Cathodic processes on zinc in alkaline zincate solutions

Alkaline aqueous electrolytes for secondary zinc-air batteries: an overview

“…HER results in water electrolysis and increases the internal pressure of the cell. This side reaction decreases the durability of a zinc–air battery generating hydrogen gas, reaction ; …”

Fabrication of High‐Performance Flexible Alkaline Batteries by Implementing Multiwalled Carbon Nanotubes and Copolymer Separator

“…The capacity of a fl exible battery obtained for optimized anode and cathode with 8% purifi ed CNTs (283 mAh g −1 ) corresponded to the utilization of 92% of the theoretical capacity of MnO 2 (308 mAh g −1 ) under a 3.6mA constant current discharge with a cut off voltage 0.9 V ( Figure 9 ). [ 31 ] Anodic corrosion can be inhibited by the addition of certain organic compounds or metals such as Bi, Pb, and Al. Therefore, excess zinc was applied to the anode to maintain the electrode conductivity.…”

“…Gas evolution in alkaline batteries is known to be a problem, excess ZnO has been reported to hinder zinc corrosion, and a decrease in KOH concentration is known to decrease hydrogen generation. [ 31 ] Anodic corrosion can be inhibited by the addition of certain organic compounds or metals such as Bi, Pb, and Al. [32][33][34] The organic and metal oxides inhibitors are nonconductive and together with polyethylene oxide (PEO) and the zinc oxide generated during the reaction, they increase the anode resistance.…”

Zinc regeneration in rechargeable zinc-air fuel cells—A review

“…The results permitted to conclude that: (i) the type of the electrode (materials, binders and additives) determines the hydrogen evolution rate; (ii) the hydrogen evolution mainly results from zinc electrode corrosion, (iii) the hydrogen evolution rate is higher at higher current densities or at lower KOH (or zincate) concentrations [116]. Further studies based on the gasometric method [30] showed that increasing ZnO content in zincate solutions significantly lowered the hydrogen evolution rate. In industry, dendrite formations with mossy and spongy morphologies have been regarded as an inherent challenge in zinc recovery, since zinc in this form will decrease power efficiency when reused in the power-generation compartment of the fuel cell or battery system.…”

“…The quantity of H2 produced due to hydrogen evolution is dependent on several factors, such as electrode and electrolyte inhibitor concentrations in spent solution, electrode material's type, form and crystal structure, water and ZnO contents in spent electrolyte, zincate saturation level, applied deposition potential/current densities, the designs of zinc-regeneration cell and spent-solution flow system, etc. According to Ravindran and Muralidharan [30], the hydrogen evolution rate is about 5 mL/s/m 2 in 6 M KOH spent electrolyte containing 0.02 M ZnO at 20 mA/cm 2 of applied deposition current density and room temperature.…”