Cars go further with lithium

UK scientists have developed a compound of lithium which may make it practical to store enough hydrogen on-board fuel-cell-powered cars to enable them to drive over 300 miles before refuelling.

Achieving this driving range is considered essential if a mass market for fuel cell cars is to develop in future years, but has not been possible using current hydrogen storage technologies.

A team from the Universities of Birmingham and Oxford and the Rutherford Appleton Laboratory in Oxfordshire, under the auspices of the UK Sustainable Hydrogen Energy Consortium (UK-SHEC), achieved the breakthrough. UK-SHEC is funded by the SUPERGEN (Sustainable Power Generation and Supply) initiative managed and led by the Engineering and Physical Sciences Research Council (EPSRC).

Current fuel-cell-powered cars only have a range of around 200 miles. To achieve a 300 mile driving range, an on-board space the size of a double-decker bus would be needed to store hydrogen gas at standard temperature and pressure, while storing it as a compressed gas in cylinders or as a liquid in storage tanks would not be practical due to the weight and size implications.

The UK-SHEC research focused on a different approach which could enable hydrogen to be stored at a much higher density and within acceptable weight limits. The option involves chemisorption, in which atoms of a gas are absorbed into the crystal structure of a solid-state material and then released when needed.

The team has tested thousands of solid-state compounds in search of a light, cheap, readily available material which would enable the absorption/desorption process to take place rapidly and safely at typical fuel cell operating temperatures. They have now produced a variety of lithium hydride, Li4BN3H10, that could offer the right blend of properties. Development work is now needed to further investigate the potential of this powder.