Graphite Anode For Lithium Ion Battery
Graphite is the go-to anode for lithium ion battery thanks to its high capacity, low cost and excellent cycle life. During charging, lithium ions move between the cathode and anode through a buffer electrolyte that separates them. In the anode, lithium ions occupy spaces inside of carbon atoms in the graphite material by insertion (intercalation) or extraction (deintercalation) to provide electrical energy to the cell.
The performance of a lithium ion battery depends on the quality and morphology of the anode. Natural graphite flakes need to be converted to spherical form before they can be used in lithium batteries. This is a time-consuming process and requires high temperature, energy-intensive conditions. The resulting spherical graphite particles have higher rate capability, energy density, first cycle irreversible capacity loss and cycling stability than non-spherical ones.
In order to improve the cyclability of these electrodes, scientists have been exploring ways to optimize their morphology. They have also been experimenting with the use of different materials to replace the traditional graphite anode, such as silicon.
Among these materials, silicon stands out due to its ultra-high theoretical specific capacity (4200 mAh g-1 [10]), 10 times that of commercial graphite. However, when silicon is used as an anode, the large volume changes of the active silicon particles during lithiation and de-lithiation create mechanical stress in the material and can cause its failure. The changes also reduce the coulombic efficiency of the anode and lead to an increase in the thickness of the solid electrolyte interphase (SEI) film, which leads to a reduction in the cycling capabilities of the battery.
