Nd−Mg−Ni alloy electrodes modified by reduced graphene oxide with improved electrochemical kinetics
To improve the electrochemical kinetics of Nd–Mg–Ni alloy electrodes, the alloy surface was modified with highly conductive reduced graphene oxide (rGO) via a chemical reduction process. Results indicated that rGO sheets uniformly coated on the alloy surface, yielding a threedimensional network layer. The coated surfaces contained numerous hydrophilic functional groups, leading to better wettability of the alloy in aqueous alkaline media. This, in turn, increased the concentration of electro-active species at the interface between the electrode and the electrolyte, improving the electrochemical kinetics and the rate discharge of the electrodes. The high rate dischargeability at 1500 mA·g−1 increased from 53.2% to 83.9% after modification. In addition, the modification layer remained stable and introduced a dense metal oxide layer to the alloy surface after a long cycling process. Therefore, the protective layer prevented the discharge capacity from quickly decreasing and improved cycling stability.
Keywordshydrogen storage alloys surface modification graphene oxide electrochemical properties kinetics
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This work was financially supported by the National Natural Science Foundation of China (NOs. 21303157 and 51771164), the Natural Science Foundation of Hebei Province (No. E2019203161), and Scientific Research Projects in Colleges and Universities in Hebei Province (No. QN2016002).
- X. Tian, G. Yun, H.Y. Wang, T. Shang, Z.Q. Yao, W. Wei, and X.X. Liang, Preparation and electrochemical properties of La–Mg–Ni-based La0.75Mg0.25Ni3.3Co0.5 multiphase hydrogen storage alloy as negative material of Ni/MH battery, Int. J. Hydrogen Energy, 39(2014), No. 16, p. 8474.CrossRefGoogle Scholar
- L.L. Xiao, Y.J. Wang, Y. Liu, D.W. Song, L.F. Jiao, and H.T. Yuan, Influence of surface treatments on microstructure and electrochemical properties of La0.7Mg0.3Ni2.4Co0.6 hydrogen–storage alloy, Int. J. Hydrogen Energy, 33(2008), No. 14, p. 395.Google Scholar
- N. Li, Y. Du, Q.P. Feng, G.W. Huang, H.M. Xiao, and S.Y. Fu, A novel type of battery-supercapacitor hybrid device with highly switchable dual performances based on a carbon skeleton/Mg2Ni free-standing hydrogen storage electrode, ACS Appl. Mater. Interfaces, 9(2017), No. 51, p. 44828.CrossRefGoogle Scholar