Faradaic losses are experienced by both
electrolytic and
galvanic cells when electrons or ions participate in unwanted side reactions. These losses appear as heat and/or chemical byproducts. An example can be found in the
oxidation of water to
oxygen at the positive electrode in electrolysis.
Hydrogen peroxide can also be produced. The fraction of electrons so diverted represent a faradaic loss and vary in different apparatus. Even when the proper electrolysis products are produced, losses can still occur if the products are permitted to recombine. During
water electrolysis, the desired products (
H2 and
O2), could recombine to form
water. This could realistically happen in the presence of catalytic materials such as
platinum or
palladium commonly used as electrodes. Failure to account for this
Faraday-efficiency effect has been identified as the cause of the misidentification of positive results in
cold fusion experiments.
Proton exchange membrane fuel cells provide another example of faradaic losses when some of the electrons separated from hydrogen at the
anode leak through the membrane and reach the
cathode directly instead of passing through the load and performing useful
work. Ideally, the electrolyte membrane would be a perfect insulator and prevent this from happening. An especially familiar example of faradaic loss is the
self-discharge that limits battery shelf-life. == Methods of measuring faradaic loss ==