Scientists worldwide research solutions to convert the electric vehicles’ batteries into structural parts thereof, so as to reduce their volume while decreasing their high manufacturing cost. The bodywork may be one of the most used elements to such end.
One of the problems that manufacturers are facing to introduce electric vehicles on the market is its high cost, derived from the manufacture of batteries. However, unlike the fuel tanks, batteries could take different forms and be made of materials resistant to physical loads. The solution to lower costs would be the introduction of the batteries in the door panels or in other parts of the vehicle, causing the weight to be significantly reduced, and the space to be increased.
The makers Tesla Motors and Volvo have already carried out demonstrations of this approach using structural materials of the car as a battery. Tesla has already used the metal case containing the battery from its Model- S to increase the car’s structure rigidity, thus reducing the amount of metal needed for its manufacture. Volvo meanwhile, used thin lithium-ion rolled or folded films to form a battery cell. These films were sandwiched between sheets of carbon fiber composite.
The ability to use batteries as structural materials is currently limited by the use of flammable electrolytes, although researchers are developing safer chemical compounds that could be used more broadly. On the other hand, battery panels that do not spoil when being dented in an accident should be designed.
Researchers from the Research Agency for Energy Advanced Projects of the U.S. Energy Department ( ARPA -E) are looking for ways to design battery packs that absorb energy in a crash and replace materials that today are being used to protect passengers . For example, instead of placing battery cells in a solid block, it could be made possible for the cells to be capable of moving and separating in the event of a crash, dissipating energy as they do so.
Returning to the high flammability of the batteries in the event of a crash, researchers are developing new chemical compounds that do not use flammable electrodes, so batteries can be used as door panels and maintain security. They are considering replacing volatile electrolytes with fire resistant polymers, water-based and ceramic materials. Once they have a safer electrolyte, researchers will look for ways to use the battery electrodes in a cell to withstand physical loads.
Volvo is trying to use carbon fibers in composite materials to store and conduct electricity but the results are still insufficient to try to move a vehicle. In this line, the Imperial College of London replaces epoxy which usually holds the carbon fibers together with a composite material with a mixture of rigid materials and ionic liquids that can conduct charged molecules. This forms a type of supercapacitor that could store enough energy to be used in lieu of a battery in a start-stop hybrid.
To store a sufficient driving range lithium-ion batteries that use carbon fiber as an electrode are being developed, but they use lithium-ion conventional materials for the opposite. Others have developed a non-volatile polymer electrolyte to replace the conventional ones, although they are flammable.
Source : MIT Technology Review