Integrated graphite–insulation sheet with cold plate for effective thermal management in pouch-type lithium-ion modules

Abstract

Efficient battery thermal management remains a major challenge in electric vehicles (EVs), as Li-ion cells need to be operated in a desired temperature range to ensure safety, performance, and longevity. This study proposes a novel interface sheet that combines a graphite layer with an insulation sheet to enhance lateral heat conduction while preserving thermal insulation between cells, tailored for side cooling designs of modules. The proposed graphite integrated insulation sheet (GIS) is first evaluated through numerical simulations on a five-cell battery module across different coolant inlet temperatures and flow rates. Simulation results reveal that GIS reduced the maximum cell temperature by 2.8 °C and improved temperature uniformity by 3.6 °C compared to modules using conventional pure insulation sheets. The side-mounted cold plate is also optimised using the TOPSIS multi-criteria decision-making method to identify the best-performing design. Subsequently, the GIS and optimised cold plates are experimentally tested on a two-cell module under different flow conditions to validate the concept. Experimental investigation further highlights the effectiveness of GIS, showing a maximum temperature drop of 10.8 to 12.8 °C, an average temperature reduction of 5 °C, and a temperature non-uniformity reduction of 10.4 to 13.5 °C for the module. Additionally, using GIS allows a 69 % reduction in coolant flow rate for the same thermal performance, underscoring its potential to reduce cooling system demands. This study highlights that the GIS concept offers a lightweight, scalable, and thermally efficient solution for side-cooled battery modules and opens a new approach for future optimisation in EV thermal management systems.