Research Progress on Thermal Management of Lithium Battery Based on Immersion Liquid Cooling

At present, a variety of cooling systems have been developed for the thermal runaway problem of lithium batteries, mainly including air cooling, liquid cooling, heat pipe cooling, phase change cooling and its combination of cooling systems. Among them, air cooling can be divided into natural convection heat transfer and forced convection heat transfer. However, due to its low heat transfer efficiency and long heat conduction relaxation time and other shortcomings, it is difficult to meet the heat dissipation needs of large-scale battery packs at high discharge multiples. Heat pipe cooling, which is characterized by high thermal conductivity, structural stability, low maintenance cost and long lifetime, has attracted much attention in battery thermal management. However, heat pipe cooling has limitations under rapid temperature fluctuations and harsh environmental conditions, and lacks a simple and generalized heat transfer model to accurately predict the thermal performance of modules and battery packs, so it has not yet been applied commercially. In recent years, phase-change cooling has also been widely studied, but the high cost and low thermal conductivity of phase-change materials and the need to use them in combination with other heat dissipation schemes make it difficult to be applied on the ground. With the gradual increase in battery energy density and the increased demand for heat dissipation, liquid cooling technology has received more and more attention from academia and industry. According to whether the coolant is in direct contact with the battery, it can be categorized into direct liquid cooling or indirect liquid cooling. Direct liquid cooling, also known as submerged liquid cooling, is one of the most effective heat dissipation technologies at present, with the advantages of efficient heat dissipation, energy saving, space saving and stable low noise. This cooling system immerses the battery in a non-conductive dielectric so that it gets uniform heat transfer, thus ensuring the uniformity of the temperature of the battery pack. Since the heat transfer medium is in direct contact with the battery, the contact thermal resistance is reduced, further improving the heat transfer efficiency. In addition, this cooling method can also reduce the complexity of the system. 4 different cooling methods and their advantages and disadvantages are shown in Figure 1. With the development of technology many combination systems have appeared.

Currently, although there are a large number of reports on the use of submerged liquid cooling for data centers, there is a lack of review on its use in battery thermal management. This paper analyzes and describes the thermal management of batteries based on submerged liquid cooling technology, including the effects of factors such as coolant type, arrangement, flow rate, and pressure on the thermal efficiency of batteries, and discusses the prospects and challenges facing this technology.