There are many rechargeable battery chemistries, each with their own advantages and disadvantages. Currently lithium-ion and similar (e.g. Li-Po) rule the roost due to their high energy density at least acceptable number of recharge cycles, but aluminium-ion (Al-ion) may become a more viable competitor after a recently published paper by Chinese researchers claims to have overcome some of the biggest hurdles. In the paper as published in ACS Central Science by [Ke Guo] et al. the use of solid-state electrolyte, a charge cycle endurance beating LiFePO4 (LFP) and excellent recyclability are claimed.
It’s been known for a while that theoretically Al-ion batteries can be superior to Li-ion in terms of energy density, but the difficulty lies in the electrolyte, including its interface with the electrodes. The newly developed electrolyte (F-SSAF) uses aluminium-fluoride (AlF3) to provide a reliable interface between the aluminium and carbon electrodes, with the prototype cell demonstrating 10,000 cycles with very little cell degradation. Here the AlF3 provides the framework for the EMIC-AlCl3 electrolyte. FEC (fluoroethylene carbonate) is introduced to resolve electrolyte-electrode interface issues.
A recovery of >80% of the AlF3 during a recycling phase is also claimed, which for a prototype seems to be a good start. Of course, as the authors note in their conclusion, other frameworks than AlF3 are still to be investigated, but this study brings Al-ion batteries a little bit closer to that ever-elusive step of commercialization and dislodging Li-ion.
All the time the same history, all on the paper, nothing on the shelves
The energy density is terribly low for those batteries, that’s why. It might be useful for energy storage for the grid, not for a car or a plane, since it has both the endurance and low cost advantage.
And again, energy storage for the grid doesn’t require batteries that last umpteen million cycles, but batteries that are extremely cheap, take very little energy to make, and can sit on the shelf virtually forever without degrading or discharging.
You want a huge battery that is charged up slowly whenever you have a surplus, to release it some time during the next year when you have a shortfall. You want to stockpile months worth of energy and keep it stored for later – to shift energy between seasons and for keeping a couple months worth of strategic reserve in case a hurricane wipes out half of your wind and solar farms. That means your big battery will only undergo a couple dozen full charge cycles in its life.
Suppose it costs $100 per kWh of capacity to make the battery, but you’ll only fully cycle it 100 times over the years. That means you pay $1 per kWh of energy stored in the battery. To make it a viable energy stockpile for the grid, it must cost less than $10 per kWh of capacity to manufacture. No battery on the market or in research is anywhere close to that price point, which is why battery storage on the grid is only good for short term load balancing where the marginal cost of electricity is high and the required storage capacity is measured in minutes and hours.
That is not what battery energy storage is for. In the Netherlands, they calculated that 8 days is the once-in-25-year maximum without solar or wind energy going above it’s avereage levels. It might vary in other climates. But battery are not meant for seasonal variations, much more for the daily peak shaving. And due to the intricacies of the power market, 500 full load cycles a year is not a weird number.
“energy density potential for aluminium-ion batteries is 1060 Wh/kg in comparison to lithium-ion’s 406 Wh/kg limit.” according to Oak Ridge National Labs, sez wikipedia.
And, given that aluminum is 5 times the density of lithium, there is the potential to make the batteries substantially smaller as well.
Aluminum is a heck of a lot cheaper than lithium too.
It will be interesting to see how this plays out.
The amount of lithium in Lion-batteries is neglegible, about 1,5%. Replacing that with aluminium isn’t gonna change that a lot.
Aluminum can also be mined pretty much anywhere in the world, whereas lithium deposits are more localized.
You can buy sodium-ion batteries on amazon now, for what it’s worth.
Yeah. It’s just that they’re not better than lithium-ion batteries and they’re not even cheaper for the capacity. The only advantage is that they don’t contain lithium.
And I thought lithium ion batteries were toxic. The SDS for fluoroethylene carbonate has all sorts of warnings.