A research team at the Pohang University of Science and Technology (POSTECH) has succeeded in creating a next-generation battery that can withstand electrodes dozens of times thicker than conventional ones. The achievement directly overturns the conventional belief that thicker electrodes lead to poorer performance.
According to POSTECH on Wednesday, a research team led by Byoungwoo Kang, a professor in the Department of Materials Science and Engineering and the Department of Battery Engineering, along with Woo Seung-jun, a doctoral researcher in the Department of Materials Science and Engineering (affiliated with LG Energy Solution), succeeded in implementing a solid-state battery platform that operates stably while using a cathode dozens of times thicker than conventional ones. The research findings were published in the Journal of Materials Chemistry A, an international energy journal of the Royal Society of Chemistry in the United Kingdom.
Solid-state batteries, which use a solid instead of a liquid electrolyte, are a next-generation battery called a "dream battery" because they carry a low risk of catching fire and can store more energy.
The challenge is that lithium ions move slowly within the solid, so the thicker the electrode, the greater the internal resistance. In response, the team changed the path through which lithium ions travel. They replaced some of the silicon and phosphorus in a LISICON-type oxide solid electrolyte material with germanium. As a result, the channels through which ions can move became much wider, and the channels could also be densely connected to one another. In practice, ionic conductivity improved about five-fold compared to before.
Contact with the cathode and anode materials also improved. The material can bond firmly with the cathode material through simple heating alone, and by using lithium metal as the anode, a stable battery can be made without separate external pressure. The team succeeded in implementing a solid-state battery applying an "ultra-thick electrode" approximately 140 micrometers thick. This is dozens of times thicker than electrodes generally reported.
The battery operated stably even at room temperature. Its volumetric energy density reached 841 Wh/L. This means a smaller, lighter battery can store more energy. "This is a case that proves energy density can be dramatically increased by introducing thick electrodes in oxide-based solid-state batteries," Professor Kang said. "It will serve as an important breakthrough for the commercialization of next-generation lithium-metal solid-state batteries that satisfy both safety and energy density."
