Ionblox.

Ionblox is a company in Fremont, California - which is where a great many battery companies are, for reasons involving proximity to Tesla, to Applied Materials, and to a lot of people who have spent their careers thinking about electrochemistry. It was founded in 2017 by Sujeet Kumar and Herman Lopez, and for its first several years it was called Zenlabs Energy, which is a fine name, and in 2022 it became Ionblox, which is a slightly more energetic name. The rebrand roughly coincided with the company raising money and getting a customer that made people pay attention, which we will get to.

The thing you should understand about Kumar and Lopez is that they have done this before. Kumar was the CTO of Envia Systems, where, per the company, his team built the world's first lithium-ion battery hitting 400 watt-hours per kilogram using a silicon anode. This is the kind of resume line that matters in batteries specifically because batteries are a field where the gap between "we did it once in a lab" and "we ship it" has swallowed enormous amounts of capital and enthusiasm. Having already crossed part of that gap once is not a guarantee. But it is not nothing.

The trick has a name: pre-lithiation

The core of what Ionblox does is a process called pre-lithiation, and the intuition is almost embarrassingly simple once someone explains it. When you first charge a fresh lithium-ion cell, some of the lithium gets permanently consumed forming a layer on the anode - the solid electrolyte interphase, if you want the term. With graphite this is a modest tax. With silicon it is a much larger one, because silicon is reactive and the swelling keeps exposing fresh surface. So the cell loses a chunk of its capacity on day one, before you've done anything useful with it.

Pre-lithiation is the accountant's answer to a chemistry problem: stuff extra lithium into the anode ahead of time, so that when the cell pays its first-cycle tax, it pays out of the surplus rather than out of the capacity you actually wanted to keep. Ionblox holds patents on doing this to silicon-based anodes, and it pairs its pre-lithiated silicon-oxide (SiOx) anode with a high-nickel NMC cathode. The result, the company says, is a cell that exceeds 330 Wh/kg, charges to about 60% in five minutes and 80% in ten, and does this for more than a thousand cycles. That is the pitch: fast, dense, and long-lived, three things that usually come at each other's expense.

The customer who became an investor

Now, the interesting corporate-finance detail. In 2022 Lilium, a German company building an all-electric vertical-takeoff jet, selected Ionblox's cells for its aircraft. This is a good customer relationship. What makes it a notable one is that Lilium didn't only agree to buy cells - it led Ionblox's Series B, putting equity into its supplier. Applied Ventures (the venture arm of Applied Materials) and Catalus Capital came in alongside, for an initial $24 million in October 2022. Then in February 2023 the round grew to $32 million, with Singapore's Temasek and Catalus adding to it.

When a customer invests in its supplier, it is telling you two things at once. One, it really wants that supplier to survive, because it has designed its product around them. Two, it has looked at the technology closely enough - closer than an ordinary investor ever would - and still wanted in. For a battery startup, a strategic aviation investor is a form of due diligence you can put on a slide.

Why aviation is the hard, honest customer

Electric aircraft are a brutal proving ground, which is exactly why they are useful. A car can be a little heavy and still work. An aircraft that is a little too heavy does not take off. eVTOL flight demands high power (to lift), high energy (to go somewhere), and high cycle life (because you cannot replace battery packs every month on an aircraft and have the economics survive). Those are the same three axes Ionblox claims to win on, which is presumably not a coincidence. If your cells satisfy an aircraft, satisfying a car is, comparatively, a step down in difficulty.

And Ionblox has leaned on third parties to make the case rather than its own marketing. Idaho National Laboratory validated a thousand charge-discharge cycles from its silicon-anode cells. An independent lab reported 88% energy retention after 800 full-depth cycles on the Lilium-bound cells, comfortably above the 80% target. The cells earned UN 38.3 certification - the transport-safety standard - in 2023. None of these are the kind of thing you tweet, and all of them are the kind of thing that determines whether a battery company is real.

Two markets, one chemistry

Ionblox's strategy is to point the same underlying cell technology at both aviation and automotive. On the car side it has taken government development money - contracts from the United States Advanced Battery Consortium (USABC), which channels Department of Energy funding, including a $4.8 million award back in 2019 as Zenlabs and a $3.5 million contract in 2022 - to build low-cost, fast-charging EV cells. In late 2023 it also signed a joint development agreement with the Australian firm Gelion aimed at battery chemistries that skip nickel, cobalt and graphite entirely, which is a different and more speculative bet about where cost and supply chains go next.

The risk in serving two demanding markets at once is the obvious one: focus. The upside is that the aviation work is a credibility engine for the automotive work, and the automotive market is where the volume - and the money - eventually is. In 2024, TIME and Statista named Ionblox one of America's top greentech companies, which is a nice piece of external validation to hang next to the lab reports.

The part nobody can promise yet

It is worth being honest about what is unproven. Ionblox is a small company - somewhere in the range of a few dozen people - and everything above describes cells at prototype and qualification scale, not a mass-production line humming out millions of units at a competitive cost. The graveyard of battery startups is full of teams whose lab coupons were genuinely excellent and whose factories never quite closed the gap. Ionblox's whole architecture - the third-party validation, the strategic customer, the government contracts, the patent wall - is arguably designed around surviving that gap. Whether it does is the only question that ultimately matters, and it is not one a profile can answer. What can be said is that the bet is a coherent one: take the material with the most headroom, fix its worst flaw, and let independent labs tell the story.