Cathode additives for a sodium rechargeable battery
Physical Sciences : Materials and Compounds
Available for licensing
- John Goodenough, Ph.D. , Mechanical Engineering
- Kyu-Sung Park, Ph.D. , Materials Laboratory
Sodium battery anode materials have an electrolyte decomposition issue (solid-electrolyte interphase (SEI) layer formation) owing to their operating voltage range and the stability limit of a liquid electrolyte. It causes irreversible sodium loss at the anode, which reduces reversible sodium ions and the corresponding reversible capacity in a battery cell.
There should be an extra sodium supply to compensate the sodium loss from the cathode and to utilize the full capacity of a cell. There are no known reports to solve this problem, but are a few in the case of lithium-ion batteries. For example, one method is to deposit metallic lithium directly on to the anode. However, it increases processing cost and deteriorates uniformity and mechanical stability of the anode. Moreover, processing the sodium metal is dangerous, so this method is not realistic.
Researchers at The University of Texas at Austin have proposed a new cathode material to compensate the irreversible capacity loss at the anode side. Once it is blended with cathode materials (e.g., sodium transition metal oxides, Prussian blue), it can introduce additional charging capacity depending on the blending ratio that can compensate for the irreversible capacity loss of the anode. During following discharge reaction, the cathode material can utilize its full capacity.
This is the first approach to add a cathode additive to compensate the sodium loss at the anode side. Since the direct deposition of sodium metal on the anode is practically impossible, this approach will be very important in the commercialization of a Na-ion battery.
The invention proposes a novel cathode additive to the conventional cathode composites. It supplies additional capacities (i.e. extra sodium ions to the anode) to compensate the irreversible capacity loss in the anode.
Battery manufacturers interested in developing alternative batteries other than lithium-ion batteries
Proof of concept
- 1 U.S. patent application filed