10x Capacity
A joint research team of Pohang University of Science and Technology and Sogang University has developed a silicon anode active material that is more stable than existing ones. According to the team, the developed material has at least 10 times the capacity of graphite if it is used in rechargeable batteries.
An anode material receives lithium ions from the cathode of a rechargeable battery that is in the process of charging. It is made up of an anode active material, a conductive material and a binder. In general, natural graphite and synthetic graphite are used in anode active materials. Graphite, however, is low in energy density.
A high-capacity anode active material such as silicon can provide at least a 10x increase in capacity. As such, it is essential in manufacturing high-energy-density lithium secondary batteries.
A silicon-based high-capacity anode active material, however, increases in volume when reacting with lithium, which may lead to a decline in battery performance or stability. An anti-volume expansion polymer binder is required in this regard.
Existing related studies have focused on chemical cross-linking and hydrogen bonding. The former is strong but not restorable once cut. The latter tends to lack strength.
The team developed a charge-based polymer capable of volume expansion control and ensuring a stronger bond than in hydrogen bonding. In addition, it used polyethylene glycol for physical property control and intra-electrode lithium ion movement facilitation to make a thick and high-capacity electrode and maximize lithium secondary battery energy density. Details of the research are available in the Advanced Functional Materials journal.