Nanoparticle-enhanced phase change materials for passive thermal management of lithium-ion batteries: A multi-variable scenario-based optimization

The growing demand for high-performance lithium-ion batteries in electric vehicles requires thermal management strategies that can limit temperature rise without adding excessive complexity or weight. This study investigates nanoparticle-enhanced phase change materials (NePCMs) as a passive thermal management option for a lithium-ion pouch cell. A validated numerical framework, combining the Newman–Tiedemann–Gu–Kim electrochemical–thermal battery model with an enthalpy–porosity formulation for the PCM, is used to analyze 25 NePCM configurations based on a commercial paraffin (RT25) with copper, aluminum, and hybrid Cu/Al nanoparticles at volume fractions of 3%, 7%, and 10%. The model shows good agreement with experimental data from the literature and is then applied to discharge rates from 1C to 5C. Under 5C discharge, a Cu-10% NePCM reduces the peak cell temperature by up to 17.7 K relative to the no-PCM case, while Al-10% achieves up to 14.7 K reduction with a lower density penalty. A compact third-order correlation between liquid fraction and density (RMSE ≈ 0.028) is identified that represents all 25 RT25-based Cu/Al configurations studied and provides a convenient way to interpret how nanoparticle loading simultaneously affects phase-change utilization and density. Within the tested set, a hybrid NePCM with 4% Cu + 3% Al achieves about 91% of the maximum thermal enhancement observed while retaining ∼35% higher phase-change capacity than Cu-10% at 5C. The results highlight trade-offs between peak temperature reduction, latent heat capacity, and added mass that may assist in selecting NePCM formulations for passive battery thermal management. The quantitative values reported are specific to the RT25 + Cu/Al system and the modeled pouch-cell geometry, but the methodology and analysis framework can be extended to other PCM and nanoparticle combinations in future work.