[Reading Science] Commercialization of All-Solid-State Batteries Accelerated Using Existing Lithium-Ion Battery Factories

Sangyoung Lee's Yonsei University Team Solves Both Manufacturing Compatibility and Thick Electrode Challenges

All-solid-state batteries are considered the "next-generation battery" due to their low risk of explosion and high energy density. However, they have long been thought to require significant time before commercialization, as they are incompatible with existing lithium-ion battery manufacturing processes. A team of Korean researchers has significantly narrowed this gap by developing a polymer electrolyte for all-solid-state batteries that can be used on current lithium-ion battery production lines without modification.

Schematic of the "Conflicting Entropy Design" concept for ZPE electrolytes. The ZPE precursor molecules, which were randomly mixed (high entropy), naturally transition into an ordered structure (low entropy) during the polymerization process, forming continuous pathways that allow ions to move easily. Provided by the research team

Sangyoung Lee, Professor in the Department of Chemical and Biomolecular Engineering at Yonsei University, together with Sangkyu Kwak’s team at Korea University, Minjae Lee’s team at Kunsan National University, and Youngjoo Lee’s team at the Korea Basic Science Institute (KBSI), announced that they have, for the first time in the world, proposed a new polymer electrolyte utilizing the concept of entropy and successfully applied it to all-solid-state batteries.

The key feature of the electrolyte developed by the research team lies in its "zwitterion" structure, which simultaneously contains both positive and negative charges within a single molecule. This structure enables strong interaction with lithium ions and allows the molecules to self-align, forming stable ion transport pathways even in the solid state.

In addition, the researchers introduced a new design concept called "entropy conflict." Initially, the electrolyte exists in a liquid state, allowing it to penetrate deep into the electrode. When exposed to light or heat, it transitions into a solid, during which the molecules spontaneously align to form pathways for ion movement. Through this approach, the team fundamentally addressed the chronic issue of low ionic conductivity that has long plagued polymer electrolytes.

The most significant achievement of this research is its high compatibility with existing lithium-ion battery manufacturing processes. The newly developed polymer electrolyte can be coated or infiltrated onto electrodes in its liquid state using the same methods as current processes, and then converted into a solid electrolyte through a simple procedure. This demonstrates the possibility of gradually converting existing lithium-ion battery production lines to all-solid-state battery processes without the need for expensive new equipment.

From the left in the photo: Kyungseok Oh, Researcher at Yonsei University; Jieun Lee, Researcher at Korea University; Sangkyu Kwak, Professor at Korea University; Sangyoung Lee, Professor at Yonsei University. Provided by Yonsei University

The research team also demonstrated an all-solid-state battery that operates stably at room temperature and under low pressure, even with thick electrodes, by applying this electrolyte. As a result, they presented the possibility of realizing high-energy all-solid-state batteries with an energy density of 516 Wh/kg-about twice that of conventional lithium-ion batteries (approximately 250 Wh/kg).

Sangyoung Lee, Professor at Yonsei University, stated, "This research is significant in that it presents a solid electrolyte platform with exceptional compatibility with existing lithium-ion battery manufacturing processes. By utilizing entropy-based polymer electrolytes, it is possible to realize high-energy all-solid-state batteries without complex additional steps, which could substantially accelerate the commercialization of all-solid-state batteries."

This research was supported by the National Research Foundation of Korea's Individual Basic Research Program and the Nano and Material Technology Development Program. The results were published on December 6 in the international journal Nature Communications under the title "Conflicting entropy-driven zwitterionic dry polymer electrolytes for scalable high-energy all-solid-state batteries."