A new fungal battery can be tossed in the compost to biodegrade

Image: a fungal battery from impact lab.com

Source: Carolina Reyes et al. 3D Printed Cellulose-Based Fungal Battery. ACS Sustainable Chemistry & Engineering, 2024.

Using fungi, cellulose, and carbon, researchers 3D printed small batteries, that can be stored dry and later activated with water and simple sugars.

January 16, 2025

Researchers have employed an unlikely organism—fungi—to make a new type of biodegradable battery. The new 3D-printed fungal battery produces enough electricity for small sensors and it can tossed into compost to degrade once its work is done. The work appears in the journal ACS Sustainable Chemistry & Engineering.

“For the first time, we use the metabolism of two different types of fungi in a microbial fuel cell to power a low temperature sensor for several days,” says Carolina Reyes, a cellulose and wood materials researcher at EMPA, the Swiss Federal Laboratory for Materials Science and Technology. “Our fungal biobattery is made from sustainable materials, including cellulose, wax and carbon, and is compostable.”

The modern world relies on batteries. But today’s batteries are made of chemicals, plastics and other materials that are not easily recyclable or degradable. As a result they add to the millions of tons of electronic waste the world produces every year.

 

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Microbial fuel cells offer a green alternative for electronics. They are battery-like devices that harness microorganisms to produce energy by digesting organic matter. The devices typically use bacteria; not too many fungal MFCs have been made before.

The EMPA team, though, are deeply familiar with fungi. They have previously harnessed the metabolism of white-rot fungi to modify the properties of wood. The researchers wanted to combine their fungal knowledge with their expertise on developing green electronic such as paper-based batteries and sensors.

They used two different fungi, yeast and white-rot fungus, for the positive and negative electrodes of the battery. Yeast cells go at the anode, where their metabolism releases electrons, while white-rot fungi produce an enzyme that captures electrons at the cathode.

To make the battery, they mixed the fungal cells separately into cellulose-based inks, and added carbon particles to the inks to increase conductivity. Then they use the inks to 3D print a battery. The devices can be stored in a dried state. Putting them to use would simply require activating and growing the fungal cells inside the inks using water and simple sugars.

These biodegradable batteries could at first find use in off-the-grid locations for powering small sensors that record temperature and humidity, Reyes says. “We envision their use in agricultural fields and in forests,” she says. “In the future, we could potentially integrate fungal fuel cells in low-power microcomputers and low-power devices destined for space exploration.”

 

 

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