Graphite Cathode Material for Li-Ion Batteries
Anodes and cathodes are two key components of a battery. Anodes are the positive polarity contact point in an electrolytic cell while cathodes are the negative polarity contact points. Graphite is well-suited as a cathode material because it is electrically and thermally conductive, chemically passive (corrosion-resistant), and relatively affordable. Graphite is used in batteries, water heaters, and other applications where positive and negative polarity are needed.
Graphite is the most popular cathode material for lithium-ion batteries. It is made from natural or synthetic graphite and can be produced by a process known as carbonization. During this process, carbonaceous fillers are bonded together using carbon-yielding pitch binder and then baked at high temperatures to form graphite. Currently, about 55 percent of Li-ion battery manufacturers gravitate towards synthetic graphite as opposed to the rest which use natural graphite.
The electrochemical performance of graphite is mainly a function of the number of ions intercalated between the planar graphene layers and the energy required to insert an anion into the graphite lattice (anion desolvation energy). These two factors vary differently depending on the size of the anions and can significantly affect the overall charge storage capacity.
Currently, extensive efforts have been focused on various types of natural and synthetic graphite to maximize the cathode charge-storage capacity and unravel the structure-electrochemical property relationship. Amongst them, kish graphite shows the highest capacity values with a clear discharge voltage plateau in aluminium ion batteries, while potato-shaped graphite particles have lower capacities and exhibit low structural quality as reflected by the d-spacing in XRD patterns and intensity of Raman’s D band.
