Non-aqueous lithium-oxygen batteries have been considered as one of the most promising power sources for electric vehicles and portable devices, due to the high theoretical capacity (3.86×10³ mAh g^-1) and energy density (1.14×10⁴ Wh kg^-1) [1]. The electrochemical reactions in the discharge and charge processes involve the formation and decomposition of the solid product Li₂O₂ in the cathode. Carbon has been regarded as one of the most attractive cathode materials, due to its good conductivity, high specific area, proper pore volume, and low cost. However, it has been shown that both the highly oxidizing environment (O₂^-) and Li₂O₂ can lead to the decomposition of carbon materials to form a thin Li₂CO₃ film at the carbon interface [2]. Besides, carbon can promote decomposition of the electrolyte to form side products (e.g. lithium carbonate and carboxylates) [3]. These irreversible side products accumulate on the cathode surface, leading to a high overpotential during charge, resulting in a short cycle life.

A new strategy to solve these issues is to promote the decomposition of side products. In this regard, we here developed a NiO-RuO₂ nanoparticle-decorated carbon powder cathode. As NiO has been reported to have activity in the oxidation of carbonate and carboxylate species [4], we used NiO nanoparticles to decorate the carbon powder with two features: i) protect the surface defects, alleviating the decomposition of the electrolyte; and ii) promote the oxidation of side products, retaining the activate surfaces. To further lower the charge overpotential, we meanwhile decorated RuO₂ nanoparticles on the carbon powder surface. As a result, this NiO-RuO₂ nanoparticle-decorated carbon powder cathode can enable a non-aqueous lithium-oxygen battery with a low charge overpotential and long cycle life.

Further analysis and electrochemical characterizations will be presented at the meeting. The lithium-oxygen battery performance employing this type of cathode will also be presented at the meeting.

References

[1] G. Girishkumar, B. McCloskey, A.C. Luntz, S. Swanson, W. Wilcke, Journal of Physical Chemistry Letters. 1 (2010) 2193-2203.

[2] B.D. McCloskey, A. Speidel, R. Scheffler, D.C. Miller, V. Viswanathan, J.S. Hummelshoj, J.K. Norskov, A.C. Luntz, Journal of Physical Chemistry Letters. 3 (2012) 997-1001.

[3] M.M. Ottakam Thotiyl, S.A. Freunberger, Z. Peng, P.G. Bruce, J. Am. Chem. Soc. 135 (2013) 494-500.

[4] M. Hong, H.C. Choi, H.R. Byon, Chemistry of Materials. 27 (2015) 2234-2241.