High Rechargeable and Efficient Li-O2 Battery Using a Novel Organic Catalyst

As an advanced large-scale energy storage and conversion system, the rechargeable non-aqueous Li-O₂ battery has recently attracted considerable attention because of its high gravimetric density since it was firstly presented in 1996[1]. In an ideal Li-O₂ battery, on discharge, O₂ is reduced at the cathode, where it combines with Li⁺ released from the Li-metal anode to yield Li₂O₂ (oxygen reduction reaction (ORR), 2 Li⁺ + O₂↑ + 2 e^- → Li₂O₂)). On charge, Li₂O₂ is converted back to Li⁺ and O₂ (oxygen evolution reaction (OER), Li₂O₂→2 Li⁺ + O₂↑ + 2 e^-))[2]. One of the critical challenges which limit the implementation of Li-O₂ batteries is the low round-trip efficiency and poor cyclability resulting from a large over-potential. Although the real effect of catalytic activity is controversial and the mechanism of catalyst is not yet clear, it has been widely accepted that the employment of catalyst can minimize the over-potential of Li-O₂ battery. Up to now, a number of materials have been employed as cathode catalysts, such as noble metal (alloy), carbon, transition-metal oxide, showing some improvement.

Herein, a highly reversible and efficient Li-O₂ cell using Dilithium (2,5-dilithium-oxy)-terephthalate (Li₄C₈H₂O₆) as a novel organic catalyst was reported. The mechanism of the increasing efficiency and cyclability was systematically investigated. In addition, operando synchrotron-based XRD (SR-PXD) as a diagnostic tool that allowed us to probe the dynamics for the degradation of Li₂O₂ during charging process was employed to further study the real-time kinetics of OER in a Li-O₂ cell.

REFERENCES

[1]                 J. Liu, M. Roberts, R. Younesi, M. Dahbi, K. Edström, T. Gustafsson, J. Zhu, The Journal of Physical Chemistry Letters 4 (2013) 4045-4050.

[2]                 R. Younesi, S. Urbonaite, K. Edström, M. Hahlin, The Journal of Physical Chemistry C 116 (2012) 20673-20680.