Abstract
The severe corrosion accompanied with hydrogen evolution reaction has become the main obstacle restricting the utilization of zinc as an electrode in alkaline batteries. Al2O3 coating helps control the corrosion of zinc in alkaline solution. Herein, a stable Al2O3 coating is fabricated through facile electrospinning from Al(NO3)3 as an efficient anti-corrosion film on zinc. The electrospinning technique facilitates uniform dispersion of Al2O3 particles, therefore the corrosion inhibition efficiency could be up to 88.5% in this work. The Al2O3 coating prevents direct contact between zinc and the alkaline solution and minimize hydrogen evolution. Further, the effects of the thickness of Al2O3 coating on corrosion behavior of zinc are investigated through hydrogen evolution reaction, Tafel polarization, and impedance test. The results show that the thicker Al2O3 coating possessed better corrosion inhibition efficiency due to the higher corrosion resistance and lower porosity. The 18 μm Al2O3 coating on zinc provides corrosion current density of 60.6 mA/cm2, while the bare zinc substrate delivers as much as 526.3 mA/cm2.This study presents a promising approach for fabricating Al2O3 coating for corrosion-resistant applications.
Highlights
Metal–air batteries are considered as the renewable energy for many devices [1,2,3,4].Zinc is one of the most widely used electrodes because of its abundance, low cost, and environmental compatibility [5,6,7]
The parasitic hydrogen evolution reaction (HER) during discharge is a major defect that leads to the degradation in the electrochemical performance of batteries [11,12,13]
The Al2 O3 coating was fabricated by electrospinning from Al(NO3 )3 and coated onto zinc substrate
Summary
Metal–air batteries are considered as the renewable energy for many devices [1,2,3,4].Zinc is one of the most widely used electrodes because of its abundance, low cost, and environmental compatibility [5,6,7]. The parasitic hydrogen evolution reaction (HER) during discharge is a major defect that leads to the degradation in the electrochemical performance of batteries [11,12,13]. Indium hydroxide, sodium stannate, and citrate are found to be effective in inhibiting the self-corrosion in alkaline solutions [16,17]. Another way is alloying elements such as Mg, Ga, Mn, In, Sn, Zr, and Ti in zinc due to their low melting temperatures and high hydrogen evolution overpotential [18,19]. Al2 O3 coating has been investigated widely for its possible use as an excellent protective film against HER corrosion due Coatings 2019, 9, 692; doi:10.3390/coatings9110692 www.mdpi.com/journal/coatings
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