Lithium cobalt oxide coated lithium zinc titanate anode material with an enhanced high rate capability and long lifespan for lithium-ion batteries

LiCoO2 coated Li2ZnTi3O8 is synthesized by a preliminary formation of Li2ZnTi3O8 by facile solid state reaction and a following coating process with LiCoO2 nano layer via a wet chemical process followed by heat treatment. The structure and electrochemical property of the as-prepared samples have been characterized comprehensively. A thin LiCoO2 layer with a thickness of about 2 nm is uniformly coated on the surface of active particles, which does not affect the crystal structure and space group. After LiCoO2 surface modification, high discharge capacities of 192.1, 163.7, 108.2 mAh g−1 with capacity retention of 99.1, 92.3, 71.4% are obtained at 1.0, 2.0, 3.0 A g−1 after 100 cycles for the coated composite, respectively, which are obviously larger than those of un-coated sample. Besides, the discharge capacity and cyclic stability of Li2ZnTi3O8 after 1000 cycles have been enhanced after coating. Cyclic voltammograms and electrochemical impedance spectroscopy measurements prove that the LiCoO2 coating can dramatically decrease polarization and reduce the charge transfer resistance during repeated Li+ intercalation/de-intercalation process. The improved electrochemical properties of LiCoO2 coated Li2ZnTi3O8 are attributed to small particle sizes, large packed holes, high surface area and better electronic conductive.