Electrochemical Performance of Lithium-Air Cells with Conductive Polymer-Coated Lithium Anode

Since the non-aqueous Li-air battery was reported in 1996, it has attracted much attention in recent years due to its high theoretical specific energy of 11,000 Wh kg^-1.  The successful development of rechargeable Li-air batteries is critically dependent on the long-term stability of all battery components.  However, the development of rechargeable lithium-air batteries has been hindered by the high reactivity of lithium metal to liquid electrolytes and the occurrence of dendrite growth during charge and discharge cycles.  Therefore, protection of lithium metal and the formation of a stable solid electrolyte interphase (SEI) layer on the lithium electrode are very important for developing lithium-air batteries with good capacity retention.  NASICON-type lithium conductors and their composites with ionic conducting polymers were applied to protect lithium metal electrode [1,2]. Recently, our group reported that a surface coating of lithium metal with poly(3,4-ethylenedioxythiophene)-co-poly(ethylene glycol) (PEDOT-co-PEG) was very effective for improving the cycling stability of Li/LiCoO₂ cell [3].

In this study, we applied a protective layer comprising bi-conductive polymer, PEDOT-PEG, without adding any inorganic materials for protecting a lithium anode.  The conductive polymer coating on the lithium electrode notably improved the cycling performance of the lithium-air batteries. The improvement in cycling stability was attributed to the conductive polymer coating suppressing lithium dendrite growth and the deleterious reaction between the lithium electrode and the electrolyte solution during cycling. The cycling performance of lithium-air cells with conductive polymer-coated lithium metal was evaluated and compared to that of cell with pristine lithium electrode.

References

1. S.Hasegawa, N.Imanishi, T.Zhang, J.Xie, A.Hirano, Y.Takeda, O.Yamamoto, J. Power Sources, 189, 371 (2009)

2. T.Zhang, N.Imanishi, S.Hasegawa, A.Hirano, J. Electrochem. Soc., 155, A965 (2008)

3. I.S.Kang, Y.S.Lee, D.W.Kim, J. Electrochem. Soc., 161, A53 (2014).