Nickel-Hydrogen Batteries?
Filed Under: green automotive technology, Green Technology on November 12, 2009
Move over nickel-hydride, your days are done. Now, it’s nickel-hydrogen instead. This is an interesting marrying of the battery-electric vehicle (BEV, or just electric vehicle) idea and the hydrogen fuel-cell (HFC or FCV for fuel cell vehicle) concept. Both are, if you read the automotive press, vying for ownership of the alternative fuel transportation markets.
Of course, they aren’t really doing that. The idea that the BEV or the FCV are the Sony and Betamax of our generation is like believing that Democrats and Republicans are different critters. In the end, they’re all the same thing (cars, movies, and assholes). It’s the paradigm that needs to change, not the technology.
First, let’s look at what this technology could potentially do to bring BEVs and FCVs together. Then we’ll look at how the technology of nickel-hydrogen works.
Both battery electric and hydrogen fuel cell cars have the same benefits: they are zero-emissions at the tailpipe, use less energy compared to their internal combustion counterparts (even if the electricity or hydrogen is from the dirtiest source possible), and they are longer-lasting (in general) as well.
The down side to battery electrics is the sliding scale of return (weight vs. range) of the batteries and the potential drain on the electrical grid if they become commonplace. At some point, BEVs reach a limit in range capability versus loss in efficiency due to weight from batteries. The current limit appears to be around 150 miles with the latest technology on the market.
The down side to hydrogen is that the infrastructure for hydrogen fueling is not as widespread as it is for electricity and the technology is still expensive, so it will be a few years before it can become marketable (all three big Japanese automakers say they’ll have models for sale by 2015). Hydrogen’s range is limited mostly by the size of the storage on the vehicle, with experimental big-rig trucks capable of 500+ miles, but most FCV cars have a range of 250 or so miles.
The idea is to combine the benefits of the two energy storage mediums (hydrogen when used in a fuel cell is, basically, a battery) and shed most of their negatives.
Currently, most hydrogen fuel cell cars like the Honda FCX Clarity use batteries for short-term storage just as their battery electric counterparts use them for longer term. An FCV usually sends hydrogen through a catalyst to create 
electricity, which is then sent to a battery and from there goes to the motor for propulsion. Batteries in any of these vehicles can be lead acid, lithium-ion, or Nickel Metal Hydride (NiMH).
Well, now it turns out that Toyota, NASA, and the Florida State University are all looking at using Nickel-Hydrogen (NiH2) batteries instead. Think of this NiH2 as a sort of mashup between a standard battery (like a lithium-ion, say) and a compressed hydrogen storage tank with a fuel cell attached (like on an FCV).
These batteries have a nickel oxide positive electrode and a hydrogen negative electrode. Pressurized hydrogen is stored on the negative side and nickel oxide on the positive. As hydrogen releases through the NO, it creates electricity as the oxygen is combined with the hydrogen as in a fuel cell. The battery’s power level can be measured directly through the remaining pressure in the hydrogen side.
So, in effect, you literally have a hydrogen fuel cell built as a single unit to be a battery. The bonus here is that the NO cells can also store power (as in a cadmium battery). Obviously, this gives the benefits of both the BEV and FCV worlds in one unit.
For more detailed (and scientific) information on how NiH2 batteries work, visit this link.
has any one ever actually made this battery.
As of November, when this article was written, they had not. They were moving towards prototyping and had done only proof of concept at NASA. They’re likely underway with it now, though I can’t see any updates on their site.