Elsevier

Intermetallics

Volume 127, December 2020, 106972
Intermetallics

An enhanced quasicrystalline Ti1.4V0.6Ni alloy electrode modified by uniformly covered RGO for nickel metal hydride battery

https://doi.org/10.1016/j.intermet.2020.106972Get rights and content

Highlights

  • RGO coating layer is prepared by electro-deposition and subsequent reduction.

  • Raman spectra measurement proves the degree of reduction of RGO enhanced by HI.

  • Cycle stability of Ti1.4V0.6Ni is enhanced by RGO for its anti-corrosion ability.

Abstract

Herein, we provided a facile route to coat a flat and uniformly covered reduced graphene oxide (RGO) film on Ti1.4V0.6Ni quasicrystal alloy electrode surface by electrodeposition of graphene oxide and subsequent reduction with HI vapor. Raman spectrum showed HI has a better reduced effect than electrochemical reduction. The RGO coated alloy electrode exhibited a higher discharge capacity of 290.3 mA h g−1 and 23.8% higher capacity retention than the bare one after 50 cycles for the RGO layer effectively forbidding the direct contact of electrode and electrolyte. Moreover, Ti1.4V0.6Ni quasicrystal alloy with RGO coating exhibited faster hydrogen uptake kinetics by initial activation curve of gaseous hydrogen storage measurement and higher maximum hydrogen storage performance of 1.66 wt% than the bare Ti1.4V0.6Ni alloy. Thus, the enhanced properties of RGO as a multifunctional layer for Ti1.4V0.6Ni quasicrystal alloy were proved which could be achieved by a facile route.

Introduction

Ti-base alloys with icosahedral quasicrystal structure have been proved possessing better hydrogen storage ability than the conventional hydrogen storage alloys owing to that there is more Pauling–Bergman and Mackay atomic clusters in the structure [[1], [2], [3]]. Ti1.4V0.6Ni quasicrystal alloy has the best cycle discharge performance among the Ti base quasicrystal alloys working as the negative electrode in nickel metal-hydride (Ni-MH) secondary battery but the stability is still unsatisfactory [[4], [5], [6]]. The major factors leading the capacity fading of the alloy are because of the dissolution of V in the alkaline electrolyte and the volume expansion of alloy structure which have been discussed in our reported works [[7], [8], [9], [10]]. To effectively enhance the electrochemical stability of Ti1.4V0.6Ni alloys, surface coating is an optional measure which could inhibit the direct contact between the alloy surface and electrolyte.

Graphene has a better anti-corrosion ability than Cu or Ni as a coating layer [13]. However, the surface of alloy electrode which is prepared under high pressure is not flat enough for the deposition of graphene by chemical vapor deposition (CVD) or plasma enhanced chemical vapor deposition (PECVD) [14,15]. Reduced graphene oxide (RGO) is an accessible substitution of graphene for it is simplified to get and do not need sophisticated equipment. For Ti1.4V0.6Ni alloy is easily to be oxidized, the conventional hydrothermal reduction of graphene oxide (GO) under a high temperature and pressure in water solution is not suitable. To coat a GO layer on the electrode surface and meantime have no side effect to the alloy, electrodeposition is the optimal choice which is reported by Liu et al. [16]. However, it remains a challenge to wrap GO evenly around the electrode surface and reduces it without causing irreversible effects to the electrode materials. Herein, we suggested a two steps route for covering alloy electrode with RGO film by a combination of electrochemical deposition and a further reduction with HI [17].

Section snippets

Materials and methods

Graphene oxide was prepared by Hummers' method [18] and the Ti1.4V0.6Ni alloy powers were prepared using pure Ti, V and Ni (>99.9 wt%) according to the method in the literature [8]. Ti1.4V0.6Ni power and carbonyl nickel power (1:1) was pressed on a nickel foam (2 × 2 cm2) under 20 MPa. For GO electrodepositon, the alloy electrode connected with negative pole and a large piece of Ni foam connects with cathode, the distance was 1 cm. The deposition process sustained for 150 s under 5 V and there

Results and discussion

Fig. 1 shows the XRD patterns of Ti1.4V0.6Ni and Ti1.4V0.6Ni@RGO materials. The diffraction peaks of the pristine sample could be indexed to the icosahedral phase (I-phase), Ti2Ni-type face center cubic (fcc) phase (JCPDS # 18-0898) and V-based body center cubic (bcc) solid solution phase (JCPDS # 22-1058). The peaks indexed to iphase use the scheme first proposed by Bancel [23]. Simultaneously, it could be observed that peaks of i-phase are so close to peaks of Ti2Ni-type FCC phase that

Conclusion

A gentle and handy method to prepare RGO coating with a reduction process on Ti1.4V0.6Ni alloy electrode was successfully accomplished in this work. The enhanced electrochemical properties of RGO coated Ti1.4V0.6Ni proves that the high quality RGO film could offer a good conductivity and thermal dispersion to strengthen hydrogen diffusion on the surface and accelerates H-kinetics. The coated electrode materials showed excellent discharge capacity of maximum 290.3 mA h/g and 23.8% higher than

Declaration of competing interest

The authors declare that they have no known financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

This work is financially supported by Science and Technology Service (STS) Network Initiative Program of Chinese Academy of Sciences (KFJ-STS-QYZD-088), the Scientific and Technological Developing Project of Jilin Province (20180201098GX, 20200401039GX), the Special Fund of Industrial Innovation of Jilin Province (2019C058-5) and Natural Science Foundation of the Education Department of Anhui Province (KJ2020A0109), Nature Science Research Project of Anhui province (1908085QE172), the Changchun

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