Passive Thermal Management of Cylindrical Lithium-Ion Cells Using Additively Manufactured Polymer Housings

Lithium-ion batteries are widely used in modern energy storage systems; however, increasing power demand makes thermal management a critical challenge, particularly for cylindrical cells operating under high discharge conditions. This study investigates the thermal behavior of cylindrical lithium-ion cells equipped with additively manufactured polymer housings produced by fused filament fabrication (FFF). PLA, PCTG, flame-retardant PLA (FG_PLA), and ASA housings were evaluated using Samsung 50S, Molicel P42A, and Reliance RS50 cells under 1C–5C discharge rates. Surface temperatures were measured at multiple locations to assess heat transfer through the housing structures. All investigated housings reduced the measured maximum cell surface temperature compared with the housing-free configuration, particularly at high discharge rates. PLA exhibited the greatest thermal buffering effect, while PCTG showed the highest estimated conductive heat-transfer rate and a more uniform temperature evolution across the housing. ASA demonstrated stable thermal behavior, with thin housings generally showing a greater measured temperature reduction than thick configurations. In contrast, flame-retardant PLA provided the smallest temperature reduction. Wall thickness influenced the transient thermal response but did not consistently result in a greater measured temperature reduction. At elevated temperatures, partial deformation of some polymer housings was observed. The results demonstrate that FFF-manufactured polymer housings can substantially modify the transient thermal response of cylindrical lithium-ion cells, while material selection and housing geometry remain key design parameters for passive thermal management applications.