Since lithium ion batteries were invented in the 1980s, anodes have been made of graphite, which is extracted or processed almost entirely in China.
The battery anode serves as a reservoir for lithium ions. When the battery is charged, the ions fill the spaces between layers of graphite. When the battery is discharged, the ions flow out toward the other side of the battery, called the cathode. Most recent advances in battery chemistry have been achieved on the cathode side.
Graphite works well as an anode material, but it comes with extra weight and volume that serve no purpose. Some automakers, including Tesla, have already been sprinkling in small amounts of lightweight silicon, which helps an otherwise identical battery charge faster and store more energy.
But the problem with silicon — and it’s a big one — is that it expands three times in size as the battery fills up with lithium ions. Even at low concentrations of silicon, the swelling can quickly degrade the battery. High-end batteries today use roughly 5 percent silicon in the mix.
The trick to making batteries with more silicon content is figuring out how to prevent expansion by encapsulating the silicon particles in some kind of binding structure.
Sila’s solution is a Swiss cheese-like scaffolding that surrounds the silicon particle and allows it to expand into the pores of the structure without damaging the outer shell.
Sila’s tiny capsules limit expansion to just 6 percent, according to the company, which is similar to graphite.
After 1,100 charge cycles — equivalent to more than 300,000 miles of driving — the battery retains 80 percent of its starting capacity. That is also on par with graphite batteries.
For the first few years of accelerating production, Titan will be sold at a premium, to be used in high-end long-range vehicles.
Once silicon-based anodes reach full production, Berdichevsky says they will cost significantly less to make than graphite and he expects them to quickly become the industry norm.