Battery thermal management under all-climate conditions based on phase change materials and heat pipes: A numerical simulation study

Various types of batteries, including lithium-ion, lead-acid, nickel-based, and sodium-based batteries, are crucial in the widespread adoption of hybrid electric vehicles (HEVs) and electric vehicles (EVs), as well as in advancing clean energy technologies such as wind and solar power. They significantly contribute to reducing greenhouse gas emissions and decreasing reliance on fossil fuels [1], [2], [3]. The performance of batteries is closely tied to their operating temperature, which is influenced by environmental conditions [4], [5]. Both excessively high and low operating temperatures can significantly impair the capacity, efficiency, and safety of batteries. To achieve optimal battery performance, it is recommended to operate them within their ideal temperature range. To ensure sustained performance, appropriate thermal management systems must be employed to control temperature, particularly in applications where environmental temperature fluctuations are expected [6]. These thermal management systems may include active cooling or heating methods. Implementing such systems allows for precise temperature regulation within the battery’s optimal operating range, thereby maximizing performance and extending lifespan.

High temperatures have a significant impact on the safety of battery, leading to increased research in battery thermal management systems (BTMS) focused on heat dissipation. Various approaches are being explored, including air-based systems that utilize heat sinks and cooling fans [7], [8], liquid-based systems that use coolants or refrigerants [9], [10], and combined systems that integrate multiple cooling methods [11], [12]. These advancements aim to enhance battery safety, performance, and longevity by effectively dissipating heat and maintaining optimal operating temperatures. In recent years, the BTMS based on phase change material (PCM-BTMS) and heat pipe (HP-BTMS) gained increasing research attention. PCM-BTMS stands out as an exceptionally promising cooling technology, primarily due to its remarkable capability to absorb the heat generated by batteries and regulate their temperature without relying on external energy sources [13]. This distinctive feature not only ensures efficient thermal management but also contributes to energy conservation, making PCM-BTMS a green technology solution. Furthermore, the cost-effectiveness, straightforward installation process, and high cooling efficiency of PCM-BTMS amplify its appeal. These advantages position PCM-BTMS as a highly viable option for improving battery safety and enhancing performance across a wide range of applications. Utilizing PCMs in BTMS can lead to a substantial reduction in the maximum temperature of batteries, with potential decreases ranging from 8 to 28 % [14], [15]. The primary limitation of PCM-BTMS lies in the inherently low thermal conductivity of phase change materials, which can impede the efficient distribution and dissipation of heat throughout the system. This challenge has spurred numerous research efforts aimed at enhancing the thermal performance of PCMs to fully leverage their potential in battery thermal management, such as incorporating Thermal Conductivity Enhancers (TCEs) into PCM formulations has emerged as an effective strategy [16], [17], [18]. HP-BTMS have gained significant traction in recent years as a passive thermal management solution. Utilizing the high thermal conductivity of heat pipes, HP-BTMS has become widely employed for effective temperature control in battery packs. The adoption of HP-BTMS showcases its potential in addressing thermal challenges and ensuring optimal operating conditions for batteries in various applications [19]. Indeed, various types of heat pipes have been extensively studied by researchers for BTMS. Some of the commonly investigated heat pipe types include tubular heat pipes [20], [21], flat heat pipes [22], [23], oscillating heat pipes [24], [25], and loop heat pipes [26], [27]. The findings of these studies consistently indicate that heat pipe-based BTMS is an efficient choice for managing battery temperatures.

To counteract the negative impacts of low-temperature environments on batteries, the preheating systems, which are designed to warm up the batteries before operation, are commonly employed. By implementing preheating systems, battery efficiency and lifespan can be improved while minimizing the detrimental impacts of low temperatures. There are several types of battery preheating systems, such as air heating [28], [29], liquid heating [30], [31], PTC thermocouple heating [32], [33], AC electric heating [34], [35], and PCM heating [36], [37]. PCM heating is an innovative method of heating that utilizes phase change materials surrounding the battery pack. When the temperature drops below a certain threshold, these materials release heat to warm the battery to the desired temperature. This approach provides a notably stable heating effect. Yazici et al. [38] utilized graphite-based PCM for battery module preheating, resulting in an 80 % faster temperature rise rate, 40 % less temperature difference, and 20 % less voltage drop compared to non-preheating conditions under a 1C discharge rate. Moreover, PCMs not only have the capacity to preheat batteries but also to cool them in high-temperature environments, effectively regulating battery temperature [36].

Given the complementary advantages of PCMs and heat pipes in battery thermal management, many researchers have explored their integration. By combining the high thermal conductivity of heat pipes with the exceptional ability of phase change materials to mitigate temperature fluctuations, such coupled systems offer a promising approach to achieving more effective and stable battery temperature control [39], [40]. Bian et al. [41] proposed a passive battery thermal management strategy based on the integration of HP and PCM. Through numerical simulations, they investigated the thermal performance of the HP/PCM coupled system under different PCMs, HP, coupling systems, and driving conditions. Their results demonstrated that the HP/PCM coupled system exhibits excellent heat dissipation and temperature uniformity, with heat pipes primarily reducing the maximum temperature and PCMs playing a critical role in maintaining temperature homogeneity.

Although significant research has been conducted on battery thermal management, most studies focus primarily on addressing either high-temperature heat dissipation or low-temperature heating separately. However, with the rapid development of electric vehicles in recent years, the operating environments for batteries have become increasingly complex, necessitating solutions that can simultaneously manage both high and low temperature extremes. This shift has heightened interest in understanding the thermal management performance of batteries under diverse climatic conditions. In 2023, the Ministry of Industry and Information Technology of China emphasized the importance of research into battery thermal management technologies that can perform across all climate conditions. Achieving effective battery thermal management under all climate conditions requires a careful balance between high-temperature heat dissipation and low-temperature preheating and insulation. However, these two objectives often present conflicting requirements in system design, creating challenges for the development of all-climate battery thermal management systems. Currently, there is limited information on battery thermal management across all climate conditions, and the conflict between heat dissipation and heat preservation remains unresolved [42], [43]. The thermal management structure has yet to be optimized for heat preservation, leading to inadequate heat retention, which prevents the battery from maintaining its temperature over an extended period after preheating.

To address this issue, this study integrates phase change materials (PCM) and heat pipes (HP), while accounting for the insulation effect of the insulating layer, to design a battery thermal management system in capable of operating under all climate conditions. Although PCM and HP coupled thermal management systems have been studied, the majority of research focuses on high-temperature heat dissipation. There remains a significant gap in studies that comprehensively address the dual functionality of low-temperature heating and insulation alongside high-temperature cooling. Phase change materials are used for their excellent potential in cooling, heating, and insulation [44], [45], [46], [47], they are also commonly explored in research on thermal management for all-climate batteries [42], [48], although studies in this area are still limited. Heat pipes, on the other hand, are employed due to their high heat dissipation capacity, while also preserving the integrity of the battery pack’s insulation system and facilitating the arrangement of PCMs [19]. A numerical investigation is conducted to comprehensively evaluate the system’s heat dissipation and heating performance under both high and low temperature conditions, and the results show that the combination of phase change materials and insulation layers can effectively maintain the battery temperature in low-temperature environments, even as low as −40 °C, ensuring it remains above 20° C for an extended period. Additionally, the heat pipe provides the battery with a high heat dissipation capacity in high-temperature environments, keeping its temperature well controlled below 40° C.