Normakhmedov Ofok O, Brylev Oleg A, Petukhov Dmitrii I, Kurilenko Konstantin A, Kulova Tatiana L, Tuseeva Elena K, Skundin Alexander M
Department of Materials Science, Lomonosov Moscow State University, Leninskie Gory, 1-73, Moscow 119991, Russia.
S.U. Umarov Physical and Technical Institute, Academy of Sciences of Republic of Tajikistan, Aini street 299, Dushanbe 734063, Tajikistan.
Materials (Basel). 2018 Jul 8;11(7):1162. doi: 10.3390/ma11071162.
A new route for the preparation of nickel and cobalt substituted spinel cathode materials (LiMnCoNiO₄ and LiMnCoNiO₄) by freeze-drying of acetate precursors followed by heat treatment was suggested in the present work. The experimental conditions for the preparation single-phase material with small particle size were optimized. Single-phase spinel was formed by low-temperature annealing at 700 °C. For discharge rate 0.2 C, the reversible capacities 109 and 112 mAh g were obtained for LiMnCoNiO₄ and LiMnCoNiO₄, respectively. A good cycle performance and capacity retention about 90% after 30 cycles at discharge rate 0.2⁻4 C were observed for the materials cycled from 3 to 4.6 V vs. Li/Li⁺. Under the same conditions pure LiMn₂O₄ cathode materials represent a reversible capacity 94 mAh g and a capacity retention about 80%. Two independent experimental techniques (cyclic voltammetry at different scan rates and electrochemical impedance spectroscopy) were used in order to investigate the diffusion kinetics of lithium. This study shows that the partial substitution of Mn in LiMn₂O₄ with small amounts of Ni and Co allows the cyclability and the performance of LiMn₂O₄-based cathode materials to be improved.
本工作提出了一种通过对醋酸盐前驱体进行冷冻干燥然后热处理来制备镍和钴取代的尖晶石正极材料（LiMnCoNiO₄ 和 LiMnCoNiO₄）的新途径。优化了制备小粒径单相材料的实验条件。通过在 700℃ 进行低温退火形成单相尖晶石。对于 0.2 C 的放电率，LiMnCoNiO₄ 和 LiMnCoNiO₄ 的可逆容量分别为 109 和 112 mAh g。对于在 3 至 4.6 V 相对于 Li/Li⁺ 循环的材料，在 0.2⁻4 C 的放电率下循环 30 次后观察到良好的循环性能和容量保持率约 90%。在相同条件下，纯 LiMn₂O₄ 正极材料的可逆容量为 94 mAh g，容量保持率约为 80%。使用两种独立的实验技术（不同扫描速率下的循环伏安法和电化学阻抗谱）来研究锂的扩散动力学。该研究表明，用少量的 Ni 和 Co 部分取代 LiMn₂O₄ 中的 Mn 可以提高基于 LiMn₂O₄ 的正极材料的循环性能和性能。
