Synthesis and Characterization of LiNi1/3Co1/3Mn1/3O2−xClx as Cathode Materials for Lithium Ion Batteries at 55°C

A series of materials based on the LiNi_1/3Co_1/3Mn_1/3 system were prepared by a sol-gel method, and their phase formation processes, crystal structures, and electrochemical performances were studied by thermogravimetric analyses (TG/DTG), X-ray diffraction (XRD), charge-discharge tests, and cyclic voltammetry (CV). The XRD patterns indicate that the LiNi_1/3Co_1/3Mn_1/3 powders with better crystalline structure could be obtained at calcining temperature 850°C for 20 h under air atmosphere and show that the chlorine addition may induce the change of lattice parameters. The charge-discharge tests show that both the specific capacities and capacity retentions of Cl-doped materials increase compared to the undoped material, especially for the capacity retention at the high-voltage region. At 55°C, the LiNi_1/3Co_1/3Mn_1/3O_2-0.10Cl_0.10 cathode material shows the highest initial discharge capacity of 180.1 mAh·g⁻¹ and the best capacity retention with the value of 91.9% after 100 cycles in the region of 2.0–4.4 V at 0.1 C, while the initial discharge capacity is 208.2 mAh·g⁻¹ when the charge cutoff voltage is up to 4.6 V.