A research team at the Korea Electrotechnology Research Institute (KERI) has developed an intermediate layer technology that reduces contact instability occurring between the lithium metal anode and the solid electrolyte in all-solid-state batteries. The team applied this technology, utilizing nano-tin, to large-area pouch cells and verified charge and discharge performance even under low-pressure conditions.

The Korea Electrotechnology Research Institute (KERI) announced on April 27 that the research results of Dr. Nam Ki-hun's team at the Battery Materials and Process Research Center were selected as the front cover article for the international academic journal 'Advanced Energy Materials'. Ga-ram Kim, a master's graduate from UST, and So-jeong Lim, a student researcher in the KERI-Changwon University industry-research program, participated as co-first authors in this research.

All-solid-state batteries are next-generation batteries that use a solid electrolyte instead of a liquid electrolyte. They are attracting attention for their ability to reduce fire risk and increase energy density, but when a lithium metal anode is applied, a problem arises where resistance increases at the interface where it comes into contact with the solid electrolyte. The dendrite phenomenon, in which lithium grows unevenly during the charging and discharging process, is also cited as a factor in reducing lifespan.

Previous studies have utilized methods such as applying high pressure or separate coating processes to maintain solid-solid contact. However, high-pressure operating conditions can increase the weight and cost of battery systems, posing a burden for actual applications in electric vehicles or energy storage devices.

The research team created a thin intermediate layer using lithium-reactive nano-tin powder and applied a method of attaching it to the surface of a lithium metal anode using a transfer process. The transfer process involves transferring a functional layer created on a separate substrate to a target surface, which can reduce the limitations of directly coating highly reactive lithium metal.

As a result of the experiment, the large-area pouch cell applying the technology showed a capacity retention rate of over 81% after 500 charge-discharge cycles under a pressure of 2 MPa. The energy density was measured at 351 Wh/kg. The research team also analyzed the effect of the tin alloy on lithium migration and interfacial resistance through simulations based on first-principles calculations.

Domestic patent applications for this technology have been completed. The research team plans to continue follow-up research tailored to commercial manufacturing processes, keeping in mind fields requiring high-performance batteries such as electric vehicles, humanoids, and energy storage systems.