In 1992, Sony unleashed a revolution in portable electronics. Taking advantage of decades of laboratory research on lithium-ion batteries, the Japanese company was able to introduce products such as mobile phones and hand-held video cameras that have changed the lives of billions of consumers. Batteries now underpin the prodigious task of overhauling the global energy and transport system to reduce reliance on fossil fuels. While the cost to make lithium-ion batteries has plummeted, allowing electric car sales to take off in recent years, the bare bones of the technology have remained little changed since commercialisation. After three decades of incremental...