PDF Publication Title:
Text from PDF Page: 216
The removal of nickel from the electrolyte is very slow when compared to removal of other additives. Typically, additives have a half-life of about one hour while that for nickel is about two hours. The half-life of nickel as determined by its removal rate in the zinc transfer cell produced an unexpected result. In 2-molar zinc chloride, no displacement reaction occurred and the removal rate is zero. Apparently, nickel will slowly co-deposit with zinc, but does not undergo simple displacement reactions with the metal. The deposition efficiency of zinc from a 2-molar zinc chloride solution containing +2 2mg/i Ni was essentially quantitative as determined by electrogravimetry. This unexpected finding and lack of correlation to battery test results suggest that the electrolyte composition near the zinc electrode was the controlling parameter for the co-deposition of nickel. Nickel removal rates were then evaluated in the zinc transfer cell using solution of 0.10-, 0.50-, and 0.01-molar zinc chloride. In these dilute zinc-chloride solutions, nickel was observed to co-deposit with the zinc, but efficiencies were meaningless because the limiting current density for zinc was exceeded. Further testing in 0.5-molar zinc chloride produced the +2 desired result. A solution containing 2mg/£ Ni caused a 10% loss in the round trip coulombic efficiency when compared to a control. The use of nickel to obtain correlation between the zinc transfer cell and battery test results is a rigorous test for duplication of electrode conditions. The use of a 0.5-molar zinc chloride solution in the transfer cell as compared to a 1- to 2-molar zinc chloride solution in the battery is believed to be due to differences in the agitation surrounding the respective electrodes. That is, the electrolyte near the zinc electrode in a battery is more stagnant than the electrolyte surround ing the rotating zinc electrode at 10-30 rpm. Other aspects of the electrolyte such as the addition of potassium chloride and a pH of 0.3 are consistent with electrolyte typically used in batteries. Also, the use of a leveling agent has been found beneficial to the reproducibility of the testing. Unmodified zinc solutions produce a nodular plate on the hydrophobic graphite while the modified, fine-grained deposits tend to be more uniform. Impurity Effects on Zinc Deposition-Dissolution Efficiencies The purpose of this testing was to identify those elements which promote hydrogen evolution from a zinc electrolyte under conditions similar to those in a battery. In addition the magnitude of the effect has been determined by testing the impuri ties at different concentration levels. With this in mind, only round-trip 37-9PDF Image | Development of the Zinc-Chlorine Battery for Utility
PDF Search Title:
Development of the Zinc-Chlorine Battery for UtilityOriginal File Name Searched:
6302789.pdfDIY PDF Search: Google It | Yahoo | Bing
Salgenx Redox Flow Battery Technology: Power up your energy storage game with Salgenx Salt Water Battery. With its advanced technology, the flow battery provides reliable, scalable, and sustainable energy storage for utility-scale projects. Upgrade to a Salgenx flow battery today and take control of your energy future.
CONTACT TEL: 608-238-6001 Email: greg@salgenx.com (Standard Web Page)