A Japanese research group announced Aug 6, 2018, that it has realized a very low interface resistance and ultra-high-speed charging with a 5V-class all-solid lithium-ion (Li-ion) battery using a cobalt (Co)-free positive-electrode material.

In regard to batteries for compact and slim devices such as IoT devices and smart cards, it can be a solution to the issues of 5V-class materials.

The group consists of researchers from Tokyo Institute of Technology, Tohoku University and Nippon Institute of Technology. It is led by Taro Hitosugi (professor, School of Materials and Chemical Technology, Tokyo Institute of Technology), Hideyuki Kawasoko (assistant professor, Department of Chemistry, Faculty of Science and Graduate School of Science, Tohoku University) and Susumu Shiraki (professor, Nippon Institute of Technology).

The research group made a positive-electrode material with an output voltage as high as about 5V and a thin-film all-solid battery using metal lithium (Li) by using an ultra-high vacuum process. The resistance of the interface between electrodes and solid electrolyte was 7.6Ωcm2, which is about 1/100 that of existing all-solid batteries and about 1/10 that of existing Li-ion batteries using liquid electrolyte, according to the group.

60nm-thick positive-electrode layer

The positive-electrode material, solid electrolyte and negative-electrode material of the cell of the all-solid battery are LiNi0.5Mn1.5O4 (LNMO), lithium phosphate (Li3PO4) and metal Li, respectively. The LNMO layer was formed by epitaxial growth in an ultra-high vacuum process on a substrate made of LaNiO3/Nb:SrTiO3 (001), the group said.

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