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If we are going to stop burning fossil fuels, it is critical that we have access to electricity from renewable sources like wind turbines and solar panels. But we can’t rely on the wind blowing or the sun shining exactly when we need power. We need a way to store electricity – and in many cases that is going to mean batteries.

Yet batteries themselves aren’t without their environmental problems. The rechargeable lithium-ion batteries in electric cars rely on lithium, among many other metals. Sizeable lithium reserves are found in only a few places: the element has to either be extracted from huge salt flats in the Atacama desert in South America, which involves using up vast amounts of water, or be obtained by environmentally destructive conventional mining of the mineral spodumene in China and Australia. This is one major reason why chemists want to design a more sustainable battery.

Lithium’s job inside a battery is to carry charge from one side to another. It does this so well because its ions are so small. Their +1 electric charge is crammed into a small space, meaning lithium batteries fit lots of power into a small, light package. But there are other contenders for this charge-carrying role. One is sodium, which has the same +1 charge as lithium and is only a little larger. It is also extremely easy to source, given that it is part of the salt in seawater. Sodium-ion batteries have to be larger to pack as much punch as their lithium cousins, but for some non-portable applications, like storing solar-generated electricity, that is fine. UK-based firm Faradion has supplied sodium-based batteries for heavy goods vehicles in India.

There are many more options for battery chemistry out there, however, including using other ions, such as magnesium. The trouble is, changing the charge carrier often means redesigning other parts of the battery too, so that everything works in synchrony.

Crucial components of all batteries are the electrodes, which in the case of lithium-ion batteries are made using cobalt. This metal is even more problematic than lithium, being mined in only one location, the Democratic Republic of the Congo, often by young children working in awful conditions.

Ideally, we would design new battery systems that work without cobalt. This involves trying out lots of combinations of materials to find the sweet spot of high performance and sustainability, a time-consuming process. , UK, has been experimenting with a way of making prototype electrodes in a microwave in just 20 minutes. It is much faster than the usual methods, but it will still probably take a lot of pings before we have the perfect battery.