The purpose of this study was to understand the electrochemical behavior of the interface between porous electrodes and electrolytes of lithium-ion batteries. We propose a new analytical approach that is a combination of the transmission line model theory for cylindrical pores and electrochemical impedance spectroscopy using symmetric cells. Mathematical model and experimental impedance behavior results agree with each other. By mathematically fitting the experimental impedance plots, the individual internal resistance components of the actual porous electrode/electrolyte interface could be described as the following four parameters: electric resistance (R e ), electrolyte bulk resistance, (R sol ), ionic resistance in pores (R ion ), and charge-transfer resistance for lithium intercalation (R ct ). In actual electrodes, the R ion obtained in this study is a characteristic parameter of the porous electrode/electrolyte interface that is important to consider for thick electrodes.
Factors affecting the cycling life of cylindrical lithium-ion batteries of LiNi0.8Co0.15Al0.05O2(NCA) with graphite were examined in terms of the rechargeable capacity and polarization of NCA derivatives of LizNi0.8Co0.15Al0.05O2−δ(0.8 ≤z≤ 1.05).
The mechanism for capacity fade of lithium-ion batteries with
LinormalNi0.8normalCo0.15normalAl0.05normalO2
as a positive electrode material associated with cycling at elevated temperatures was investigated by the combination of electrochemical and spectroscopic methods. The total capacity fade of the battery after charge/discharge cycle test at
80°C
was found to be almost explained by the capacity fade of the positive electrode, which indicates that the degradation of the positive electrode is mainly responsible for capacity fade of the battery at this temperature. Quantitative analyses revealed a strong positive correlation between the capacity fade of the positive electrode and the amount of inactive Ni ions in the active material after the cycling test. It is concluded that the capacity fade is mainly caused by the formation of inactive Ni(II) and Ni(III), presumably associated with oxygen loss in the active materials, which act as obstacles to Li intercalation/deintercalation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.