Hybrid phase change material techniques for battery thermal management in electric vehicles: A comprehensive review and bibliometric analysis

The sudden increase in electric vehicle (EV) interest has created a surge in demand for sophisticated battery thermal management systems (BTMS). BTMS maintains the battery temperature within a safe range, preventing thermal runaway and extending the lifespan. Hence, to improve consumer safety perceptions, effective BTMS are necessary. Phase-change materials (PCMs) based BTMS have passive cooling capability to store latent heat and have attracted significant attention. The low thermal conductivity of PCMs limits their cooling capacity in long-term or high-discharge-rate battery operations. Therefore, hybrid BTMS approaches that integrate PCMs with active or secondary cooling techniques—such as liquid cooling, air cooling, heat pipes, thermoelectric coolers, and finned structures—have become promising options. This paper provides a detailed summary of recent progress, shortcomings, and pioneering ideas on hybrid PCM-based thermal management systems in electric vehicles. It conducts an in-depth bibliometric evaluation to identify knowledge gaps and examine correlations among different cooling techniques, presenting a structured summary of proven and emerging thermal management technologies. In addition, it provides some explicit recommendations on areas to be explored in future research, such as studies on thermoeconomic feasibility, long-term stability tests of composite phase-change materials, investigations into vibration-induced phenomena, and design methodologies to incorporate scalability and manufacturability. This work presents a bibliometric study that reveals a high level of focus on the energy efficiency of hybrid cooling techniques. It also shows that research is concentrated on air cooling, liquid cooling, heat pipes, and hybrid systems that incorporate fins or heat sinks. This work also emphasizes the need for long-term performance analysis, thermoeconomic studies, the impact of mechanical shocks, and the cyclic performance of EV BTMS. This review aims to make a valuable contribution that will inform research into developing efficient, effective, economically viable, and easily deployable hybrid battery thermal management systems, ultimately promoting the widespread adoption of electric vehicles.