The Storage Capacity of Water-Based Batteries

Texas A&M University researchers found a 1,000% difference in the storage capacity of metal-free, water-based battery electrodes versus lithium-ion batteries that contain cobalt. The team says that metal-free batteries are better for the domestic supply chain since cobalt and lithium are outsourced. They can also prevent battery fires. They published their findings in Nature Materials.

An alternative battery avoids the increased price of lithium-ion batteries whenever there are materials shortages. Water-based batteries have a much more stable supply and can be manufactured in the US.

Aqueous batteries have a cathode, electrolyte, and an anode. The cathodes and anodes are where polymers store energy, and the electrolyte is water mixed with organic salts. The electrolyte is key to ion conduction and energy storage through its interactions with the electrode. When an electrode swells too much during cycling, it can’t conduct electrons well, and you lose performance. They claim there is a 1,000% difference in energy storage capacity, depending on the electrolyte choice due to swelling effects.

The team says that redox-active, non-conjugated radical polymers (electrodes) are promising candidates for metal-free aqueous batteries given the polymers’ high discharge voltage and fast redox kinetics. The reaction is complex and challenging to resolve because of the simultaneous transfer of electrons, ions, and water molecules.

Researchers macroscopically observed if the battery cathode was working better in certain kinds of salts by measuring how much water and salt was going into the battery as it operated.