The negative electrode material in lithium-ion batteries plays a crucial role in storing and releasing energy during the charging process, acting as a carrier of lithium ions and electrons. It accounts for approximately 5%-15% of the battery cost and is one of the most important raw materials for lithium-ion batteries.
Global sales of lithium-ion battery anode materials are approximately 100,000 tons, with my country and Japan being the main production countries. Given the current upward trend in new energy vehicles, the demand for anode materials is expected to continue to rise. Currently, natural/artificial graphite remains the dominant anode material for lithium-ion batteries globally, while new anode materials such as mesophase carbon microspheres, lithium titanate, silicon-based anodes, HC/SC, and lithium metal are also rapidly gaining traction.
The positive electrode material accounts for a large proportion of lithium-ion batteries (the mass ratio of positive to negative electrode materials is 3:1 to 4:1), because the performance of the positive electrode material directly affects the performance of lithium-ion batteries, and its cost directly determines the cost of the battery.
Lithium insertion into or extraction from cathode materials is accompanied by a phase change. Therefore, the electrode films in lithium-ion batteries require very thin films, typically on the order of tens of micrometers. The lithium intercalation compound in the cathode material serves as a temporary storage container for lithium ions in the battery. To obtain higher single-cell voltages, high-potential lithium intercalation compounds are preferred.
The difference between positive and negative electrode materials in lithium-ion batteries
The key difference between the positive and negative electrode materials in lithium-ion batteries lies in their potentials. The positive electrode material has a higher potential, while the negative electrode material has a lower potential. This creates a larger potential difference, a crucial prerequisite for battery construction. The negative electrode primarily uses graphite, a type of carbon (C), while the positive electrode uses oxides of transition metals, such as lithium cobalt oxide, lithium manganese oxide, or lithium iron phosphate.
I. Basic Requirements for Cathode Materials in Lithium-ion Batteries
1. The material itself has a high potential, which allows for a larger potential difference between it and the negative electrode material, resulting in a high energy density cell design.
2. The material has a large specific surface area, a large number of lithium insertion sites, and relatively short lithium ion insertion channels, making insertion and extraction easier.
3. The material has a large diffusion coefficient and a strong ability to insert and extract lithium ions, which allows lithium ions to move rapidly inside the material. This is a factor that affects the internal resistance of the cell and also affects the power characteristics.
II. Basic Requirements for Negative Electrode Materials in Lithium-ion Batteries
1. Allows for a greater number of reversible lithium ion insertions and extractions, resulting in higher specific capacity.
2. The structure is relatively stable during charging and discharging, and has a long cycle life.
3. It can form a stable solid electrolyte membrane with the electrolyte, ensuring high coulombic efficiency.
Cathode materials are the most critical raw materials in lithium-ion batteries, determining their safety performance and whether they can be scaled up. The development of cathode materials has led the development of lithium-ion batteries. As the market demand for high-capacity, high-power anode materials gradually increases and the manufacturing processes for next-generation anode materials mature, the market focus will gradually shift towards these new-generation anode materials.
