Additionally, despite the characterization of battery separators using bulk properties, the heterogeneity of the separators lead to vastly different local transport outcomes. The findings from the simulations suggest that the tortuosity of the separator is a key property affecting transport. Using SPH, the geometrical parameters of the separator are characterized based on their effect on mass transport and dendrite growth. The first goal is to understand the effects of local transport through battery separators on dendrite growth by explicitly representing commercial battery separator structures taken from SEM images. Using the SPH model, the effect of various structures in the electrolyte on mass transport and dendrite growth are investigated.
Effect of dendrite structure code#
The model is implemented in the LAMMPs code base and includes the ability to model charge/discharge cycles. The SPH model simulates the physics at this interface by solving the governing equations for diffusion, migration, and potential distribution in a binary electrolyte and near a reactive, moving interface and dendrite surfaces. The dendrites are also common in cast products, where they may become visible by etching of a polished specimen.ĭendrites also form during the freezing of many nonmetallic substances such as ice.ĭendrites usually form under non-equilibrium conditions.Ĭommon dendritic metal material is nickel carbonyl, where the particles have a classical "spiky" morphology.In this dissertation, a meso-scale computational model, using the smoothed particle hydrodynamics (SPH) numerical method, is used to simulate the deposition process at the electrolyte/anode interface of a lithium metal battery. One application where dendritic growth and resulting material properties can be seen is the process of welding. Smaller dendrites generally lead to higher ductility of the product. Conversely, a rapid cooling cycle with a large undercooling will increase the number of nuclei and thus reduce the size of the resulting dendrites(and often lead to small grains). The dendritic growth will result in dendrites of a large size. If the metal is cooled slowly, nucleation of new crystals will be less than at large undercooling. Note also that a curved interface is less energetically favourable, thus limiting the sharpness of the dendrites. This fact increases the solidification rate at the most protruding points, thus resulting in dendrite formation. A small distance away from the solidification front, the concentration is more favourable for solidification as well as the temperature is lower. Solidification also releases energy, thus impeding solidification even more. The increased concentration results in an increased melting point impeding solidification near the front. But, at increased cooling rates, the solidification may be so rapid that the alloy concentration at the solidification front will be different from the overall concentration. At slow cooling rates, the solidification front will be planar and stable. The requirement is that the molten metal is supercooled below the freezing point of the metal. Safe Weighing Range Ensures Accurate Resultsĭendrites usually form in multiphase alloys.
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