Currently, electric vehicles and energy storage systems mostly use lithium-ion batteries. Although they have high energy density and fast charging speeds, they also have safety issues. Therefore, the industry is actively developing solid-state batteries, hoping they can replace traditional lithium-ion batteries.
In the current lithium-ion battery system, the combination of high-nickel ternary cathode, silicon-carbon anode, and electrolyte will reach its performance limit (energy density ceiling of 350Wh/Kg) within 3-5 years, but it still cannot completely meet the requirements of power batteries for safety, energy density, and cost. Solid-state batteries, on the other hand, have received widespread attention from academia and industry in recent years due to their greater potential in terms of safety and energy density.
Lithium-ion batteries use liquid electrolytes, which present issues related to weight, safety, and lifespan.
The main difference between solid-state batteries and lithium-ion batteries lies in the electrolyte. Lithium-ion batteries use a liquid electrolyte, existing in the form of a gel or polymer, making it difficult to reduce battery weight. Furthermore, a single lithium-ion battery pack has low energy density, necessitating multiple packs connected in series, further increasing weight. The engineering, manufacturing, and installation costs of battery packs account for a significant proportion of the overall cost of an electric vehicle.
Besides weight issues, electrolytes are also flammable, unstable at high temperatures, and prone to thermal runaway, potentially causing serious fires in the event of a car accident. Electrolytes also freeze easily at low temperatures, reducing battery life. Furthermore, electrolytes can corrode internal battery components, and the charging and discharging process can generate dendrites, reducing battery capacity, performance, and lifespan.
Solid-state batteries use solid electrolytes, resulting in high energy density.
Solid-state batteries do not contain a heavy liquid electrolyte; instead, they use a solid electrolyte in the form of glass, ceramic, or other materials. While their overall structure and charging/discharging methods are similar to traditional lithium-ion batteries, the absence of liquid makes them more compact, smaller, and increases energy density. Theoretically, replacing lithium-ion batteries in electric vehicles with solid-state batteries of the same volume could more than double the capacity.
Moreover, solid-state lithium batteries are lighter and do not require the monitoring, cooling, and insulation systems of lithium-ion batteries, freeing up more space in the chassis to house the battery and greatly increasing the range of electric vehicles.
In addition, solid-state batteries charge faster than lithium-ion batteries, do not have corrosion issues, and have a longer lifespan. Regarding operating temperature, solid-state batteries have thermal stability and will not freeze at low temperatures, which ensures the range of electric vehicles for users living in mid- to high-latitude regions.
