Hydride ion (H^-), with their low mass and high redox potential, is considered promising charge carriers for next-generation electrochemical devices. However, the lack of efficient electrolyte with fast hydride ion conductivity, thermal stability, and electrode compatibility has hindered their practical applications.

In a study published in Nature on Sept. 17, Prof. CHEN Ping's group from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) developed a novel core-shell hydride ion electrolyte, and constructed the first rechargeable hydride ion prototype battery.

Using a heterojunction-inspired design, researchers synthesized a novel core-shell composite hydride, 3CeH₃@BaH₂, where a thin BaH₂ shell encapsulates CeH₃. This structure leverages the high hydride ion conductivity of CeH₃ and the stability of BaH₂, enabling fast hydride ion conduction at room temperature along with high thermal and electrochemical stability.

Furthermore, researchers constructed a CeH₂|3CeH₃@BaH₂|NaAlH₄ all-solid-state hydride ion prototype battery using NaAlH₄, a classical hydrogen storage material, as the cathode active component. Positive electrode of the battery delivered an initial discharge capacity of 984 mAh/g at room temperature and retained 402 mAh/g after 20 cycles. 

In a stacked configuration, the operating voltage of the battery reached 1.9 V, powering a yellow light-emitting diode lamp, which was a compelling example for practical applications. This marks that Chinese researchers have developed the first hydride ion prototype battery, achieving a leap from "fundamental concept" to "experimental verification" of hydride ion battery.

By adopting hydrogen as the charge carrier, this technique avoids dendrite formation, paving the way for safe, efficient, and sustainable energy storage. With the tunable properties of hydride-based materials, hydride ion batteries hold potential for clean energy storage and conversion.