New Science Breathes Life Into Ageing Nickel-Metal Hydride Batteries

By Jamie Condliffe on at

Nickel-hydride metal batteries have fallen out of favour in recent years despite their inherent safety, because they're not as small or light as lithium-ion cells. But scientific advances could significantly boost the capacity of the ageing batteries — and make them attractive once more.

Researchers at BASF have recently doubled the capacity of nickel-hydride metal batteries, reports Technology Review, and they have plans to raise that factor from two to eight. They're also aiming to slash costs, making batteries that cost $146 (£95) per kilowatt-hour, which is about half as much as the cheapest lithium-ion batteries.

To boost capacity, the team at BASF is playing with the microstructure of the nickel-based materials used in the batteries. Fine details remain under wraps, but the advances have allowed the team to make the energy storage structure more durable, allowing them to trim weight. In turn, that means the batteries can now provide 140 watt-hours per kilogram, which isa little way off the 230 watt-hours per kilogram of most lithium-ion batteries.

But, crucially, nickel-hydride metal batteries are much safer than Li-ion cells — mainly because they don't contain flammable liquids. While Li-ion batteries can catch fire (surprisingly easily) if they overheat or are overcharged, nickel-hydride metal cells don't suffer such problems. Given safety systems add a further 50 per cent in weight to Li-on batteries, according to Technology Review, that means that, in reality, the two aren't as far from level-pegging as it may seem.

If BASF engineers can push the capacity of nickel-hydride metal batteries by even just a factor of two, they could bring them back into the mainstream. The hope is that their new-found energy density could appeal in use cases where the inherent bulk of the batteries isn't as much of a problem, such as electronic vehicles. [Technology Review]

Image by Andy Armstrong under Creative Commons licence