If the cathode material is where lithium ions are released, the anode material serves as the space where lithium ions from the cathode are inserted. So, what role does the anode play inside a battery, and what materials are used for anodes? Let’s take a closer look.
Anode Material Affecting Battery Charging Speed and Lifespan
The anode enables the flow of current by inserting and releasing lithium ions. The lithium ions in the anode material move through the electrolyte to the cathode, while the electrons separated from the lithium ions travel along the conductor connecting the anode and cathode, generating electrical energy.
In this process, the anode material is a key factor influencing the battery’s charging speed and lifespan. The more lithium ions the anode can store, the longer the battery lifespan, and the better it can accommodate lithium ions, the shorter the charging time. In other words, an anode material used in long-lasting batteries must be capable of repeatedly inserting and releasing lithium ions. Even if the cathode generates a large amount of energy, if the anode cannot effectively store lithium ions, the battery’s energy cannot be utilized efficiently. For this reason, the importance of anode material technology development is increasing day by day.
Graphite, the Representative of Anode Material
Graphite is currently the most widely used anode material. Made entirely of carbon, it consists of thin layers with a repeating hexagonal pattern, where each carbon atom bonds with three others. These layers stack to form a stable structure, allowing lithium ions to be efficiently inserted, making graphite well-suited for anodes. Graphite is classified into natural graphite and synthetic graphite. Natural graphite has a high lithium-ion storage capacity and is cost-effective. However, when lithium ions are inserted, its internal structure expands, and its surface becomes unstable, reducing insertion and release efficiency and shortening battery lifespan. In contrast, synthetic graphite, produced through a high-temperature graphitization process, has a more stable internal and surface structure, resulting in less expansion and better cycle life compared to natural graphite.
Silicon, the Emerging Next-generation Anode Materials
With the increasing demand in the electric vehicle battery market, the demand for next-generation anode materials is also growing. The material receiving attention as the next-generation anode material is silicon.
If silicon is used as an anode material instead of graphite, the energy density per gram of the battery increases by more than four times, making the design for rapid battery charging easier. Furthermore, silicon is considered an environmentally friendly material, which is why it is garnering attention as the next-generation anode material.
LG Energy Solution is also putting significant efforts into the development of silicon anode materials. In 2019, they achieved a groundbreaking accomplishment by applying silicon anode material with a 5% content to BEV batteries for the first time globally. Additionally, we are continuously driving technological innovation by accelerating the development of technology for applying silicon anode materials with 7% content, another world-first achievement.
Up to this point, we’ve explored the role of the anode material, a crucial component in lithium-ion batteries, as well as the characteristics of two materials commonly used for anodes: graphite and silicon. In our next session, we will continue to provide insightful and easily understandable information about batteries through infographics!