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Hybrids, Plug-Ins and Electric Cars: Which Batteries Are Best?

We couldn't have had this conversation about 10-12 years ago, mainly because back then, you could count mass-produced hybrids and electric cars the old-fashioned way, by using your fingers.
Tesla Model S floorplan 1 photo
We're now at the end of 2020, and there are tens of hybrids, plug-in hybrids, and fully electric cars to choose from most mainstream carmakers. Heck, the fastest ever road cars from Ferrari, Porsche, and McLaren were and/or will be hybrids, so people no longer look at you like at a weird hippie whenever you mention the words “hybrid” or “electric cars.”

That said, there are now hordes of vehicles powered either partially or entirely by electricity via onboard batteries, also known as the primary reason for range anxiety in these types of vehicles. This is why we decided to offer some thorough explanations for each type of automotive batteries currently available.

The two best-selling electric vehicles in the world are the Nissan Leaf, with over half a million units sold until this year, followed by the Tesla Model S, which has sold well over 300,000 units so far. By coincidence or not, both the Leaf and the Model S are powered by Lithium-ion (Li-ion) batteries, so we'll start with them.Lithium-ion (Li-ion) Batteries
Initially used to power handheld consumer electronics mostly, Li-ion batteries have continuously evolved in the last decade or so, and pretty much all current and upcoming hybrids or full-electric cars feature them.

Keep in mind that not all Li-ion batteries are the same, with the main differences consisting in their applications. Most handheld devices such as smartphones, tablets, or laptops are based on lithium cobalt oxide (LiCoO2), which gives them a much higher energy density but also comes with some disadvantages.

LiCoO2 cathodes are more susceptible to so-called thermal runaway, which kicks in during overcharging or high-temperature operation. In other words, they can pretty much explode when operated incorrectly, which is probably one of the main reasons lithium cobalt oxide Li-ion batteries haven't been used in cars much.

For more power-intensive applications, such as electric power tools, medical hardware and most of all cars, there are Li-ion batteries based on lithium iron phosphate (LiFePO4), lithium manganese oxide (LMO), and lithium nickel manganese cobalt oxide (NMC). All of these have slightly lower energy density than LiCoO2, but also better built-in safety and longer life spans.

Most modern hybrid and electric cars use NMC lithium-ion batteries, but that doesn't mean that Li-ion, on the whole, is the way to go for carmakers in general, especially since older types of batteries can still hold their own if they are engineered right.

Advantages


Li-ion's biggest advantages consist of a better energy-to-weight ratio, rapidity of charging, and almost no memory effect.

More energy density means that they can weigh less. This feature obviously makes them better suited for automotive use since a lower weight improves range and performance while also infusing cars with better handling on the twisties - the Achilles Heel in most electric cars, whether they are sporty or not.

The rapidity of charging is obviously something to be desired from any battery type, but don't think that having Li-ion to the detriment of other types of batteries will make your car charge a whole lot faster, as the differences in real life are minor at best.

As far as the memory effect goes, Li-ion batteries are apparently the least affected by the problem. In short, some types of batteries gradually lower their maximum energy capacity with each charging cycle. This usually happens when they are repeatedly charged after having been only partially discharged. Nickel-based batteries suffer the most from the so-called memory effect, in which the batteries seem to “remember” they have a smaller energy capacity over time.

Disadvantages

By far, the biggest downside to Li-ion batteries, in general, revolves around production cost, which is much higher than with other types of batteries. Compared to nickel-based batteries, for example, they are around 40 percent more expensive to manufacture, a price that usually trickles down to car buyers. That said, keep in mind that manufacturing costs have been gradually decreasing over time for all types of batteries.

Although Li-ion batteries self-discharge at a much lower rate than others, they are subject to aging, especially when not stored in proper conditions. In short, apart from suffering a slight voltage reduction with each charging cycle, the amount of energy they can hold decreases over time no matter what. In automotive use, their current life cycles are of about ten years, although none of them has been tested that long yet. Some Li-ion batteries have shown a decrease in energy capacity even after one year (of use or storage, since aging is not prejudiced).

In short, Li-ion batteries have the least number of disadvantages compared to most of their rivals, but they're still far from being the perfect solution. Nickel-metal-hydride (Ni-MH) Batteries
The oldest type of so-called modern batteries, Ni-MH are still used in some current hybrids, even though Li-ion have slowly started to severely outnumber them whether we're talking about hybrids, plug-in hybrids, or full-electric vehicles.

A lot cheaper to manufacture than Li-ions, Nickel-metal-hydride batteries also have some ups and downs, which for most could represent a real deal-breaker when pondering what to look for in their hybrid or electric car.

Unlike Li-ion, NiMH batteries need hydrogen, nickel, and titanium, or a similar metal to store energy. This translates into a much lower cost to manufacture compared to Lithium-ions, but as more carmakers switch to Li-ion (such as Tesla and its Gigafactory), that huge pricing discrepancy should shrink.

Advantages

By far, the biggest upside with NiMH batteries is their durability. More modern types of batteries need to be pampered to last longer, but NiMH are in it for the long haul if you take care of them properly.

Closely related to their durability is the lack of extra precautions needed when they're eventually recycled because they contain only a small amount of mild toxins compared to other batteries. Also, the high content of nickel in them actually makes recycling them profitable.

Disadvantages

The main hurdle with NiMH is their low energy density, which is about 40 percent lower than Li-ions. Making them much larger and heavier partially solves this problem but creates another one by adding weight.

In hybrids, plug-in hybrids, and electric cars, batteries are put to a lot of work during driving, and this is where some of the limitations of NiMH batteries come into focus. If they are fast-charged and then discharged with a high load, they tend to generate a lot of heat, so a separate cooling system is required, which in turn adds even more weight.The others
There are lots of other types of batteries that could, eventually, become the most used in automotive applications, but none of them has emerged as truly revolutionary from all perspectives until now.

Cobalt Dioxide, Iron phosphate (FePo) and Lithium-iron phosphate (LiFePO4), Lithium-Air (Li-Air), Lithium Polymer (LiPo), Nickel-cobalt-manganese (NCM), Nickel-cobalt-aluminum (NCA), and Manganese oxide spinel (MnO) are just some of the types of batteries that may appear in an electric or hybrid car near you in the future.

Cobalt Dioxide batteries have been on the market for over a decade, powering small appliances such as mobile phones, toy, or laptops. Their two main disadvantages, especially in larger applications, are thermal runaway and production costs, but on the whole, they're excellent when it comes to energy density.

One of the most stable and inexpensive batteries are Iron Phosphate, but they do work at a lower voltage, so you would need quite a lot of them to power a large electric car.

Even though their name may not imply it as eloquently, LiPo batteries are actually just another form of Li-ion batteries. The main difference resides in the fact that lithium-ion polymers are designed in a so-called “pouch format,” which comes with its own advantages and disadvantages. This is why they have only recently started to be used in cars.

NCM and NCA batteries are still a long way from becoming cost-effective enough to be used in cars, not to mention that both are somewhat susceptible to thermal runaway.

By far, one of the most intriguing new battery technologies is Lithium-Air (LiAir), which uses the oxidation of lithium at the anode and the reduction of oxygen at the cathode to induce a current flow. Their two main advantages are a great energy density, almost comparable to gasoline, and 5 to 15 times higher than current lithium-ion batteries.

Either way, we're still a couple of years away from these alternative types of batteries populating at least a small percentage of our hybrid, plug-in, and electric cars. The good news is they're coming, and range anxiety will soon be a thing of the past. We'll update this guide as soon as more battery technologies become available.

 
 
 
 
 

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