Facile Conversion of Commercial Coarse-Type LiCoO₂ to Nanocomposite-Separated Nanolayer Architectures as a Way for Electrode Performance Enhancement

Coarse-type LiCoO2 is the state-of-the-art cathode material in small-scale lithium-ion batteries (LIBs); however, poor rate performance and cycling stability limit its large-scale applications. Here we report the modification of coarse-type LiCoO2 (LCO) with nanosized lithium lanthanum titanate (Li3xLa2/3-xTiO3, LLTO) through a facile sol-gel process, the electrochemical performance of commercial LiCoO2 is improved effectively, in particular at high rates. The crystalline structure of pristine LiCoO2 is not affected by the introduction of the LLTO phase, while nanosized LLTO particles are likely incorporated into the space of the LiCoO2 layers to form a LCO-LLTO nanocomposite, which separate the LCO layers with the increase of layer spacing to ∼100 nm. The LLTO incorporation through the facile post-treatment effectively reduces the charge-transfer resistance and increases the electrode reactions; consequently, the LLTO-incorporated LCO electrode shows higher capacity than LiCoO2 at a higher rate and prolonging cycling stability in both potential ranges of 2.7-4.2 V and 2.7-4.5 V, making it also suitable for high-rate operation. This novel concept is general, which may also be applicable to other electrode materials. It thus introduces a new way for the development of high rate-performance electrodes for LIBs for large scale applications such as electric vehicles and electrochemical energy storage for smart grids.