Model 3 batteries with 10% silicon anodes for higher energy density and lower cost

Sanford C. Bernstein’s Mark Newman wrote to his clients on March 31 describing a significant advance in battery technology that would make the Model 3’s batteries far more energetic and cheaper than anything else on the market.

Telsa’s Model 3 batteries, made by Panasonic, start with a negative electrode—an anode—made up of 10% silicon

A large part of the battery research field has been focused on creating a working silicon anode because the resulting battery would be significantly more powerful. Graphite anodes, the current standard, store one lithium atom for every six carbon atoms (lithium being the energy in a battery). The more lithium, the more energy. But silicon anodes can store up to 4.4 lithium atoms for every silicon atom.

Fortune discussed the usage of more silicon in the battery anode earlier in 2015.

The 10% silicon provides a 30% boost in energy density.

The trouble with it, though, has always been swelling. When you use silicon, and start charging and discharging, the anode swells, eventually causing the battery to self-destruct.

The Model 3 battery will achieve energy density of 300 watt hours per kilogram, and cost $200 per kilowatt-hour.

The Telsa model 3 has 325000 pre-orders in its first week. That is $14 billion in implied future sales.

After 30% silicon anodes then anodeless batteries

Solid Energy Systems is developing “Anode-less” battery designs with ultra-thin metal anode improves the cell-level energy density by 50% compared to graphite anodes and 30% compared to silicon-composite anodes.

It would be a new kind of lithium-ion battery that could let portable electronics such as smartphones and smart watches last twice as long between charges.

The secret to boosting energy storage lies in swapping the conventional electrode material—graphite—for a thin sheet of lithium-metal foil, which can store more lithium ions.

Battery makers have been trying to use lithium-metal electrodes in batteries for decades, with only limited success. SolidEnergy seems to have solved a couple of key problems, which have caused such batteries to either stop working after a few charges or burst into flames

SolidEnergy’s solution is to use both a solid electrolyte and a liquid one. The solid electrolyte is applied to the lithium-metal foil—the ions don’t have far to travel through this thin material, so it doesn’t matter that they’re moving relatively slowly.

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