Self-discharge behavior and its temperature dependence of carbon electrodes in lithium-ion batteries

• Published in: Journal of power sources 2011-10, Vol.196 (20), p.8598-8603
• Main Authors: Utsunomiya, Takashi, Hatozaki, Osamu, Yoshimoto, Nobuko, Egashira, Minato, Morita, Masayuki
• Format: Article
• Language: English
• Subjects: Activation energy; Applied sciences; Carbon; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; Electrodes; Exact sciences and technology; Graphite; Hard carbon; Lithium-ion batteries; Lithium-ion battery; Monitoring; Self-discharge; Storage temperature; Temperature dependence
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2011.05.066

► We monitored changes in the potential of charged carbon electrode with storage time. ► This was done to characterize the self-discharge behavior of lithium-ion battery. ► Clear difference was observed in the self-discharging rate among the materials. ► The results contribute to material designing in developing advanced batteries. Self-discharging characteristics of negative electrodes with different carbon materials have been investigated by monitoring the open circuit potential (OCP), the capacity loss and the ac impedance change during the storage at different temperatures. The OCP change with the storage time reflected state-of-charge (SOC), which depended on both the carbon material and the storage temperature. Higher specific surface area of the material and higher storage temperature lead to higher self-discharging rate. The activation energy for self-discharging was estimated from the temperature dependence of the self-discharging rate. Although small difference was observed among the materials, the value of the activation energy suggests that the self-discharging reaction at each electrode is controlled by a diffusion process. Changes in the interfacial resistance with the storage time reflected the growth of so-called Solid Electrolyte Interphase (SEI) at carbon surface. The rate of SEI formation at lower temperature does not depend on the carbon material, but at higher storage temperature the rate on spherical graphite was much higher than those on the other carbon materials.