Effect of high temperature thermal treatment on the electrochemical performance of natural flake graphite

Natural graphite is currently considered as a critical raw material in EU. The demand for graphite is still increasing as it is commonly used in the anodes of the Li-ion batteries (LIBs). The total graphite content for energy storage applications such as LIBs should be more than 99.95%. Several purification processes for natural graphite exist but the requirement of high purity is challenging. Here we present the high temperature thermal treatment for natural graphite ores. Thermal treatment at 2400 °C for 15 min can produce battery-grade graphite with high purity and crystallinity needed for the optimum performance of the battery cells. In addition, the crystallinity and crystalline structure of graphite was improved during the treatment. The electrochemical studies of thermally treated graphite powders showed increased electrochemical performance compared to the untreated graphite samples. The improved performance was attributed to the increased purity and crystallinity of the thermally treated powders. Graphical Abstract Effect of thermal purification on the electrochemical performance of natural flake graphite