Rechargeable Grid Storage Batteries: Over the past few years, scientists have been hard at work trying to develop rechargeable zinc-manganese dioxide batteries into a viable technology for grid storage applications. Now, engineers at the University of Illinois at Chicago (UIC) and their colleagues have identified the reasons why these zinc-based battery systems often fail.
The scientists did this by employing advanced electron microscopy, electrochemical experiments and theoretical calculations to look more closely at how the zinc anode works with the manganese cathode in these battery systems. They report their findings in a paper in Nature Sustainability.
“Zinc and manganese separately have very favorable properties for high-quality sustainable batteries; however, when paired in a full system their intercalation – their rechargeability – has been debatable, with some recent studies suggesting zinc insertion and deinsertion in manganese dioxide is responsible for the rechargeability of the cells,” explained lead author Reza Shahbazian-Yassar, professor of mechanical and industrial engineering in the College of Engineering at UIC. “With this study, we showed there is actually no microscopic evidence of zinc reinsertion into manganese dioxide, and what was previously thought to be indicators of recharging was from positively charged hydrogen ions being inserted in the manganese, not zinc.”
In their experiments, the researchers built aqueous zinc-manganese dioxide cells and tested them over 100 cycles. They discharged and attempted to recharge the batteries in experiments while using electron microscopy to capture atomic-level images of the reactions.
“We saw that the hydrogen is responsible for the damage to the tunnel structures of manganese dioxide, further reducing the potential of the battery for recharging,” said Shahbazian-Yassar. “The information we’ve obtained with these experiments reveals important atomic insights into the mechanisms of the zinc-manganese battery. Now that we know what is happening at the cell level, we have a compass for finding better strategies.”
Shahbazian-Yassar added that different cell structures could make the system more favorable for zinc insertion and that strategies could be developed to harness the hydrogen protons.
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