It was the much quieter moment when people stopped describing it as unconventional and began treating it as ordinary.… In November 2026, in a technology development center in Nagoya, Japan, a young battery engineer named Takumi Sato, 34, stood before a room full of executives and investors. Displayed on the enormous screen behind him was a sentence that immediately attracted attention: “The future of batteries may not belong to lithium.” For decades, lithium-ion batteries had dominated the rechargeable battery industry. They powered smartphones, laptops, electric vehicles, and increasingly large-scale energy storage systems. Their energy density, manufacturing infrastructure, and established supply chains had made them the industry’s unquestioned standard. But Takumi believed that the industry had become too comfortable with its own assumptions. His proposal was to develop sodium-ion batteries as a serious alternative. Sodium w...