Solid-state sodium batteries that offer potential to replace lithium built

Researchers have developed solid-state sodium batteries that maintain performance even at subzero temperatures, marking a significant advancement toward making sodium a viable alternative to lithium in battery technology. Sodium is abundant, inexpensive, and environmentally less damaging than lithium, but prior solid-state sodium batteries struggled with ionic conductivity and performance at room temperature. The team combined computational and experimental methods to stabilize a metastable form of sodium hydridoborate by heating it to its crystallization point and then rapidly cooling it, a technique not previously applied to solid electrolytes. This process kinetically locks the orthorhombic phase, which exhibits fast sodium-ion mobility and significantly higher ionic conductivity—up to an order of magnitude greater than previously reported structures. By pairing this stabilized sodium hydridoborate phase with a chloride-based solid-electrolyte-coated cathode, the researchers created thick, high-areal-loading composite cathodes that retain performance down to subzero temperatures. This design contrasts with earlier strategies that used thin cathodes,