Changing the future

Five truths about the electric car

The electric car is making inroads around the world. But many drivers still have reservations about battery drives. High costs, long recharge times, weak batteries in frosty weather. So what is true and what is myth? We present a fact check.

China is promoting e-mobility more energetically than any other country. Already the world’s largest sales market for electric vehicles, China aims to be building five million e-cars a year by 2025. The country is showing the rest of the world the way to new mobility. The big automakers are converting their production processes to e-cars, and Chinese technology companies like Alibaba and Foxconn are increasingly investing in the new market.

In this context, the focus is more than ever on the technical challenges of e-mobility. Apart from the need for an adequate charging infrastructure, the success of battery-powered electric cars depends above all on the batteries themselves and their performance. Batteries significantly influence the purchase price, reliability, safety and service life of electric vehicles. But many drivers have reservations about battery drives. Don’t the large batteries make electric cars too expensive? Does the battery cause problems in freezing temperatures? How long does it take to charge them? Do I have enough time for that? We put five statements about electric cars, batteries and separators on the test bench.

1. Electric cars are too expensive.

Changing the future

Despite a state purchase premium in Germany of up to 4,000 euros, most electric cars are still much more expensive to buy than diesel or gasoline vehicles. This is mainly due to the battery, which determines around 40 percent of the cost of an electric vehicle. However, prices for lithium-ion batteries fell by 80 percent between 2010 and 20161. Currently, the battery pack costs around 170 euros per kilowatt hour (kWh)2. From about 130 euros/kWh, the price of electric cars and gas burners would be the same. Experts expect that costs will continue to fall due to higher volumes and innovations in battery cell construction, and will come to match the price of the internal combustion engine. The Freudenberg Safety Separator helps to streamline the production process (see box). Because this separator can withstand high temperatures, it enables separators and electrodes to be dried in only one process step in contrast to polymer film separators. Incidentally, in operation, electric cars are already cheaper than fuel burners because they have fewer wearing parts and require no exhaust maintenance or lubricants.

2. Charging takes too long and there are too few charging stations.

Changing the future

It takes at least six hours to charge the battery using a standard household power outlet. That sounds like a lot, but it’s not a problem if the electric car charges in your own garage or at a charging station at work. Bear in mind that a private car stands idle for more than 21 hours a day on average. Long charging times are a shortcoming on the road, although charging stations with a fast-charge function require a maximum of an hour, sometimes less than 30 minutes to recharge the battery of an e-car. Nevertheless, there is still a shortage of charging stations. That is why for example the German state is providing 300 million euros to fund the construction of new charging stations. By 2020, the aim is to have built 5,000 new fast-charging stations and 10,000 charging poles using normal charging technology. Electric car batteries react similar to cell phone batteries: they become considerably warmer during fast-charging. Freudenberg’s temperature-stable separator can provide increased safety in this respect.

3. Electric cars are adversely affected by cold weather.

Changing the future

Frost is a challenge for electric cars. As with the combustion engine, cold conditions cause increased friction between all parts, leading to higher energy consumption. In addition, the battery not only needs to drive the car in winter but must also provide power to the lighting and heating systems. For this reason, the ADAC subjected three models – BMWi3, Nissan Leaf and Opel Ampera – to a winter endurance test in 2016. The results showed that the cars all worked flawlessly at temperatures as low as -20 degrees Celsius.

4. Lithium-ion batteries can catch fire.

Changing the future

In recent years, lithium-ion batteries in electric cars have occasionally caught fire or exploded. Although protective measures such as electronic battery management systems or thermal fuses largely prevent fires and explosions, the inherent battery safety has to be ensured previously. The use of temperature-stable cell components such as Freudenberg’s flexible and ceramic Safety Separator (see box) can reduce the risk of short-circuits causing fires. However, they cannot completely eliminate the risk of fire in the event of operating errors, design faults or accidents. Freudenberg’s ceramic-impregnated polyester nonwoven remains stable at high temperature and does not shrink. Consequently large-area short circuits in a battery cell are avoided and the “thermal runaway” in the complete battery system is prevented. In the event of a fire, electric and hybrid cars with lithium-ion drive batteries are at least at the same level of safety as petrol and diesel vehicles, according to the testing organization Dekra.

5. The life of the batteries is limited.

Changing the future

Manufacturers of batteries for electric cars currently guarantee mileages of 100,000 to 160,000 kilometers. Experts give the life of the battery as eight to ten years and 500 to 1,000 charging cycles. Precisely how long a battery lasts will depend on many factors, such as the number of charging cycles, the type of charging, the driving style or external conditions such as temperatures. After that, the battery doesn’t simply fail but loses charge capacity and thus range. After a few years, capacity drops to 70-80 percent although this process can be delayed by proper care. Avoiding extreme charge levels and having the battery inspected once a year will increase its lifetime.

 

More information about Freudenberg’s separator:

https://separators.freudenberg-pm.com

Making rechargeable batteries safe

Whether or not battery-powered electric cars succeed in becoming a major presence on the market depends largely on powerful and safe batteries. This requirement was the inspiration behind Freudenberg’s development of the Safety Separator. The ceramic impregnated nonwoven material withstands extremely high temperatures and increases the safety and service life of lithium-ion batteries.

In recent years, there have been incidents of lithium-ion batteries catching fire or even exploding. Often, entire cell phones, notebooks or electric cars have caught fire as a result. How is that possible? During “thermal runaway” triggered by an electronic malfunction or mechanical damage, the battery interior heats up. It might result in a large-area short circuit if for example during this temperature increase the membrane between anode and cathode shrinks. In contrast to the normal charging and discharging the subsequent chemical reaction is totally uncontrolled and generates high temperatures. The battery catches fire and, in the worst case, the entire product explodes and goes up in flames.

To minimize the risk of fire, Freudenberg has developed the Safety Separator. “The ceramic-impregnated polyester nonwoven fabric remains stable at high temperature and does not shrink. This prevents the battery from a thermal runaway”, explained Margarita Messerle, Sales & Marketing Manager at Freudenberg Performance Materials.

The Safety Separator is significantly less sensitive to heat and mechanical stress than polymer membrane separators. These can melt and shrink at temperatures as low as 80 degrees. A secured temperature stability enables a drying process of electrodes and separators in only one step before filling in the electrolyte. The reduced water content in the cell increases the life of the battery significantly. The ultra-thin, temperature-stable separators are installed in lithium-ion batteries for energy storage and in electric vehicles, such as e-buses. As a key component, they play an important role in making the batteries safer and more efficient.

Futher information

E-Mobility

The electric car is making inroads around the world. But many drivers still have reservations about battery drives. High costs, long recharge times, weak batteries in frosty weather. So what is true and what is myth? We present a fact check.

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