Although electric cars are becoming more and more popular, they still have limited range. The Tesla Model 3 can travel approximately 560 kilometers before needing to be recharged. Additionally, the lithium-ion batteries that dominate the market are plagued with safety concerns. The Solid Power start-up wants to solve both problems. In the search for electric car batteries that take us safely over long distances, the company is developing solid-state batteries that can store more energy in a smaller space.
To test the technology, Solid Power started a large-scale pilot production line as a first step. New battery cells must be produced there. With them, the electrolyte liquid in lithium-ion batteries, which carries the charge, is replaced by ceramic layers. The cells are the size of a small laptop and correspond to the cells that will later be used in electric cars.
Objective: To offer material for the solid electrolyte
This solid state battery technology is still years away from commercial distribution. Solid Power expects to produce enough material for 800,000 cars per year by 2028. However, if the technology proves valid, the batteries could significantly increase the performance of electric vehicles. Solid Power does not want to manufacture and sell complete batteries, but rather to supply the material for the solid electrolyte to other battery manufacturers, says CEO Doug Campbell.
Although solid state batteries are only slowly gaining ground, they open up new possibilities for battery chemistry. In particular, lithium metal and silicon chemicals are unstable or unsafe when combined with a liquid electrolyte in the cell. However, they could theoretically be used if a solid were used instead.
The result would be a battery that could store more energy in a smaller space. This means that the cars could go on before they run out. According to Campbell, Solid Power batteries could also improve the energy density of lithium-ion batteries by about half. An electric car that previously could travel 560 kilometers on a single charge could increase its range to over 800 kilometers.
Save space with solid state batteries
Eliminating the liquid electrolyte would also make it easier to build safer cells, Campbell adds. Although lithium-ion batteries are equipped with protections that ensure they do not catch fire or explode, disposing of the liquid would eliminate the need for these expensive additives. Battery packs made up of many cells could be denser because their internal temperature controls and safety systems would take up less space.
The concept of removing liquid electrolytes from battery cells is not new, says Lei Cheng, a chemist and battery researcher at Argonne National Laboratory’s Materials Division. For years, however, research on solid-state batteries has focused on the use of organic polymers such as polyethylene oxide. Although these materials are cheap and easy to produce, their performance has not been satisfactory. For this reason, various research groups and start-ups such as QuantumScape are taking steps to commercialize solid-state batteries using materials such as sulfides and oxides, which have higher conductivity.
The question, however, is whether companies that produce solid electrolytes will be able to produce them on a large scale. Inorganic materials, such as the sulfides used by Solid Power, can be brittle and difficult to move during production when made in thin layers on large production lines, says Cheng.
Another problem with solid-state batteries is how well they can withstand degradation over time, particularly with regard to dendrites, root-like structures that lithium commonly forms in batteries and which can affect their performance.
Solid Power faces big challenges as it grows, says Jeff Chamberlain, chief executive of Volta Energy Technologies, a major investor in the company. However, Volta was interested in the company not only because the technology shows promise, but also because the team thought about scaling from the start. According to Chamberlain, “The best technology is the one that can be produced.” The question is: will solid state batteries find their way into this category.