A Finnish startup called Donut Labs announced at CES 2026 that it had a production-ready solid-state battery with 400 Wh/kg energy density, five-minute full charges, and 100,000 cycle life. The battery world immediately split in two. Independent VTT testing confirmed some claims while leaving the most extraordinary ones untouched. Robert brings in Dave Borlace from Just Have a Think and battery chemist Dr. Euan McTurk to work through what the chemistry can actually support, which parts of the pitch are credible, and which parts are still running ahead of the evidence. The best breakdown of this story you will find anywhere.