Battery cell research: China has the super batteries

 

The fact that German carmakers have not paid enough attention to battery cells for a long time is now taking its toll: Reports of new technologies for long range batteries are piling up. A noticeable number of them come from China. The next electric cars will probably come with them.

 

Very specifically: the BYD Han. The manufacturer “Build your Dreams” (BYD), known to us through its cooperation with Daimler and the associated Denza model, is China’s largest electric car manufacturer. In addition to the Tang SUV, the group also wants to bring the Han sedan to Europe. Initially to Norway, where electric cars are booming the most due to government subsidies. Thanks to an 82 kWh battery, the range is to be 600 kilometers according to the NEDC, and the price between 45,000 and 55,000 euros. In addition to a front-wheel drive version with 163 kW (222 hp), the approximately five-meter-long sedan will also be available as a 363 kW(494 hp) all-wheel drive version, and the four-door model is expected to reach 100 km/h in under four seconds.

BYD brings simple materials to car batteries

High performance and lightning acceleration are what we are used to from e-cars, and the price may still rise until the actual market launch. What makes people sit up and take notice is the battery technology. BYD calls it blade technology and claims that it is less dangerous than conventional lithium-ion batteries (lithium-nickel-manganese-cobalt, Li-NMC). This is because a lithium-iron-phosphate battery sits in the Han. This type actually has a lower fire risk.

That is why lithium iron phosphate batteries are mainly used as stationary storage for photovoltaic systems in houses. There, their manageable energy density does not interfere. With a capacity of 11 kWh, common examples are about the size of a wall cabinet. As I said, the battery in the Han has a good 82 kWh.

Maximilian Fichtner, professor of solid-state chemistry and deputy director of the Helmholtz Institute in Ulm, Germany, says: “BYD’s new battery is apparently only a little more than half the size of the previous one, manages 600 km and fits in a car that costs the equivalent of just $33,000 in China and does 0 to 100 km/h in 3.9 seconds. We have to fear that German manufacturers are out of the race here for the time being. Lithium iron phosphate batteries are also much less susceptible to damage. If you hammer a nail into it, the temperature at that point will only rise to 50 degrees. In such a case, a Li-NMC battery is thermally run down and burns off.

5/2020, BYD Han

From stationary storage to the car

How could BYD surprise with this technology in the car? “Lithium iron phosphate already existed in the automotive sector in the late 2000s: when KERS was introduced in Formula 1 in 2008, Lewis Hamilton became world champion – with a lithium iron phosphate battery behind him. The Chinese originally worked with it, but then swung with the international community to NMC because of its higher storage capacity. Apparently, however, they haven’t completely stopped working on iron phosphate in China, and through some process have managed to get the batteries small and compact. BYD calls it blade battery, which translates as “blade” battery. This apparently puts them in the area of interest for mobile applications,” says Fichtner.


McLaren

The Kinetic Energy Recovery System (KERS) in Formula 1 cars initially worked with lithium-iron-phosphate batteries.

And at the same time have one or two fewer raw material problems. Iron is much easier to come by than manganese, nickel or even cobalt. This is obviously also reflected in the price.

GAC – with new materials to a range of 1000 kilometers

The Guangzhou Automobile Group (GAC) recently announced at a technology day that it had produced square hard-shell cells with an energy density of 275 watt hours (Wh) per kilogram using silicon as the anode material. By comparison, Tesla manages just under 160 Wh/kg. According to GAC, cars with batteries of this technology are expected to achieve a range of 1000 kilometers.


GAC Aion LX

GAC sells electric cars under the name Aion, here the LX.

Silicon replaces graphite at the anode and, according to the Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology (FEP), promises “almost a tenfold increase in the specific charging capacity of the anode.” However, the material expands enormously or shrinks during charging and discharging. As a result, the material composite is destroyed quite quickly, leading to cell failure. The FEP has therefore developed “a cost-efficient and environmentally friendly process to produce porous silicon layers that do not break down so quickly.” Apparently, GAC has found a similar way. At any rate, at the Technology Day, Mei Untong, head of battery research at GAC, stated that he had developed unique key technologies for materials, cell construction, production processes for the next generation of batteries, so that silicon anodes could be used for the first time in the world in the production of large, high-performance battery cells. In addition to increased range, this should also result in greater safety and lower costs.

Turbo-charging thanks to special compound

In addition, GAC promised a breakthrough in fast-charging capability several months ago. The GAC Group has been researching the production of graphene on a large scale since 2014 and holds numerous patents. Graphene consists of just one layer of carbon atoms and is considered a wonder material. It was only in 2004 that a group led by AndrĂ© Geim and Konstantin Novoselov at the University of Manchester succeeded in producing monatomic graphene layers for the first time. Thanks to graphene’s special conductivity and structure, GAC has reportedly developed a super-fast-charging battery. It is said to be 80 percent charged in eight minutes, 100 percent charged in ten minutes, and allow a range of 200 to 300 kilometers. Compromises may have to be made in terms of service life and cycle stability.

Graphen

Graphene is carbon arranged in ultra-thin layers just one atom thick.

According to Hengxing Ji, a professor at the University of Science and Technology of China, black phosphorus and graphite are the perfect mix for a super battery. Thanks to it, e-car owners in the future should be able to charge their vehicles within ten minutes, even with a range of 500 kilometers. Compared to lithium-ion batteries, black phosphorus has more electrons that can react with more lithium ions. This is expected to increase efficiency and thus range. The material could not be used at present because it has a tendency to deform along its layer edges, making the transfer of lithium ions inefficient. To increase the service life of the battery, the scientists have now developed a mixture with a 15 percent graphite content. It is designed to prevent the problematic edge deformation.

Survey

Sure, if it’s good and cheap – always.

No, I’d rather wait and see.

Conclusion

Yes, so far we haven’t been able to see the new batteries powering cars, let alone try them out. But the BYD Han is supposed to be available for purchase in China since June. And even if the new batteries are not yet in series production like the developments from GAC: The diversity and multitude of development results alone show that the Chinese are gaining a head start in battery cells, as the German manufacturers are said to be doing in the development of combustion engines. But their heyday is over.

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