Hydrogen ion battery begins to become a reality

Energy

Technological Innovation Website Editorial Team - September 18, 2025

Schematic diagram of the first prototype hydride-ion battery. [Image: DICP]

Hydride-ion battery

Scientists have managed to build the first working prototype of a hydrogen-ion battery - hydride ions, or H ^- .

While most current batteries are based on the movement of positive ions (cations), such as lithium (Li ⁺ ), hydride batteries work with a negative ion: H ^- .

This radical concept of using a hydrogen atom with an extra electron as a charge carrier paves the way for a revolution in battery energy density and safety, making it one of the most promising bets for the next generation of energy storage.

But it's also one of the most challenging, since until now, no one had managed to synthesize a suitable electrolyte—the medium responsible for conducting ions from one pole of the battery to the other, generating electric current. And the lack of an electrolyte efficient at conducting negative ions, with thermal stability and compatibility with the electrodes, had been hindering the development of this type of battery.

Jirong Cui and colleagues at the Dalian Institute of Physical Chemistry in China have now finally overcome this challenge, and have demonstrated the viability of their hydride-ion electrolyte in a working hydrogen battery prototype.

There are still challenges to be overcome, but the technology is very promising. [Image: Jirong Cui et al. - 10.1038/s41586-025-09561-3]

Electrolyte for hydrogen battery

The team created a composite electrolyte, following a core-shell architecture, where a thin outer layer of barium hydride (BaH ₂ ) encapsulates a cerium hydride (CeH ₃ ) core - the compound is called CeH ₃ @BaH ₂ .

This structure takes advantage of the high hydride ion conductivity of CeH ₃ and the stability of BaH ₂ , allowing rapid hydride ion conduction at room temperature, along with high thermal and electrochemical stability.

Researchers have built a prototype all-solid-state hydride-ion battery using sodium aluminum hydride (NaAlH ₄ ), a classic hydrogen storage material, as the active cathode component. The battery's positive electrode exhibited an initial discharge capacity of 984 mAh/g at room temperature.

In a stacked configuration, the operating voltage reached 1.9 V, powering an LED lamp, suggesting practical applications. Durability, however, remains an issue, with storage capacity dropping to 402 mAh/g after just 20 cycles.

Very high density

It is just the first prototype, which should improve greatly with research into new materials and new combinations of electrolytes and electrodes.

And it's worth it. Hydrogen is the most abundant element in the universe, making it potentially very cheap and virtually inexhaustible, unlike lithium. Furthermore, the hydride ion is extremely light, which paves the way for batteries to achieve extremely high energy density—that is, storing more energy in less weight.

Safety is another key consideration. Unlike lithium-ion batteries, hydride batteries can be designed to be more stable and less prone to dangerous reactions.

But there are also risks, as hydride ions are highly reactive. Because they are negative ions with an extra electron, they are extremely unstable and prone to reacting with other materials, requiring their encapsulation in other compounds, as the Chinese team has now done.

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