BMW just hit a major milestone: it’s now actively testing all-solid-state battery (ASSB) cells in a BMW i7 prototype. Developed in collaboration with Solid Power, these smaller, lighter next-gen batteries are finally seeing their first road testing—marking a meaningful step forward for BMW, but perhaps even more for MINI.

So, what exactly is a solid-state battery?

In short: it ditches the flammable liquid electrolyte found in traditional lithium-ion batteries and replaces it with a solid one. That change brings some big benefits:

  • More energy density, which could mean more range with smaller batteries.
  • Better safety, since solid electrolytes are far less prone to thermal runaway.
  • Faster charging, thanks to improved ion conductivity.
  • Lighter weight, smaller, simpler batteries mean less of a weight penalty for EVs.

What this means for BMW and MINI

While BMW is starting with high-end applications like the i7, the real promise comes when this tech trickles down the lineup. Here’s what it could deliver:

  • Extended range, especially important for MINI’s next-gen EVs like the J01 Cooper and Aceman.
  • Lower weight, which could help bring back some of the agility that heavier EVs have dulled.
  • Smaller packaging, freeing up space and unlocking design flexibility—key for MINI’s compact proportions.

For MINI, this tech could be transformative. Think about it: a true small electric MINI with real range, lighter curb weight, and packaging that doesn’t compromise interior space or design character. That’s the dream—and solid-state could help get us there.

Don’t expect it tomorrow

This is still early-stage testing. Widespread adoption of solid-state tech isn’t likely before 2030, and scaling it will take major investment. But BMW’s commitment—both financially and strategically—is real. And if it pays off, it could give MINI something no other premium small EV offers: a truly uncompromised electric driving experience.

MINI’s electric future just got a little more interesting.