In contrast to Li-ion batteries, which employ the intercalation mechanism to move Li-ions into and out of the graphite anode to produce energy, Li-metal batteries use metallic Li as the anode instead of the bulky and heavy graphite. As the Li-metal shows a ten times higher theoretical capacity (3,860 mAh/g) than graphite (372 mAh/g), it has steadily gained much attention from areas that need high-capacity batteries.
Despite this benefit, Li can grow into a branch-like structure known as a Li dendrite if it is not uniformly and effectively stored during the cycling process. This causes a significant volume expansion of the electrode, which reduces the battery’s cycle life and increases the risk of safety issues like fire and explosion caused by internal short circuits.
To tackle this issue, scientists at the Next-Generation Battery Research Center of Korea Electrotechnology Research Institute (KERI) have developed 1D Li-confinable porous carbon structure. Their structure consists of a hollow core, and a small number of gold nanoparticles with Li affinity were added to the hollow core.
By preferentially interacting with Li, the gold controls the growth direction of Li and causes Li to accumulate inside the core. Numerous nano-sized pores are also generated in the shell to increase the Li-ion movement toward the core space.
By generating numerous nano-sized pores in the shell, scientists achieved significantly improved coulombic efficiency without Li dendrite growth even under a high-current testing condition of 5 mA/cm2.
Scientists collaborated with Prof. Janghyuk Moon at Chung-Ang University for theoretical validation of the effectiveness of this material’s design. The simulation result showed that the shell pores reduced Li ion diffusion length and improved Li affinity by the gold nanoparticles keeping Li deposition inside the structure even under high-current charging conditions.
The designed Li host was also found to have excellent cycling performance of over 500 cycles under a high current density of 4C.
Scientists noted, “This technology meets practicality because the team used the electrospinning technique with advantages in mass production for material synthesis.”
Dr. Byung Gon Kim at Next-Generation Battery Research Center of KERI said, “Despite the merit of high capacity, the Li-metal batteries have many hurdles to be overcome for commercialization mainly due to stability and safety issues. Our study is invaluable because we developed a technique for mass production of Li-metal reservoir with high coulombic efficiency for fast-rechargeable Li-metal batteries.”