(202e) Multifunctional O2-Electrodes for Reversible Li-O2 Batteries

The interest in developing rechargeable lithium batteries with high energy capacity and longevity is steadily increasing with the realization of their potential capabilities, especially in electric vehicles.[1] Recently, Li-O₂ (Li-air) batteries have been excessively explored as one of the most promising energy storage technologies due to their high theoretical specific capacity (3.86 Ah/g) and energy density (~11,140 Wh/kg). Key challenges with this technology include high overpotential losses associated with the electrochemical reactions (i.e. oxygen reduction and evolution reactions) at the cathode of the battery and the instability of the electrolyte layer when exposed to the electrochemical oxidizing conditions of the cathode. In this contribution, we aim to address these challenges by (1) investigating the electrochemical activity of layered nickelate (K₂NiF_4+δ) oxides as promising cathode electrocatalysts for oxygen evolution, and (2) exploring the functionality and stability of carbon cathodes functionalized with 12-crown-4 ether moieties to facilitate Li⁺ transport at the cathode. We show, using controlled electrochemical experiments and electron microscopy studies that nickelate oxides decrease the charging potential of the battery cells due to (i) their impact in the formation of the discharge product, Li₂O₂, during discharge, and (ii) lowering of the activation barrier for the oxygen evolution reaction.[2]  Furthermore we show that the functionalization of the carbon with 12-crown-4 ether moieties exhibits promising Li⁺ conduction at the carbon electrodes, opening up opportunities to shield the aprotic electrolyte from the electrochemical oxidizing conditions at the cathode.

REFERENCES

[1] G. Girishkumar, B. McCloskey, A.C. Luntz, S. Swanson, W. Wilcke, Lithium - Air Battery: Promise and Challenges, J Phys Chem Lett, 1 (2010) 2193-2203.

[2] A. Nacy, X. Ma, E. Nikolla, Nanostructured Nickelate Oxides as Efficient and Stable Cathode Electrocatalysts for Li–O2 Batteries, Topics in Catalysis, 58 (2015) 513-521.