Na-doped Ni-rich LiNi_(0.5)Co_(0.2)Mn_(0.3)O_2 cathode material with both high rate capability and high tap density for lithium ion batteries

摘要

Na-doped Ni-rich LiNi_(0.5)Co_(0.2)Mn_(0.3)O_2 cathode material, Li_(0.97)Na_(0.03)Ni_(0.5)Co_(0.2)Mn_(0.3)O_2, is synthesized by a hydroxide co-precipitation route. The structural characterization reveals that the substitution of Na for Li results in a more ordered α-NaFeO_2 structure, enlarges Li layer spacing, and reduces the degree of cation mixing. The Li_(0.97)Na_(0.03)Ni_(0.5)Co_(0.2)Mn_(0.3)O_2 material has a high tap density of 2.17 g cm~(?3) that meets the commercial requirement in lithium ion batteries (LIBs). The galvanostatic charge/discharge results show that the electrochemical performance of the Li_(0.97)Na_(0.03)Ni_(0.5)Co_(0.2)Mn_(0.3)O_2 is significantly improved. At 0.2, 1, 10, 30 and 50 C, the specific capacities of the Li_(0.97)Na_(0.03)Ni_(0.5)Co_(0.2)Mn_(0.3)O_2 are 228.43, 163.12, 121.43, 95.56 and 60.09 mA h g~(?1), respectively, which are superior to those of the undoped LiNi_(0.5)Co_(0.2)Mn_(0.3)O_2 due to the enlargement of Li layer spacing, the decreased degree of cation mixing, and the rapid diffusion of Li-ion in the bulk lattice after the substitution of Na for Li. Therefore, the Na-doped Ni-rich LiNi_(0.5)Co_(0.2)Mn_(0.3)O_2 material is a promising cathode candidate for the next generation of LIBs.