Want batteries fit for the Grid? Just add copper
We almost headlined this “material other than graphene makes splash in battery research”, but then decided that would be silly and childish.
But it is true.
Researchers at Stanford University report a breakthrough in electrode technology they say could make it possible to build rechargeable batteries that could be used to store excess power on a national grid – for example from wind farms or solar arrays.
Lab tests showed that an electrode made with copper nano particles was capable of maintaining 80 per cent of its original charge capacity through 40,000 recharge cycles. By contrast, traditional lithium-ion batteries can usually be recharged around 400 times before deteriorating beyond usefulness.
Behind the long life of the electrode is the open crystalline structure of copper hexacyanoferrate and the choice of hydrated potassium ions over sodium or lithium, for example. The hydrated potassium is the same size as the gaps in the copper crystal, allowing free movement of the ions within the electrode, without damage to the structure.
The charge/discharge cycle very fast – another advantage if you need to use the battery on the national grid. In part this is to do with the size match between the crystal lattice and potassium ions, but it is also to do with the size of the particles of electrode material: just 100 atoms across.
The researchers say they were looking for a new chemistry for a battery on a different scale. Energy density – a major advantage of Li-ion batteries – is not so important if you don’t need to power a mobile device. The battery could be the size of a house and still be useful.
"At a rate of several cycles per day, this electrode would have a good 30 years of useful life on the electrical grid," said Colin Wessells, a graduate student in materials science and engineering who is the lead author of a paper describing the research, published this week in Nature Communications.
As for commercialising the breakthrough: "There are no technical challenges to producing this on a big-enough scale to actually build a real battery. We put chemicals in a flask and you get this electrode material. You can do that on any scale," Wessells said.
The team says it has some promising candidates already lined up for the anode, so watch this space.