A solid-state battery is a battery technology that uses solid electrodes and a solid electrolyte, instead of the liquid or polymer gel electrolytes found in lithium-ion or lithium polymer batteries. Materials proposed for use as solid electrolytes in solid-state batteries include ceramics (e.g. oxides, sulfides, phosphates), and solid polymers. Solid-state batteries have found use in pacemakers, RFID and wearable devices. They are potentially safer, with higher energy densities, but at a much higher cost.
That means your next Tesla could have a range of 5000 miles on a single charge that takes 20mins to charge fully.
Lithium ion (Li-ion) batteries have led the EV market since their revival in the late-2000s due to their high energy density, cycling ability, and light weight. However, conventional Li-ion battery technology may be nearing full potential, and solid-state batteries are on the horizon. Major automakers like Ford, Hyundai, Nissan, Toyota, and Volkswagen are investing in solid-state battery research, as are some Chinese EV companies and Fisker. Production release dates vary, but it is possible a solid-state battery powered EV could reach the market in 2020 if Toyota meets its target. However, most automakers are aiming to get into the market between 2022 and 2025.
What Are the Advantages?
The solid-state battery is distinguished from conventional Li-ion batteries by the replacement of the liquid or polymer electrolyte with a solid electrolyte. The solid electrolyte enables batteries that are more energy dense and durable. The density improvement is significant, making commercialized versions of these batteries smaller and cheaper on a dollars per kilowatt-hour basis. Furthermore, some researchers believe solid-state batteries could give EVs over 500 miles of range.
The improved battery durability could also lead to reduced concerns of use in bidirectional charging, higher charging capabilities, and diminished concerns of recycling and disposal due to longer life of the battery.
What Are the Challenges?
Most challenges for solid-state batteries are technical, limiting commercial viability. For example, identifying a uniform material for the solid-state portion of the battery that conducts electricity efficiently in large battery packs has proven to be a key challenge for developers. Lithium metal is believed to be the prime material for solid-state batteries because of its high capacity potential and stability. Additionally, researchers at MIT have identified a way to make thinner lithium electrolytes that would allow for faster charging and higher voltage solid-state batteries.
Many do not believe solid-state batteries are commercially viable yet due to potential issues with low temperatures. The physical limitations of solid electrolytes makes them less conductive than liquid electrolytes. The conductivity is dependent on temperature, so there is potential for the energy density of solid-state batteries to decrease more in cold temperatures compared to current Li-ion batteries.
Future of Solid-State Batteries
If solid-state batteries can meet expectations in the next 3-5 years, the technology could drastically change the vehicle market. EVs would become price competitive sooner than expected, have higher range capabilities, and be a less bulky component of the vehicle.
Companies like Tesla have doubled down on conventional Li-ion batteries, but solid-state batteries have a strong disruption potential on the EV market.