World’s first gas-solid hydride ion battery capable of storing hydrogen and electricity simultaneously under ambient conditions

https://interestingengineering.com/energy/hydride-ion-battery-prototype-93-efficiency

"utilizes magnesium metal/ hydrogen gas as its 2 electrodes to bypass extreme conditions required by conventional containment... charging securely locks hydrogen inside solid metal as magnesium hydride/ discharging reverses process releasing gas while generating electric power, operates from -20 to 90°C maintaining >70% initial capacity after 60 cycles, 93.9% hydrogen energy utilization efficiency, outperforming traditional thermal hydrogen storage methods by a full third"