Thickness Reduction Strategy for Graphite Composite Bipolar Plates: Materials, Structure, and Manufacturing Process

ABSTRACT The proton exchange membrane fuel cell (PEMFC) converts clean hydrogen's chemical energy into electricity and is vital for carbon neutrality. However, its development is limited by low volumetric power density and high cost. Thickness‐reduced composite bipolar plates (CBPs) offer a promising solution to boost power density and reduce costs. CBPs are critical PEMFC components, comprising 70%–80% of the stack's volume and weight, and function for current collection, gas separation, and mechanical support. On this basis, this review explores strategies to achieve thickness reduction in CBPs from the perspectives of material, structure, and manufacturing processes, analyzes the primary factors influencing CBP thickness and key performance metrics starting from the theoretical minimum thickness limitation, and proposes enhancement approaches to improve the electrical conductivity, mechanical properties, and gas barrier properties of CBP following thickness reduction. The conductivity is improved by optimizing carrier transport, and the influence of material interface modification on gas permeability is analyzed. The design innovation of novel biomimetic structures optimizes the mechanical properties. By synthesizing these perspectives, this review offers valuable insights for reducing thickness and optimizing the performance of CBPs.