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Zinc–Nickel Single Flow Battery
Published in Huamin Zhang, Huamin Zhang, Xianfeng Li, Jiujun Zhang, Redox Flow Batteries, 2017
Qinzhi Lai, Chenhui Wang, Yang Song, Xianfeng Li, Huamin Zhang
Since the use of porous zinc electrodes in the battery, the surface area is larger, however the self-discharge issue is very serious, and the temperature effect also is obvious. Self-discharge of zinc electrode is one of the main factors affecting the working life of zinc electrode. For batteries and long-life flow batteries, the capacity loss due to self-discharge is greater, and the gas produced by corrosion is very detrimental to the sealing of the battery. To reduce the corrosion of zinc electrodes, ZnO-saturated KOH electrolytes are usually used as a practical application. With the increasing of zincate concentration, the corrosion rate of zinc electrode decreased significantly. Ina saturated alkaline solution for a long time on hold, zinc oxide or hydroxide film can be formed on the electrode surface. In recent years, a great deal of research has been done on its corrosion mechanism and corrosion inhibitor. According to electrochemical calorimetric method, it is considered that the thermal change of TΔS is one of the determinants. The electrochemical quartz crystal microbalance is used on the zinc electrode by laser irradiation, and the quartz oscillation frequency will dramatically increase at the beginning of irradiation. At present, there are three measures to suppress the corrosion of zinc electrodes which are shown as follows: Strengthen the control of the zinc electrode process and reduce the harmful impurities contentImprovement of the battery itself, including the control of temperature and sealing to prevent self-discharge of zinc electrodeImprovement of the hydrogen overpotential, decreasing hydrogen precipitation rate in the zinc electrode or adding inhibitor into electrolyte solution
Zinc Dust and Compounds
Published in Frank Porter, Zinc Handbook, 1991
The chemical and electrochemical properties of zinc dust and zinc powder are those of zinc metal itself. Zinc is amphoteric, forming divalent zinc ions in acid or neutral media and zincate ions in alkaline solutions. The metal is thus a good reducing agent. The high reducing potential of zinc in both acidic and basic solutions is shown by the standard electrode potentials: E0Â Acidic:Â Zn→Zn2++2e−+0.763Â VÂ Basic:Â Zn+2OH−→Zn(OH)2+2e−+1.245Â VZn+4OH−→Zn(OH)42−+2e−+1.216Â V
Enhancement of electro-thermal and mechanical properties for Cu-SWCNT coated 6061Al
Published in Surface Engineering, 2020
Prosun Mandal, Subhas Chandra Mondal
The natural oxide layer of aluminium and its alloys is the main obstacle for electroplating. It prevents formation of a strong adhesive bond. This natural oxide film needs to be removed from aluminium alloy specimen. The natural oxide film can be removed by mechanically or dissolved chemically. Owing to its easy reformation, the aluminium surface is quickly covered with a new oxide layer [6]. This problem can be solved by pre-treatment of aluminium surface using zincate treatment, anodisation [2], chromate conversion coating [7] and plasma electrolytic oxidation or micro arc oxidation [8], etc. The zincate process is most widely used surface preparation method for aluminium and its alloys before electrodeposition [9]. This process requires additional heat treatment. Moreover, this process does not ensure a strong adherent bond between aluminium component and metal coatings [2]. In this paper, anodisation technique was used for surface treatment of aluminium alloy in order to achieve a strong bond. In this process, the natural oxide layer was utilised rather than its removal from the aluminium surface for solving the problem of electroplating. Highly porous structure is generated on the aluminium surface during anodising process. The electrodeposition process starts with the penetration of metals into pores of anodised aluminium surface which strengthens the bond of aluminium substrate and coatings [6]. Tremmel et al. [10] achieved a strong adhesive nickel coating by anodising the aluminium surface with anodising solution which was composed of sulphuric acid, phosphoric acid and an organic acid. An excellent adhesive copper coating was achieved by surface preparation of aluminium with anodising solution [11]. Devyatkina et al. [12] formulated a combined effective electrolytic bath for both anodising and copper plating of aluminium and its alloy. A fine crystalline structure of deposited copper was achieved by introducing fluorides in electrolytic bath. The copper coating which was developed from combined electrolytic bath exhibited high adhesion to aluminium.