A red bread mold could be the key to producing more sustainable electrochemical materials for use in rechargeable batteries. The researchers show for the first time that the fungus Neurospora crassa can transform manganese into a mineral composite with favorable electrochemical properties.
“We have made electrochemically active materials using a fungal manganese biomineralization process,” says Geoffrey Gadd of the University of Dundee in Scotland. “The electrochemical properties of the carbonized fungal biomass-mineral composite were tested in a supercapacitor and a lithium-ion battery, and it [the composite] was found to have excellent electrochemical properties. This system therefore suggests a novel biotechnological method for the preparation of sustainable electrochemical materials.”
In earlier studies, the researchers showed that fungi could stabilize toxic lead and uranium. That led the researchers to wonder whether fungi could offer a useful alternative strategy for the preparation of novel electrochemical materials too. “We had the idea that the decomposition of such biomineralized carbonates into oxides might provide a novel source of metal oxides that have significant electrochemical properties,” Gadd says.
In the new study, Gadd et al incubated N. crassa in media amended with urea and manganese chloride (MnCl2) and watched what happened. The researchers found that the long branching fungal filaments (or hyphae) became biomineralized and/or enveloped by minerals in various formations. After heat treatment, they were left with a mixture of carbonized biomass and manganese oxides. Further study of those structures show that they have ideal electrochemical properties for use in supercapacitors or lithium-ion batteries.
“We were surprised that the prepared biomass-Mn oxide composite performed so well,” Gadd says. In comparison to other reported manganese oxides in lithium-ion batteries, the carbonized fungal biomass-mineral composite “showed an excellent cycling stability and more than 90% capacity was retained after 200 cycles,” he says. Gadd says they’ll continue to explore the use of fungi in producing various useful metal carbonates. They’re also interested in investigating such processes for the biorecovery of valuable or scarce metal elements in other chemical forms.
http://www.eurekalert.org/pub_releases/2016-03/cp-cbm031016.php
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