Liquid-Free Lithium-Oxygen Battery

Non-aqueous Li-O₂ batteries are considered as most advanced power sources, albeit they are facing numerous challenges concerning almost each cell component. Herein, we diverge from the conventional and traditional liquid-based non-aqueous Li-O₂ batteries to a solid polymer electrolyte (SPE) Li-O₂ system, operated at a temperature higher than the melting point of the polymer electrolyte, where useful and most applicable conductivity values are easily achieved. The proposed SPE-based Li-O₂ cell is compared to glyme-based Li-O₂ cells through potentiodynamic and galvanostatic studies, showing higher cell discharge voltage by 80mV and most significantly, a charge voltage lower by ∼400mV. The solid state battery demonstrated a comparable discharge specific capacity to glyme-based Li-O₂ cells when discharged at the same current density. The discharge products were identified as lithium peroxide by XRD analysis and FT-IR combined with quantitative ¹H and qualitative ¹³C NMR spectroscopies identified lower molecular PEO as the main degradation products, as well as in-chain ester and formates in negligible amounts. The results shown here demonstrate that safer PEO-based Li-O₂ battery is highly advantageous and can potentially replace liquid-based cells contingent upon further investigation. While safety is a prime concern in Li-metal based battery, it is of greater challenge once a viable Li-O₂ battery development is being considered. A polymer-based system, which is liquid electrolyte-free, seems to be another and important step towards resolving this issue.

* Balaish, M., Peled, E., Golodnitsky, D. and Ein-Eli, Y. (2014), Liquid-Free Lithium–Oxygen Batteries. Angew. Chem. Int. Ed.. doi: 10.1002/anie.201408008