Summary A novel indentation theory with homogenized, isotropic, and continuum model based on different shape functions is investigated to predict the mechanical behavior triggering internal short circuit of lithium‐ion pouch battery (LIPB) under indentation loading. By taking energy conservation principle into account, the relationship among indentation force, indentation displacement, and indentation region of LIPB is proposed. The results conclude that the effects of deformation region and indentation displacement play an important role in mechanical behavior triggering internal short circuit. The theoretical results based on sine, cosine, and quadratic shape functions agree well with experimental results. Both of increasing compressed yield stress of jellyroll core and punch radius and decreasing flow stress of soft casing and thickness of soft casing can avoid triggering internal short circuit of LIPB. According to current research, the indentation loading is reduced to flat compression when punch radius approaches infinity, and the internal short circuit of LIPB under flat compression is very difficult to be triggered. Effectiveness and application scope of different shape functions are also discussed. The theoretical model provides guidance for improving mechanical behavior, decreasing internal short circuit, and optimizing structure of LIPB in industrial manufacture.

Lithium-ion battery (LIB), as energy storage devices, is widely used in portable electronic devices and have promising applications in electric vehicles. The volume change and large stress can lead to electrode pulverization and the resultant loss of electrical contact from the current collector, which is considered to be one of the main reasons for the capacity degradation of LIB. To reduce diffusion-induced stress of the electrode system during lithium-ion diffusion, a chemo-mechanical coupled theoretical model of bilayer electrode system of electrode layer bonded to the current collector is established. The theoretical results show that diffusion-induced stresses at the electrode–collector interface and maximum tensile stress at the top surface of the electrode layer are alleviated greatly by introducing pre-strain. The effects of pre-strain and lithium-ion concentration on chemo-mechanical coupled behavior of the bilayer electrode system are discussed. In particular, the lithium-ion concentration difference strongly depends on the diffusion thickness and time. The curvature when considering plastic deformation is smaller than that when not considering the plastic deformation. In addition, the effects of plastic deformation of the current collector and diffusion time on biaxial stress distribution are also discussed. The biaxial stress decreases with the increase of pre-strain and decrease of dimensionless time during galvanostatic charging. The biaxial stress when considering plastic deformation is smaller than that when not considering the plastic deformation. The results obtained from this investigation will provide a reference to reduce the diffusion-induced stress and improve the ion diffusion performance of LIB.

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Summary The corrugated solid oxide fuel cell (SOFC) can effectively improve energy density and transformation efficiency compared with conventional planar SOFC, but its stability and durability have not been systematically analyzed. The residual stress of SOFC may lead to crack initiation and propagation during cooling process, so stress distributions of planar and corrugated SOFCs are simulated to analyze the location of crack initiation. The materials of electrolyte, anode, and cathode in this paper are yttria‐stabilization zirconia (YSZ), Ni‐YSZ, and strontium‐doped lanthanum manganite (LSM), respectively. The result shows that the edge of cell is more prone to cracking. Therefore, precracks including edge crack and middle crack are introduced into anode‐electrolyte interfaces to investigate crack propagation of two types of SOFCs during cooling process. For corrugated SOFC, the cracks propagate more slowly, and the cell is less prone to interfacial delamination compared with planar SOFC. In addition, the interface energy release rates are obtained to further analyze crack propagation of two types of SOFCs, and the corrugated SOFC has lower energy release rate. The research in this paper provides guidance for stability analysis and lays a foundation for future mechanical analysis of corrugated SOFC.

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