Sila recently announced that it has raised $70 million to expand its new silicon-lithium battery technology from prototype to commercial scale. The company claims that its technology can increase the capacity of lithium-ion batteries by 40%.
By optimizing existing materials, lithium-ion batteries have been able to achieve performance improvements of around 5% per year. The most straightforward way to increase battery capacity is to increase the amount of lithium ions stored in either electrode. To date, most of the improvement in battery life has been achieved through certain combinations of nickel, manganese and cobalt in the cathode. When these metals are bonded together, their crystal structure can store lithium ions more efficiently, and it is easier to move ions through the cathode to the anode than other materials. But the anodes are basically made of the same material - graphite.
Many companies are currently experimenting with silicon to make higher capacity anodes. In theory, they can store up to 25 times more lithium ions than similarly sized graphite anodes, but all failed because the silicon anode ruptures under the pressure of many lithium ions. Sila tried to solve this problem by filling silicon atoms in a relatively empty nanoparticle matrix. When the silicon anode absorbs lithium ions, the ions fill the voids rather than squeezing the silicon atoms, ensuring that the structure does not break.
Sila said that after seven years of development, its silicon anode lithium battery technology has been proven in small electronic devices such as wireless headsets, smart watches and smart phones. The latest injections from investors, including Samsung and Siemens, will help Sila to build a facility in Silicon Valley with an annual capacity of 20 megawatts of battery capacity, enough to power 2 million smartphones or 10 million smart watches.
If successful, Sila will switch to manufacture large batteries that power electric vehicles. Earlier this year, the company had established a partnership with BMW, and BMW said it was willing to be the first car manufacturer to use silicon-lithium batteries.