Functionalized Graphene Cathode for High Energy and Power Na Rechargeable Batteries

Developing low-cost and high-performance energy storage devices is important for sustainable energy utilization. Recently, sodium (Na) ion batteries have been highlighted as a possible competitor to lithium (Li) ion batteries because of their potential merit in the cost effectiveness. Na resources are earth-abundant, and Na electrochemistry shares many similarities with Li. However, their relatively low energy/power densities and unreliable cycle stability need to be addressed. In this work, we propose a novel high-performance cathode for Na rechargeable batteries based on functionalized graphene nanoplatelets. Starting from natural graphite, functionalized graphene nanoplatelets were fabricated via simple scalable routes, which could control the chemical composition and porous nanostructure of the sample in one-step. By using surface reactions between Na and functionals on graphene nanoplatelets, (i) no significant lattice change occurred during battery cycling, and (ii) much faster Na kinetics could be achieved through porous network without solid-state diffusion.[1] Furthermore, the high electrical conductivity of the material could aid in improving the rate capability.[2] While previous studies of graphite-based electrodes are mostly found in anode applications for NIB and only very recently its cathode application was discovered, [3, 4] this work manipulated the carbon into a cathode with a tunability of composition and nanostructure by simple one-step chemical modification. The functionalized graphene cathode could deliver the energy of ~500 Wh kg^-1 without capacity decay during 300 battery cycles and could also exhibit an unprecedentedly high power of ~55 kW kg^-1with a less-than-10 s charge/discharge rate for NIB.

References

[1] H. Kim, H.-D. Lim, S.-W. Kim, J. Hong, D.-H. Seo, D.-c. Kim, S. Jeon, S. Park, K. Kang, Sci. Rep., Scalable Functionalized Graphene Nano-platelets as Tunable Cathodes for High-performance Lithium Rechargeable Batteries 3 (2013) 1506.

[2] S.-M. Oh, S.-T. Myung, J. Hassoun, B. Scrosati, Y.-K. Sun, Electrochem. Commun., Reversible NaFePO₄electrode for sodium secondary batteries 22 (2012) 149-152.

[3] Y.-X. Wang, S.-L. Chou, H.-K. Liu, S.-X. Dou, Carbon, Reduced graphene oxide with superior cycling stability and rate capability for sodium storage 57 (2013) 202-208.

[4] Z. Wang, L. Qie, L. Yuan, W. Zhang, X. Hu, Y. Huang, Carbon, Functionalized N-doped interconnected carbon nanofibers as an anode material for sodium-ion storage with excellent performance 55 (2013) 328-334.