A novel preheating systems for columnar lithium batteries for below zero degrees celsius environment based on topology optimization

The performance and lifespan of lithium batteries will significantly deteriorate at zero degrees Celsius. Low temperature not only significantly reduces the discharge capacity and charging efficiency of lithium batteries, but also causes internal side reactions, accelerating battery aging. Therefore, preheating lithium batteries is very important. However, there is currently limited research on preheating lithium batteries. At the same time, the current surface contact or sleeve contact methods are not suitable for different types of cylindrical batteries. After the battery size changes, it is necessary to redesign the size details of the thermal management system. Therefore, this article proposes a topology optimization based preheating system design for columnar lithium batteries below zero degrees Celsius. The optimization problem of thermal structure design was decomposed into three objective functions, including two thermal objective functions and one hydraulic objective function (TOP1), and a three-dimensional thermal fluid coupling model was established. The topology optimization results using the TOP1 problem formula were compared with the design results using traditional two objective functions (TOP2) and traditional straight channel and curved battery preheating systems. The results showed that compared to using a straight channel heat exchange plate, the design generated by the TOP1 target formula increased the average heating rate of the battery by 24.8%. Compared to preheating systems with curvature, The design of the TOP1 target formula reduced the standard deviation of battery temperature by 32.65%. In addition, we conducted numerical studies on the TOP1 model and analyzed the effects of different inlet flow rates, heat transfer fluid temperatures, and battery spacing on battery preheating. We conducted experimental tests on the optimized topology and verified our simulation results.