Two main structural forms of liquid cooling plates

With the increasing development of the social economy, the demand for energy has further increased, especially in the context of "dual carbon", the call for new energy technology is getting higher and higher, and the development of electric vehicles has become the general trend. As the core part of electric vehicles, the performance and service life of power batteries directly determine the performance and cost of electric vehicles. Lithium-ion power batteries have become the main choice for electric vehicles due to their advantages of long life, low self-discharge rate, high specific power, high energy density and no pollution. However, there is an optimal temperature range for the charging and discharging of lithium-ion batteries, and a large amount of heat will be generated when the battery is charged and discharged, and the accumulation of heat leads to the continuous rise of the battery temperature. When the battery temperature rises, beyond its allowable operating temperature range, it will lead to a sharp decrease in charge and discharge capacity, and even make the discharge unable to complete, in order to ensure the normal operation of the battery, auxiliary cooling measures need to be taken. In winter, lithium precipitation occurs when charging at low temperatures, which affects the performance and life of the battery, so the battery needs to be heated. Usually a set of liquid cooling plate is provided at the bottom of the module in the battery system, and the liquid cooling plate is connected to the circulating pump, heat exchanger and overwater heater to form a circulating heating and cooling system by connecting the pipeline. When the high-temperature battery needs to be cooled, start the air conditioning system and water pump, use the heat exchanger to cool the cooling medium, and the cooled cooling medium flows through the inside of the battery pack to exchange heat with the module to take away the heat of the battery. When the low-temperature battery needs to be heated, the water pump and the water heater are started, and the heated cooling medium circulates through the liquid cold plate to heat the battery.

At present, the liquid cooling plate used by battery manufacturers mainly has two structural forms. One is aluminum micro channel tube, which adopts aluminum alloy porous flat tube, and the two ends are brazed with the collection tube. This structure is lightweight, but its own rigidity is not high, and it needs the support of structural parts to make the flat tube press the bottom of the module to ensure good heat conduction. The other is a double-layer stamping plate structure, the upper layer is a flat aluminum plate, the lower layer is an aluminum plate stamping runner structure, and the upper and lower aluminum plates are connected by high-temperature brazing. The flow channel design of this structure is relatively free, and it can well adapt to the irregular module arrangement in the battery pack.

However, whether it is aluminum micro channel tube or a stamping plate structure, the runner forming needs to adopt the brazing process, and the welding area is large, the welding part is more, and there is a certain hidden danger of leakage. And because the liquid cooling plate is arranged inside the battery pack, once the liquid cold plate leaks, it may cause the risk of short circuit or even fire inside the battery pack. In addition, the distribution of branch flow channel flow in most liquid cooling solutions is fixed, and the supply of coolant cannot be flexibly adjusted according to the cooling needs of the module, resulting in inconsistent cooling speed of the partition and increasing the internal temperature difference of the battery system.