Stannum doping of layered LiNi 3/8Co 2/8Mn 3/8O 2 cathode materials with high rate capability for Li-ion batteries

Abstract

Sn doped lithium nickel cobalt manganese composite oxide of LiNi 3/8Co 2/8Mn 3/8− x Sn x O 2 (0 ≤ x ≤ 0.10) was synthesized by stannum substitute of manganese to enhance its rate capability at first time. Its structure and electrochemical properties were characterized by X-ray diffraction (XRD), SEM, cyclic voltammetry (CV), galvanostatic intermittent titration technique (GITT) and charge/discharge tests. LiNi 3/8Co 2/8Mn 3/8− x Sn x O 2 had stable layered structure with α-NaFeO 2 type as x up to 0.05, meanwhile, its chemical diffusion coefficient D Li of Li-ion was enhanced by almost one order of magnitude, leading to notable improvement of the rate capability of LiNi 3/8Co 2/8Mn 3/8O 2. The compound of x = 0.10 showed the best rate capability among Sn doped samples, but its discharge capacity reduced markedly due to secondary phase Li 2SnO 3 and increase of cation-disorder. The compound with x = 0.05 showed high rate capability with initial discharge capacity in excess of 156 mAh g −1. It is a promising alternative cathode material for EV application of Li-ion batteries.