'Superionic conduction' could improve batteries

Chinese researchers recently achieved the superionic conduction of negatively charged hydrogen atoms at ambient temperatures, which they say promises to pave the way to advanced clean energy storage and electrochemical conversion.

"Materials that exhibit superionic conduction in ambient conditions would provide huge opportunities for new batteries, fuel cells and electrochemical cells", said Chen Ping, a professor at the Dalian Institute of Chemical Physics of the Chinese Academy of Sciences.

The study, conducted by a research team led by Chen and associate professor Cao Hujun, was published in the journal Nature on April 5.

They were able to create a pure hydride ion conductor with record-high conductivities in the temperature range of-40 to 80 C.

As current commercial new energy vehicle batteries do not perform well at extreme temperatures, the breakthrough may help expand the range of temperatures at which batteries can operate, although there's still a long way to go before other high-performance electrode materials to can be found, and a new all-solid-state hydride ion battery can be made, Cao told China Daily on Sunday.

Cao said that hydride ion conductors have emerged as promising candidates for energy storage and conversions that allow ions to move without a liquid or soft membrane to separate the electrodes.

In recent years, several hydride ion conductors displaying fast hydrogen migration have been developed, but none were able to achieve superionic conduction in ambient conditions until the DICP team took a new approach.

The team targeted the structure and morphology of the trihydrides (hydrides containing three atoms of hydrogen per molecule) of certain rare-earth elements.

By creating nano-sized grains, defects and other crystalline mismatched zones in a known ionicelectronic mixed conductor, they made it possible to transform lanthanum hydride — a substance synthesized from hydrogen and rare-earth element lanthanum — into a hydride ion superionic conductor.

"With fast hydride ion conduction and a high ion transfer number, deformed lanthanum hydride enables a hydride ion battery to operate at room temperature, or lower," said Chen.

"This demonstrates the effectiveness of lattice deformation in suppressing electron conduction in rare earth hydrides," she added.

The researchers plan to extend the method developed in this study to other hydride materials. Chen said their short-term goal is to demonstrate a new all-solid-state hydride ion battery with practical potential.