Mouldy bread leads to better rechargeable batteries

Bread mould doesn’t seem to be good for much at all except for ruining that hand-made artisan sourdough loaf you paid too much for at the markets over the weekend. But researchers say they’ve found a use for it: producing more sustainable electrochemical materials for use in rechargeable batteries.

Reporting in the Cell Press journal Current Biology, the researchers show that the red bread mould Neurospora crassa can transform manganese into a mineral composite with favourable electrochemical properties.

“We have made electrochemically active materials using a fungal manganese biomineralisation process,” said Geoffrey Gadd of the University of Dundee in Scotland.

“The electrochemical properties of the carbonised 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.”

Having found that fungi can stabilise toxic lead and uranium, the researchers wondered whether it could offer a useful alternative for the preparation of novel electrochemical materials.

“We had the idea that the decomposition of such biomineralised carbonates into oxides might provide a novel source of metal oxides that have significant electrochemical properties,” Gadd said.

In the study, Gadd and his colleagues 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 biomineralised and/or enveloped by minerals in various formations. After heat treatment, they were left with a mixture of carbonised biomass and manganese oxides. Further study of those structures shows 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 said. In comparison to other reported manganese oxides in lithium-ion batteries, the carbonised fungal biomass-mineral composite “showed an excellent cycling stability and more than 90% capacity was retained after 200 cycles”, he said.

The study is the first to demonstrate the synthesis of active electrode materials using a fungal biomineralisation process, suggesting these fungal processes could be a source of useful biomaterials.

Originally published here.