An international team of researchers has made a manganese-based lithium-ion battery, which performs as well as conventional, costlier cobalt-nickel batteries in the lab.
They’ve published their discovery in ACS Central Science.
Lithium is not the only precious metal involved in making batteries. Lithium-ion battery cathodes typically use cobalt and nickel, which both present their own sourcing and challenges.
Manganese, as the fifth most abundant metal in the Earth’s crust, has been explored by many researchers as a cheaper and more sustainable electrode material. But in practice, it’s harder to make into a powerful battery.
This Japanese and Australian team of researchers studied lithium manganese oxide (LiMnO2), to see if they could make it perform better.
They looked at different crystal structures of LiMnO2 – the way atoms are arranged inside a solid crystal.
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The team determined one type of crystal structure, called “monoclinic”, could react in a way that allows a battery to hold a greater charge, and do so more quickly.
Then, they figured out a way to grow monoclinic LiMnO2 crystals with a “simple” process: calcination, or heating to high temperatures.
The process needed just 2 solid ingredients. This reduces the environmental impact of making the battery electrodes, which often require longer lists of materials and multiple steps in their manufacturing.
The lithium-manganese substance had an energy density of 820 watt-hours per kilogram, while conventional nickel-based materials boast about 750 watt-hours per kilogram.
Unlike other manganese-based materials, the researchers didn’t observe any decrease in voltage (voltage decay) in their material over time.
The researchers point out there are still issues that need to be countered before manganese can replace cobalt in EVs – for instance, it has a tendency to dissolve over time.
But other parts of the battery can be modified to stop this, like using a very concentrated electrolyte and a coating of lithium phosphate.
The researchers hope their discovery can lead to the commercialisation of manganese-based electrodes, suggesting an “ideal” future for the substance would be as a component of luxury electric vehicles.