The batteries in our portable devices never seem to be big enough, in fact in some cases they seem to be getting worse. Gone are the days when forgetting to charge your phone for days at a time wasn’t an issue and you’ll be lucky to get a full day’s worth of use out of your laptop before it starts screaming to be plugged back into the wall. The cold hard fact of the matter is that storing electrical energy in a portable fashion is hard as energy density is often a function of surface area, meaning those lovely slim smartphones you love are at odds with increasing their battery life. Of course there are always improvements to be made however many breakthroughs in one aspect or another usually come at the cost of something else.
Take for instance the latest announcement to come out of Stanford University which shows a battery that can be fully charged in under a minute and, if its creators are to be believed, replace the current battery tech that powers all our modern devices. Their battery is based on a technology called aluminium ion which works in a very similar way to the current lithium ion technology that’s behind most rechargeable devices. It’s hard to deny the list of advantages that their battery tech has: cheaper components, safer operation and, of course the fast charging times, however those advantages start to look a lot less appealing when you see the two disadvantages that they currently have to work past.
The voltage and energy density.
As the battery tech stands now the usable voltage the battery is able to put out is around 2 volts which is about half the voltage that most devices currently use. Sure you could get around this by using various tricks (DC step up converter, batteries in series, etc.) however these all reduce the efficiency of your battery and add complexity to the device you put them in. Thus if these kinds of batteries are going to be used as drop in replacements for the current lithium ion tech they’re going to have to work out how to up the voltage significantly without impacting heavily on the other aspects that make it desirable.
The latter problem is the more difficult one and is something that all new battery technology struggles with. With any battery tech you’re usually balancing quite a few factors in order to make the best tradeoffs for your particular use case however one of the most typical is between charge times and the amount of power you can store. In general the quicker your battery can charge the less dense it is energywise, meaning that fast charge time comes at the cost of usable life once it’s off the charger. Indeed this is exactly the issue that the new aluminium ion battery is struggling with as its current power density does not match that of lithium ion.
Now this isn’t to say that the idea is worthless, more that when you hear about these amazing kinds of batteries or supercapacitors (different kind of technology, but they’re an energy storage medium all the same) that have some kind of revolutionary property your first reaction should be to ask what the trade offs were. There’s a reason why sealed lead acid, nickel metal hydride and other seemingly ancient battery technologies are still used the world over; they’re perfect at doing the job they’ve found themselves in. Whilst charging your phone in a minute might be a great thing on paper if that came with a battery life that was a mere 20% of its long charging competitors I’m sure most people would choose the latter. Hopefully the researchers can overcome their current drawbacks to make something truly revolutionary but I’ll stay skeptical until proven otherwise.
