Final answer:
The electrolyte used in nickel-cadmium (NiCad) batteries is potassium hydroxide (KOH). The design of NiCad batteries allows for high discharge currents and the ability to be recharged hundreds of times due to the solid discharge products that adhere to the electrodes.
Step-by-step explanation:
The solution used as the electrolyte in a nickel-cadmium (NiCad) battery is potassium hydroxide (KOH). These batteries consist of a cadmium anode, a highly oxidized nickel cathode described as nickel(III) oxo-hydroxide (NiO(OH)), and a potassium hydroxide electrolyte. During discharge, the chemical reactions involve the oxidation of cadmium and the reduction of nickel atoms in NiOOH. NiCad batteries are designed to maximize the electrode surface area and minimize the distance between electrodes, which decreases internal resistance and allows for high discharge currents. They also use a "jelly-roll" design to deliver more current than a similar-sized alkaline battery.
NiCad batteries can be recharged hundreds of times due to the solid nature of the reaction products during discharge, which are Cd(OH)2 and Ni(OH)2 that adhere to the electrodes. The overall discharge reaction is: Cd(s) + 2NiO(OH)(s) + 2H2O(l) → Cd(OH)2(s) + 2Ni(OH)2(s) with a cell potential of 1.4V. The reaction is easily reversed upon recharging, contributing to the battery's reusability.