Archimedean polyhedron LiCoO2 for ultrafast rechargeable Li-ion batteries

Internal interfaces within electrode materials play crucial roles in the rate capability of lithium cobalt oxide (LiCoO2) based batteries. In this work, we apply an acetate-assisted molten-salt method to synthesize Archimedean concave cuboctahedron-shaped LiCoO2 (ACO-LiCoO2), which possesses abundant built-in 109.5 degrees twin boundaries (TBs) originating from its O3 stacking pattern. The ACO-LiCoO2 cathode material presents outstanding rate capability, including an ultra-high discharge capacity of over 151 mAh/g at 5C and a discharge capacity of 136 mAh/g at 50C (1C = 140 mA/g). Density functional theory (DFT) calculations reveal that the coherent TBs not only introduce Co-3dz2 orbitals in the forbidden band, resulting in higher electrical conductivity, they also provide new migration pathways for faster Li-ion diffusion, compared to commercial LiCoO2. The TB-rich ACO-LiCoO2 material might pave the way for the design of ultrafast rechargeable Li-ion batteries.