Central regions | Technology & innovation | Energy, utilities
Russian scientists work to address deficiencies of Li-air batteries
8 Feb '17
Chemists and material science researchers at the Moscow Lomonosov State University (MSU) have looked into emerging problems behind the operation of new ultra-capacity Li-air storage batteries, specifically into reasons for their damage because of oxygen reduction, and now appear to see ways of slowing down the process.
Compared to conventional Li-ion solutions, Li-air batteries are believed to offer ten times the energy density (about 12kW*h/kg). In the new type of batteries, oxygen is reduced through electrochemical reactions in a contact area between electrolyte and carbon-based positive electrodes. Electrons couple with oxygen molecules and then react with lithium to produce solid-state Li peroxide.
That’s where problems arise. Superoxide anions are formed in the process, and the formations oxidize both the electrolyte and the positive electrode. That results in the system failing to conduct electricity after just a few recharging cycles, and has prompted some of the world’s key developers in the field to discontinue research and shelve plans for Li-air commercialization.
The Russian researchers appear to have just shown that the oxygen reduction process is not homogeneous, or the same for any possible situation. For example, in graphite electrodes superoxide anions seem to limit their electrolyte oxidation activity to areas with certain imperfections, or defective areas, since there are no ideal materials. That causes any Li-air battery to fail sooner or later.
However, if the reaction zone is moved away from the electrode to a certain distance, the deterioration process can be slowed down quite noticeably, the MSU scientists claim.
The Moscow team keeps working on the problem and has to admit that any tangible results won’t be achieved until 2025 or so. The current research process has been recently described in English in The Journal of Physical Chemistry C.