Fabrication pressures and stack pressures in solid-state battery

Solid-state batteries(SSBs)have received widespread attention with their high safety and high energy density characteristics.However,solid-solid contacts in the internal electrode material and the electrode material/solid electrolyte(SE)interfaces,as well as the severe electrochemo-mechanical effects caused by the internal stress due to the volume change of the active material,these problems hinder ion/electron transport within the SSBs,which significantly deteriorates the electrochemical performance.Applying fabrication pressures and stack pressures are effective measures to improve solid-solid contact and solve electrochemo-mechanical problems.Herein,the influences of different pressures on cathode material,anode material,SEs,and electrode/SEs interface are briefly summarized from the perspective of interface ion diffusion,transmission of electrons and ions in internal particles,current density and ion diffusion kinetics,and the volume changes of Li^(+)stripping/plating based on two physical contact models,and point out the direction for the future research direction of SSBs and advancing industrialization by building the relationship between pressures and SSBs electrochemistry.

Micro-scale behavior of granular materials during cyclic loading

This study presents the micro-scale behavior of granular materials under biaxial cyclic loading for differ- ent confining pressures using the two-dimensional （2D） discrete element method （DEM）. Initially, 8450 ovals were generated in a rectangular frame without any overlap. Four dense samples having confining pressures of 15, 25, 50, and 100 kPa were prepared from the initially generated sparse sample. Numeri- cal simulations were performed under biaxial cyclic loading using these isotropically compressed dense samples. The numerical results depict stress-strain-dilatancy behavior that was similar to that observed in experimental studies. The relationship between the stress ratio and dilatancy rate is almost indepen- dent of confining pressures during loading but significantly dependent on the confining pressures during unloading. The evolution of the coordination number, effective coordination number and slip coordina- tion number depends on both the confining pressures and cyclic loading. The cyclic loading significantly affects the microtopology of the granular assembly. The contact fabric and the fabric-related anisotropy are reported, as well. A strong correlation between the stress ratio and the fabric related to contact normals is observed during cyclic loading, irrespective of confining pressures.