Surface modification of LiNi0.8Co0.1Mn0.1O2 with conducting polypyrrole

A facile method for the surface modification of high-voltage and high-temperature LiNi0.8Co0.1Mn0.1O2 cathode materials is demonstrated. In order to prepare polypyrrole (PPy) coating LiNi0.8Co0.1Mn0.1O2 material, the facile chemical polymerization method uses Fe(III) tosylate as oxidant and ethanol as solvent to avoid the side reaction with solvent. TEM depicts that LiNi0.8Co0.1Mn0.1O2 serves as hard template and the nanoscale PPy layer grows along the surface of LiNi0.8Co0.1Mn0.1O2 during the synthesis process. Because of flocculent and nanofiber coating layer, much improved rate performance, high temperature cycling, as well as high voltage performance are obtained. Cyclic voltammetry (CV) and electrochemical impedance spectroscopic (EIS) results demonstrate that the PPy coating layer effectively alleviates the side reactions between liquid electrolytes and LiNi0.8Co0.1Mn0.1O2 surface that are highly unstable at high temperature and high charge voltage.