Researchers at the Tokyo Institute of Technology and collaborating institutions have announced a solid-state hydrogen battery that operates at much lower temperature than existing hydride systems, i.e., about 90°C (194°F) compared with conventional 300–400°C. This marks a significant shift, making hydrogen storage in battery form more practical and energy-efficient for devices including electric vehicles, tells Live Science.
The battery’s architecture uses a magnesium hydride (MgH₂) anode, gaseous hydrogen as the cathode, and a crystalline electrolyte composed of barium, calcium, and sodium hydride. This electrolyte permits high ionic conductivity of hydrogen species and exhibits electrochemical stability at the relatively low operating temperature. Because of this design, the battery can reach the full theoretical storage capacity of MgH₂, yielding a capacity of up to about 2,030 mAh per gram, far higher than typical lithium-ion cell capacities.
In operation, hydride ions move through the electrolyte during charge and discharge. During discharge, hydrogen at the cathode is reduced to hydride ions, which travel through the solid electrolyte and oxidize at the magnesium anode to form MgH₂ while releasing electrons into the external circuit. During charging, the reverse occurs: MgH₂ releases hydride ions that travel back to the hydrogen electrode and reform hydrogen gas.
Because this battery does not require extreme temperatures or high pressures, it sidesteps major issues in conventional hydrogen storage systems and fuel cells. However, the current design is not suitable for small electronics yet, but could be transformative for EVs in the future. If scaled, it could lead to lighter energy storage systems with longer service life and greater efficiency compared with lithium-ion batteries.
This breakthrough suggests that hydrogen batteries may become viable alternatives in the electrification of transport, potentially overcoming key drawbacks of lithium-ion systems such as degradation, weight, and thermal constraints.