Application Of 3D Printing Technology In Solid Oxide Fuel Cell

Solid oxide fuel cell?SOFC?is an attractive electrochemical energy conversion device due to its environmental friendliness and flexible fuel choices.A complete SOFC stack via the conventional manufacturing processes commonly requires steps of single cell fabrication,assembling and sealing process.These complex and lengthy processes are time-consuming and difficult for reproducibility.Moreover,the presence of multiple interconnects,joints and seals required for SOFC stack further increase the preparation uncertainty which often negatively affects the reliability and durability of SOFC systems during thermal cycling in operating process.To overcome these issues,in this paper,one-step fabrication method is attempted to prepare the dense electrolyte supports?8 mol%yttria-stabilized zirconia,8YSZ?for SOFC stack,simplifying the procedure by avoiding the two conventional steps of assembling and sealing.The one-step fabrication is via the digital light processing?DLP?-stereolithography three dimensional?3D?printing technology.The rheological behavior of 8YSZ-photosensitive resin suspension is firstly investigated.Together with an optimized printing parameters,and debinding and sintering procedure,the 8YSZ green body changes into a dense electrolyte,and the density of the sintered electrolyte is measured by Archimedes'water displacement method.The results show that the intact green body printed at curing time of 10 s using 8YSZ suspension prepared with polyethylene glycol and 1,5 pentaerylene as dispersants becomes sufficiently dense with the density of the sintered part achieving 99.96%.The symmetric cell fabricated of silver-Ce_0.8Gd_0.2O_1.9?Ag-GDC?as cathode/anode and dense 8YSZ electrolyte printed by DLP-stereolithography delivers a high open circuit voltage of approximately1.04 V and a peak power density up to 176 mW?cm^-2 at 850°C by using hydrogen as the fuel and air as the oxidant.The electrochemical performance of the symmetric cell Ag-GDC|YSZ|Ag-GDC with 8YSZ electrolyte fabricated via DLP-stereolithography is comparable to that of the same cell with 8YSZ electrolyte fabricated by conventional dry pressing method.This 3D printing technique provides a novel method to prepare dense electrolytes for solid oxide fuel cell?SOFC?with good performance,suggesting a potential application for one-step fabrication of complex structure SOFC stack.Compared with 3D printing of the simple electrolyte pellets,3D printing of electrolyte supports for cube-shapedtubular SOFC stack requires highdemands on rheological and stability behaviors of suspension,curing parameters,debinding and sintering procedure.Therefore,the effect of various dispersants such as polyvinylpyrrolidone?PVPK15?and oleic acid?OA?on rheological behaviorand stability of 8YSZ ceramic suspenison,and the relationship between curing depth and exposure time are investigated..Ultimately,the optimal procedure for debinding and sintering is established.Our results show that the intact green body printed using 30 vol.%8YSZ-photosensitive resin suspension with 0.1 wt%oleic acid as the dispersant by the optimized printing parameters becomes sufficiently dense without connected porosity after vacuum debinding and sintering in air atmosphere.Density of the sintered part is measured as 99.76%via Archimedes'water displacement method,in agreement with the observation of scanning electron microscopy characterization.The successful one-step fabrication of dense electrolyte supports for complex-shaped SOFC stacks by 3D printing technology provides a novel and simple method to scale up SOFC for practical applications,which no doubt would expand the application of 3D printing technology to the energy field.