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Title page for etd-0727115-190959


URN etd-0727115-190959 Statistics This thesis had been viewed 774 times. Download 0 times.
Author Ken-Huan Ho
Author's Email Address No Public.
Department Chemical Engineering
Year 2014 Semester 2
Degree Master Type of Document Master's Thesis
Language zh-TW.Big5 Chinese Page Count 81
Title Study on Cycling Aging of Commercial Lithium Ion Battery
Keyword
  • Cycling Aging
  • Lithium Ion Battery
  • Lithium Ion Battery
  • Cycling Aging
  • Abstract The charge-discharge cycling effect on the battery capacity decay for commercial LMO-NMC lithium-ion battery has been studied with the same charge rate and various discharge rates. Three sets of batteries were all charged at 0.5C but discharged at 0.5C, 1C and 2C, respectively, until decaying to 70% of the original capacity at 25oC. The batteries were set to rest for three hours after each charge and discharge process and the reference performance test (RPT) was done every 100 cycles. Similar experiments were carried out again without rest and RPT.
    Experimental results show that with increasing number of cycling, the capacity decreases, the positions of the peaks in incremental capacity (IC) curve shift toward the high voltage side, whereas the heights of the peaks decrease. The shifting of the peak position is due to the loss of lithium ions and formation of SEI, whereas the decrease of the peak height is due to the loss of active material. With RPT after each 100 cycles and 3-hour rest after each charge and discharge, the end of life (EOL), defined as the cycling number of decaying to 70% of original capacity, are 197, 236 and 276, for discharging at 0.5C, 1C and 2C, respectively. This indicates that the EOL increases with increasing discharge rate. One of the possible reasons is that the commercial battery used in this study is designed for large current discharging.
    Without RPT and rest, the EOLs increase to 317, 463 and 1000+ (over 1000), for discharging at 0.5C, 1C and 2C, respectively. This indicates that the rest after the discharge results in significant capacity decay.
    According to the experimental results, we have developed a mathematical model for the effect of cycling number and rest time on the capacity of battery. The parameters in the model have been obtained by nonlinear data regression. Comparison between model calculations and experimental data show that both are consistent with R2>0.98, indicating the model can be used to estimate the battery capacity decay during charge-discharge cycling.
    Advisor Committee
  • Jan-Chen Hong - advisor
  • none - co-chair
  • none - co-chair
  • Files indicate in-campus access at one year and off-campus not accessible
    Date of Defense 2015-07-17 Date of Submission 2015-07-28


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