Batteries hold a strong place in today’s lifestyle, from remote controls, mobile phones, to hybrid and all-electric car batteries. Battery research is one of the hottest subjects in material science, with researchers promising new creative ideas from their labs. Despite battery capacity slowly increasing in recent months and years, we need something radical to appear that could already have been invented; locked away in a lab somewhere.
Right now, batteries cost roughly $300 per each kiloWatt-hour. For all-electric cars to become a serious and affordable contender to rule out fossil fuels, we need that figure to drop to around $100. Dropping the price could be easy, just increase the size of the battery. However, for electric cars to take off, they need to have small enough batteries that can provide long-term power supply. Currently electric vehicles (EV’s) have a battery density of around 200 W-hr/kg, that needs to rise to around 600 W-hr/kg.
Today’s batteries contain lithium, pretty good for what we’ve got out of them, but researchers have started playing with silicone. Using silicone, can yield 1 silicone atom for every 4.4 lithium atoms. The problem with using silicone? The massive expansion under load.
They first experimented with silicon nanowires, adjusting the spacing enough to allow for expansion, the issue here is after a few charge and discharge cycles; the nanowires lose form and become a mess, losing all benefits to using silicon.
Tests then moved on to using solid wire inside a silicon shell and then placed inside a rigid shell. The issue with this again is the expansion of the silicon. Tests proved that the silicon expanded to the extent of breaking the shell beyond safe use.
At this point, the researchers changed their field of view to self-fixing polymers, which basically rearrange hydrogen bonds to potentially restore breaks. They coated their silicon beads with this polymer and if a break does occur they will gradually heal over the breaks “While you’re sleeping, your battery can self-heal” Cui, head researcher, said.
There is now a commercially available 270 W-hr/kg battery on the market, with a 360 W-hr/kg version on the way. However, we do not know on which of the previous technologies this is based on.
To read more on this subject, see ArsTechnica’s full coverage here.