Green Car Congress reports on Panasonic announcing they’ll be showing off a new 1.5kWh Li-Ion battery pack at a New Energy expo in Japan this week, using a relatively uncommon formulation of Lithium Nickel Oxide.
The performance of the batteries and the modular design have attracted attention. The 1.5kWh pack weighs 8kg (17.6lbs) and has a volume of 7L, or about 187Wh/kg and 214Wh/L. These figures are both extremely high considering most other batteries have energy-to-weight and energy-to-volume figures below 140Wh/unit. No information in the press release announced a release window for these battery packs.
The raw figures indicate excellent performance characteristics. Attempting to research the cycle life characteristics of the Lithium Nickel Oxide batteries yielded an paper from 1995 (abstract available) had shown a LiNoO2 cathode to withstand more than 1000 cycles with extremely strong performance characteristics almost 15 years ago. The reason that it had not been used previously is safety problems, which Panasonic indicates they have solved by using a metal oxide layer in the battery that will prevent the anode and cathode from shorting out and causing thermal runaway (heat and possibly fire). If the batteries can be proven to be safe, it would be a significant step in improving battery technology.
As far as applications in cars go, the modules are a perfect fit for EVs and E-REVs because they are significantly ahead of other battery technology to date. This would reduce a 16kWh battery from 160kg (100Wh/kg) to about 90kg, and reducing the volume from approximately 140L (114Wh/L) to 74L (almost half the volume). Specific power is said to be comparable to Lithium Cobalt-based cells, however it is unknown whether or not the values scale up commensurately with the increases in Wh/kg and Wh/L – since the battery pack would have about half of the mass and volume, it would need twice the specific power (W/kg or W/L) to maintain the same power output for a given battery weight or volume. This means it would need about 1,200 W/kg (1,500W/L) to provide 110kW of power with 16kWh (90kg/74L) of batteries. If the batteries aren’t able to produce that kind of power, they’ll be relegated to pure EVs, where you could have a large 25kWh pack (80% DoD) at 135kg/117L and need only 820W/kg and 940W/L. A research study (PDF, mostly in Japanese, but the abstract and charts are readable) on Panasonic Lithium Nickel Oxide batteries from Japan showed specific power between 4,400W/kg and 1,000W/kg (chart, page 4), however those figures quoted a very low specific energy (94Wh/kg), and assuming that specific power would decrease as specific energy increases, it could be estimated that for a SoC between 85% and 30%, the battery with twice the specific energy would have half the specific power, or roughly between 1,200W/kg and 2,200W/kg. This would be suitable for both E-REVs and EVs, however the restrictions on depth of discharge would remain (no expanding of the Volt’s D0D).
As batteries grow in energy density, they’ll become more practical for larger vehicles. Vehicles like the H3E E-REV demo model produced by Raser Technologies would be able to carry fewer battery packs, reducing the weight of electrification – what was probably 30kWh of batteries weighing 300kg could be reduced to about the size and weight of the current Volt battery pack (160kg/140L), which would be easy to “hide” on an H3 or any full sized truck.
Again, since there is no word on the release date and any numbers for how many cells they would produce per year, its still a bit up in the air – definitely not vaporware, but in that gray area between we’ve made demo models and mass production. Even if these batteries don’t arrive for another 3 years, that’s still far ahead of the 5-7% average annual performance increase we’ve had for Li-Ion batteries the past 10 years or so, batteries with this level of performance would not otherwise be expected until 2017.
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