Empa develops novel battery
Empa is getting to more powerful batteries through layers. For their prototype stacked thin-film solid-state battery, the research group led by Yaroslav Romanyuk used the expertise of Empa's photovoltaic laboratory, according to a media release from the Bern-based Swiss National Science Foundation (SNSF). The team builds on its thin-film technology, depositing fine films of material onto a substrate in a vacuum. To achieve higher energy density, "we had to reduce the weight fraction of the substrate," explains the first author of this study, Moritz Futscher.
The solution is to stack two thin-film cells (rechargeable batteries) on top of each other. The biggest hurdle, he says, was the connection between two cells: "Here, vacuum coating proved to be central: We were able to make a stable connection hundreds of times thinner than a human hair and stack the cells exactly on top of each other."
Lab tests show that it works: the prototype is charged in just one minute. The amount of energy stored can rival current and future lithium-ion batteries. And solids are not flammable. This prototype is thus the first battery ever to combine the three criteria of large storage capacity, high safety and fast charging.
Now the team, which is supported by the SNSF, plans to expand from two to multiple battery layers on the same substrate. "Our simulations show that the optimum is ten batteries," says Futscher.
Because manufacturing is still very costly, these batteries will tend to be reserved for applications where high storage capacity, performance and safety are critical and cost is secondary, according to the release. Candidates are therefore aircraft, drones or even satellites.