Large-scale energy storage system is essential for storing and integrating the intermittent renewable energy such as wind and solar into the electricity grid. This system needs to show a high round-trip efficiency (80%), longer-life cycle (5000 cycles) and favorable cost ($100/kWh) as specified by the U.S Department of Energy (DOE) [1]. Ni-Fe and Fe-air are among the cheapest and long life batteries that could meet the DOE performance target. However, iron electrodes used in this system needs to be improved in terms of discharge capacity, rate capability, Faradaic efficiency and cycle life [2].

Recently, nanomaterials have exhibited a high initial capacity whereas after few cycles the capacity faded fast due to particle agglomeration and increase in resistance by the discharged product [3-5]. To avoid this phenomenon, we have used the Cu-doped Core/Shell structure Nano-Iron/Iron Carbide that showed 367 mAh g^-1 with stable performances for more than 200 cycles [6]. In this work, Cu/Sn-doped iron carbon composite was utilized and achieved high initial capacity between 457 and 600 mAh g^-1 around 90% efficiency. We have tried to limit the electrode capacity by adjusting the depth of discharge (DoD) and extend the cycle life to more than 500 cycles.

References

[1] A.K. Manohar, S. Malkhandi, B. Yang, C. Yang, G.K. Surya Prakash, S.R. Narayanan, Journal of The Electrochemical Society, 159 (2012) A1209-A1214.

[2] R.D. McKerracher, C.P.d. Leon, R.G.A. Wills, A.A. Shah, F.C. Walsh, ChemPlusChem, 80 (2015) 323-335.

[3] D. Lei, D.C. Lee, A. Magasinski, E. Zhao, D. Steingart, G. Yushin, ACS Appl Mater Interfaces, 8 (2016) 2088-2096.

[4] W. Jiang, F. Liang, J. Wang, L. Su, Y. Wu, L. Wang, Rsc Adv, 4 (2014) 15394-15399.

[5] C.-Y. Kao, Y.-R. Tsai, K.-S. Chou, Journal of Power Sources, 196 (2011) 5746-5750.

[6] A.R. Paulraj, Y. Kiros, B. Skårman, H. Vidarsson, Journal of The Electrochemical Society, 164 (2017) A1665-A1672.