Zinc-air batteries cannot be used in a sealed battery holder since some air must come in; the oxygen in 1 liter of air is required for every ampere-hour of capacity used. The benefits of mechanical recharging systems over rechargeable batteries include the decoupling of energy and power components, providing design flexibility for different charge rate, discharge rate, and energy capacity requirements. Mechanically recharged systems were investigated for military electronics uses in the 1960s because of the high energy density and easy recharging. Profire is a leader in burner management technology and combustion control systems that provide mission-critical combustion automation and control solutions and services to improve environmental efficiency, safety and reliability for industrial thermal applications globally. Rechargeable systems may mechanically replace the anode and electrolyte, essentially operating as a refurbishable primary cell, or may use zinc powder or other methods to replenish the reactants. Stacking prismatic cells requires air channels in the battery and may require a fan to force air through the stack. The following table shows the calculation of specific energy for a specific zinc-air battery and several other commonly available batteries of different chemistries. Zinc-air batteries have higher energy density than many other types of battery because atmospheric air is one of the battery reactants, in contrast to battery types that require a material such as manganese dioxide in combination with zinc.

Some approaches use a large zinc-air battery to maintain charge on a high discharge-rate battery used for peak loads during acceleration. Miniature cells have high self-discharge once opened to air; the cell’s capacity is intended to be used within a few weeks. Zinc-air cells have long shelf life if sealed to keep air out; even miniature button cells can be stored for up to 3 years at room temperature with little capacity loss if their seal is not removed. Zinc-air batteries can be used to replace now discontinued 1.35 V mercury batteries (although with a significantly shorter operating life), which in the 1970s through 1980s were commonly used in photo cameras and hearing aids. The effect of oxygen was known early in the 19th century when wet-cell Leclanche batteries absorbed atmospheric oxygen into the carbon cathode current collector. However, primary lithium batteries offered higher discharge rates and easier handling. Electrically reversing the reaction at a bi-functional air cathode, to liberate oxygen from discharge reaction products, is difficult; membranes tested to date have low overall efficiency. Oxygen entry into the cell must be balanced against electrolyte water loss; cathode membranes are coated with (hydrophobic) Teflon material to limit water loss. Power capacity is a function of several variables: cathode area, air availability, porosity, and the catalytic value of the cathode surface.

Low temperature reduces primary cell capacity but the effect is small for low drains. Wellwater for personal use is often filtered with reverse osmosis water processors; this process can remove very small particles. Development in the 1970s of thin electrodes based on fuel-cell research allowed application to small button and prismatic primary cells for hearing aids, pagers, and medical devices, especially cardiac telemetry. These were sold under the brand name “Tronox” and used for medical applications. Possible future applications of this battery include its deployment as an electric vehicle battery and as a utility-scale energy storage system. The term zinc-air fuel cell usually refers to a zinc-air battery in which zinc metal is added and zinc oxide is removed continuously. AZA Battery has announced development of pilot production of prismatic zinc air cells with characteristics suitable for both stationary storage and mobility applications. Zinc granules serve as the reactant. Vehicles recharge via exchanging used electrolyte and depleted zinc for fresh reactants at a service station. The electrolyte loses water more rapidly in conditions of high temperature and low humidity. A satisfactory electrically recharged system potentially offers low material cost and high specific energy.

Air brakes are effective even with considerable leakage, so an air-brake system can be designed with sufficient “fail-safe” capacity to allow the vehicle to carry on working even when leaking. Alternatively, this term may refer to an electrochemical system in which zinc is a co-reactant assisting the reformation of hydrocarbons at the anode of a fuel cell. It was also embraced by the clean and renewable energy crowd as a battlefield win in the war to used hydrogen — one of the most plentiful elements in the universe — as a viable future fuel source. Energy density, when measured by weight (mass) is known as specific energy. Charging voltage is much higher than discharge voltage, producing cycle energy efficiency as low as 50%. Providing charge and discharge functions by separate uni-functional cathodes increases cell size, weight and complexity. Lower temperature also reduces cell voltage. Because the cathode does not change properties during discharge, terminal voltage is quite stable until the cell approaches exhaustion. Because the potassium hydroxide electrolyte is deliquescent, in very humid conditions excess water accumulates in the cell, flooding the cathode and destroying its active properties. From 1991 to 1995, several Type/Model/Series (T/M/S) aircraft were phased out of the active inventory (e.g., Regular Navy and Naval Air Reserve), to include the RF-8G Crusader, the A-7E Corsair II, ES-3A Shadow, SH-3H Sea King and the A-6E and KA-6D Intruder.