The solid-state battery as an alternative to the conventional liquid-electrolyte lithium-ion battery
Lithium-ion (Li-ion) batteries have become the technology of choice for many applications. Li-ion battery-powered systems range from mobile phones, laptops, and power tools to electric vehicles, electric trucks and buses, and even electric aircraft. The traditional lithium-ion battery comprises a cathode, anode, separator, and liquid electrolyte. The flammable liquid electrolyte is responsible for Li-ion battery safety issues, such as electrolyte leakage, fire, or explosion. In a solid-state battery, as its name suggests, the flammable liquid-electrolyte is replaced by a solid-state electrolyte, which results in greater safety and enhanced battery characteristics. Solid-state battery development aims for a next-generation battery with higher energy density, fast charging capability, lower cost, and greater safety.
Solid-state batteries have many potential applications across multiple industries, such as automotive, consumer electronics, industrial, aerospace, etc. There are two distinct categories of solid-state batteries: solid-state batteries with a very small energy capacity, already commercially available from several suppliers, aimed at applications in consumer electronics, while the biggest drive is for large-energy capacity (“bulk”) solid-state batteries for electric and hybrid electric vehicles (EV/HEVs)
Electric vehicles as a key driver for solid-state battery development
Internal combustion engines (ICEs) have powered automobiles for more than 100 years, but the era of the ICEs is now coming to its end. EVs will progressively replace ICE vehicles and become mainstream in the automotive industry in the coming years.
However, today many car users still have concerns regarding the short driving range, long charging time, cost, and safety of EVs. To increase the driving range, a simple approach would be to increase the battery capacity. The energy capacity can be increased either by increasing the number of battery cells (basic units) per battery pack (big battery in the vehicle) – in which case, the battery price and weight go up, and batteries take up a lot of space in the vehicle – or by increasing the battery energy density, a more suitable solution. A solid-state battery approach can result in a higher cell energy density, and therefore fewer battery cells will be needed per vehicle. This is one of the reasons why many battery producers and automotive OEMs aim at the development of solid-state batteries.
Although it is claimed that solid-state batteries have several advantages over conventional Li-ion batteries, their development is associated with many challenges, like low ionic conductivity, poor wettability of solid electrolytes, high operating temperature, etc. The final choice of the solid-electrolyte material and related equipment and processes is still being researched.
A safe and high-performance battery is an important differentiation factor against competitors. Therefore, many battery and automotive manufacturers have already presented their target roadmaps for mass production to secure a leadership role in the solid-state battery market despite the remaining technology and supply chain challenges.
For example, Toyota is planning mass production of solid-state batteries from 2025. QuantumScape and Panasonic are also planning mass production of solid-state batteries from 2025-2026, and Samsung SDI is working on solid-state batteries with mass production from 2027. In addition, many EV makers, such as Volkswagen, Hyundai, and BMW, have made investments in solid-state battery startups and are planning to launch their EVs with solid-state batteries in the coming years. For example, Volkswagen plans to launch its EV with solid-state batteries in about 2025, forging a partnership with the startup QuantumScape.
Based on the achievement of technology milestones and growing supply chain collaborations, Yole Développement expects that solid-state battery commercialization will start in about 2025. However, small-scale production may happen even earlier. According to Yole Développement, the bulk solid-state battery market will represent about 2.36 GWh by 2027, with accelerated growth expected after this period. Due to at least initially higher cost compared to conventional Li-ion batteries, solid-state batteries will probably be first adopted in lower series premium electric passenger vehicles or as a battery option available at a “premium” price. Successful adoption of solid-state batteries in passenger electric vehicles will lead to an accelerated transition from hybrid electric vehicles to fully electric vehicles. After that, solid-state batteries will spread to other applications, such as aerospace.
Bringing solid-state technology to mass production is a difficult task, and partnerships are more important than ever to bring all the necessary solid-state battery know-how together: technology, equipment, high-volume / high-yield production, and end-systems.
EV makers will have a unique position in this partnership as they can provide $100M+ funding, require solid-state battery technology to differentiate from competitors, have high-volume battery requirements (a lot of battery cells per vehicle and a lot of vehicles per year), and boast established sales and distribution networks.
Conclusion
The solid-state battery is considered the ultimate battery technology for next-generation battery systems. The intensive development efforts of EV/HEV makers and their partners will result in a progressive adoption of the solid-state battery as a “premium” battery in the 2025-2030 period. After further optimization and production scaling, solid-state batteries will spread to other applications, but their high added value will remain mainly in e-mobility applications.
