05 April 2023

By Peter Brown

Water-based battery increases storage capacity 1,000%

The goal is to create a battery that will be free of lithium and cobalt that are not only increasing in price but prone to fires. Source: Texas A&M

Looking to find an alternative to lithium-ion batteries that contain cobalt, researchers at Texas A&M University have discovered a 1,000% difference in the storage capacity of metal-free, water-based battery electrodes.

The goal is to find metal-free batteries due to cobalt and lithium being outsourced and these raw materials increasing in price substantially as electric vehicles become the model of choice among automotive OEMs. Additionally, these lithium-ion batteries are also more prone to fires.

“There would be no battery fires anymore because it's water-based,” said Jodie Lutkenhaus, chemical engineering professor at Texas A&M. “In the future, if materials shortages are projected, the price of lithium-ion batteries will go way up. If we have this alternative battery, we can turn to this chemistry, where the supply is much more stable because we can manufacture them here in the United States and materials to make them are here.”

This comes as AlixPartners reported that the average raw materials costs for EVs increased four fold during the last two years with materials such as cobalt, nickel and lithium have increased in demand.

The insight echoes statements made by Stellantis CEO Carlos Tavares in May that raw material shortages are coming in the years ahead and could jeopardize the transition of the automotive industry as it leaves gasoline- and diesel-powered engines behind in favor of electrified models.

Inside the water battery

The aqueous batteries consist of a cathode, electrolyte and an anode. The cathodes and anodes are polymers that can store energy and the electrolyte is water mixed with organic salts, which is key to ion conduction and energy storage through its interactions with the electrode.

“If an electrode swells too much during cycling, then it can't conduct electrons very well, and you lose all the performance,” Lutkenhaus said. “I believe there is a 1,000% difference in energy storage capacity, depending on the electrolyte choice because of swelling effects.”

These redox-active, non-conjugated radical polymers are promising candidates for metal-free batteries due to the polymers’ high discharge voltage and fast redox kinetics. The research team used simulations to give insights into the microscopic molecular-scale picture of the structure and dynamics.

“Theory and experiment often work closely together to understand these materials,” said Daniel Tabor, chemistry assistant professor at Texas A&M. “One of the new things that we do computationally in this paper is that we actually charge up the electrode to multiple states of charge and see how the surroundings respond to this charging.”

The next steps involve expanding the simulations to future systems and to get a better molecular level picture of what makes some battery electrodes work better than others.

The full research can be found in the journal Nature Materials.