Fitness company Whoop has a new tracker that squishes five LEDs, four photodiodes, a pulse oximeter, skin temperature sensor, and more into a package that is 33 percent smaller than its predecessor — all while still offering five days of battery life. But a particular change to the tracker’s battery chemistry is one of the biggest reasons Whoop was able to do all this in the first place.
The change was pioneered by a Silicon Valley company called Sila Nanotechnologies, which was co-founded in 2011 by Gene Berdichevsky, one of Tesla’s earliest employees. And it’s one that, if it scales up, could help break some of the biggest limitations currently facing lithium-ion technology.
On paper, it’s a simple change: the battery’s anode is now made of silicon instead of graphite, which allows for greater energy density (up to 20 percent, Sila claims). Greater energy density means device makers can use a smaller battery to accomplish the same tasks — or free up more space to do things they couldn’t before. And it doesn’t require any hardware changes to the cell production process. In fact, that’s one of Sila’s biggest selling points to battery makers: its silicon anode is more or less plug-and-play.