120,217 research outputs found
Effects of Nanoparticle Geometry and Size Distribution on Diffusion Impedance of Battery Electrodes
The short diffusion lengths in insertion battery nanoparticles render the
capacitive behavior of bounded diffusion, which is rarely observable with
conventional larger particles, now accessible to impedance measurements.
Coupled with improved geometrical characterization, this presents an
opportunity to measure solid diffusion more accurately than the traditional
approach of fitting Warburg circuit elements, by properly taking into account
the particle geometry and size distribution. We revisit bounded diffusion
impedance models and incorporate them into an overall impedance model for
different electrode configurations. The theoretical models are then applied to
experimental data of a silicon nanowire electrode to show the effects of
including the actual nanowire geometry and radius distribution in interpreting
the impedance data. From these results, we show that it is essential to account
for the particle shape and size distribution to correctly interpret impedance
data for battery electrodes. Conversely, it is also possible to solve the
inverse problem and use the theoretical "impedance image" to infer the
nanoparticle shape and/or size distribution, in some cases, more accurately
than by direct image analysis. This capability could be useful, for example, in
detecting battery degradation in situ by simple electrical measurements,
without the need for any imaging.Comment: 30 page
Strategies for balancing exploration and exploitation in electromagnetic optimisation
The paper focuses on the advantages and drawbacks of different strategies which may be used to assist kriging surrogate modelling with the purpose of selecting multiple design vectors for evaluation when stepping forward in optimisation routines. The combined criteria include the efficiency of finding the global optimum but also the quality of the approximation of the shape of the objective function; the latter may be used to make judgements about the robustness of the optimised design
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