United States Of America – Texas A&M University researchers have recently discovered a 1,000% difference in the storage capacity of metal-free, water-based battery electrodes. Such new batteries vary from the standard lithium-ion batteries which contain cobalt.
The group of researchers engaged in the study to better obtain control over the domestic supply chain since cobalt and lithium are outsourced. In doing so, the risk of battery fires has been lowered.
Dr. Jodie Lutkenhaus, chemical engineering professor, and chemistry assistant professor Dr. Daniel Tabor have published their discoveries regarding lithium-free batteries in Nature Materials.
“There would be no battery fires anymore because it’s water-based” says Lutenhaus. “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.”
Water-based batteries contain a cathode, electrolyte, and an anode. The cathodes and anodes are polymers which store energy. The electrolyte is water mixed with organic salts. The electrolyte’s interactions with the electrode are crucial to ion conduction and energy storage.
“ If an electrode swells too much during cycling, then it can’t conduct electrons very well, and you lose all the performance” continues Lutkenhaus. “I believe that there is a 1,000% difference in energy storage capacity, depending on the electrolyte choice because of the swelling effects.”
Redox-active, non-conjugated radical polymers, or electrodes, are promising candidates for metal-free aqueous batteries since the polymers’ have a high discharge voltage and fast redox kinetics. Due to the simultaneous transfer of electrons, ions and water molecules, the reaction is complex and difficult to resolve.
According to the research group, the nature of the redox reaction was demonstrated through the examination of aqueous electrolytes of varying chaao-/kosmotropic character. An electrochemical quartz crystal microbalance with dissipation monitoring was used at a range of timescales.
Tabor’s research group utilized computational simulation and analysis, giving insight to the microscopic molecular-scale picture of the structure and dynamics. “Theory and experiment often work closely together to understand these materials, 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” says Tabor.
Researchers studied if the battery cathode worked better in the presence of certain salts by measuring how much water and salt goes into the battery as it operates. “We did that to explain what has been observed experimentally” Tabor continues. “Now, we would like to expand our simulations to future systems. We needed to have our theory confirmed of what are the forces that are driving that kind of injection of water and solvent.”
“With this new energy storage technology, this is a push forward to lithium-free batteries. We have a better molecular level picture of what makes some battery electrodes work better than others, and this gives us strong evidence of where to go forward in materials design,” said Tabor.