Effect of interface morphology on the residual stress distribution in solid oxide fuel cell

Abstract

Summary Solid oxide fuel cell directly and efficiently converts chemical energy to electrical energy. However, the necessity for high operating temperatures can result in mechanical failure. Fuel cell is a multilayer system and its stress distribution is greatly affected by the interface morphology. In this work, cosine interfaces with different amplitudes are used to approximate the fluctuation of actual interface. The effects of interface morphology on stress state, energy release rate of crack and creep behavior have been investigated. The results show that if the interface is planar, the residual normal stress component is zero on the interface, while the nonplanarity of interface can cause the normal stress Sn and shear stress St on the interface. When the amplitude is relatively small, the max values of Sn and St on the interfaces vary linearly with increasing amplitudes in both anode and cathode. Above a certain value, nonlinearity of the interface becomes important. Max tensile Sn always occurs at the peak of convex interface, but the position of max compressive Sn varies. Max shear stress is prone to occur at 1/4 of the wavelength at small amplitude and moves towards 1/2 of the wavelength when the amplitude increases. Fracture mechanics analysis shows that the surface crack possibly penetrates into the anode function layer and then is constrained by the stiff electrolyte. On the other hand, the horizontal crack likely penetrates into the electrolyte layer when the interface is not planar. Creep analysis shows that 11 800 hours of continuous operation at high temperature cannot remove stress undulation introduced by nor‐planar interface but can make max value of Sn and St decrease around 30%.

Effects of non‐planar interface and electrode parameters on the residual stress of solid oxide fuel cell

“…The maximum tensile S 22 occurs at the wave peak of the interface, reaching 87 MPa, and the maximum compressive S 22 reaches 70 MPa at the valley. Tensile S 22 can provide elastic energy for the initiation and propagation of the cracks in the x 1 direction according to our previous study, 24 thereby reducing the active three‐phase boundary density of SOFCs. Moreover, the non‐planar interface stimulates shear stress S 12 , which reaches extremely high values but occurs at the middle position of the half wavelength.…”

“…23 The effects of interface morphology on the stress state of SOFCs have been rarely reported. In the previous study, 24 we investigated the effect of undulation interface on stress distribution. The effect of amplitude on the stress distribution, the energy release rate of cracks with different lengths, and the effect of creep are investigated.…”

Carbon and graphene quantum dots in fuel cell application: An overview

“…Some methods can use the dumping of carbon‐based raw material to produce new material rich in oxygen‐containing functional groups, and this is great for solubility and functionalization. Table 1 describes the different origins and synthesis methods of GQDs 13‐33,35 . GQDs can be produced by physical or chemical means of cutting from materials such as graphene, graphite oxide, coal, CNTs, or carbon fibers (CFs).…”

“…A major difference since the last “hyper cycle’ in the 2000s has been that the production scale up to decreases the costs mean that hydrogen and fuel cells have become commercialized in various industries, since the portable cycle has started to rise: the large production of fuel cell cars has started and hundreds of thousands are now fuel cell‐powered. Fuel cells and hydrogen are becoming more and more popular 24,25 …”

“…Fuel cells and hydrogen are becoming more and more popular. 24,25 Several types of fuel cells can be categorized according to the operating environment (eg, temperature), fuel cell size and configuration (eg, massive, small, or mini scale system), and the features of the polymer electrolyte membrane (PEM). [26][27][28] Fuel cell systems include anion exchange membrane fuel cells (AEMFCs), proton exchange membrane fuel cells (PEMFCs), direct alcohol fuel cells, phosphoric acid fuel cells, molten carbonate fuel cells (MCFCs), 29 and solid oxide fuel cells (ceramic ion-conducting electrolyte).…”