BAE systems developed structural batteries to lighten the load of soldiers carrying rucksacks, which can weigh up to 76kg and be filled with numerous electrical items. The structural batteries store the electrical energy within the physical structure of a device and thus helping to reduce or eliminate the need for traditional batteries, which create weight and bulk, as well as the burden and cost of carrying spares. Potentially the technology could be a substitute for existing carbon-composite structural materials.
Fully operational, rechargeable, structural batteries have been demonstrated based on conventional composites materials and fabrication processes. Virtually any form or shape has proven possible and the physical density and mechanical properties of current materials are similar to unmodified Carbon Fibre Reinforced Polymer/Glass Fibre Reinforced Polymer.
To demonstrate the technology’s application beyond the battlefield, BAE Systems have also applied the technology through a partnership with leading race car manufacturer Lola. The Lola-Drayson B12/69EV, zero emission 850 horsepower Le Mans Prototype car will incorporate structural batteries to power some of the on-board electronic systems. Upon completion, the Lola-Drayson B12/69EV aims to become the world’s fastest electric racing car.
However, the power density of the batteries, the energy they can store for a given weight, is currently quite low – about a third that of a car battery, and a 10th that of the lithium-based batteries used in laptops and phones.
“We’re not particularly high in terms of power density,” Mr Penney admitted.
“We do have a lab demonstrator which is approaching the realms of a car battery,” he added.
Alex Parfitt, Capability Technology Leader for Materials at BAE Systems said: “Structural batteries can be used in virtually anything that requires electricity from small gadgets to entire vehicles. It can not only support our soldiers on the frontline, but also revolutionise technology in the consumer market by allowing more efficient, elegant and lighter designs.”
To develop this technology, scientists at BAE Systems merged battery chemistries into composite materials that can be moulded into complex 3D shapes and so form the structure of the device itself. It can then be plugged in when it needs recharging or utilise renewable power sources, such as solar energy.
The process makes use of nickel-based battery chemistries, which are commonly used in defence technology and future developments will allow integration of Li-ion and Li-Polymer chemistries found in consumer electronic products such as mobile phones, MP3 players, laptops, tablets and portable games. This will not only lead to improved product designs, but eliminating the need to buy batteries will reduce the lifetime cost to the consumer, as well as having environmental benefits.
Current development has demonstrated the ability to store useful energy in composites such as carbon fibre and glass reinforced plastic, but in the future it could also be incorporated into fabric for a wide range of lightweight applications, from tents with their own power supply to making electric blankets a literal reality.
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.
However, the company says it hopes to develop lithium-based batteries that will store more power in the future.