High entropy electrode materials have attracted extensive attention due to their excellent structure stability during cycling, leading to super long cycle life. However, the traditional equimolar strategy is not suitable for electrode materials if high-capacity is considered. Here, we successfully prepared LiNi_0.5Mn_1.5O₄ cathode with high stability and long cycle life by using a multiple-element doping strategy (medium entropy). Combining with differential scanning calorimetry (DSC), Raman spectra and X-ray photoelectron spectroscopy, it is found that Co, Cr, Al co-doped LiNi_0.5Mn_1.5O₄ (medium entropy sample) exhibits disordered structure (Fd$\bar{3}$m) with limited Mn³⁺ and enriched Al³⁺ on the surface, which can inhibit the dissolution of Mn²⁺ ions and surface side reaction. With disordered structure and medium entropy, the Li⁺ ion diffusivity in co-doped LiNi_0.5Mn_1.5O₄ is improved, leading to better rate performance. In-situ X-ray diffraction indicates mostly solid solution process in co-doped LiNi_0.5Mn_1.5O₄ and less volume change (5.4 % vs. 5.8 % in undoped sample) during charge-discharge. Owing to the better structure and interface stability, co-doped LiNi_0.5Mn_1.5O₄ shows excellent cycle stability, with 92 % capacity retention after 500 cycles at 1 C rate. Meanwhile, the specific capacity of the medium entropy sample is even increased from 132 mAh/g to 138 mAh/g, proving the advantage of medium entropy strategy in electrode materials.

高熵电极材料因其在循环过程中优异的结构稳定性、超长的循环寿命而受到广泛关注。然而，如果考虑高容量，传统的等摩尔策略不适用于电极材料。在这里，我们通过使用多元素掺杂策略（中熵）成功制备了具有高稳定性和长循环寿命的LiNi _0.5 Mn _1.5 O _4正极。结合差示扫描量热法（DSC）、拉曼光谱和X射线光电子能谱，发现Co、Cr、Al共掺杂LiNi _0.5 Mn _1.5 O ₄（中熵样品）呈现无序结构（Fd$\overline{\mathrm{3个}}$m)表面有限的Mn ³⁺和富集的Al ^{3+ ，可以抑制Mn 2+}离子的溶解和表面副反应。具有无序结构和中等熵，共掺杂的LiNi _0.5 Mn _1.5 O _4中的Li ⁺离子扩散率得到改善，导致更好的倍率性能。原位 X 射线衍射表明在共掺杂 LiNi _0.5 Mn _1.5 O ₄中主要是固溶过程，在充放电过程中体积变化较小（5.4%对未掺杂样品中的 5.8%）。由于更好的结构和界面稳定性，共掺杂 LiNi _0.5 Mn_1.5 O ₄表现出出色的循环稳定性，在 1 C 倍率下循环 500 次后容量保持率为 92%。同时，中熵样品的比容量甚至从132 mAh/g增加到138 mAh/g，证明了中熵策略在电极材料中的优势。