With the demand for batteries for electric vehicles (EVs) expected to exceed 4,500-gigawatt hours by 2040, lots of companies are trying to find ways to satisfy this demand.
Silicon nanoparticles are a potential solution for improved battery capacities, and Advano, a New Orleans start-up, is hoping to help out battery makers by producing it at scale using conventional manufacturing techniques.
This is because silicon has ten times as much storage as graphite, the material currently used in a lithium-ion (Li-ion) battery’s anode. If graphite in a battery’s anode can be replaced with silicon, it will have a much higher capacity and enable EVs to run for longer.
However, silicon bloats during charging up to three to four times its size, which is dangerous and can rupture a battery’s internal structure, breaking it completely. This is because silicon and lithium combine to form lithium silicide, a bulky alloy. In contrast, graphite does not bloat at all because during charging, graphite slips lithium ions between its one-atom-thick layers, a process known as intercalation.
Advano official company logo. Image Credit: Advano.
A Top-Down Approach to Solving Silicon Bloating
Advano is attempting to sidestep this problem by taking a top-down approach. Instead of attempting to fine-tune the microstructure of silicon by building it from the bottom-up, the company is instead producing silicon particles in massive quantities that are less-than-perfect but still good enough for use in Li-ion batteries.
“We start with bulk material and reduce the size; it’s like grinding, and it’s infinitely scalable,” says Alexander L. Girau, the founder of Advano. “True, you get a wide distribution of sizes; it’s not as controllable as a bottom-up process, where you start with a gas or liquid and then make it self-assemble. Again, that would be a beautiful, finely tuned material. But how the hell do you scale?”
To do this, Advano grinds down bulk material–usually repurposed silicon, such as that found in old solar panels—until the resulting nanoparticles are good enough. Repurposed silicon is processed into nanoparticles and these are then incorporated into a micron-scale carbon matrix. Subsequent chemical treatment then causes fibers of silicon carbide to grow, creating a ‘fuzz’ that links up to other particles for structural support.
“It looks like graphite, and we can process it like graphite, but it has silicon on the inside,” says Girau. “And we protect the silicon surface from degradation.”
Scaling Up Production Alongside Demand from Battery Manufacturers
Advano claims that it can currently produce up to one ton of silicon nanoparticles each year and that it will soon begin production at a new facility with ten times the capacity. Although this amount is still relatively low when compared to the company’s goals, the idea is that as Advano scales up its process, battery manufacturers will incorporate varying amounts of nanoparticles to improve capacity.
“That’s peak production capacity—we actually make kilograms per day, which is what customers want to test”, added Girau.
And because Advano is using conventional techniques that are typically reserved for graphite anodes, it is easier for the company to tap into pre-existing supply chains. Ultimately, Advano hopes to drive the price of silicon nanoparticles down to $500-10,000 per kilogram to between $15-150 per kilogram.
Advano is a small company with only 20 employees at the time of writing. It has raised a sum of $12 million of venture capital for its research and has previously partnered with Mitsui, a Japanese battery materials company that supplies Japanese OEMs.