Fully charged in just 12 minutes! Next-generation lithium–sulfur battery developed for over 1,000 cycles

□ The research team led by Professor Jong-sung Yu of the DGIST (President Kunwoo Lee) Department of Energy Science and Engineering has developed an innovative technology to dramatically improve the charging speed of lithium–sulfur batteries. The team used a new nitrogen-doped porous carbon material to address the slow charging speed issue that has hindered the commercialization of existing lithium–sulfur batteries.

□ On the one hand, lithium–ion batteries are indispensable for eco-friendly technologies such as electric vehicles. However, they are limited by low energy storage capacity and high costs. On the other hand, lithium–sulfur batteries have gained attention as next-generation batteries due to their high energy density and the low cost of sulfur as a material. Despite these advantages, commercialization has been challenging due to insufficient sulfur utilization during rapid charging, which reduces battery capacity.

□ Another issue is the lithium polysulfides produced during the discharge process. These compounds migrate within the battery, degrading its performance. To address this, researchers have been developing batteries by incorporating sulfur into porous carbon structures. However, they have yet to achieve performance levels suitable for commercialization.

□ To solve these challenges, Professor Yu’s team synthesized a novel highly graphitic, multiporous carbon material doped with nitrogen and applied it to the cathode of a lithium–sulfur battery. This technology successfully maintained high energy capacity even under rapid charging conditions.

□ The newly developed carbon material was synthesized by employing a thermal reduction method^[1] that involves magnesium and ZIF-8^[2], a metal-organic framework. At high temperatures, magnesium reacts with the nitrogen in ZIF-8, making the carbon structure more stable and robust while creating a diverse pore structure. This structure not only allows for higher sulfur loading but also improves the contact between sulfur and the electrolyte, significantly enhancing battery performance.

□ The lithium–sulfur battery developed in this study utilized the multifunctional carbon material synthesized, through the simple magnesium-assisted thermal reduction method, as a sulfur host. Even under rapid charging conditions with a full charge time of just 12 minutes, the battery achieved a high capacity of 705 mAh g⁻¹, which is a 1.6-fold improvement over conventional batteries. Furthermore, nitrogen doping on the carbon surface effectively suppressed lithium polysulfide migration, allowing the battery to retain 82% capacity even after 1,000 charge–discharge cycles, demonstrating excellent stability.

□ During the research, the collaborative team, led by Dr. Khalil Amine of Argonne National Laboratory, performed advanced microscopic analyses. These analyses confirmed that lithium sulfide (Li₂S) was formed in a specific orientation within the layered structures of the newly developed carbon material. This finding validated that nitrogen doping and the porous carbon structure enhanced sulfur loading, while the graphitic nature of the carbon accelerated sulfur reactions, thereby improving charging speed.

□ Professor Jong-sung Yu remarked, “This research focused on improving the charging speed of lithium–sulfur batteries using a simple synthesis method involving magnesium. We hope this study will accelerate the commercialization of lithium–sulfur batteries.”

□ This research was supported by the National Research Foundation of Korea’s Mid-Career Researcher Support Program. The results, conducted in collaboration with Argonne National Laboratory (First Authors: Jung-hoon Yu, Integrated Master-PhD Student, and Byung-jun Lee, Ph.D.), were published in the prestigious journal ACS Nano.

- Corresponding Author E-mail Address : jsyu@dgist.ac.kr

^[1] Thermal reduction method: A process that uses heat to reduce substances, commonly employed to extract metals from metal oxides or to synthesize new materials.

^[2] ZIF-8 (Zeolitic Imidazole Framework-8): A metal-organic framework (MOF) formed by the coordination of metal ions and organic ligands. It is characterized by its high thermal and chemical stability, as well as its distinctive porous structure.