[Reading Science] Development of New Composite Materials, the Winning Move of 'K-Ion Battery'

KRICT Develops New Composite Material with Over 3 Times Longer Lifespan
Expected to Solve Main Cause of Secondary Battery Life Reduction
Ministry of Science and ICT's 'Global TOP Strategy Team' Project Also Supports Secondary Batteries

Senior Researcher Kim Doyeop (right) and Student Researcher Jeong Sangyun of the Secondary Battery Research Team at the Korea Research Institute of Chemical Technology are smiling brightly while holding a battery pouch cell applying a new lithium composite material. Photo by Chemical Research Institute

Domestic researchers have succeeded in developing next-generation lithium secondary battery materials that are safer and have more than three times the lifespan of existing ones. Coupled with government policies to support research aimed at securing a foothold to continue leading the secondary battery market, a rapid advancement of 'Made in Korea' secondary batteries is anticipated.

The Korea Research Institute of Chemical Technology (President Young-Kuk Lee) announced on the 7th that Dr. Do-Yeop Kim's research team has developed a new lithium composite material that solves the problem of uncontrollable, random growth of lithium metal inside secondary batteries, which had been hindering performance and safety. The highly stable lithium composite material developed by the research team can be utilized in lithium metal batteries, lithium-sulfur batteries, lithium-air batteries, and other next-generation lithium secondary batteries that are attracting attention through follow-up and commercialization research.

Schematic Diagram of Lithium-Ion Migration Pathway (Cathode → Anode) and Lithium Growth

Graphite, which offers economic efficiency and safety, is mainly used as the anode material in lithium-ion batteries. However, graphite has a lower energy density compared to lithium metal, a significantly smaller theoretical capacity, and occupies a relatively larger volume.

Lithium metal, which can compensate for these drawbacks, is emerging as the most ideal anode material for next-generation lithium secondary batteries, but there is a prerequisite challenge. In typical lithium secondary batteries, lithium ions move from the cathode to the anode during charging to store electrical energy. In lithium-ion batteries, lithium ions move into the layered structure of graphite at the anode and are stably stored, whereas in lithium metal batteries, lithium ions are converted into lithium metal on the surface of the lithium metal anode and accumulate there.

At this time, lithium does not grow evenly but grows locally like tree branches, forming 'lithium dendrites.' These accelerate electrolyte decomposition, degrade battery performance, and in severe cases, penetrate the separator and cause a short circuit by contacting the cathode, which can lead to battery explosions.

To develop high-performance next-generation secondary batteries such as lithium-sulfur and lithium-air batteries that use lithium metal as the anode material, technology to suppress lithium dendrite growth is essential.

After repeatedly depositing and stripping lithium on the surface of the control lithium foil and the developed composite material several times, lithium was deposited again, and scanning electron microscope images of the surface and cross-section of the deposited lithium were taken. While many lithium dendrites were formed on the lithium foil, lithium was observed to be stably and relatively cleanly deposited on the developed composite material.

Accordingly, the research team introduced a material with high ionic conductivity and dendrite suppression capability for the first time, successfully developing a new secondary battery anode composite material that promotes uniform lithium growth while efficiently conducting lithium ions.

While existing composite material manufacturing technologies required reactions with lithium under conditions such as high temperature, this study produced the composite material by physically mixing a material that efficiently conducts lithium ions with lithium metal using a very simple method.

Tests on the developed lithium composite material showed a significant reduction in lithium dendrite growth compared to regular lithium metal, resulting in more than three times longer battery lifespan.

Along with lifespan extension, stable performance was also secured. When using regular lithium metal, capacity degradation increases after 70 charge-discharge cycles, but with the developed material, no rapid capacity decline was observed even after 250 cycles. Additionally, the charge-discharge rate increased by more than 20% under certain conditions.

The research team applied the developed composite material to large-area pouch cells and conducted experiments that demonstrated stable charge-discharge characteristics, confirming the potential for successful application in actual batteries.

An optical microscope image observing the growth pattern of lithium as it accumulates on the surface of the control group’s conventional lithium anode and the developed composite material anode (top). On the conventional lithium anode, lithium dendrites form extensively and rapidly increase in size (bottom), whereas on the developed composite material, lithium accumulates much more densely and safely.

Dr. Do-Yeop Kim stated, "Research on lithium composites for lithium growth stabilization is still at the basic applied stage, and follow-up studies for commercialization are necessary," adding, "Based on this research achievement, we plan to promote collaboration with the industry in the lithium secondary battery materials field and continue research to develop core technologies for commercialization through the recently selected ‘Global TOP Strategic Research Group’ project." The research team will continue to develop process technologies for high performance and large-area scaling of lithium composite materials linked to the ‘Global TOP Strategic Research Group’ project.

◆ Secondary batteries selected for the 'Global TOP Strategic Group' project... Government-level support continues = The Korea Research Institute of Chemical Technology was selected on the 31st of last month by the Ministry of Science and ICT and the National Science and Technology Research Council (NST) for the 'Global TOP Strategic Group' project, which promotes convergence research among national research institutes. It oversees the ‘Market-leading Next-generation Secondary Battery Innovation Strategic Research Group.’ The goals include developing high-capacity secondary batteries capable of domestic travel on a single charge, lightweight secondary batteries using eco-friendly materials for future air transportation, non-flammable secondary batteries, lithium-free secondary batteries that alleviate resource depletion concerns, and world-class process and equipment technologies. The Korea Electrotechnology Research Institute, Korea Institute of Science and Technology, Korea Institute of Energy Research, Korea Institute of Industrial Technology, Electronics and Telecommunications Research Institute, and Korea Institute of Machinery and Materials will also contribute.

To verify the applicability of the newly developed composite material to large-area cells, pouch cells measuring 3 cm in width and 4.2 cm in length were assembled and subjected to charge-discharge testing. As shown in the graph on the right, the cells exhibited a capacity of 50 mAh, confirming the potential for application in large-area cells.

Although concerns have arisen in the battery sector due to a slowdown in electric vehicle growth, the Chemical Research Institute holds the position that research must be accelerated given predictions that the lithium secondary battery market will reach 517 trillion won by 2030. Securing technological superiority through the development of core lithium secondary battery materials and preempting the next-generation lithium secondary battery market are particularly important points.

Young-Kuk Lee, President of the Korea Research Institute of Chemical Technology, said, “The technology developed through this research is a core material technology for next-generation secondary batteries, and we expect it to secure technological superiority in the secondary battery market and preempt the next-generation secondary battery market.”

The research results were published as the inside cover paper in the January 2024 issue of the prestigious international journal in the materials field, Advanced Functional Materials (IF: 19).

This content was produced with the assistance of AI translation services.