The Nikkei reports that Toyota Motor Corp. and its partners the Tokyo Institute of Technology and the High Energy Accelerator Research Organization have devised a prototype solid-state Li-ion storage battery and aim to improve and then commercialize it in the 2015-2020 timeframe.
Since the battery can easily be processed into sheet form, it can store several times the amount of electricity, volume for volume, than the current generation of electric vehicle batteries, according to the developers. This added capacity may extend the maximum driving distance per charge for compact EVs to around 1,000 km [621 miles] from the 200km or so for existing vehicles.
Currently, Li-ion batteries with high energy and power densities use organic liquid electrolytes; these, however, require relatively stringent safety precautions, making large-scale systems more complicated and expensive. The use of solid electrolytes—which would address many of those issues associated with the liquid electrolytes—is currently limited by their conductivities.
Toyota and its partners earlier this year published a paper in the journal Nature Materials describing the development of a lithium superionic conductor Li10GeP2S12 that has a new three-dimensional framework structure. Kamaya et al. reported that the new material exhibits an extremely high lithium ionic conductivity of 12 mS cm−1 at room temperature, representing the highest conductivity achieved in a solid electrolyte, exceeding even those of liquid organic electrolytes.
The new solid-state battery electrolyte has many advantages in terms of device fabrication (facile shaping, patterning and integration); stability (non-volatile); safety (non-explosive); and excellent electrochemical properties (high conductivity and wide potential window).
Noriaki Kamaya, Kenji Homma, Yuichiro Yamakawa, Masaaki Hirayama, Ryoji Kanno, Masao Yonemura, Takashi Kamiyama, Yuki Kato, Shigenori Hama, Koji Kawamoto and Akio Mitsui (2011) A lithium superionic conductor. Nat Mat. 10, 682–686 (2011) DOI: 10.1038/nmat3066