The Korea Institute of Energy Research (KIER) has recently introduced a groundbreaking redox-active metal-organic hybrid electrode material known as SKIER-5. This innovative material is specifically designed to address the limitations of traditional graphite anodes in lithium batteries, especially in freezing temperatures as low as minus 20 degrees Celsius.
Graphite has been the conventional material of choice for anodes in lithium-ion batteries due to its stability and cost-effectiveness. However, graphite anodes face significant challenges in cold conditions. At subzero temperatures, the storage capacity of batteries with graphite anodes decreases dramatically, and dendrites can form on the anode surface during the charging process. These issues can potentially lead to thermal runaway and even explosions.
A team of researchers led by Dr. Jungjoon Yoo, Dr. Kanghoon Yim, and Dr. Hyunuk Kim at KIER have developed SKIER-5, a redox-active conductive metal-organic framework. This framework is constructed from a trianthrene-based organic ligand and nickel ions, making it a highly efficient alternative to graphite anodes.
One of the key advantages of SKIER-5 is its exceptional discharge capacity, which is five times higher than that of graphite in subzero environments. In fact, SKIER-5 achieved a discharge capacity of 440 mAh/g, surpassing the 375 mAh/g capacity of graphite at room temperature. Moreover, even after 1,600 charge-discharge cycles, the capacity of SKIER-5 increased by approximately 1.5 times, a result that defies the typical decrease in discharge capacity with repeated cycles.
Unlike graphite, SKIER-5 interacts with lithium ions to enable redox reactions through electron transfer. This unique process, facilitated by the presence of nickel ions and heteroatoms in the organic ligands, allows for increased electron storage and, consequently, higher discharge capacity. The discharge capacity of SKIER-5 at minus 20 degrees Celsius was an impressive 150 mAh/g, five times greater than that of graphite in similar conditions.
The operating principle of SKIER-5 was confirmed through high flux X-ray analysis at the Pohang Accelerator Laboratory. Additionally, first-principles calculations based on quantum chemistry were used to determine the crystalline structure of SKIER-5 and predict lithium adsorption sites. These calculations closely aligned with experimental results, providing a solid foundation for SKIER-5’s outstanding performance as a lithium battery anode.
SKIER-5 has emerged as a game-changer for lithium batteries, especially in cold conditions where traditional graphite anodes fall short. With its superior discharge capacity and stability, SKIER-5 offers immense potential for a wide range of applications, including electric vehicles, drones, and ultra-small electronic devices. The innovative redox-active metal-organic hybrid electrode material has paved the way for the next generation of lithium-ion batteries, setting a new benchmark for efficiency and performance in challenging environments.
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