【摘要】 采用固相燃烧法制备出包含{111},{110}和{100}晶面且呈单晶截角八面体形貌的LiMg_0.02Mn_1.98O₄（LMMO）正极材料.结果表明，联合Mg掺杂和截角八面体单晶形貌调控所制备的尖晶石型LiMn₂O₄材料，既能有效抑制Jahn-Teller效应，又能减缓Mn溶解及增加部分Li⁺迁移通道，这对其晶体结构起稳定作用.与纯LiMn₂O₄（LMO）样品相比，Mg掺杂促进了尖晶石型LiMn₂O₄材料的结晶性和单晶截角八面体颗粒的形成.在1 C倍率下，LiMg_0.02Mn_1.98O₄材料的初始放电比容量为116.8 mAh/g, 200次循环后保持率为78.3%;在5 C和10 C高倍率下，LiMg_0.02Mn_1.98O₄样品经1 000次循环后，其容量保持率分别为64.2%和56.3%,而未掺杂Mg的LiMn₂O₄样品的容量保持率分别为52.7%和38.7%.单晶截角八面体形貌的LiMg_0.02Mn_1.98O₄材料有较大的Li⁺扩散系数和较低的表观活化能，这证明其有较好的倍率性能和长循环寿命.更多还原

【Abstract】 A single-crystal truncated octahedral LiMg_0.02Mn_1.98O₄（LMMO） cathode material with {111}, {100}, and {110} crystal faces is synthesized via a solid-state combustion method. The results exhibit that the spinel LiMn₂O₄ prepared by Mg doping and single-crystal truncated octahedral morphology strategy can not only effectively inhibit the Jahn-Teller effect, but also reduce the Mn dissolution and increase the Li+ diffusion channel, which could stabilize the crystal structure. Compared with pure LiMn₂O₄（LMO）, Mg doping promotes the crystallization of spinel LiMn₂O₄ and the formation of single-crystal truncated octahedral particles. At 1 C, 78.3% of the initial discharge capacity（116.8 mAh/g） can be maintained after 200 cycles. At high rates of 5 C and 10 C, the initial discharge capacity is 102.3 mAh/g and 90.3 mAh/g, whose capacity retention rate is 64.2% and 56.3% after 1 000 cycles, respectively, while the capacity retention rates of the LiMn₂O₄ without Mg-doping is 52.7% and 38.7% respectively. The LiMg_0.02Mn_1.98O₄ material with a single-crystal truncated octahedral morphology has a larger Li⁺ diffusion coefficient and a lower apparent activation energy, which indicates an excellent rate performance and a long cycle life.更多还原