%0 Journal Article
%T <br>
%A 何磊.
%A 张昌锦.
%A 徐俊敏.
%A 王永建.
%J 物理化学学报
%D 2017
%R 10.3866/PKU.WHXB201704145
%X 采用简单水溶液法制备LiFePO4包覆的Li1.2Mn0.54Ni0.13Co0.13O2富锂正极材料，包覆后的材料分别经过400℃或500℃煅烧处理5 h。测试结果显示，400℃煅烧处理的包覆样品在0.1 C（1 C=300 mA·g-1）电流密度下充放电时，首次库仑效率可以高达91.9%，同时，首次放电比容量可达到295.0 mAh·g-1。此外，该包覆样品还具有良好的循环性能，在1 C电流密度下循环100次放电比容量仍可保持在206.7 mAh·g-1。进一步的研究发现LiFePO4的包覆不仅可以提高Li1.2Mn0.54Ni0.13Co0.13O2富锂材料的首次库仑效率和循环稳定性能，而且还能够有效抑制材料在充放电过程中的电压衰减。上述电化学性能的有效提升主要归因于LiFePO4包覆层可以阻碍Li1.2Mn0.54Ni0.13Co0.13O2富锂材料与电解液之间的直接接触，减少副反应的发生，增强材料表面的结构稳定性，同时还可以为富锂材料提供额外的可逆容量。<br>In this work, we present a new design for a surface protective layer formed by a facile aqueous solution process in which a nano-architectured layer of LiFePO4 is grown on a Li-rich cathode material, Li1.2Mn0.54Ni0.13Co0.13O2. The coated samples are then calcined at 400 or 500℃ for 5 h. The sample after calcination at 400℃ demonstrates a high initial columbic efficiency of 91.9%, a large reversible capacity of 295.0 mAh·g-1 at 0.1 C (1 C=300 mA·g-1), and excellent cyclability with a capacity of 206.7 mAh·g-1after 100 cycles at 1 C. Meanwhile, voltage fading of the coated sample is effectively suppressed by protection offered by a LiFePO4 coating layer. These superior electrochemical performances are attributed to the coating layer, which not only protects the Li-rich cathode material from side reaction with the electrolyte and maintains the stability of the interface structure, but also provides excess reversible capacity
%U http://www.whxb.pku.edu.cn/CN/Y2017/V33/I8/1605