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Ivanishchev A. V., Ivanishcheva I. A., Churikov A. V. Approaches to the investigation of lithium tran- sport in intercalation electrodes based on thin film structures and multiphase composites . Electrochemical Energetics, 2016, vol. 16, iss. 3, pp. 100-121. DOI: 10.18500/1608-4039-2016-16-3-100-121, EDN: YQYJVZ

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Russian
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Article
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YQYJVZ

Approaches to the investigation of lithium tran- sport in intercalation electrodes based on thin film structures and multiphase composites

Autors: 
Ivanishchev Aleksandr Viktorovich, Saratov State University
Ivanishcheva Irina Anatol'evna, Saratov State University
Churikov Aleksei Vladimirovich, Saratov State University
Abstract: 

УДК 541.136

DOI:  https://doi.org/10.18500/1608-4039-2016-16-3-100-121

Approaches to the theoretical description of electrochemically stimulated processes of transport in solid lithium intercalation compounds were presented; results of experimental verification of the developed approaches and found ion transport parameters in the thin film and composite electrodes based on a number of known and proven lithium-accumulating compounds: LixC6, LixSn, LixWO3, LixTiO2, LiFePO4, Li3V2(PO4)3 were given. The stepwise mechanism of lithium transport in intercalation electrode was shown; it comprises stages of lithium transfer in the bulk of lithium-accumulating material and through the electrode | electrolyte interface. This isreflected in the features of electroanalytical responses of intercalation electrodes in different electrochemical methods. An original method of constructing of thermodynamic potential vs. concentration dependence of intercalation electrode was proposed with the application of the method of coulometric titration: it is based on the prediction of variation of electrode potential over time by extrapolation of the initial portion of the potential transient on an infinite time in the coordinates E t?0.5. The reasons for the differences (the hysteresis) between E(c) dependencies, when measured by stepwise change of electrode composition (potential) in the anodic and cathodic directions. The necessity of introduction of a correction parameter z in the Randles–Shevchik equation to account for differences between the activity and concentration of lithium ions in solids for the purpose of correct determination of the diffusion coefficient from the data of cyclic voltammetry with linear sweep of electrode potential. The method for determination of the parameter z from the slope of the experimental dependence E(c) in the Nernst coordinates E – ln c. Various solutions of the diffusion task for data analysis of pulse chronoamperometry and chronopotentiometry methods in the variant of intermittent titration techniques based on various geometric and phase configuration of diffusion space in intercalation electrode were considered. The dependences of the lithium diffusion coefficient D on potential of intercalation electrode were analyzed. The applicability of various models – electric equivalent circuit (EC) for the data analysis of the method of electrode impedance spectroscopy in the application to the intercalation electrode was discussed. The method of EC constructing on the basis of analysis of the shape of impedance spectrum assuming transport mechanism in lithium intercalation electrode was proposed. The dependences of found EC parameters on the electrode potential were analyzed. The kinetic parameters of lithium transport found from the data of different methods were compared. The difference in the values of kinetic parameters depending on the concentration perturbations in the electrode was shown.

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Received: 
19.09.2016
Accepted: 
19.09.2016
Published: 
30.11.2016