LiZr2(PO4)3 surface coating towards stable layer structure Li1.2Mn0.54Ni0.13Co0.13O2 cathode materials with long cycle performance
Hao Yang, Jie Wang, Changsheng Xu, Kewei Wu, Fangfang Zou, Xuebu Hu, Zhongli Hu
Abstract
Li-rich manganese-based materials are considered to be the mainstream cathode materials for next-generation lithium-ion batteries due to high discharge capacity and low cost, but poor cycle life and high temperature performance limit their development. Herein, LiZr2(PO4)3 (LZPO) is coated on the surface of spherical Li1.2Mn0.54Ni0.13Co0.13O2 (LMNCO) material by a simple wet chemical method. The LZPO layer not only has the function of traditional coating layer to inhibit the occurrence of side reactions between electrolyte and LMNCO surface but also promotes the formation of spinel phase in the layered structure, increases the content of lattice oxygen, and reduces the content of absorbed oxygen. Thus, LZPO coated LMNCO has a more stable layered structure during cycling compared pure LMNCO, which improves effectively its long life and high temperature performance. The capacity loss rate of LZPO coated LMNCO is only 16.2% and 11.9% after 350 cycles at 25 °C and 200 cycles at 50 °C, respectively. Moreover, the capacity retention rate of the full cell composed of LZPO coated LMNCO and graphite is 70.7% after 200 cycles at 1.0 C. The coating layer toward stable surface structure can provide an idea for the modification of cathode materials, especially for Li-rich manganese-based materials.