All-solid-state Li-S Battery Developed Using Complex Hydride

Aug 28, 2014
Motohiko Hamada, journalist
The newly-developed all-solid-state Li-S battery. Part of the metal lithium negative electrode was peeled on purpose so that the structure of the battery can be easily seen.
The newly-developed all-solid-state Li-S battery. Part of the metal lithium negative electrode was peeled on purpose so that the structure of the battery can be easily seen.
[Click to enlarge image]

A Japanese research group developed an all-solid-state lithium-sulfur (Li-S) battery using a sulfur (S) positive electrode and metal lithium (Li) negative electrode.

It was developed by using the group's own technology to use lithium borohydride (LiBH4), which is a complex hydride, as a solid electrolyte.

The group is led by Atsushi Unemoto and Shinichi Orimo, lecturer and professor, respectively, at the Advanced Institute for Materials Research (AIMR), Tohoku University. For the development, it cooperated with the Institute for Materials Research (IMR) of the university and Mitsubishi Gas Chemical Co Inc.

This time, the group combined C and S by using a mechanical milling method and obtained composite particles (C-S composite particles) that are highly dispersed on a nanoscale. Because the LiBH4 complex hydride is easily deformed, it was possible to form a positive-electrode layer with a stable, high-density interface between electrode and electrolyte, which promotes cell reaction, just by applying a pressure to a mixture of C-S composite particles and LiBH4 particles.

Then, the group made an all-solid-state ion battery using the C-S composite particles and metal Li for the positive and negative electrodes, respectively. And it proved that the battery's energy density is 1,410Wh·kg-1 or higher and that the battery can be repeatedly and stably charged and discharged for at least 45 cycles at a temperature of 120°C.