Engineers create a silicon all-solid-state battery that is safe, long lasting, and energy dense, showing their applicability in a wide range of applications from grid storage to electric vehicles.
In battery technologies, silicon anodes are highly popular due to their energy density, which is 10 times greater than the graphite anodes used in lithium-ion batteries available commercially. However, these anodes expand and contract as the battery charges and discharges, and they degrade with liquid electrolytes. Therefore, they aren’t used in commercial lithium-ion batteries.
Solid state batteries, on the other hand, rely on metallic lithium as an anode. But this restricts the charge rates and the need for elevated temperature (usually 60 degrees Celsius or higher) during charging. The silicon anode overcomes this limitation as well, allowing much faster charge rates at room to low temperatures, while maintaining high energy densities.
A team of nanoengineers from University of California San Diego, in collaboration with researchers at LG Energy Solution, have created a battery that uses both a solid state electrolyte and an all-silicon anode, making it a silicon all-solid-state battery.
“With this battery configuration, we are opening a new territory for solid-state batteries using alloy anodes such as silicon,” said Darren H. S. Tan, the lead author on the paper.
The researchers demonstrated a laboratory scale fuel cell that can deliver 500 charge-discharge cycles with 80% capacity retention at room temperature.
“As battery researchers, it’s vital to address the root problems in the system. For silicon anodes, we know that one of the big issues is the liquid electrolyte interface instability,” said UC San Diego nanoengineering professor Shirley Meng, the corresponding author on the Science paper, and director of the Institute for Materials Discovery and Design at UC San Diego. “We needed a totally different approach,” said Meng.
The researchers solved this problem by swapping out the liquid electrolyte for a solid electrolyte, and at the same time removing the carbon and binders from the silicon anode. With this approach, they managed to avoid a series of problems that arise when anodes become soaked in the organic liquid electrolyte as the battery functions.
“The solid-state silicon approach overcomes many limitations in conventional batteries. It presents exciting opportunities for us to meet market demands for higher volumetric energy, lowered costs, and safer batteries especially for grid energy storage,” said Darren H. S. Tan, the first author of the work published in Science journal.
“LG Energy Solution is delighted that the latest research on battery technology with UC San Diego made it onto the journal of Science, a meaningful acknowledgement,” said Myung-hwan Kim, President and Chief Procurement Officer at LG Energy Solution. “With the latest finding, LG Energy Solution is much closer to realizing all-solid-state battery techniques, which would greatly diversify our battery product lineup.”
“As a leading battery manufacturer, LGES will continue its effort to foster state-of-the-art techniques in leading research of next-generation battery cells,” added Kim.