Torches, drones and an electric Le Mans racing car are all test-beds for a new kind of "structural battery", BAE Systems has said.

The batteries use carbon fibre and can form part of the body of a device.

By effectively building the power source into the fabric of an object they can save weight.

The batteries are nickel based. Originally intended for use in the military, they had to be resistant to fire and have a long working life.

"You need a battery chemistry that will last for many decades, you basically can't just take a wing off and throw it away as you would a mobile phone [battery]," Mr Penney said.