[Reading Science]"No Need for High Pressure"... All-Solid-State Battery 'Interfacial Instability' Solved

The critical challenge of "anode interfacial instability," which has hindered the commercialization of all-solid-state batteries, has been resolved by a domestic research team. This technology enables stable performance without the need for high-pressure equipment, bringing the next-generation batteries for electric vehicles one step closer to commercialization.

The Korea Electrotechnology Research Institute (KERI) announced on April 27 that the research team led by Dr. Nam Kihoon from the Battery Materials and Process Research Center has addressed the issue of interfacial instability between the lithium metal anode and the solid electrolyte using a "nano tin (Sn) interlayer control technology." This research achievement has been selected as the cover paper for the international academic journal Advanced Energy Materials, which specializes in the fields of energy and materials.

KERI's research results on nano tin interlayer control technology have been selected as the cover paper of Advanced Energy Materials. Photo by KERI

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All-solid-state batteries, which use a solid electrolyte instead of a liquid, are considered the next-generation battery due to their low risk of fire and high energy density, earning them the nickname "dream batteries." However, when using lithium metal as the anode to achieve high performance, imperfect contact with the solid electrolyte leads to "interfacial resistance" that hinders ion movement. Additionally, during charging and discharging, "dendrites"-lithium growing in a branch-like form-are formed, which shortens the battery’s lifespan.

Previously, solving these issues required applying high pressure of several tens of megapascals (MPa) or using complicated coating technologies. However, if applied to actual electric vehicles, this resulted in increased device weight and costs.

KERI suppressed the growth of lithium dendrites during charging and discharging of all-solid-state batteries by introducing a nano tin intermediate layer. Photo by KERI

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The research team used nano tin powder, which has excellent lithium absorption capability, to form a thin interlayer and precisely attached it to the surface of lithium metal using a "transfer printing" process. This interlayer reduces interfacial resistance and secures ion migration pathways, greatly improving battery performance.

Experimental results showed that, based on a large-area pouch cell, a capacity retention rate of over 81% was maintained after 500 charge-discharge cycles even at a low pressure of 2MPa. The energy density reached 351Wh/kg, far surpassing that of conventional lithium-ion batteries (150~250Wh/kg).

The research team also used first-principles calculation-based simulations to elucidate, at the atomic level, the mechanism by which the tin alloy controls lithium migration. By combining experimental and theoretical approaches, they demonstrated the mechanism of interfacial stabilization.

Research team photo. From the left: Senior Researcher Kihoon Nam, Principal Researcher Yuncheol Ha, Senior Researcher Youngoh Kim, Student Researcher Sojung Lim. Provided by KERI.

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Dr. Nam Kihoon of KERI stated, "By achieving both large-area scalability and interfacial stability, we have offered a practical solution for the commercialization of all-solid-state batteries. We will continue to advance the technology so it can be applied in various fields, such as electric vehicles, humanoids, and energy storage systems (ESS)."

Co-corresponding author Dr. Ha Yuncheol of KERI also emphasized, "All-solid-state batteries are a key area in the global battery competition. This achievement will contribute to domestic technological independence and enhanced competitiveness."

This research included Garam Kim (UST) and Sojung Lim (KERI-Changwon National University cooperative program) as co-first authors, and the related technology has already been filed for a domestic patent. The study was supported by projects including the Global Top Strategy Research Group (GT-3) of the Ministry of Science and ICT.

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