This battery, being developed in a company based in Berkeley, California, is purported to use the surrounding air as the cathode. The company, PolyPlus, will soon partner with a manufacturing company to develop the single-use (non-rechargeable) lithium metal-air batteries for the US Federal Government. However, the batteries will take several years to proliferate commercial markets.

The company is also working on a rechargeable version of the battery for use in electric vehicles and what not.

Like in Li-ion batteries, the anode is made of Lithium metal but unlike Li-ion, the cathode is not composed of graphite but makes use of the surrounding air. They have the energy density of fuel-cells but are far more compact. Because there is no need to pack in a second reactant (cathode) the battery is far lighter than others in the market today.

Using Lithium in the elemental form in batteries has been problematic because of how violently Lithium reacts with moisture which is present in air. Hence manufacturers have preferred to use graphite as the cathode which is relatively safer but potentially less efficient.

PolyPlus has solved the problem by developing a protected lithium electrode which is nothing but a flat, rectangular piece of lithium metal overlaid on either side with a ceramic electrolyte material called lisicon. The electrolyte material lets lithium ions to permeate it and hence pass through at the same time disallowing water or moisture to pass through.

The device is fitted with a gas-diffusion electrode similar to those used for zinc metal-air hearing-aid batteries. On turning the battery on, the electrode draws in oxygen to react with Li-ions.

An advantage is that these batteries won’t discharge when in closed internal circuit because the membrane protects the Lithium metal from degenerating.

These batteries can be used in underwater conditions too where the surrounding oxygen-rich water acts as the cathode.