A lithium-air battery and gas handling system demonstrator

The lithium-air (Li-air) battery offers one of the highest practical specific energy densities of any battery system at >400 W h kg_system^-1. The practical cell is expected to operate in air, which is flowed into the positive porous electrode where it forms Li₂O₂ on discharge and is released as O₂ on charge. The presence of CO₂ and H₂O in the gas stream leads to the formation of oxidatively robust side products, Li₂CO₃ and LiOH, respectively. Thus, a gas handling system is needed to control the flow and remove CO₂ and H₂O from the gas supply. Here we present the first example of an integrated Li-air battery with in-line gas handling, that allows control over the flow and composition of the gas supplied to a Li-air cell and simultaneous evaluation of the cell and scrubber performance. Our findings reveal that O₂ flow can drastically impact the capacity of cells and confirm the need for redox mediators. However, we show that current air-electrode designs translated from fuel cell technology are not suitable for Li-air cells as they result in the need for higher gas flow rates than required theoretically. This puts the scrubber under a high load and increases the requirements for solvent saturation and recapture. Our results clarify the challenges that must be addressed to realise a practical Li-air system and will provide vital insight for future modelling and cell development.