QuantumScape, a battery startup backed by Bill Gates and Volkswagen, said its new technology is on track to be able to power cheap, long-range electric vehicles within four years.

The company’s lithium-metal battery offered greater capacity in testing than similar-size current lithium-ion batteries, could recharge more quickly, and could operate at low temperatures, the company said Tuesday. The battery could also be recharged repeatedly without degrading, avoiding a common problem with batteries.

QuantumScape argued that its technology would be cheaper for car manufacturers and provide cars with power over a longer period of time. If the company can manufacture the new batteries in large numbers, they could displace the lithium-ion batteries currently used by companies like Tesla and Chevrolet.

“That’s really our goal, to build a battery that could help EVs become more mainstream,” CEO Jagdeep Singh told Fortune. “The potential now exists for this technology to make its way into real cars on real roads within the next few years.”

Still, the demonstrations were carried out on a small version of QuantumScape’s battery, about the size of a thick playing card, instead of the hefty battery packs used in cars. The company must still prove that it can manufacture larger batteries and in high quantities.

Volkswagen has agreed to invest up to $300 million in the startup, taken an ownership stake, and also agreed to partner with QuantumScape on a manufacturing joint venture. Volkswagen has said it’s looking to produce car batteries with QuantumScape’s technology in 2025.

For QuantumScape, ramping up production will take time. If all goes as planned, it expects revenue to grow gradually from $39 million in 2025 to $275 million in 2026 to $3.2 billion in 2027.

“We’d love it to be faster than that, but the reality is you can’t,” Singh said. “Where we are today is, we’ve got the materials, we’ve shown they work, and now we need a good team that knows what it’s doing scaling up production and building factories.”

QuantumScape appears to be taking the lead in a crowded field. A number of startups are working to improve batteries as are the big automakers. Tesla said in September that planned modifications to its batteries will lower costs and increase range without requiring new technology. However, Tesla CEO Elon Musk has previously made big promises about batteries and then failed to achieve them.

One of QuantumScape’s key innovations is to replace the liquid in today’s lithium-ion batteries with a strip of metal. That makes the batteries smaller and is supposed to make them safer, since the liquid in today’s batteries is combustible.

In its demonstrations, QuantumScape said it was able to recharge a depleted battery to 80% full in just 15 minutes, about one-third the time required by today’s EV batteries. It also ran the battery at temperatures as low as –30 degrees Celsius. And the company frequently recharged the battery over time to show that it could power a car over hundreds of thousands of miles, just as good as today’s battery technology.

QuantumScape went public last month by merging with a special purpose acquisition company called Kensington Capital Acquisition. That has drawn additional scrutiny, since other companies that have used the technique, like emission-free vehicle builder Nikola, later ran into problems.

But QuantumScape appears to be on firmer ground since it has already been working with Volkswagen for several years and has filed copies of its signed agreements with the major manufacturer with the Securities and Exchange Commission. Nikola did not have a signed deal with General Motors when it announced its partnership, and GM ultimately backed out of investing in the startup.

Also, unlike some other hyped startups that later ran into trouble, outside experts have been able to assess QuantumScape’s new technology.

Stanley Whittingham, a professor at State University of New York, Binghamton, who won the Nobel Prize in chemistry for his work developing lithium-ion batteries, endorsed QuantumScape’s demonstration. Data from the company, he said, backs its claims and is “something that has never before been reported. If QuantumScape can get this technology into mass production, it holds the potential to transform the industry,” Whittingham noted.

Other researchers have been working for decades to develop lithium-metal batteries, but without demonstrating all of the necessary characteristics, said Carnegie Mellon professor Venkat Viswanathan, who has been advising QuantumScape. “Most notable, the fast-charging results are unprecedented for lithium-metal batteries and even for traditional EV batteries,” he told Fortune.

QuantumScape CEO Singh said that Bill Gates, an early investor in the 10-year-old company, has given him advice. “I didn’t honestly think he knew anything about chemistry, and we are all about chemistry,” Singh said. But “when he thinks something is important he can dive really deep and become an expert in that area…He has gotten very deep into this area.”

QuantumScape’s board includes Tesla cofounder and former chief technology officer JB Straubel, well-known Kleiner Perkins venture capitalist John Doerr, and Frank Blome, who oversees battery research at Volkswagen.