Zinc–air battery
In 1878, a porous platinized carbon air electrode was found to work as well as the manganese dioxide (MnO2) of the Leclanche cell.
Large primary zinc–air cells such as the Thomas A. Edison Industries Carbonaire type were used for railway signaling, remote communication sites, and navigation buoys.
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.
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.
Large zinc–air batteries, with capacities up to 2,000 ampere–hours per cell, are used to power navigation instruments and marker lights, oceanographic experiments and railway signals.
Hybrid cell cathodes include manganese dioxide to allow high peak currents.
Button cells are highly effective, but it is difficult to extend the same construction to larger sizes due to air diffusion performance, heat dissipation, and leakage problems.
Challenges include dendrite formation,[11] non-uniform zinc dissolution, and limited solubility in electrolytes.
Providing charge and discharge functions by separate uni-functional cathodes increases cell size, weight and complexity.
[6] A satisfactory electrically recharged system potentially offers low material cost and high specific energy.
[12] Fluidic Energy has apparently covered hundreds of thousands of outages in Asia[13] at distributed critical load sites.
EOS Energy Storage has deployed a 1MWh system for a microgrid at a New Jersey wastewater treatment plant[14] and has previously tested grid-scale backup applications.
[15] AZA Battery has announced development of pilot production of prismatic zinc air cells with characteristics suitable for both stationary storage and mobility applications.
[16] [17] 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.
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.
[19][20] Rechargeable Zn–air batteries in a tri-electrode configuration exhibited an unprecedented small charge–discharge voltage polarization of ~0.70 V at 20 mA/cm3, high reversibility and stability over long charge and discharge cycles.
Organic compound aniline, polymerized into long chains in a phytic acid solution, was freeze-dried into a stable, mesoporous carbon aerogel with 2–50 nm pores, providing high surface area and room for the battery electrolyte to diffuse.
The researchers pyrolized the aerogel to 1,000 degrees Celsius, turning the foam into a graphitic network, with many catalytic graphene edges.
[26] [27] The Eos Energy System battery is about half the size of a shipping container and provides 1 MWh of storage.
This can build up pressure, which is used in certain applications to expel another liquid over a longer period, like automatic lubricators[30] or air fresheners.
Older designs used mercury amalgam amounting to about 1% of the weight of a button cell, to prevent zinc corrosion.
[6] In United States waters, environmental regulations now require proper disposal of primary batteries removed from navigation aids.
