Batteries have recently come in various configurations: stretchable, as discussed in R&D World’s article “Stretchable batteries and body-conformable electronics poised to advance in 2025,” and batteries using alternative chemistries, including lithium-iron-phosphate (LFP) and sodium-ion (SIBs), among others. One battery material that might not have been on your bingo card is fungi.
Researchers at Empa have developed a 3D-printed microbial fuel cell powered by fungi, designed to generate electricity and biodegrade once its task is done. This innovative battery produces enough energy to power small devices, such as temperature sensors for agricultural or environmental research, for several days. Unlike conventional batteries, the fungal battery is entirely non-toxic and biodegradable.
Fungi are still under-researched in the field of materials science. Image: Empa
Fungal fuel cell design
The microbial fuel cell relies on two types of fungi. “For the first time, we have combined two types of fungi to create a functioning fuel cell,” says Carolina Reyes, a researcher at Empa, on empa.com. Yeast fungi are used at the anode, where their metabolism releases electrons. White rot fungi produce an enzyme that captures and conducts electrons at the cathode. This complementary metabolic interaction allows the fungi to generate power.
The grid-printed electrode contains the fungus used in the anode compartment of the battery. Image: Empa
The fungi are not added to the battery later but integrated during manufacturing. Researchers create the electrodes using a 3D-printing technique, mixing fungal cells into a cellulose-based printing ink. “It is challenging enough to find a material in which the fungi grow well,” explains Gustav Nyström, head of the Cellulose and Wood Materials lab. The ink must also be electrically conductive, biodegradable, and capable of being extruded without harming the cells.
Activation and applications
The fungal batteries can be stored in a dried state and activated on-site with water and simple sugars. “You can store the fungal batteries in a dried state and activate them on location by simply adding water and nutrients,” says Reyes. After use, the fungi help decompose the battery, as they can metabolize the cellulose-based components.
Challenges and future directions
Developing the fungal battery required combining microbiology, materials science, and electrical engineering. Reyes adapted electrochemistry techniques for use with living materials. Although the battery is functional, researchers aim to improve its power output and longevity. They are also exploring additional fungal species to optimize energy generation. “Fungi are still under-researched and under-utilized, especially in the field of materials science,” noted Reyes and Nyström.
