Toyota Motor Corp prototyped an all-solid-state battery whose output density is five times higher than that of the company's previous model.
Toyota showed the battery at a meeting that the company had for explaining its green technologies Sept 24, 2012. This time, it improved the conductivity of lithium (Li) ions to 1 x 10-2S/cm or higher, which the company said is "equivalent to electrolyte."
Toyota used Li10GeP2S12, which is based on sulfide, as a solid electrolyte. The company also used a sulfide-based solid electrolyte for the previous model. But germanium (Ge) was added this time.
"Germanium enables to realize a structure in which crystals have refined shapes and Li ions are linearly arranged," the company said.
Each cell was made by sandwiching the solid electrolyte between negative and positive electrodes, stacking seven layers of it and putting it in a laminated film. Each of the seven layers has a voltage of about 4V. And the voltage of the cell is about 28V.
The sizes of the electrodes and the solid electrolyte are approximately 70 x 105 x 2.5-3mm. For the negative and positive electrodes, Toyota used a three-dimensional type that contains graphite and Ni-Co-Mn, which are commonly used for Li-ion rechargeable batteries.
This time, Toyota mounted the prototyped all-solid-state battery on an electric scooter. Eighteen cells were connected in parallel to realize a voltage of about 28V.