What they took out paid for the production line

Flint’s paper battery is usually described by what it removes. Carlo Charles’s even more interesting point is that removing the materials also removed a lot of machinery, and that is why two products reached production on roughly US$4 million.

Asked what is inside his battery, Carlo Charles starts with what is not.

No lithium. No nickel. No cobalt. No fluorine. No lead. No cadmium. No solvents. No NMP. No PFAS.

Flint refers to it as the Power of No.

“What we remove is equally as important as what goes inside,” the founder and chief executive of Flint said in the interview.

What remains is four things. Manganese, which he notes is abundant, safe and present in food and in the body. Water as the electrolyte, in place of flammable or solvent-based alternatives. Zinc. And cellulose, the material that holds and binds the rest together.

That is a sustainability story, and it is the one the company is usually described by. It is also the less commercially interesting half of what he said.

The consequence of removing those materials is that you can also remove the equipment that exists only to handle them.

Carlo’s worked example is solvent recovery. A conventional lithium production line requires NMP solvent recovery systems to manage the drying ovens. Flint does not use NMP or solvents.

“So we can strip that entire recovery system and tell the manufacturer, we don’t want that.”

Repeat that across a line and the capital requirement changes shape. A normal battery production line, on his figures, costs somewhere between US$2 million and US$5 million. Flint built theirs for under US$500,000, by buying only the necessary off-the shelf machinery combined with designing certain key components in-house and stripping out what the chemistry made unnecessary.

The same logic shows up in the process itself, which he says went from 16 steps to six.

The aggregate claim is the one investors will test. Two products in production in under 12 months, supported by six core inventions with more than 40 patents filed across different jurisdictions, on roughly US$4 million raised to date. He contrasts that with battery companies raising US$20 million or US$100 million to bring a single product to production.

Whether those comparisons are like for like is worth asking. But the mechanism behind the efficiency is coherent rather than lucky, and it follows directly from the chemistry choice. It is also the result of a capital-light strategy choosing to work with selected contract manufacturing partners for scaling up, avoiding the CapEx.

Carlo’s view of the competitive position is a view about sunk cost.

Most of the industry, in his description, is iterating. Making a slightly better lithium battery, or a slightly different one. The work Flint has done sits at the materials level and is built from the ground up.

For a manufacturer producing lithium cells at billion-unit scale, switching is not a technical problem so much as an abandonment problem. Decades of supply chain, and billions of dollars of investment, are configured around a different set of inputs.

“It will be very hard to change to our material, our process, our chemistries,” he said. “I guess that is one of the biggest advantages we have right now as a startup, where we can just move fast, pivot and scale really quickly.”

That is the standard incumbent-inertia argument. It is more persuasive here than usual, because the thing being displaced is not a product feature but a procurement system.

The most deliberate part of the business is how little of it is written down in public.

Flint files patents only on what leaves the factory, which is the battery itself. Carlo’s test is reverse engineering: if a battery expert with the right equipment could determine it from a finished cell, it gets filed.

Everything upstream stays unfiled. Material density. Particle size. The synthesis process. Those are held as trade secrets, on the reasoning that a filed patent is published knowledge.

“We want to protect it the same way Coca-Cola protects their secret recipe,” he said. “Only very few people know the actual recipe, and in some cases they don’t even file for those recipes for patents, because if they file it becomes public knowledge.”

Two operational choices reinforce it. Patent work is distributed across several law firms, so no single outside party sees the whole picture. And the battery powder itself, the “secret sauce”, is produced inhouse in Flint’s own facility, with partners carrying the scale-up around it.

The strategic intent is to stay asset-light. The company’s balance sheet is not meant to carry the factories, which means the IP and the ability to commercialize it have to carry the valuation.

He is also candid that this is a budgeting exercise rather than a maximalist one. “Spending more on IP is also very dangerous,” he said, framing it as a balance between protection and burn.

Flint reports more than500 inbound inquiries, with more than 120 NDAs signed with customer prospects, of which more than 20 of those are Fortune 500 / Fortune Global 500 companies. Logitech is a public example of a customer already progressing through supplier onboarding.

Carlo’s read is that two unrelated pressures arrived at once, and neither is actually about sustainability, although that issue is clearly driving a lot of enquiries.

The first is geography. Most battery manufacturing sits in China, and a large share of the companies approaching Flint are looking to move out of that ecosystem.

The second is regulation. European rules are moving to the materials level, with carbon reporting obligations and PFAS removal requirements approaching at the end of the decade. Flint’s position is that its chemistry already complies, which converts a future compliance cost into a present switching argument.

“If you want to switch, now is the time,” he said.

That is the more durable commercial logic. Supply chain relocation and regulatory deadlines are budgeted decisions with dates attached, which is a different kind of buyer from one motivated by preference.

The useful part of Carlo’s account of the last six years is that he lists the objections rather than the milestones.

It started as close to impossible. Then a working prototype existed, and the objection became that it was a low-power battery. He says voltage now reaches up to 4.2 volts. Then the objection was that it could not be rechargeable, and then that it would manage only a few cycles. He now puts cycle life at up to 1,000.

Those are company figures. Flint has not published a white paper and describes its design details as proprietary, so they are not independently verified, and the 4.2 volt figure in particular invites scrutiny given that the underlying zinc and manganese dioxide chemistry is the same family as alkaline cells, which deliver around 1.5 volts.

What is verifiable is that customers are testing. Carlo says they receive batteries, test internally, and that Flint has passed technical validation with them, but all those test results are naturally confidential.

On his own account, the remaining risk is execution rather than chemistry.

Flint has a production facility in Singapore with capacity for 5 million ultra-thin pouch cell batteries, and is scaling in Europe and China with the help of production partners. Getting from there to the hundreds of millions its customers would require is a matter of certifications, factory audits and throughput.

“The chemistry has been proven, it has been validated, and now it is just bringing it to the masses.”

That framing deserves one qualification the interview does not supply. A company whose remaining risk is scaling is a company whose remaining risk is capital, timing and counterparties, and those have ended more battery ventures than chemistry has.

The paper battery gets attention for the thing that is easy to photograph.

The more interesting claim is structural. Flint removed a list of materials, and in doing so removed the equipment, the solvent handling, the recovery systems and roughly ten process steps. The sustainability case and the capital efficiency case are the same decision viewed from two directions.

If that holds at a hundred times the current volume, the company’s advantage is not that its battery is greener. It is that it costs less to build the means of making it.