The technical developments expected in electric cars: From lithium-sulfur batteries to new manufacturing techniques

The electric car is as old as the car itself. In fact, electricity seemed to be the predilection energy for the newly invented car. Finally, the hegemony of the combustion engine over more than a century slowed the development of the electric.

Due to the pressure of new anti-pollution standards increasingly hard with the internal combustion engine, the development of electric mobility advanced more in the last 20 years than in the entire twentieth century. Even so, he has a lot of development ahead to be able to impose himself definitively.

Solid state batteries

The soul of the electric car is its battery. From the classic lead and acid battery of the early days (and still used in the prototypes at the beginning of the 90s, as in the electric Toledo SEAT) to the current lithium polymer passing through the “classic” ion lithium, progress has been evident.

If one day the electric car wants to impersonate the thermal engine car as a means of transport, the batteries should offer greater autonomy, greater stability and even safety. And it is something that could be achieved with the so-called solid state batteries.

They are still under development, although Toyota says that in 2022 it will have its first 100% electric car equipped with a solid state battery in the market. It is a lithium-ion battery in which the conductive liquid they contain is replaced by a solid material (crystal, gel, gold threads, etc.). We explain it more in detail here . These batteries would have a much higher autonomy than the current ones as well as being safer in the event of a crash.

Lithium-sulfur batteries

In the end, the objective of the manufacturers is to obtain batteries with greater density, that is to say smaller batteries (for reasons of weight and cost) but with greater capacity (to be able to offer more autonomy). And in that sense, lithium-sulfur batteries (sulfur is basically sulfur combined with another chemical element) can be the progress that the electric car has to impose.

Researchers at the University of Texas, Dallas, have developed a battery whose cells are lithium-sulfur with a power density much higher than current batteries. It could be the progress that the automotive industry needs for the electric car to make its mark. The three main advantages of this type of battery versus a lithium-ion battery are its price (the raw material used is cheaper), its capacity and its reduced weight.

Researchers at the University of Texas, Dallas, have developed a battery whose cells are lithium-sulfur with a power density much higher than current batteries.

A lithium-sulfur battery can store three to five times more energy than a lithium-ion battery of the same size. In this way, it would significantly increase the autonomy of a car. These batteries can also be lighter, thanks to the higher energy density. Thus, large batteries would not be necessary, as in the Tesla batteries, in order to grant an important autonomy.

To be a commercial reality, lithium-sulfur batteries must, however, overcome an important defect: their degradation. After 100 cycles of loading and unloading, this type of battery will have lost 30% of its capacity. We are already working on lithium-sulfur batteries with a thin metallic layer of molybdenum.

A battery cost less than $ 100 / kWh for a more affordable electric car

Electric cars are still mostly expensive cars. Few are those that come down from the 35,000 euros price fare. And the main reason is the price of their batteries. These are expensive so the car is expensive and therefore few units are manufactured, which does not reduce the unit cost and make it possible to offer a more affordable price.

In the industry it is considered that for the electric car to be imposed, the cost of a battery must be below 100 $ / kWh. The price of batteries has not stopped falling in the last 10 years. And according to Bloomberg estimates, the price would go down to reach $ 100 / kWh in 2025. However, Elon Musk, CEO of Tesla, destroyed all the forecasts at its last meeting of shareholders: Tesla will be able to manufacture batteries ions of lithium for less than $ 100 / kWh at the end of 2018.

The engines

The electric motor applied to the car still has room for development. In fact, most manufacturers develop their own electric motors, which is an indication that maybe they can be improved. Or in any case, they think they can achieve a significant enough advance to give them a commercial advantage over the rest of the brands.

Lighter materials in the construction of engines, optimizing engine performance depending on the vehicle (tourism, heavy cargo, light industrial, etc.) and alternatives to metals called rare earths (essential in engines that use electromagnets) are some of the the best-known examples of the improvement of electric motors.

Lighter materials in the construction of engines, optimizing engine performance depending on the vehicle and alternatives to metals called rare earths are some of the best known examples of the improvement of electric motors.

BMW, Toyota and Honda are already working on the development of rare earth electromagnets for their engines. The objective is clear, to reduce the cost of increasingly expensive materials at the same time that they get rid of a dependence on those materials that is harmful to the business. What would happen if the producers closed the tap?

One of the key points that can be improved, and where Tesla, for example, has a certain advantage is in the management of energy. In an electric motor, the torque and speed of rotation of the motor determine its consumption, while the maximum power is necessary for performance. Managing these parameters in the most efficient way helps to increase battery life. On the other hand, the cooling of the motors, as well as the batteries, when they are very requested is something in which there is also room for improvement.

Chassis, packaging and composite materials

Electric cars tend to be much heavier than their combustion engine equivalent. A Telsa Model S, for example, weighs about 2,100 kg. Overweight is mainly due to the weight of the batteries, which is why working to improve the energy density of a battery is essential for the industry. Meanwhile, we also work on lightening the weight of the car in general, starting with its own structure and the materials that compose it.

BMW was one of the first to launch an electric car in series with carbon fiber frames and other composite materials. Obviously, he is not the only one to explore new avenues. One of the most interesting examples of the industry comes from the great Gordon Murray, father of McLaren F1.

According to Gordon Murray, the development of engines, tires and transmissions has reached a level where possible progress is minimal. If we want to reduce significantly the consumption of cars – and therefore their pollution – we have only one way to explore and develop: reduce the weight of vehicles. Something that is vital for electric cars.

Gordon Murray, with the iStream and iStream Carbon proposes a structure composed of a simple network of steel tubes covered with composite materials (fibers, plastics, etc.). The steel tubes will serve as support for different elements, such as the door hinges, the motor or the body panels. Newly created carbon fiber panels are added between the tubes. It is a construction system much faster than the current and infinitely less expensive.

Developed in collaboration with the Japanese company Toray, it is characterized by using a paper fiber base in honeycomb trapped between two sheets of traditional carbon fiber, thus forming the “carbon fiber” panels, worth the redundancy.

You can also expect progress in the packaging of the car. For example, going back to electric motors. For example, in the current Honda NSX the Japanese firm opted for two small electric motors to move the front axle instead of a single engine. Thus, the function of torque distribution and regenerative braking is much more efficient, since each of the two engines can function differently from the other.

The development of tomorrow’s electric car covers so many areas that focusing on batteries would be a mistake. And is that from the electric “La Jamais Contente” of 1899 (first car in history to overcome the barrier of 100 km / h), progress has been enormous in all fields: batteries, tires, materials, construction techniques , electronic energy management, gearboxes, etc. This is just the beginning and there are many ways to explore.

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