The seperation has becoming clear in the past decade – nickel-metal hydride, or NiMH, batteries will now be utilized exclusively for plug-in hybrid vehicles, or at least those that are made by Toyota, a top auto manufacturer who is at the forefront when it comes to the use of the NiMH batteries.
On the other hand, lithium-ion batteries have sufficient density in terms of energy, and are therefore ideally used by the plug-in hybrid vehicles.
Plug-in hybrid vehicles by Toyota find success with NiMH
In fact, this designation of battery types to various plug-in hybrid vehicles and other EV models has been increasingly becoming the norm for the last couple of years. However, as researchers and battery tech experts are able to improve the energy density of NiMH cells, this might be great news, and the result that the BASF chemical supplier wants to get.
In a Technology Review article by Kevin Bullis, he discussed the possibility of NiMH cells having 10 times energy density compared to conventional battery cells, making them highly practical for application in plug-in hybrid vehicles.
NiMH batteries a perfect fit for hybrid vehicles according to Bullis
The goal is having a cost per kilowatt-hour lower than $150, which is better than the cost of commodity-format cells distributed by Tesla Motors and Panasonic after they are manufactured at the currently-constructed Nevada gigafactory.
The BASF research is focused on the modifications of nickel-metal electrodes microstructure. The changes will render the unique structure stronger and ultimatelydecreasing the amount of material used.
It is expected that even though a smaller amount of the NiMH electrode is utilized, it will still produce the same power. The researchers at BASF have already come up with NiMH cells that possess twice the energy density of ordinary cells, which currently brings them to about 140 watt-hours a kilogram.
NiMH electrode currently harnessing 140 watt-hours per kilogram
It is below the 230 watt-hours of the superior Li-ion cells available today. Still, the light-weight characteristics of NiMHcells is negated by two factors.
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The first is the fact that lithium-ion cells are more likely to deteriorate over time, at a rate faster than NiMH cells. Li-ion battery packs currently have extra cells in order to compensate for the expected loss.
NiMH batteries are also safer in terms of internal parts and chemistry compared to Li-ion type. This is because of the absence of liquid electrolytes that can spill or leak in case of an accident.
Safety measures are needed in order to prevent any added weight to the battery beyond that of the lighter lithium-ion cells. Still, researchers at BASF continue to find out ways that will further improve their cell’s energy density.
Lithium-ion batteries are still the favourite in EV battery industry
BASF maintain the ultimate target of improvement is capability, which is ten times more than the present nickel-metal-hydride battery. At any rate, lithium-ion type of battery is still considered to be the favourite for most plug-in hybrid vehicles and EVs.
The research performed at BASF only emphasizes all the efforts being done by development teams all over the world and since batteries are bound to experience continuous evolution, this is great news for the industry. In the end, plug-in hybrid vehicles and their owners will be the ultimate beneficiaries.