614 ISSN 1068-3755, Surface Engineering and Applied Electrochemistry, 2018, Vol. 54, No. 6, pp. 614–622. © Allerton Press, Inc., 2018. Original Russian Text © O.L. Riabokin, A.V. Boichuk, K.D. Pershina, 2017, published in Elektronnaya Obrabotka Materialov, 2017, No. 6, pp. 105–114. Control of the State of Primary Alkaline Zn–MnO 2 Cells Using the Electrochemical Impedance Spectroscopy Method O. L. Riabokin a , A. V. Boichuk a , and K. D. Pershina a, * a Joint Department of Electrochemical Energy Systems, National Academy of Sciences of Ukraine, Kiev, 03142 Ukraine *e-mail: katherinepersh@gmail.com Received April 27, 2017; in final form, September 4, 2017 Abstract—The commercial primary alkaline zinc–manganese cells after current loads and thermal treatment are studied using electrochemical impedance spectroscopy. The components of electric circuits and spectrum data responding to the changes in the investigated samples are identified on the basis of the analysis of imped- ance spectra and model equivalent circuits. It is found experimentally that the capacity dispersion is a param- eter sensitive to any effects on alkaline zinc–manganese cells. The model of the electrode–electrolyte inter- face is used to evaluate the endurance of primary cells at thermal action. Keywords: alkaline zinc–manganese cell, impedance, equivalent circuit, battery endurance DOI: 10.3103/S1068375518060108 INTRODUCTION Electrochemical cells are the principal compo- nents of many modern devices whose functional capa- bilities are often restricted because of these cells. Any breakdown in the cell can cause a decline in productiv- ity, operational disturbances, and even an emergency situation [1]. Therefore, the monitoring of the battery efficiency is of great importance, and the electro- chemical system parameters such as the discharge degree and electrolyte density as well as the processes due to the destruction of the whole system (the electric cell ageing) must be automatically controlled [2]. Modern trends in the control of ageing mecha- nisms and the estimation of electrochemical system destruction degree include the development of nonde- structive physico-chemical and electrochemical test- ing methods (for instance, electrochemical imped- ance spectroscopy (EIS)) [1, 3–6]. The EIS method is the simplest and quickest test to determine the struc- ture and transport functions of the system under study, thus, it is promising both for research and applications when it is necessary to evaluate the life time and destruction rate of electrochemical cells [6–8]. Alkaline zinc–manganese cells are the most widely used types of batteries, and they are most often stud- ied. Works [9–17] thoroughly investigate the mecha- nisms of zinc electrode destruction with the formation of various zinc compounds in the alkaline medium, the growth in dendrites, and the change in the electro- lyte density as a result of chemical reactions and immobilization of KOH (potassium hydroxide, the principal component of the electrolyte system) on the graphite surface. It is shown in [10–13] that diffusion and natural convection are processes that are too slow and they do not notably influence the variation in the electrode form. It was experimentally proved [10, 12– 17] that the electrolyte flow (whose composition and properties are continuously changed) in the cell is the main method of reagent transport. Therefore, the monitoring of the electrolyte properties is the basis for many methods to control the changes which deter- mine the level of the service reliability of the whole electrochemical system. However, for the primary cells this approach is impossible because the samples which are being monitored do not leak. More infor- mation on the mechanisms of electrochemical pro- cesses and operating peculiarities of alkaline Zn– MnO 2 cells can help them to be used as test-systems for the EIS investigation of the external actions. The aim of this work is to reveal the parameters of the impedance spectra of the alkaline Zn–MnO 2 cells after current loads and thermal treatment determining their operating condition. MATERIALS AND RESEARCH TECHNIQUE We chose alkaline zinc–manganese cells (Dura- cell) in AAA size (MN 2400) with a voltage of 1.5 V as the samples under investigation. Their EIS was taken using the electrochemical Autolab-30 PGSTAT301N Metrohm Autolab module equipped with the FRA (Frequency Response Analyzer) module within the range 10 –2 –10 6 Hz. The FRA module was controlled with the help of the Autolab 4.9 software with the dis- turbing signal amplitude ±5 mV with the following processing of the results using the Zview 2.0 package.