Stepwise co-precipitation to synthesize LiNi1/3Co1/3Mn1/3O2 one-dimensional hierarchical structure for lithium ion batteries

Abstract LiNi 1/3 Co 1/3 Mn 1/3 O 2 one-dimensional (1D) hierarchical microrods assembled with nanoparticles have been successfully prepared through post-heat treatment of MC 2 O 4 · x H 2 O (M = Ni, Co, Mn) microrod precursor which was obtained via stepwise co-precipitation. The CoC 2 O 4 ·2H 2 O microrod crystallites formed in the first step can effectively template the subsequent formation of manganese, cobalt and nickel oxalates on the initial CoC 2 O 4 ·2H 2 O microrods during the second step co-precipitation, without assistance of any surfactants. The LiNi 1/3 Co 1/3 Mn 1/3 O 2 1D hierarchical microrods with pores and voids as cathode material for lithium ion batteries exhibit superior initial coulombic efficiency, reversible capacity, rate capability and cycling stability to the LiNi 1/3 Co 1/3 Mn 1/3 O 2 microsized particles. They deliver high specific discharge capacities of 163.3 and 104.9 mAh g −1 at rates of 0.1 and 20 C, respectively. At 0.5 C, they achieve a discharge capacity of 152.2 mAh g −1 with a capacity retention of 89.5% after 160 cycles. The excellent electrochemical performance can be attributed to the novel hierarchical microrod structure with much porous and void space, which shortens the diffusion path of electron and lithium ion, and benefits for their transfer. In addition, this unique structure provides not only appropriate contact area between electrode and electrolyte, but also good accommodation for the strain relaxation during charge and discharge.