Testing & Analysis Techniques

Mapping Battery Kinetics Using Minimal Charges And Discharges Mapping of battery kinetics using traditional methods, such as recording EIS at various SOCs and temperatures, takes an enormous amount of time, making these methods impractical for industrial R&D or cell production. Various new methods for mapping electrochemical kinetics from just one charge or discharge using AC 1] or both AC and DC signals 2] have been recently demonstrated, enabling highly detailed characterization of batteries for materials development or cell production and quality control purposes without requiring any additional test time. NONSTATIONARY ODD RANDOM PHASE MULTISINE IMPEDANCE AND EQUIVALENT CIRCUIT MODELING As well as being an exceptional review of nonlinear and nonstationary EIS, Hallemans et al 1 demonstrate kinetic mapping and equivalent circuit model fitting using a single charge or discharge.

RAPID ELECTROCHEMICAL MAPPING VIA COUPLED ACDC Huang et al. 2] report both a novel measurement technique and a new method for model agnostic EIS analysis DRTDOP, using Bayesian methods to estimate continuous surfaces across SOC and C-rate from discrete measurements. EIS 9.4s + rest 2s + DC pulses 28.2s = Hybrid 40s

Top Voltage and current of nonstationary EIS over charge. Right Frequency dependent current and voltage spectra. Note at low frequency the increase in OCV due to charging obscuring the impedance response.

Source: 1 Hallemans et al, Electrochimica Acta 466 142939, 2 Huang et al, Joule 8 20492072 Further theory and application of nonlinear EIS Ji and Schwartz, Journal of the Electrochemical Society, Part 1 and Part 2

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