An Oak Ridge National Laboratory (ORNL) team created and tested two different formulations for stationary batteries that could utilize CO2 from industrial sources while storing energy from wind turbines and solar panels. Consisting of two electrodes in a saltwater solution, the battery pulls atmospheric CO2 into its electrochemical reaction and releases only valuable byproducts. The CO2 batteries form carbonate byproducts that dissolve in the battery’s electrolyte solution. Battery design can be tuned to remove the byproducts for use in other industrial processes, the ORNL researchers say.
In one formulation, a sodium-CO2 battery combines gas with sodium from saltwater using an inexpensive iron-nickel catalyst. The electrodes are separated into wet and dry chambers, with a solid ion conductor between them. To make the battery work, the researchers overcame the formation of a film on the electrode surface that deactivates the battery. The team, led by ORNL scientist Rahul Amin, found that uneven pulses of charging and discharging prevented the buildup.
In a second formulation, the scientists created an aluminum-CO2 battery that was capable of operating for more than 600 h without losing capacity, far longer than the only other aluminum-CO2 battery that has been reported. Also, the new aluminum-CO2 battery captures almost twice as much CO2 as the sodium-CO2 battery and the system can be designed to operate with both electrodes in the same liquid solution, so there is no barrier to ion movement. ORNL scientists are improving the batteries for scaleup.