In the field of Engineering, Mechanical Innovation and Advanced Technology, thermal runaway risks and non-uniform cell temperature gradients impair lithium-ion battery safety and cycle life in fast-charging EVs. This empirical investigation systematically examines Thermal Management of High-Power Density Electric Vehicle Battery Packs Using Phase Change Material Composites through a multi-stage experimental methodology and rigorous quantitative analytical framework. Utilizing computational fluid dynamics (CFD) simulation and experimental testing of paraffin wax composites reinforced with expanded graphite, data were gathered across multiple operational cycles and validated against established international benchmarks. The statistical and computational results reveal that the composite PCM jacket maintained battery module maximum temperatures below 42 degrees Celsius during continuous 3C high-rate discharge cycles. Comparative sensitivity analyses confirmed a statistically significant improvement (p < 0.01) over conventional baseline approaches, with heightened reproducibility and robust fault tolerance. These comprehensive findings provide actionable theoretical insights and practical implementation guidelines for electric vehicle battery system designers and automotive thermal engineers. Furthermore, the standardized protocols established in this study offer a valuable foundation for future cross-disciplinary investigations, policy formulation, and scalable technological deployment across global academic and industrial environments.