Abstract
The charging efficiency of a lithium-ion capacitor (LIC) is an important problem. Until now, due to the stepwise charging method, the charging efficiency of 95.5% has been realized. However, the problem is that the issue of what level the charging efficiency can be increased to, is yet to be well investigated. In this article, the problem is investigated under the galvanostatic charging condition. The charging efficiency is measured as a function of the charging current. As a result, it can be more than 99.5% when the charging is quasi-static, in other words, an adiabatic process is realized. Next, the problem of how much energy can be taken out from the energy-stored capacitor is investigated with a load resistor circuit. It is clarified that the discharging energy from the capacitor is equal to the stored energy in the case when a load resistor is used and the discharging is quasi-static. It is confirmed that LICs are suitable for use as energy storage devices.
Highlights
The energy storage of renewable energy is an important problem
For energy storage of renewable resources, lithium-ion capacitator (LIC) are attractive for the lifetime and safety in comparison with lithium-ion batteries
The charging efficiency of the LIC was investigated with a stepwise charging circuit, and it was 95.5%
Summary
The energy storage of renewable energy is an important problem. To store energy, supercapacitors are considered to play an important role. The LICs have many advantages over lithium-ion batteries. The cycle lifetime of LICs is 1,000,000 cycles [2], while that of lithium-ion batteries is about 2000 cycles [7,8]. The energy density of commercial LICs is 13 Wh/kg [9], while that of lithium-ion batteries is 100 Wh/kg [1], i.e., LICs are 13% that of the batteries. When there is a large space, it is not a serious problem These advantageous characteristics make LICs very suitable for storing energy from renewable resources. The paper is organized as follows: Section 2 gives the charging measurement system and experimental results, Section 3 presents the discharging measurement system from the energy-stored. The conclusion is given in discusses the experimental results.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
