April 7, 2024, 2:10 pm | Read time: 10 minutes

This concern can be addressed with two approaches: a well-developed fast-charging network and a highly efficient electric car battery. The battery is the heart of the electric car, as it determines its range, safety, lifespan, and charging times. TECHBOOK provides an overview of the common electric car batteries and the hopes researchers have for them.

What’s Inside an Electric Car–Battery or Accumulator?

In the context of electric cars, people sometimes refer to an accumulator, but more often to a battery. This can cause confusion. “Battery” is initially just a general term for an energy storage device that converts chemical energy into electrical energy. Batteries in the narrower sense, also called primary batteries, discharge once and cannot be recharged.

Accumulators or secondary batteries, on the other hand, can be recharged and reused after discharge. Accumulators are therefore a subset of batteries in the broader sense. When talking about batteries in electric cars, it technically means accumulators. Ultimately, the term battery in this context is not incorrect and is especially common in everyday language.

Fundamentally, an electric car battery consists of three components: a cathode (negative pole), an anode (positive pole), and an electrolyte that connects the two poles. The electrolyte can be a gel or a solid. In electric cars, viable solid-state batteries are still a long way off. Electrons move from pole to pole through the electrolyte. In a charged battery, the negatively charged electrons gather at the positive pole, the anode.

During discharge, the excess electrons move to the cathode, causing the current to flow. When charging, the supplied charging current returns the electrons to the anode, creating an imbalance in electron distribution again. This process is called a reduction-oxidation reaction–or simply: redox reaction.

Further, Smaller, Lighter

In an electric car, the electric motor and the battery form the heart of the vehicle. In fact, the battery is also the most expensive component, following the principle: the more power it provides, the more expensive it is. Therefore, the goal of electric car manufacturers is to develop batteries that are as powerful, small, light, and affordable as possible. The larger and heavier an electric car is, the more energy it needs for propulsion.

A second problem–in several respects–is raw material extraction. So far, lithium-ion batteries are mainly used in Germany, requiring lithium, cobalt, nickel, and manganese, among other things. These metals are mined in Australia, Russia, and the Congo.

The extraction often occurs–especially in the Congo–with the use of child labor, disregarding human rights and environmental protection standards. This is not only bad for the eco-balance of electric cars but also morally questionable at the very least. Since nickel and cobalt are toxic heavy metals, their disposal is also correspondingly expensive. Apart from that, the global supply of these metals is limited, so it’s only a matter of time before alternative batteries need to be developed.

Lithium Batteries as Standard in Many Electric Cars

So far, lithium batteries are the predominant accumulators for electric cars, especially among European and American brands. Nickel-manganese-cobalt accumulators (NMC) and lithium iron phosphate accumulators (LFP) are primarily used. These energy storage devices now enable solid ranges. In a practical test, the ADAC tested the actual range of common electric car models, which ranged from 150 to 610 kilometers in total. The middle range was between 250 and 500 kilometers per full charge. Parameters such as speed and outside temperature strongly influence the actual range.

Since these lithium batteries have been particularly widely used so far, they have also been extensively researched. On one hand, developers have managed to double the energy density of lithium-ion accumulators over the past eight years. On the other hand, experts estimate that the optimization potential is largely exhausted. And the need for innovation is great for several reasons.

The Classic: Nickel-Manganese-Cobalt Battery (NMC)

The NMC battery gets its name from the nickel-manganese-cobalt oxides that make up the cathode. An NMC battery is characterized by high performance and long lifespan. This includes low self-discharge when not in use, at 1 to 2 percent per month. However, it is recommended to charge the battery only to 80 percent to promote its longevity.

The high performance of NMC batteries is partly due to the high reactivity of lithium. However, this property also comes with high flammability. “Thermal runaway” of a battery describes the chemical chain reaction that triggers a fire or even an explosion. To reduce this risk, the battery cells must be hermetically sealed and carefully cooled. However, if the battery is physically damaged–which can certainly happen in a car accident–the fire risk increases significantly.

At the same time, NMC accumulators are sensitive to large temperature fluctuations. Below five degrees and above 40 degrees, the cell chemistry becomes comparatively sluggish and loses performance. Even in the climatically moderate Germany, problems or lasting damage to the battery can occur. All this requires a complex battery management system, which in turn takes up additional space and drives up the price.

The Alternative: Lithium Iron Phosphate Battery (LFP)

The use of LFP batteries was touted as a breakthrough in the electric car industry–at least by CATL, the world’s largest car battery cell manufacturer. The Chinese company raised the bar for LFP cells even higher in 2023 with its Shenxing battery. Shenxing is supposed to have short charging times and a range of 700 km under ideal conditions. Nowadays, more or less powerful LFP accumulators are found in about one-third of electric cars. Tesla and Chinese manufacturers like BYD and XPeng have particularly specialized in using LFP batteries.

Unlike NMC batteries, an LFP battery is characterized by a cathode made of lithium iron phosphate. Toxic heavy metals like cobalt, nickel, and manganese are not needed for this type of lithium battery. This, along with the simpler extraction of lithium iron phosphate, makes LFP cells significantly cheaper than NMC batteries. Consequently, more affordable electric car models are possible, putting pressure on the competition.

Compared to NMC accumulators, LFP batteries also have the advantage of being more robust. While NMC cells undergo thermal runaway at about 198 degrees Celsius, the fire risk for LFP accumulators only unfolds at 256 degrees Celsius. Additionally, it is almost impossible to trigger a fire through purely mechanical impact. This significantly increases road safety, and manufacturers can forgo a complex battery management system. This saves space, weight, and money.

In return, more or larger LFP cells can be installed in the same space. This is sometimes necessary because LFP accumulators do not achieve the same energy density as NMC batteries. For a long time, this was the main disadvantage, as it also reduces the range of electric cars–a decisive buying argument. Especially in small city cars, the lack of space for a more powerful battery also means a lack of power for longer ranges. However, developers have improved LFP accumulators in recent years to the point where electric cars equipped with them are still a good alternative to those with NMC batteries, depending on customer needs.

Read also: The Pros and Cons of an E-License Plate for Cars

New Player: Sodium-Ion Battery

Sodium-ion batteries have actually been known since the 1980s. But the biggest drawback–then as now–is the comparatively low energy density. It has been improved in recent years to the point where their use in electric cars is worthwhile. However, they are (still) not a direct competitor to NMC and LFP accumulators. Research on sodium-ion cells is mainly driven by Chinese companies. The result is electric cars that aim for a low price rather than a long range, thus serving important market segments. However, BYD’s Seagull model is still supposed to have a range of 300 km.

Sodium-ion accumulators are fundamentally comparable to lithium-ion batteries in terms of functionality, except that sodium replaces lithium–as the name suggests. The big advantage of sodium-ion cells lies in their inexpensive materials. Sodium is abundantly found in sea salt and salt deposits and is easy to extract. The globally limited lithium can be dispensed with, as can toxic heavy metals. This makes the sodium-ion battery less environmentally harmful and significantly cheaper. The price is up to 40 percent lower than that of lithium batteries. German manufacturers, in particular, could also free themselves from supply chains associated with political dependencies, unplanned outages, and price fluctuations.

Sodium-ion batteries are also said to be relatively insensitive to cold and mechanical impacts. In terms of longevity and low storage loss, this battery alternative can also compete with NMC and LFP accumulators. Only the disadvantage of lower energy density can never be completely overcome. This is due to the sodium ions, which are significantly larger and heavier than lithium ions. Therefore, the energy density is up to 40 percent lower than that of lithium batteries. An electric car with a sodium-ion battery will therefore never achieve the same range with the same design. Whether this is actually a disadvantage for customers, given the lower price, depends on individual requirements.

More on the topic

The Reason Why Your Phone Battery Drains Faster in the Cold

Developed by Chinese Researchers Is the “Tofu Battery” Coming With a Lifespan of Several Centuries?

More Research Needed

German car manufacturers are already facing strong competition in terms of electric car sales and research. At the same time, the global use of electric cars is expected to continue to rise, as will the energy consumption and extraction of non-renewable resources required for them. Further research into sustainable batteries for electric cars is therefore essential.

Various alternatives are already being discussed, such as the magnesium-sulfur battery. Magnesium is available in large quantities, and sulfur often arises as a byproduct, for example, in desulfurization plants. Magnesium-sulfur batteries have a significantly higher energy density than lithium cells and could be used in electric trucks in the future. However, developers would still need to increase the currently low number of charge cycles and energy efficiency. Lithium-sulfur batteries, on the other hand, are light and inexpensive to produce, but the wear and tear is still too high.

Solid-State Batteries as Key Technology for Electric Cars?

A real revolution in the industry would mean a breakthrough in solid-state batteries. Instead of a liquid electrolyte, the cell contains a solid, combining many advantages of the various existing accumulators. First of all, a solid cannot leak. The risk of thermal runaway is also lower, which could eliminate the need for temperature management systems. All this would make a battery lighter, cheaper, and safer. At the same time, solid-state accumulators theoretically offer high energy density and range, as well as high charging capacity and longevity.

But all this is not yet practical on the necessary scale. The charging time is far too long, and the battery loses a significant portion of its capacity after just a few charge cycles. There is a process to improve this property, but it only occurs at 700 degrees Celsius. Moreover, even for a solid-state battery, the currently limited lithium is needed. A very practical hurdle also lies in the battery factories: new production facilities would have to be built for solid-state accumulators, while NMC factories have mainly been established in recent years. To sum it up: there is still much research and development needed for both solid-state batteries and other accumulators to develop a truly sustainable alternative to the internal combustion engine in cars.