But also for industrial productions, batteries are soldered as for example the battery modules of the full electric MINI E by the BMW AG . In principal, soldering and brazing are based on a joining process where the joining partners are connected by melting and putting a filler metal, the solder, into the joint , .
Of course, due to its massive heat input iron soldering is not the ideal soldering technique for connecting lithium-ion battery cells. Nevertheless, if a solder with a low liquidus temperature is chosen, this technique is applicable for battery cells, as the results proof.
The soldering irons were taken from the battery cells shortly after the solder completely melted. The welding and soldering processes were recorded by the thermographic camera A325sc by the Flir Systems Inc. to track the temperature distribution of the battery cells.
Nevertheless, if a solder with a low liquidus temperature is chosen, this technique is applicable for battery cells, as the results proof. For the investigations on the heat input into battery cells, solders with 90 °C, 124 °C, and 145 °C liquidus temperature were used.
To reduce the safety risk associated with large battery systems, it is imperative to consider and test the safety at all levels, from the cell level through module and battery level and all the way to the system level, to ensure that all the safety controls of the system work as expected.
Hazardous conditions due to low-temperature charging or operation can be mitigated in large ESS battery designs by including a sensing logic that determines the temperature of the battery and provides heat to the battery and cells until it reaches a value that would be safe for charge as recommended by the battery manufacturer.