The Key Role of Graphite Anode Materials in Lithium Batteries

Graphite anode material is a commonly used anode material for lithium-ion batteries with high energy density and low cost. It consists of graphite with good electrical conductivity and chemical stability.

 

Graphite anode material is a commonly used anode material for lithium-ion batteries with high energy density and low cost. It consists of graphite with good electrical conductivity and chemical stability. According to the research firm, global anode material shipments reached 1.556 million tons in 2022, up 71.9% year-on-year. Among them, China's negative electrode material shipments increased by 84.0% year-on-year to 1.433 million tons, a record high year-on-year growth rate. The proportion of negative electrode material shipments by Chinese companies in the global market continues to rise and has exceeded 90%.

 

01.Graphite negative electrode material classification and application

 

•Graphite can be divided into two types: natural graphite and manufactured graphite.

 

•Natural graphite is mined from rocks and can be classified as amorphous, flaky (crystalline) or massive and flaky (crystalline) depending on its crystallinity, grain size, morphology and reserve position.

 

•Artificial graphite, on the other hand, is produced through a graphitization process and has a high purity of 99.9%. Compared to natural graphite, manufactured graphite typically has a lower density, lower electrical conductivity and slightly higher porosity.

 

 

•Natural and synthetic graphite are widely used in batteries, carbon brushes, conductive materials, fuel cells and lubricants. Most anodes in commercial lithium-ion batteries are still made of graphite due to its good electrochemical properties and low-cost manufacturability.

 

02.Graphite negative electrode material energy storage principle

 

•Graphite anode material plays an important role in the charging and discharging process of batteries. It realizes the storage and release of electrical energy through the embedding and detaching of lithium ions. During the charging process, lithium ions are transferred from the positive electrode of the battery to the negative electrode through the electrolyte.

 

•Graphite as the negative electrode has a structure of carbon bands and micropores, and lithium ions are embedded in these layers and micropores when they reach the negative electrode. The greater the number of embedded lithium ions, the higher the charging capacity.

 

•The performance of anode materials has an important impact on the first time efficiency and cycle performance of lithium-ion batteries. In graphite anode materials, the size and morphology of graphite crystals play a key role in battery performance.

 

•Typically, smaller graphite crystals have a larger specific surface area and higher reactivity, providing better electrochemical performance. By improving the structural morphology and physical properties of graphite anode materials, the energy density and cycle life of lithium-ion batteries can be further improved.

 

03. Advances in graphite anode materials for batteries

 

•Graphite anode materials have a theoretically high capacity of about 372 mAh/g. However, in practice, the reversible capacity of graphite anodes is usually in the range of 330 to 370 mAh/g due to charge/discharge cycling and structural changes in the battery.

 

•This is due to the fact that graphite anode undergoes volume expansion during lithium ion embedding and detachment and its structure gradually becomes unstable, which leads to a decrease in reversible capacity and a reduction in cycle life.

 

•To overcome these problems, researchers are developing new graphite anode materials. One approach is to introduce additives into graphite to form composites, or to prepare nanostructured graphite materials, which can also be doped with graphene, among others.

 

•These new graphite anode materials have higher reversible capacity, more stable structure and longer cycle life, and are expected to become mainstream battery anode materials in the future.

 

•The results show that this anode material has excellent performance in lithium-ion batteries, improving lithium storage performance and enhancing the stability of the anode. However, nevertheless, this material is limited in large-scale applications due to its high preparation cost and complex preparation process.

 

04.Characterization of graphite anode materials

 

•In the production process of graphite-based anode materials, it is common to include capping and doping processes. These processes may introduce other elements to improve the performance of the anode material. As the energy density of batteries increases, the stability of graphite-based anode materials is increasingly required.

 

•Therefore, in order to ensure the quality and performance of the products, it becomes particularly important to effectively determine and remove trace impurity elements in graphite-based anode materials.