crystal facets such as {110}and {111}. Among them, {110} facets are conducive for the lithium-ion diffusion, although it will worsen manganese dissolution. In contrast, densely arranged {111} surfaces can reduce manganese dissolving but hinder lithium-ion diffusion. To balance ion diffusion and manganese dissolution, the ratio of {110} and {111} planes is regulated using the Mg/Al/Ti multi-doping approach. The percentage of {110} facets exposed is effectively increased by Mg/Al co-doping, and the exposure of the truncated facets improves the lithium-ion diffusion coefficient from 7.17 × 10-12 to 1.02 × 10-11 cm2 s−1, while also increasing the manganese dissolution from 1.15 % to 1.67 %. The addition of Ti reduces the proportion of truncated surfaces and mitigates manganese dissolution (1.39 %). The lithium-ion diffusion coefficient is maintained at 9.17 × 10-12 cm2 s−1, and Mg/Al/Ti co-doping maintained a discharge specific capacity of 94.0 mAh/g after 500 cycles with a degradation rate of 0.062 % per cycle. Surface optimization and reconfiguration of regulated electrode materials can provide new possibilities for the development of lithium-ion batteries.