Battery giants are exploring sodium-based technology as an alternative to lithium, signaling a potential shift in the energy storage industry. Sodium, more abundant and cheaper than lithium, has not been widely used due to the superior range and performance of lithium cells. However, recent breakthroughs, including Sweden's Northvolt AB and China's BYD Co. signing a deal for a $1.4 billion sodium-ion battery plant, suggest a growing interest in sodium technology.