(670c) An Air Breathing Lithium-Oxygen Battery

The Li-air batteries possess the highest theoretical energy density compared to any other battery chemistries^1,2. However, these batteries suffer from a poor cycle life in the presence of real air components such as nitrogen, oxygen, carbon dioxide and moisture because of anode degradation, electrolyte instability, and slow kinetics of oxygen reduction and evolution in the air cathode^3–5.

Here, we report a new Li-Air battery system working with the actual air components (N₂, O₂, CO₂ and H₂O) with very high cycle life and energy efficiency that can work up to 550 continues cycles with the capacity of 500 mAh/g. This Li-Air battery benefits from a protected Li-anode, an air cathode based on MoS₂ catalyst and a mixture electrolyte. Different characterizations including differential electrochemical mass spectroscopy (DEMS), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy on the cathode reveal that the only discharge product in our system is lithium peroxide (Li₂O₂) without any evidence of side products e.g., lithium hydroxide (LiOH) and lithium carbonate (Li₂CO₃). Nuclear magnetic resonance (NMR) results also show the stability of the electrolyte after 550 cycles. DFT calculations reveal that the combination of MoS₂ cathode and mixture electrolyte make the system kinetically favorable for Li₂O₂ formation hindering the formation of other possible products. The Li-air system studied here is a key step toward the development of next generation of lithium batteries with higher energy density.

References:

1. Aurbach, D., McCloskey, B. D., Nazar, L. F. & Bruce, P. G. Advances in understanding mechanisms underpinning lithium–air batteries. Nat. Energy 1,16128 (2016).

2. Bruce, P. G., Freunberger, S. A., Hardwick, L. J. & Tarascon, J.-M. Li–O2 and Li–S batteries with high energy storage. Nat. Mater. 11,19–29 (2011).

3. Ye, L. et al. Lithium-Air Batteries: Performance Interplays with Instability Factors. ChemElectroChem 2,312–323 (2015).

4. Asadi, M. et al. Cathode Based on Molybdenum Disulfide Nanoflakes for Lithium-Oxygen Batteries. ACS Nano 10,2167–75 (2016).

5. Geng, D. et al. From Lithium-Oxygen to Lithium-Air Batteries: Challenges and Opportunities. Adv. Energy Mater. 201502164, 1–14 (2016).