Surface architecture modification of high capacity Li1.2Ni0.2Mn0.6O2 with synergistic conductive polymers LiPPA and PPy for lithium ion batteries

Abstract Lithium-rich layered oxide is considered to be a very promising cathode material for next-generation lithium-ion batteries for its high specific capacity. However, some intrinsic drawbacks, such as large initial irreversible capacity, poor rate performance and inferior cycling stability, limit its commercialization process. Here, acidic lithium polyacrylate (LiPPA) and polypyrrole (PPy) mixed coating layer is designed to modify Li1.2Ni0.2Mn0.6O2 cathode materials. The characterization results of morphology, structure and element analysis technologies confirm that a mixed conductive network of LiPPA-PPy layer is uniformly coated on the surface of Li1.2Ni0.2Mn0.6O2 particles. The LiPPA-PPy coating layer has ion and electron conductivity, and it can protect the active materials from the corrosion of acidic species and alleviate superficial side reactions. In addition, a portion of lithium can be chemically pre-extracted during the coating process. Therefore, the LiPPA-PPy coated Li1.2Ni0.2Mn0.6O2 shows a greatly improved electrochemical performance. Specifically, it can deliver the higher initial coulombic efficiency (~83.09%), enhanced rate capability (120 mAh g−1 at 5 C) and superior cycle performance.