Representatives from Toyota (including H. Iba from the Battery Research Division of Toyota Motor Corporation) recently participated in 17th International Meeting on Lithium Batteries in Como, Italy from June 10 to 14, 2014.

In their article "Invited Presentation: Innovative Batteries for Sustainable Mobility," the Japanese company stated that it is developing new batteries with higher densities - solid state and lithium-air to be more accurate.

"And now, we are going to develop next-generation vehicles with more energy efficiency; for this reason we need to develop innovative batteries with higher energy densities than traditional batteries.  Figure 1 represents a rough sketch of Ragone plots for traditional Ni-MH and Li-ion batteries together with next-generation batteries such as all-solid-state batteries and Li-air batteries.  Although we have already developed prototype cells of all-solid-state batteries and Li-air batteries with energy densities of 400 Wh/L and 1000 Wh/L, respectively, it is also true that there are still many issues to be overcome until their practical application.  In the presentation, we will overview our recent effort on developing innovative batteries."

Rechargeable Lithium-ion Batteries (credit to AESC)

Rechargeable Lithium-ion Batteries (credit to AESC)

As it turns out. the Li-air battery prototypes, which have at least 15-20 years to commercialization, reach energy densities of 1000 Wh/L (yes, we know that they intentionally do not give numbers in kg/L). But more interesting is that solid state lithium batteries achieved 400 Wh/L in the prototype stage and could be commercialized in 6 years. Toyota shows on the graph that this is progress compared to lithium-ion batteries (without solid state electrolyte).

We applaud all developments, but this is pretty strange, because we thought that a level of 400 Wh/L is already behind us. Here is a graph from AESC, which is a joint venture between NEC and Nissan. Li-ions (high capacity cells) are rated from 300-400 Wh/L (not 50-300 Wh/L). And Panasonic's 18650 cells, at least 5 years ago, had 620 Wh/L in production with 800 Wh/L scheduled for 2013.

This puts us in dismay!

However relying on such data explain to us why executives from Toyota do not hurry up with EVs. And finally, current lithium-ion batteries need higher energy density and lower price, not higher power density.

Maybe some of our readers will tell us what is going on with these numbers from Toyota.

Source: Invited Presentation: Innovative Batteries for Sustainable Mobility via Green Car Congress

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