Development of highly effective and environmentally friendly battery technology is crucial to the energy storage system and electronic vehicle.[1,2] Recently, the aprotic lithium-oxygen (Li-O₂) battery has attracted much attention due to its high specific energy density of 3500 Wh kg^-1 (based on the mass of Li₂O₂) and a favorable potential of 3.0 V, which are defined by the chemistry of the reversible reaction Li + O₂ ↔Li₂O₂.[3,4] The high specific energy density of Li-O₂ battery renders it a promising candidate for the electrical vehicle with extended-range driving. One of the challenges in Li-O₂battery is to find a catalyst that can improve the sluggish electrochemical kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) during the discharge and charge process, respectively.[5]

Herein, we employ Magneli phase Ti₄O₇ as a support and construct a hybrid with MnCo₂O₄ (MCO) nanoparticles being anchored on the surface of Ti₄O₇ for the first time. This hybrid is employed as a non-carbon cathode material for Li-O₂ batteries. The synergistic interaction between Ti₄O₇ support and MCO nanoparticles further promotes the catalytic activity and stability of the hybrid. Benefiting form these advantages, the as-synthesized Ti₄O₇-MCO hybrid exhibits excellent catalytic activity to decrease the voltage gap between discharge and charge. The Ti₄O₇-MCO presents excellent discharge performance when compared with other carbon-free cathode materials. Moreover, due to the excellent chemical durability of Ti₄O₇ in organic electrolyte and the interaction between Ti₄O₇and MCO, the hybird is very stable during the battery cycling without agglomeration and detachment.

The Discharge/charge profile, rate capability and cycling performance of Ti₄O₇-MCO are shown in Figure 1.

 

 

Figure 1.  (a) Discharge/charge profile of Ti₄O₇-MCO cathode under different current densities; (b) First discharge/charge profile of Ti₄O₇-MCO, Ti₄O₇, C and C-MCO with a limited capacity of 500 mAh g^-1; (c) Cycling performance of Ti₄O₇ cathode; (d) Cycling performance of Ti₄O₇-MCO cathode.

 

Acknowledgements

This work is supported by National Natural Science Foundation of China (51572181), the National Key Research and Development Program of China (2016YFB0100200)，Natural Science Foundation of Jiangsu Province, China (BK20151226).

References

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[3] G. Girishkumar, B. McCloskey, A. C. Luntz, S. Swanson, W. Wilcke, J. Phys. Chem. Lett. 1(2010) 2193.

[4] F. Y. Cheng, J. Chen, Chem. Soc. Rev. 41(2012)2172.

[5] Z.-L. Wang, D. Xu, J.-J. Xu, X.-B. Zhang, Chem. Soc. Rev. 43(2014)7746.