LiMn₂O₄ is a very important cathode material in the field of plug-in hybrids. However, it has limited large-scale practical application because of its severe electrode polarization and rapid capacity decay. By means of synergistic enhancement of double-cation (Na⁺, Mg²⁺) doping and three-dimensional graphene (3DG) coating, the Li_0.94Na_0.06Mg_0.08Mn_1.92O₄/3DG composite cathode material was successfully synthesized via hydrothermal synthesis, high-temperature solid-phase sintering, and freeze-drying. Electrochemical test results display that the initial discharge specific capacity of the Li_0.94Na_0.06Mg_0.08Mn_1.92O₄/3DG material reaches 146 mAh/g (137 mAh/g for LiMn₂O₄) at 0.5C, and the specific capacity remains at 130 mAh/g after 100 cycles (99 mAh/g for LiMn₂O₄). At 10C, the initial discharge specific capacity of the Li_0.94Na_0.06Mg_0.08Mn_1.92O₄/3DG material is 90 mAh/g (69 mAh/g for Li_0.94Na_0.06Mg_0.08Mn_1.92O₄ and 38 mAh/g for LiMn₂O₄), which should be resulted from the synergistic enhancement of double-cation (Na⁺, Mg²⁺) doping and 3DG coating. Na⁺, Mg²⁺ codoping effectively expands the Li⁺ diffusion path and the diffusion coefficient of Li_0.94Na_0.06Mg_0.08Mn_1.92O₄/3DG, and inhibits the dissolution of Mn³⁺. 3DG coating effectively improves the conductivity and reduces electrode polarization during the charge and discharge course. In addition, 3DG coating also plays an important role in inhibiting the dissolution of Mn³⁺.

中文翻译：

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通过协同增强双离子（Na ⁺，Mg ²⁺）掺杂和3DG涂层用于动力锂离子电池的性能优异的LiMn ₂ O ₄阴极材料

LiMn ₂ O ₄是插电式混合动力汽车领域中非常重要的阴极材料。然而，由于其严重的电极极化和快速的容量衰减，它限制了大规模的实际应用。通过双阳离子（Na ⁺，Mg ²⁺）掺杂和三维石墨烯（3DG）涂层的协同增强，通过水热合成成功合成了Li _0.94 Na _0.06 Mg _0.08 Mn _1.92 O ₄ / 3DG复合正极材料，高温固相烧结和冷冻干燥。电化学测试结果表明，Li的初始放电比容量为_0.94Na _0.06 Mg _0.08 Mn _1.92 O ₄ / 3DG材料在0.5C时达到146 mAh / g（LiMn ₂ O ₄则为137 mAh / g ），在100次循环后的比容量仍保持在130 mAh / g（99 mAh / g LiMn ₂ O ₄）。在10 °C下，Li _0.94 Na _0.06 Mg _0.08 Mn _1.92 O ₄ / 3DG材料的初始放电比容量为90 mAh / g（Li _0.94 Na _0.06 Mg _0.08 Mn _1.92 O ₄为69 mAh / g，而Li _0.94 Na _0.06 Mg _0.08 Mn _1.92 O _4为38 mAh / g。锰酸锂₂ O₄），这应归因于双阳离子（Na ⁺，Mg ²⁺）掺杂和3DG涂层的协同增强。Na ⁺，Mg ²⁺共掺杂有效地扩展了Li ^+的扩散路径和Li _0.94 Na _0.06 Mg _0.08 Mn _1.92 O ₄ / 3DG的扩散系数，并抑制了Mn ³⁺的溶解。3DG涂层在充电和放电过程中可有效提高电导率并减少电极极化。另外，3DG涂层在抑制Mn ³⁺的溶解中也起重要作用。