A battery electrode interacts with lithium and oxygen to form lithium peroxide. (Credit: MIT)Lithium-air batteries have received considerable attention over the recent years. Nevertheless, the technology requires significant research in a variety of fields before a viable commercial implementation is required. Most of the current limitations in Li-air battery development are at the cathode, which is also the source of its potential advantages. Now, researchers at MIT have found that genetically modified viruses can help to produce better cathodes for Li-air batteries.
The new study is described in a paper published in the journal Nature Communications, co-authored by graduate student Dahyun Oh, professors Angela Belcher and Yang Shao-Horn, and three others.
According to the article, recent studies have focused on finding stable electrolytes to address poor cycling capability and improve practical limitations of current lithium-oxygen batteries. The authors of the article investigated the catalyst electrode, where discharge products are deposited and decomposed, as according to them, it has a vital role in the operation of rechargeable lithium-oxygen batteries. Based on their findings, the authors propose a new electrode design principle that improves specific capacity and cycling performance of lithium-oxygen batteries by utilizing high-efficiency nanocatalysts assembled by M13 virus with earth-abundant elements such as manganese oxides.
An MITnews article by David L. Chandler explains that the researchers produced an array of nanowires, each about 80 nanometers across, using a genetically modified virus called M13, which can capture molecules of metals from water and bind them into structural shapes. In this case, wires of manganese oxide were actually made by the viruses. But unlike wires “grown” through conventional chemical methods, these virus-built nanowires have a rough, spiky surface, which dramatically increases their surface area, which can provide advantage in Li-air batteries’ rate of charging and discharging. The process can be carried out at room temperature.
Also, also the aforementioned article states that rather than isolated wires, the viruses naturally produce a three-dimensional structure of cross-linked wires, which provides greater stability for an electrode.
The new method, however, cannot completely eliminate the use of expensive electrode materials such as palladium, as the final part of the process is the addition of a small amount of this or other similar metal to increase the electrical conductivity of the nanowires and allow them to catalyze reactions that take place during charging and discharging.
Dahyun Oh, Jifa Qi, Yi-Chun Lu, Yong Zhang, Yang Shao-Horn, Angela M. Belcher (2013). Biologically enhanced cathode design for improved capacity and cycle life for lithium-oxygen batteries Nature Communications, 4 DOI: 10.1038/ncomms3756
