Most of today’s energy storage devices for electric vehicles and other applications use lithium secondary batteries, which have low energy storage efficiency and density and limited safety. Industry and academia worldwide are actively conducting research and development on future energy storage devices. One promising battery type to overcome the limitations of current lithium batteries is the lithium–sulfur battery, but it remains at an early stage with durability and performance limitations.

A research team led by Jeonbuk National University (JBNU) professors Lee Jung-hee and Kim Nam-hoon (Department of Nano Convergence Engineering) has proposed a new research direction capable of overcoming these limitations, attracting attention from the global academic community. This research was carried out with support from the Ministry of Science and ICT's Regional Leading Research Project (RLRC) and was conducted through collaborative research with Jeo Yeong-yeong (Ph.D. candidate) and Nguyen Tan Tuan (postdoctoral researcher) from the Department of Nano Convergence Engineering. The study was published in the latest issue of Advanced Energy Materials (IF = 29.368), a world-leading journal in the energy field.

Lithium–sulfur batteries use sulfur, which is abundant in nature, as the cathode material, offering the advantage of low cost. Compared with conventional lithium‑ion batteries (~420 Wh kg−1), they can theoretically achieve a fivefold increase in energy density (2600 Wh kg−1). If realized, this would significantly reduce the weight of electric-powered vehicles, making early commercialization a key technology to secure the next-generation global secondary battery market.

However, lithium–sulfur batteries face challenges such as sulfur’s low electrical conductivity, rapid volume expansion of sulfur during charge–discharge, easy dissolution of lithium polysulfides into the electrolyte leading to capacity and durability loss, and the risk of battery explosion (or ignition) due to lithium dendrites. These drawbacks have hindered wider market adoption.

To address these issues, JBNU researchers used metal–organic frameworks (MOFs) to develop a cobalt selenide/cobalt oxide hetero-nanostructure encapsulated by a nitrogen-doped nano carbon layer and nitrogen-doped carbon nanotubes—creating a CoSe2/Co3O4@NC-CNT electrode—to greatly increase the sulfur loading that determines lithium–sulfur battery performance (≈10.1 mg cm−2), reduce the amount of electrolyte used, substantially raise energy density, and significantly extend battery life (≈1457 mAh g−1 @0.1 C, ≈688 mAh g−1 @5 C).

The research team explained that cobalt oxide used in this study exhibits strong sulfur adsorption properties, while cobalt selenide can enhance catalytic properties for polysulfide conversion reactions. By hybridizing the two materials, they achieved excellent electrical conductivity, strong binding with lithium polysulfides, and high catalytic activity, suppressing the shuttling effect in lithium–sulfur batteries and enabling the development of high-performance, highly durable lithium–sulfur batteries.

Professor Lee Jung-hee stated, “This research presents a technology that not only improves operating time and reduces the weight of energy storage systems but also accelerates the commercialization of lithium–sulfur batteries, which are inexpensive. We expect that the mass-production techniques for the high-performance cathode material developed through this study can be applied not only to lithium–sulfur batteries but also to electrode materials for various energy storage and conversion devices.”