Design of electrical contact surfaces for fast charging systems

E-mobility is of high interest for the energy transition and the achievement of climate targets. Nevertheless, this forward-looking technology still has a number of drawbacks. One example is the very long charging time of battery systems. To counteract this, an innovative fast charging system using a face contact instead of classic plug-in contacts is being developed that significantly reduces conventional charging times. To enable this, an electrical contact surface is functionalized in such a way that, on the one hand, the contact resistance is reduced and, on the other hand, the thermal as well as mechanical properties are improved. This can be achieved by a special design of the microstructure of the electrical contact surface. In the following, the procedure is described in detail. First, a single microcontact is designed to break up the oxide layers and minimize the constriction resistance. The thermal, mechanical and the electrical properties are described and optimized using analytical and numerical methods. Special attention must be paid to the heating of an a-spot during current flow. Then, the single microcontact is multiplied to exploit the principle of a parallel connection. This can significantly reduce the constriction resistance. Finally, this designed microstructure is manufactured and tested in experiments. Consequently, high charging currents can be transmitted via a face contact on a relatively small contact area.