The Li-ion batteries that are commonplace today in EVs, home storage systems, laptops and other consumer electronics are impressive, but not without their problems. The two that everybody should be aware of are that they have a limited number of charge cycles, losing a little of their capacity with each cycle, and they have a nasty habit of catching fire when damaged, or overheated.
Perhaps less well known, they are also dependent on cobalt. Cobalt’s price has been increasing, but far worse than that it has also earned the title of the “blood diamond of batteries” – with mines in Congo being accused of all kinds of human rights violations, and use of children. Unsurprisingly, the larger producers of batteries are working to eliminate the need for cobalt from their technology.
Solid State Batteries
Replacing the cobalt in the Li-ion battery chemistry is a short(er) term solution. Slightly further out is the promise of solid state batteries. Unlike Li-ion, these do not need a liquid electrolyte, and research suggests they will also achieve much higher energy densities. The lack of the liquid electrolyte makes them less likely to catch fire when damaged too.
Audi announced a concept car at Pebble Beach this year, the PB18 e-tron, which checked a lot of the boxes for a typical concept car, but also included a “liquid-cooled solid-state battery.” A solid state battery capable of delivering the power needed for a high performance EV is an achievement. The VW group has been a big investor in a silicon valley startup working in this space called Quantumscape. Their website just says “Solid-State Batteries That Work.”
The inventor of Li-ion batteries, John Goodenough, is also working on solid state battery technology and has recently published a paper suggesting he had created a solid battery chemistry that not only has higher density, lower fire risk and uses no cobalt, but it can also be cycled tens of thousands of times (compared to around one thousand for Li-ion cells used in EVs and storage solutions today). The strangest thing about this battery, and this is calling into question the results documented in his paper, is that it actually increased in capacity with each cycle.
Solid state batteries are all well and good, but they are still batteries and they still need to be recharged. The Audi PB18 claims, with its 800V technology, that it can charge in 15 minutes, but that is still longer than it takes to pump fossil fuels into the tank of a typical ICE vehicle.
Enter the chemists from the University of Glasgow and their hybrid electric-hydrogen flow battery. Capable of storing energy to be released either as electricity or hydrogen, the most interesting part of it is that the energy is stored in a liquid. When the nano-molecules that store the energy are kept in a concentrated solution not only does their storage capacity increase (giving these batteries a higher energy density than today’s Li-ion technology too), but the charged liquid can be pumped into the battery more like a fuel. Unlike a fuel, however, the old liquid is removed at the same time and can be recharged for use again.
Current generation Li-ion is going to be the way we start moving away from burning fossil fuels towards a cleaner, renewable energy future, but it does not look like it will reign supreme for long. Battery technology is suddenly accelerating as the demand for energy storage grows at all scales, from the massive installations utilities will need to help smooth out the supply all the way down to our vehicles and even homes.