Continued: 4680 Battery-Battery Technology Upgrade-Silicon Anode
4. Silicon anode
4.1. Advantages
- Higher theoretical energy density: the theoretical maximum battery capacity of graphite anode is 372Wh/kg, and the theoretical maximum battery capacity of silicon anode can reach 4200Wh/kg.
- Better safety: the voltage platform of silicon is higher than that of graphite, now the anode electrode graphite will produce lithium dendrites, because their voltage platform is close to the precipitation potential of lithium, the branch crystals pierce the diaphragm, the cathode and anode electrodes will be short-circuited, which threaten battery safety.
- Lower cost: silicon material has a wide range of sources, abundant reserves, low production cost, and environmentally friendly. The mass energy density of lithium-ion batteries using silicon anode materials can be increased by more than 8%, the volume energy density can be increased by more than 10%, and the cost per kilowatt-hour of the battery can be reduced by at least 3%.
Tesla Silicon Anode Process Principle
4.2. Disadvantages
- Poor cycle performance: the volume expands after lithium insertion, graphite has no obvious volume expansion after lithium ion insertion, but the volume of silicon expands more than four times after lithium ion insertion, and the battery is scrapped after several rounds of expansion and contraction.
- Poor conductivity: the low conductivity of silicon limits the full utilization of its capacity and the rate performance of silicon electrode materials, volume changes make the active material poorly contact with the conductive agent binder, and the conductivity decreases, the SEI film on the silicon surface is thick and not uniformity, which affects the conductivity and the overall specific energy of the battery.
4.3. Innovative design of 4680 battery
Tesla redesigned the raw materials, adopted highly elastic materials, and increased the elastic ionic polymer coating to stabilize the silicon surface structure and reduce the cost by 5%.
4.4. Silicon carbon anode is the direction
- Battery companies are actively applying silicon carbon anodes: silicon carbon anodes are currently mainly used in cylindrical batteries. In the high specific capacity battery solutions of power battery manufacturers such as CATL, the silicon carbon anode is a clear development direction.
- Speeding up the application of silicon-carbon anodes: Chinese anode manufacturers have increased investment in silicon-carbon anodes. Some battery companies, such as CATL, is actively deploying in silicon carbon.
An inevitable trend of high energy density
Silicon carbon batteries are an inevitable trend in the development of high energy density, with the overcoming of technical difficulties and the increase in customer acceptance, silicon carbon will reduce the cost and achieve large-scale mass production.
CNCET predicts that the output and consumption of silicon carbon anode materials in my country in 23 years will be reaching 60,000 tons, the future market prospects for silicon carbon anodes are huge.
……To be continued
