Abstract: Facing the risks of thermal runaway and challenges associated with wide-temperature-range operation in high-energy-density lithium-ion batteries, phase change material (PCM) cooling and liquid cooling technologies have emerged as key research areas. This paper provides a comprehensive review of recent advances in lithium battery thermal management technologies based on PCM enhancement and its integration with liquid cooling systems. First, three primary approaches to enhance the thermal conductivity of organic PCMs are discussed: the development of composite PCMs incorporating nano-metals, carbon-based materials, and biomass-derived carbon materials; the integration of PCMs with heat pipes; and the formulation of PCM-metal foam composites. Second, recent progress in flexible, flame-retardant composite PCMs is presented, focusing on improvements in mechanical strength and safety performance. Subsequently, the synergistic mechanisms between various liquid cooling techniques—non-direct contact, single-phase direct contact, and two-phase direct contact—and PCM systems are analyzed, along with their respective heat dissipation capabilities and application scenarios. Additionally, the advantages and disadvantages of various PCM-based battery thermal management technologies are comprehensively analyzed and discussed. Research indicates that hybrid PCM-liquid cooling systems combine the advantages of passive thermal stability and active cooling efficiency, demonstrating superior performance under extreme operating conditions. Finally, current limitations such as PCM leakage, corrosion of metal foams, and high system costs are summarized. Prospects for future research directions include the development of novel high-thermal-conductivity materials, structural optimization of thermal management systems, and cost-effective, environmentally sustainable designs, offering valuable insights for the next generation of high-performance lithium-ion battery thermal management solutions.