Achieving high-performance spherical natural graphite anode through a modified carbon coating for lithium-ion batteries

Abstract

The electrochemical performance of modified natural graphite (MNG) and artificial graphite (AG) was investigated as a function of electrode density ranging from 1.55 to 1.7 g·cm−3. The best performance was obtained at 1.55 g·cm−3 and 1.60 g·cm−3 for the AG and MNG electrodes, respectively. Both AG, at a density of 1.55 g·cm−3, and MNG, at a density of 1.60 g·cm−3, showed quite similar performance with regard to cycling stability and coulombic efficiency during cycling at 30 and 45◦ C, while the MNG electrodes at a density of 1.60 g·cm−3 and 1.7 g·cm−3 showed better rate performance than the AG electrodes at a density of 1.55 g·cm−3. The superior rate capability of MNG electrodes can be explained by the following effects: first, their spherical morphology and higher electrode density led to enhanced electrical conductivity. Second, for the MNG sample, favorable electrode tortuosity was retained and thus Li+ transport in the electrode pore was not significantly affected, even at high electrode densities of 1.60 g·cm−3 and 1.7 g·cm−3. MNG electrodes also exhibited a similar electrochemical swelling behavior to the AG electrodes.