UK Researchers Developing Rechargeable Lithium-Air Battery; Up to 10X the Capacity of Current Li-ion Cells
|Diagram of the STAIR (St Andrews Air) cell. Oxygen drawn from the air reacts within the porous carbon to release the electrical charge in this lithium-air battery. Click to enlarge.|
Researchers in the UK are developing a rechargeable lithium-air battery that could deliver a ten-fold increase in energy capacity compared to that of currently available lithium-ion cells. The research work, funded by the Engineering and Physical Sciences Research Council (EPSRC), is being led by researchers at the University of St Andrews with partners at Strathclyde and Newcastle.
Initial results from the project delivered a capacity of 1,000 mAh g-1, while recent work has obtained results of up to 4,000 mAh g-1.
Lithium-air batteries use a catalytic air cathode in combination with an electrolyte and a lithium anode. Oxygen from the air is the active material for the cathode and is reduced at the cathode surface. An issue with Li-air batteries can be the accumulation of solid reaction products on the electrode, which blocks the contact between electrolyte and air.
The four-year EPSRC research project, which reaches its halfway mark in July, is targeting the development of a Li-air cell that is rechargeable and can sustain cycling. The project addresses a number of the materials issues necessary to realize this high energy storage battery based on a non-aqueous O2 electrode. During the project, the team has so far more than tripled the capacity to store charge in the STAIR (St Andrews Air) cell.
The project is focused on understanding more about how the chemical reaction of the battery works and investigating how to improve it. The research team is also working towards making a STAIR cell prototype suited, in the first instance, for small applications, such as mobile phones or MP3 players.
The key is to use oxygen in the air as a re-agent, rather than carry the necessary chemicals around inside the battery. Our target is to get a five to ten fold increase in storage capacity, which is beyond the horizon of current lithium batteries. Our results so far are very encouraging and have far exceeded our expectations.—Professor Peter Bruce of the Chemistry Department at the University of St Andrews, principal investigator
Bruce estimates that it will be at least five years before the STAIR cell is commercially available.
The four-year research project “An O2 Electrode for a Rechargeable Lithium Battery” began on 1 July 2007 and is scheduled to end on 30 June 2011. It has received EPSRC funding of £1,579,137 (US$2.4 million).
Earlier this year, researchers at Japans’s AIST (Advanced Industrial Science and Technology) also reported progress on the development of a very high capacity Lithium-air battery.