Germany: Battery Research Improved Oxygen Chemistry Could Drastically Increase Battery Capacity

KIT researchers have shown how silicates make more durable lithium-ion batteries possible.

Karlsruhe/Germany — Mobile devices with longer battery life or electric vehicles with greater range — lithium-ion batteries with a higher energy density could make many things possible. The largest capacities are theoretically achieved with oxygen-based chemistry, but in practice the possibilities are limited by decomposition processes such as bloated cells or sudden voltage drops. Scientists at the Karlsruhe Institute of Technology (KIT) have now demonstrated how the use of special silicates can mitigate such aggressive oxidation processes. This could significantly increase the energy density of lithium-ion batteries. They report on their results in the journal Angewandte Chemie.

In silicates, oxygen is bound to silicon together with active metals such as nickel, cobalt or even manganese in relatively stable compounds. “If you use the right silicates at the battery cathode, this favours a specific form of oxidation during the operation of a battery. Instead of destroying the crystal structure, the oxygen will bind with oxygen and form so-called peroxo-dimers,” says Professor Helmut Ehrenberg, head of KIT's Institute for Energy Storage Systems (IAM-ESS). His research team, together with partners, succeeded in detecting this oxygen variant via characteristic changes in the electronic excitations (X-ray absorption spectroscopy) and atomic vibrations (Raman spectroscopy) in the active materials. "In addition to greater material stability, this form of oxidation also favours charge equalisation at constant voltage," Ehrenberg says.

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