类球形正交LiMnO2的制备、微结构和电化学性能

以共沉淀法得到的类球形MnCO₃为前驱物，制备了类球形正交LiMnO₂(So-LiMnO₂)，采用XRD、SEM和N₂吸附技术对样品进行表征；与非球形正交LiMnO₂(No-LiMnO₂)进行了对比研究。结果表明：o-LiMnO₂的堆垛层错度、结晶状况、颗粒形貌和大小与前驱物的微结构密切相关；在80次电化学循环测试过程中，So-LiMnO₂经15次循环可达最大的放电容量152 mAh·g^-1，其容量衰减平均每次循环0.58 mAh·g^-1；而No-LiMnO₂要经过38次循环才能达到最大放电容量128 mAh·g^-1，容量衰减平均每次循环高达1.24 mAh·g^-1。TEM和EDS分析证明：由一次粒子团聚的类球形So-LiMnO₂能有效地抑制电解液对材料的腐蚀、减少Mn的溶解，从而提高了电化学循环能力。

Preparation, Microstructure and Electrochemical Properties of Spherical-like Orthorhombic LiMnO2

Spherical-like morphology orthorhombic LiMnO₂ (So-LiMnO₂) powders were prepared using spherical MnCO₃ precursors obtained by a carbonate co-precipitation method. The materials were characterized using XRD, SEM and low temperature nitrogen adsorption desorption. Non-spherical orthorhombic LiMnO₂ (No-LiMnO₂) powders were also studied for comparison. The characteristics of o-LiMnO₂ such as the stacking faults, crystallization, particles morphology and size were significantly dependent on the microstructure of precursors. The electrochemical performances of o-LiMnO₂-based cathodes were tested during 80 cycles. The So-LiMnO₂ cathode had a maximum capacity of 152 mAh·g^-1 on the 15^th cycle, and exhibited an average capacity decay of approximately 0.58 mAh·g^-1 per cycle. By contrast, the No-LiMnO₂ sample had a maximum capacity of 128 mAh·g^-1 on the 38^th cycle, and experienced an average capacity decay of 1.24 mAh·g^-1 per cycle. TEM observation and EDS analysis confirmed that So-LiMnO₂ particle, agglomerated by primary particles, could reduce the erosion of positive material by electrolytes and the dissolution of manganese, which results in the enhanced electrochemical cycleability.