3D-printed honeycomb-structured BaTiO3-based PTC ceramics formed by digital light processing for the thermal management of hydrogen fuel cells

Abstract

Honeycomb-structured and high-Curie-point positive temperature coefficient (PTC) heating elements are promising for thermal management in hydrogen fuel cell vehicles, which require highly safe and efficient hydrogen supply and fuel cell start-up. However, it is still challenging to prepare honeycomb structures by traditional manufacturing methods because of the high dependence on molds and poor mixing uniformity of raw materials. Additionally, the poor curing performance of leaded PTC ceramic slurry tends to hinder the preparation of complex geometries by the emerging digital light processing (DLP) 3D printing. Herein, an innovative method for functionalizing PTC powder, introducing polymethyl methacrylate (PMMA) and Al₂O₃, and optimizing the honeycomb structure was developed to fabricate high-performance PTC ceramics in this study. Notably, with 10 vol% PMMA and 3 vol% Al₂O₃, a low room-temperature resistivity (ρ = 42 Ω cm), a high temperature coefficient of resistance (α_10–25 = 15.02%/°C) and a large PTC jump (log(R_max/R_min) = 4.01) are obtained, showing significant improvement over unmodified printed PTC ceramics (ρ = 225 Ω cm, α_10–25 = 8.03%/°C, and log(R_max/R_min) = 2.59) while slightly outperforming conventionally pressed PTC ceramics (ρ = 71 Ω cm, α_10–25 = 15.89%/°C, and log(R_max/R_min) = 3.93). Meanwhile, the experimental and simulation results indicate that the honeycomb structure with 60% porosity exhibits excellent electrical properties, rapid thermal response and strong heat storage capacity for hydrogen supply and fuel cell preheating. Therefore, this work provides a viable strategy for additive manufacturing of advanced functional ceramics with customized structural designs for sensors and heaters.