Lithium-air batteries provide a promising high-energy-density alternative to traditional Lithium-ion technologies, particularly for use in electric vehicles. Current Li-air batteries can be recharged, but their usefulness is limited by their short lifetime. The discharge capacity of the battery is dictated by the build-up of reaction products, which choke the cathode by blocking further reactions between the electrolyte and the air [1]. As the breakdown of these reaction products during charging is never fully complete, subsequent charging cycles reduce the discharge capacity until the battery is no longer useful.

We investigate the use of soft materials to create a Li-air cathode that brings the three key components: electrolyte, electrode and air, into close contact with each other, increasing the contact area between the components and thereby reducing the likelihood of the reaction product keeping the electrolyte and air apart from each other. We use high internal phase Pickering emulsions (Pickering HIPE) (Fig. 1) to create a ‘tricontinuous’ structure (Fig. 2), in which the conducting particles on the interface and both liquid phases are all continuous in 3D space [2]. When fully realised, this structure should allow us to create a cathode where the build-up of reaction product over repeated charge cycles has very little effect on the ability of the electrolyte to react with oxygen from the air during discharge.

[1] J. Read, J. Electrochem. Soc. 149 (2002) A1190.

[2] D. Cai, J.H.J. Thijssen, P.S. Clegg, Appl. Mater. Interfaces 6 (2014) 9214 – 9219.