Performance and Limitations of 3D-Printed Bipolar Plates in Fuel Cells

Abstract

3D-printing is being touted as a tool for prototyping and manufacturing metal fuel cell bipolar plate (BPP) designs as it may speed development and lower costs by avoiding costly tooling, plus the 3D parts can be made as a single piece without welding. We use the 3D-printing method of direct metal laser sintering (DMLS) to make 21 cm2 titanium-alloy BPPs with embedded flow channels. To minimize the contact resistance in an individual cell, the surface of each BPP is polished to the appropriate roughness and coated with a conductive corrosion barrier. The coated BPPs are assembled with the appropriate seals, catalyst coated membranes and gas diffusion layers into both a single-cell and a 40-cell stack and tested. The single-cell stack performs well compared to a standard, but the 40-cell fuel cell stack power is 400 W, or 20% less than expected due to inadequate flatness of several of the DMLS BPPs. This cell-to-cell mismatch leads to high contact resistance in several of the cells. DMLS clearly shows the benefit of being able to make complex flow fields and hollow parts with no welds and is useful for prototyping flow fields in single cells or short stacks. More work is needed toward reducing the weight and increasing the flatness of BPPs made by DMLS before they can be used in larger stacks.