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 (Li_3xLa_2/3-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.