A Study on the Improvement of the Electrochemical Performance of Graphite Anode by Controlling Properties of the Coating Pitch

A pitch coating method was proposed for the purpose of improving the electrochemical properties of natural graphite. The synthesis conditions of pitch coating were optimized via measuring electrochemical properties of pitch-coated graphite anodes. As the synthesis temperature increased, the thermal stability was improved in addition to an increase in the softening point and residual carbon weight. However, the synthesis temperature of 430 degrees C resulted in the synthesis of a large amount of NI (NMP Insoluble) due to excessive condensation reaction. As the surface uniformity and coating thickness increased due to high thermal stability, the initial coulombic efficiency and rate capability of the pitch-coated graphite were improved. However, the graphite coated with the pitch containing excessive NI showed lower electrochemical properties than the un-coated graphite. NI had low dispersibility and formed spheres after heat treatment, so it formed the heterogeneous and thicker SEI layer. The optimum conditions for forming a uniform surface and an appropriate coating layer were investigated.