Just as road signs provide directions and distances to help travelers avoid getting lost, "signposts" guide people in specific situations. In the field of chemistry, structures that serve a similar purpose have recently been discovered and are drawing significant academic interest.
Professor Soojin Park and Dong-Yeob Han, a PhD candidate, from the Department of Chemistry at Pohang University of Science and Technology (POSTECH) in collaboration with Dr. Gyujin Song of Korea Institute of Energy Research (KIER) and a team of researchers at POSCO N.EX.T HUB have developed a three-dimensional polymeric structure. This lightweight structure facilitates the transport of lithium (Li) ions. Their research was recently published in the online edition of the international journal "Advanced Science".
Battery technology used in electronic devices such as electric vehicles and smartphones continues to evolve. Notably, lithium metal anodes have an energy capacity of 3,860 mAh/g, more than ten times that of currently commercialized graphite anodes. Lithium metal anodes can store more energy in a smaller space and, unlike graphite or silicon, can directly participate in electrochemical reactions as electrodes.
However, during the charging and discharging process, the uneven distribution of lithium ions creates areas known as "dead Li," which reduce the battery's capacity and performance. Additionally, when lithium grows in one direction, it can reach the cathode on the opposite side, causing an internal short circuit. Although recent research has focused on optimizing lithium transport in three-dimensional structures, most of these structures rely on heavy metals, significantly compromising the battery's energy density per weight.
To address this issue, the team developed a hybrid porous structure using polyvinyl alcohol, a lightweight polymer with high affinity for lithium ions, combined with single-walled carbon nanotubes and nanocarbon spheres.
This structure is more than five times lighter than the copper (Cu) collectors typically used in battery anodes and has a high affinity for lithium ions, facilitating their migration through the spaces in the three-dimensional porous structure and enabling uniform lithium electrodeposition.
In experiments, lithium metal anode batteries incorporating the team's three-dimensional structure demonstrated high stability after over 200 charge-discharge cycles and achieved a high energy density of 344 Wh/kg (energy to total cell weight). Notably, these experiments were conducted using pouch cells, which are representative of actual industrial applications, rather than lab-scale coin cells, highlighting the technology's strong potential for commercialization.
Professor Soojin Park of POSTECH expressed the significance of the research by stating, "This research opens up new possibilities for maximizing the energy density of lithium metal batteries." Dr. Gyujin Song of the KIER emphasized, "This structure, which combines lightweight properties with high energy density, represents a breakthrough in future battery technology."
The research was conducted with support from a project of the Ministry of Science and ICT.
