# Design and Optimization of Cooling Plate for Battery Module of an Electric Vehicle
## 1 Introduction  
As an important type of energy storage units, lithium batteries have been developed for many years and their performance has been greatly improved. They have been gradually applied to artificial satellites, robots, and electric vehicles (EV) [1; 2; 3; 4]. Nowadays, more and more electric vehicles are being produced, and lithium batteries are being widely used, but a lot of the heat in the process of using has appeared [5]. The service life, capacity, and internal resistance of the batteries are sensitive to temperature changes. In order to prolong the service life of the battery, it is particularly important to design a battery module with good heat dissipation performance.  
Air cooling can meet the requirements of the vehicles in common conditions, but the battery temperature will be higher. When the EV changes the speed frequently or it is at high velocity, the battery is discharging at a high rate, air cooling is unable to meet the requirements of cooling alone [6; 7]. Although the cooling effect can be optimized by changing the position, number, and angle of the entrance, adding a guide plate and changing the battery arrangement, it is still difficult to meet the needs of different electric vehicles [8; 9; 10]. Phase change material (PCM) cooling system controls the temperature of the battery module by the heat absorption and heat release when its material phase changes. Power battery cooling experiments using PCM are easier to meet the needs of the lithium battery cooling system, but the cost is high, and it is used less in electric vehicles [11; 12; 13].  
Since the introduction of a liquid cooling system with high cooling efficiency and reliability [14; 15; 16], it has gradually occupied the electric vehicle market. The liquid cooling system in the BMW I3 and the Tesla model S, have good sealing and reliability, and can take away the heat of each battery evenly andexhibit good performance in electric vehicles. [PERSON] et al. [17] studied the cooling performance of 20 Ah lithium-ion pouch cell with cold plates along both surfaces by changing the inlet coolant mass flow rates and the inlet coolant temperatures. The enhanced cooling energy efficiency was achieved with a low inlet coolant temperature, low inlet coolant mass flow rate, and a high number of the cooling channels. [PERSON] et al. [18] experimentally investigated the temperature and velocity distributions within the mini-channel cold plates placed on a prismatic lithium-ion battery cell using water cooling methods. [PERSON] et al. [19] carried out experimental and simulations to study the effect of cooling channels, flow rates, and flow directions at different discharge C-rates. It was found that the maximum temperature reached within the battery decreased as the amount of thermal silica plates and liquid channels increased. [PERSON] et al. [20] designed a new liquid cooling strategy based on thermal silica plates combined with the cooling effect of water. The experimental results demonstrated that the addition of thermal silica plates can greatly improve the cooling capacity.  
In this paper, a lithium iron phosphate battery was used to design a standard module which can be quickly interchanged by EV, and then the liquid cooling plate for the module was analyzed by numerical heat transfer analysis. A surrogate model was utilized to further optimize the geometry of the cooling plate.