Applicability of Heat Generation Data in Determining the Degradation Mechanisms of Cylindrical Li-Ion Batteries

Kirill Murashko,Peter H L Notten,Juha Pyrhönen,Dongjiang Li,Jorma Jokiniemi,Dmitri L Danilov

doi:10.1149/1945-7111/abd832

Abstract

The applicability of heat generation data obtained after cylindrical Li-ion cells discharging with a constant current was analyzed thoroughly to determine cell degradation mechanisms. Different commercial and noncommercial cylindrical Li-ion cells, wherein graphite was used for negative electrode creation, were considered in this study and the degradation mechanisms were analyzed during cycling and storage. The heat generation in the cylindrical cells was estimated using heat flux and temperature measurements of the cell surface. The results obtained using analysis of the heat generation data were compared with those obtained using differential voltage analysis. The use of the heat generation data was shown to improve the detection and separation of the degradation mechanisms in Li-ion batteries during cycling and storage. The differential curve, which is based on the heat generation data, was proposed to investigate the degradation mechanisms. Moreover, the effects of the C-rate current and temperature on the form of the proposed differential curve were evaluated.

Highlights

To cite this article: Kirill Murashko et al 2021 J
The degradation mechanisms in the cylindrical Li-ion cells during cycling and storage were analyzed by using an approach similar to the differential voltage (DV) analysis method, by considering the changes in the features of the ¶UOCV/¶Q curves during Li-ion cell aging
Consideration of heat generation in the Li-ion cells during their aging improved the accuracy of the degradation mechanism determination even in case when a relatively high C-rate current was used for the differential curve measurement

Summary

Introduction

To cite this article: Kirill Murashko et al 2021 J. Rechargeable Li-ion batteries are currently considered the most suitable choice to power portable electronics, power tools, electrical vehicles, and various energy storage systems. These batteries have been widely used because of their significant advantages such as adequately high energy and power densities, long cycle life, low self-discharge rate, and negligible memory effect. A constant temperature and a low constant current are required in differential curve measurements.[16] the DV and IC curves are obtained on the basis of the terminal voltage of the Li-ion batteries. The change in ΔS with the aging of Li-ion cells, which can be obtained from the measured heat flux and temperature data, was investigated to elucidate the determination of the degradation mechanisms. The accuracy of the ΔS measurements was confirmed by comparing the obtained results with the ΔS results measured by applying commonly used methods at different states of charge (SoCs)

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