W. J. Kwak (Department of Energy Engineering, Hanyang University), L. Curtiss, Y. K. Sun (Hanyang University), K. C. Lau (Materials Science Division, Argonne National Laboratory), and K. Amine (Argonne National Laboratory)
The five times higher energy density compared to conventional Li-ion batteries and its environment friendly reaction system make Li–O2
batteries a promising energy storage system. In spite of their great prospect, practical use of Li−O2
batteries still suffer many challenges such as low energy efficiency, poor rate capability and a poor cycle life. These problems are mainly attributable to excessive accumulation of discharge products (Li2
), which induce poor reversibility and high polarization when they decompose during charging.1,2
Consequently, the number of operating cycles for Li−O2
batteries cannot yet match those of Li-ion batteries. Moreover, the energy efficiency (< 80%) of the present Li−O2
battery system is also too low. To improve the performance of Li−O2
battery systems, a key factor is finding ways to enhance the catalytic activity of the cathode for formation and decomposition of Li2
, which is critical to decrease the polarization and increase the reversibility.3,4
Herein, we introduce well dispersed molybdenum carbide nanoparticles onto carbon nanotubes (Mo2
C/CNT) as a cathode material for Li−O2
C could be a good catalyst for the oxygen evolution reaction (OER) in Li−O2
batteries and the carbon nanotubes could help the Mo2
C nanoparticles be an ORR catalyst due to its electrical conductivity. In this report, a Mo2
C/carbon nanotube composite as a cathode is demonstrated to reduce high over potentials during charge and improve the cycling performance of Li−O2
(1) Lu, Y. C.; Shao-Horn, Y. Probing the Reaction Kinetics of the Charge Reactions of Nonaqueous Li–O2 Batteries J. Phys. Chem. Lett. 2013, 4, 93-99.
(2) Xu, J. J.; Wang, Z. L.; Xu, D.; Zhang, L. L.; Zhang, X. B. Tailoring deposition and morphology of discharge products towards high-rate and long-life lithium-oxygen batteries Nat. Commun. 2013, 4, 2438-2449.
(3) Lu, J.; Lei, Y.; Lau, K. C.; Luo, X.; Du, P.; Wen, J.; Assary, R. S.; Das, U.; Miller, D. J.; Elam, J. W. et al. A nanostructured cathode architecture for low charge overpotential in lithium-oxygen batteries Nat. Commun. 2014, 5, 2383-2391.
(4) Li, F.; Tang, D. M.; Chen, Y.; Golderg, D.; Kitaura, H.; Zhang, T.; Yamada, A.; Zhou, H. Ru/ITO: A Carbon-Free Cathode for Nonaqueous Li–O2 Battery Nano Lett. 2013, 13, 4702-4707.