Dec 7, 2022 • 59M

Working on the cheapest possible lithium-ion battery

A conversation with scientist and entrepreneur Charlotte Hamilton.

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When I was working on my series about lithium-ion batteries (LIBs), one thing I heard from several experts stuck in my head: As production of LIBs scales up and costs continue coming down, eventually the cost of batteries will fall to near the cost of the materials that compose them. That means that the long-term winner of the LIB race will be the battery chemistry composed of the cheapest materials that can perform adequately.

However, as Keynes reminded us, in the long run we are all dead. In between now and that nebulous future are many challenges and uncertainties.


Currently, the leading battery chemistries involve cobalt, nickel, manganese, and lithium itself. All of those minerals are currently mined and processed in socially, economically, and environmentally harmful ways, and with demand rapidly expanding, supply chain shortages loom in the short- to mid-term.

There is one alternative that's coming on strong lately, particularly in China — lithium-iron-phosphate (LFP) batteries, which use iron. However, LFP batteries lack the energy density of their competitors and are not suitable for the high-end electric vehicles that comprise most of the US market today.

The true holy grail for LIBs is sulfur. As Purdue University’s Rebecca Ciez told me for my battery story, “the true least-cost system for a lithium-based, rechargeable battery is lithium metal [as the anode] and a sulfur cathode.” Sulfur is cheap, ubiquitous, abundant, and already produced to the tune of 77 million tons a year. The US is the world’s second largest producer.

What’s more, sulfur’s “specific capacity” (energy it can hold per unit of weight) is higher than its competitors’, so in theory it could compete with or even best other LIBs in energy density. Of course, this has been well known for a while, and people have been pursuing it, but the engineering challenges remain substantial. Lithium-sulfur batteries have not reached the market in any appreciable numbers. Is there a pot of gold at the end of this rainbow?

Charlotte Hamilton
Charlotte Hamilton

Today I'm talking with someone who believes that there is. Charlotte Hamilton is the CEO of Conamix, a company that is working to commercialize lithium batteries with sulfur cathodes. The company was founded in 2014 using technology from Cornell, Stanford, Berkeley Lab, and elsewhere; last year it emerged from stealth, closed a B round of funding, and secured an $8.6 million dollar contract from the federal Intelligence Advanced Research Projects Activity.

I'm excited to talk to Hamilton about why lithium-sulfur batteries are needed, how close they are to commercialization, how easily they could fit into current LIB production infrastructure, and what kinds of technological advances they could bring in their wake.