Scientists at MIT have developed a new bio-battery leveraging viruses that has two to three times better energy density than currently developed lithium-air batteries, the latter of which is being eyed as a top contender to power the future electric car.
Researchers, including MIT Professor of Energy Angela Belcher, created the virus-based battery by adding genetically modified viruses to the production of nanowires used as one of the battery’s electrodes. The addition of these viruses -- common bacteriophage that infect bacteria but are harmless to humans -- increases the surface area where the electrochemical activity takes place during charging or discharging of the battery, increasing the number of cycles possible and thus extending the potential life of the battery, according to Belcher. “We are aiming to develop a high-power, longer cycle battery in a cost-efficient way,” she told Design News in an email.
The battery also will have less impact on the environment because the chemical structure is derived from natural materials and processes, she said.
The idea to use biology to grow materials comes from natural biomaterials like shell and bone. In that case proteins from the organism grow and assemble the natural organic materials. In the case of the natural systems, like shell, they are made at ocean temperature and pressure and do not use toxic materials. Organisms in nature do not assemble battery electrodes. We wanted to make technologically important materials in a low temperature way using environmentally friendly materials.
To develop the battery, Belcher and fellow researchers produced a nanowire array, with each wires about 80 nanometers across, using a genetically modified virus called M13. The viruses created manganese oxide, which is often a material used for lithium-air battery cathodes. However, unlike the wires that have been developed through typical chemical methods for lithium-air batteries, the wires built by the virus have a rough, spiky surface, which increases their surface area, according to researchers.
This increase in surface area can provide an advantage not only for the rate of charging and discharging, but also in creating a more eco-friendly fabrication process for the battery design, Belcher said. This is because the process of developing the virus-based battery can be done at room temperature using a water-based process rather than needing a high-temperature process and hazardous chemicals, like conventional battery-fabrication methods.
The new battery also could potentially be more stable because the viruses naturally produce a three-dimensional structure of cross-linked nanowires rather than use isolated wires.
The researchers also as the final part of the process added a small amount of a metal, such as palladium, which increases the electrical conductivity of the nanowires, enabling catalytic reactions for charging and discharging. Typically, a larger amount of pure or highly concentrated metals is needed for this process, which makes it more expensive to fabricate a battery.
When all is said and done, while in the early stages of development, the battery still holds promise for mass production, Belcher told us. “We are currently developing the process to test these materials in larger batteries,” she said. “They are currently very small structures -- 1 to 2 centimeters. The process should not be more expensive compared to traditional approaches.”
However promising it appears, the research has a way to go before commercial viability. Researchers so far have only successfully tested and produced the battery’s cathode and not the electrolyte or other essential parts, which need further development, according to Belcher. Moreover, the cathode was only tested through 50 charging and discharging cycles, while a commercially viable battery for an electric car or other electronic devices must be capable of withstanding thousands of cycles.
The US Army Research Office and the National Science Foundation supported the work.