A three-dimensional polymeric structure was developed by 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 the Korea Institute of Energy Research (KIER) and a team of researchers at POSCO N.EX.T Hub. This lightweight construction aids in the transportation of lithium (Li) ions. Their findings were published in the online edition of the international journal Advanced Science.
Schematic representation of the internal geometry of the hybrid structure after lithium electrodeposition. Image Credit: Pohang University of Science and Technology
Road signs give directions and distances to help passengers avoid becoming lost, and “signposts” instruct individuals in certain situations. Structures that fulfill a similar role have just been identified in chemistry, generating a lot of academic attention.
Battery technology for electronic devices like electric vehicles and smartphones is constantly evolving. Notably, lithium metal anodes have an energy capacity of 3860 mAh/g, more than 10 times higher than currently available graphite anodes.
Lithium metal anodes, unlike graphite or silicon, can store more energy in a smaller space and operate as electrodes in electrochemical processes.
However, throughout the charging and discharging process, the uneven distribution of lithium ions results in regions known as “dead Li,” which impair the battery's capacity and performance. Furthermore, when lithium increases in one direction, it might reach the cathode on the other side, resulting in an internal short circuit.
Although recent research has focused on enhancing lithium transport in three-dimensional structures, most of these structures contain heavy metals, drastically reducing the battery’s energy density per weight.
To solve this issue, the researchers created a hybrid porous structure that combines polyvinyl alcohol, a lightweight polymer with a strong affinity for lithium ions, with single-walled carbon nanotubes and nanocarbon spheres.
This structure has a strong affinity for lithium ions, facilitating their movement across the voids in the three-dimensional porous structure and enabling uniform lithium electrodeposition. It is also more than five times lighter than the copper (Cu) collectors commonly employed in battery anodes.
Experiments revealed that lithium metal anode batteries with the team’s three-dimensional structure had a high energy density of 344 Wh/kg (energy to total cell weight) and showed excellent stability after more than 200 charge-discharge cycles.
The method has considerable potential for commercialization, highlighted by the fact that pouch cells, which are reflective of real industrial applications, were used in these experiments instead of lab-scale coin cells.
This research opens up new possibilities for maximizing the energy density of lithium metal batteries.
Soojin Park, Professor, Pohang University of Science and Technology
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 Ministry of Science and ICT provided funding for the study.
Journal Reference:
Han, D.-Y., et. al. (2024) Facile Lithium Densification Kinetics by Hyperporous/Hybrid Conductor for High-Energy-Density Lithium Metal Batteries. Advanced Science. doi:10.1002/advs.202402156.