Graphite Anode and Cathode in EV Batteries
graphite anode and cathode
A battery has two electrodes, the anode (negative electrode) and the cathode (positive electrode). In an electrochemical cell, the anode is where reduction takes place. During this process, the negative charge on the anode is lost and the positive charge gains electrons. This is what gives a battery its capacity to store energy and also power devices like laptops, TVs and smartphones.
As the anode in an electrochemical battery, graphite is an efficient and stable reducing material that has high conductivity and a low cost. Its atomic structure means that it contains a large number of delocalised (free) electrons which allow it to conduct electricity.
Unlike metals, graphite is inert and therefore can be used without worrying about it reacting with the chemicals in the battery. Hence, it is used as an electrode in most electrochemical cells.
Anode and Cathode in EV Batteries
Graphite is used as the anode in electric vehicles because it has a low cost, is easily accessible and can be made in large volumes. It also offers superior energy density when compared to other alternatives such as lithium or silicon.
However, it has a significant drawback - during charging, the anode absorbs a large number of lithium ions, which swell the anode to more than 300%, causing it to crack and reduce its energy storage performance. Nevertheless, it is still used in the majority of present-day commercial lithium-ion batteries.
Despite this, there is a need to find new, better anode materials for EV batteries. Several firms are exploring the possibility of using silicon or lithium as anode materials in combination with speciality chemical binders. These compounds are expected to have significantly improved energy density, cycling stability and safety compared to graphite.