As electric vehicles multiply across the world's roads, the question of what becomes of their aging batteries has quietly grown into one of the defining material challenges of the energy transition. Researchers have now answered part of that question with a thermochemical treatment that restores degraded lithium-ion batteries to 95 percent of their original capacity — not by dismantling them, but by healing them. Grounded in decades-old chemistry and applied with new purpose, the method suggests that the life of a battery need not end where usefulness once seemed to.