Licube aims to supply lithium-6 fuel for fusion power

If fusion power pans out, the world will need a lot more lithium — and that’s the bet behind Licube, a startup that has licensed technology from Hirosaki University in Japan to purify lithium-6, the form of lithium that fusion plants need to make their own fuel, out of naturally occurring lithium.

Most planned fusion plants would run on a mix of two fuels, deuterium and tritium. Deuterium is easy to come by, but tritium is extremely rare in nature, and it’s an open secret in the fusion world that there isn’t enough of it to power every planned plant. The proposed workaround is to make tritium on site, inside the power plant itself: a fusion reaction gives off a stream of fast-moving neutrons, and startups plan to surround the reactor with a blanket of lithium so that when a neutron strikes a lithium atom, the atom splits into helium and tritium, which can then be collected, purified, and fed back into the reactor as fuel.

Not all lithium does this job equally well. It comes in two forms, lithium-6 and lithium-7, named for their weights; lithium-6 is far better at capturing neutrons and producing tritium, but it makes up only about 7.5% of natural lithium, with the rest being the heavier lithium-7. Separating the two is difficult, and there’s little capacity to do it today, so the world doesn’t have enough lithium-6 either. “If fusion comes online, it should be a $50 billion market by 2040,” Yohei Kiguchi, co-founder and CEO of Licube, told TechCrunch.

Licube’s core technology is based on an electrolyzer, a device that uses electrical current to drive chemical reactions: lithium is dissolved in a liquid on one side of a ceramic membrane, and as current flows from one side to the other, lithium-6 moves faster, letting Licube draw off that liquid and separate the lithium-6. The goal is to enrich the lithium to at least 99.995% lithium-6, which fusion companies can feed into their fuel-breeding systems. Until fusion becomes a major market, Licube plans to use the same technology to purify lithium for the semiconductor, pharmaceutical, fission-reactor, and spacecraft industries. Licube is one of 20 startups presenting this week at TechCrunch Disrupt’s Startup Battlefield pitch competition in San Francisco.

Kiguchi was inspired to start Licube after visiting ITER, the experimental fusion reactor being built in the south of France, while living a couple of hours’ drive away in Monaco, having just retired from his previous company, Enechange, an energy-switching platform network in Japan. The visit convinced him he was too young to retire, and that as someone who describes himself as an energy specialist, he wanted to pursue something bigger.

Why it matters

If Licube’s enrichment numbers hold up, it positions the company as a supplier to an entire generation of fusion startups that all need the same scarce input — a bet that pays off whether or not fusion itself arrives on schedule, since the same lithium-6 purification serves the semiconductor industry and others in the meantime.