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하이브리드 커패시터의 열안정성 개선을 위한 LiFePO4 복합양극 소재에 관한 연구

Study on LiFePO4 Composite Cathode Materials to Enhance Thermal Stability of Hybrid Capacitor

  • 투고 : 2016.10.20
  • 심사 : 2017.01.09
  • 발행 : 2017.04.01

초록

고온에서 Mn 이온 용출에 의한 성능저하를 보이는 스피넬 결정구조의 $LiMn_2O_4$ 양극 하이브리드 커패시터의 대안으로 열안정성이 높은 올리빈 결정구조의 $LiFePO_4$ 기반 복합양극 소재의 적용가능성을 연구하였다. $LiFePO_4$/활성탄셀을 이용한 1.0~2.3 V의 충 방전을 통한 수명평가에서 상온($25^{\circ}C$) 및 고온($60^{\circ}C$) 조건 모두에서 충 방전 사이클이 진행됨에 따라 음극(활성탄)의 저전압화에 따른 열화로 인한 용량저하 현상이 나타났다. 이의 해결을 위해 50:50 중량비율로 $LiFePO_4/LiMn_2O_4$, $LiFePO_4$/Activated carbon 및 $LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ 복합양극을 제조하여 모노셀 충 방전 실험을 수행한 결과, 층상구조의 $LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$를 사용한 전극이 안정적인 전압거동을 보였다. 또한, 2.3 V 및 $80^{\circ}C$에서 1,000시간 부하를 통한 고온 안정성 실험에서도 $LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ 복합양극이 상용 $LiMn_2O_4$ 양극에 비해 약 2배 가량 높은 방전용량 유지율을 보였다.

The application of composite cathode materials including $LiFePO_4$ (lithium iron phosphate) of olivine crystal structure, which has high thermal stability, were investigated as alternatives for hybrid battery-capacitors with a $LiMn_2O_4$ (spinel crystal structure) cathode, which exhibits decreased performance at high temperatures due to Mn-dissolution. However, these composite cathode materials have been shown to have a reduction in capacity by conducting life cycle experiments in which a $LiFePO_4$/activated carbon cell was charged and discharged between 1.0 V and 2.3 V at two temperatures, $25^{\circ}C$ and $60^{\circ}C$, which caused a degradation of the anode due to the lowered voltage in the anode. To avoid the degradation of the anode, composite cathodes of $LiFePO_4/LiMn_2O_4$ (50:50 wt%), $LiFePO_4$/activated carbon (50:50 wt%) and $LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ (50:50 wt%) were prepared and the life cycle experiments were conducted on these cells. The composite cathode including $LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ of layered crystal structure showed stable voltage behavior. The discharge capacity retention ratio of $LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ was about twice as high as that of a $LiFePO_4/LiMn_2O_4$ cell at thermal stability experiment for a duration of 1,000 hours charged at 2.3 V and a temperature of $80^{\circ}C$.

키워드

참고문헌

  1. Yu, G., Xie, X., Pan, L., Bao, Z. and Cui, Y., "Hybrid Nanostructured Materials for High-performance Electrochemical Capacitors," Nano Energy, 2(2), 213-234(2013). https://doi.org/10.1016/j.nanoen.2012.10.006
  2. Lee, S. W., Park, D. K., Lee, J. K., Ju, J. B. and Sohn, T. W., "Discharge Capacitance of Electric Double Layer Capacitor with Electrodes Made of Carbon Nanotubes Directly Deposited on SUS304 Plates," Korean J. Chem. Eng., 18(3), 371-375(2001). https://doi.org/10.1007/BF02699180
  3. Sharma, P. and Bhatti, T.S., "A Review on Electrochemical Doublelayer Capacitors," Energy Conv. Manag., 51, 2901-2912(2010). https://doi.org/10.1016/j.enconman.2010.06.031
  4. Ko, H. S., Choi, J. E. and Lee, J. D., "Electrochemical Characteristics of Hybrid Capacitor using Core-shell Structure of $MCMB/Li_{4-}Ti_5O_{12}$ Composite," Korean Chem. Eng. Res., 52(1), 52-57(2014). https://doi.org/10.9713/kcer.2014.52.1.52
  5. Choi, J. E., Bae, G. Y., Yang, J. M. and Lee, J. D., "The Electrochemical Characteristics of Hybrid Capacitor Prepared by Chemical Activation of NaOH," Korean Chem. Eng. Res., 51(3), 308-312 (2013). https://doi.org/10.9713/kcer.2013.51.3.308
  6. Yao, Y., McDowell, M. T., Ryu, I., Wu, H., Liu, N., Hu, L., Nix, W. D. and Cui, Y., "Interconnected Silicon Hollow Nanospheres for Lithium-ion Battery Anodes with Long Cycle Life," Nano Lett., 11(7), 2949-2954(2011). https://doi.org/10.1021/nl201470j
  7. Wang, Y. G., Lou, J. Y., Wu, W., Wang, C. X. and Wang, Y. Y., "Hybrid Aqueous Energy Storage Cells using Activated Carbon and Lithium-ion Intercalated Compounds:III. Capacity Fading Mechanism of LiCo1/3Ni1/3Mn1/3O2 at Different pH Electrolyte Solutions," J. Electrochem. Soc., 154, A228(2007). https://doi.org/10.1149/1.2432056
  8. Karthikeyan, K., Aravindan, V., Lee, S. B., Jang, I. C., Lim, H. H., Park, G. J., Yoshio, M. and Lee, Y. S., "A Novel Asymmetric Hybrid Supercapacitor Based on $Li_2FeSiO_4$ and Activated Carbon Electrodes," J. Alloy. Compd., 504(1), 224-227(2010). https://doi.org/10.1016/j.jallcom.2010.05.097
  9. Cericola, D., Novk, P., Wokaun, A. and Ktz, R., "Hybridization of Electrochemical Capacitors and Rechargeable Batteries: An Experimental Analysis of the Different Possible Approaches Utilizing Activated Carbon, $Li_4Ti_5O_{12}$ and $LiMn_2O_4$," J. Power Sources, 196(23), 10305-10313(2011). https://doi.org/10.1016/j.jpowsour.2011.07.032
  10. Jiang, J., Tan, G., Peng, S., Qian, D., Liu, J., Luo, D. and Liu, Y., "Electrochemical Performance of Carbon-coated $Li_3V_2(PO_4)_3$ as a Cathode Material for Asymmetric Hybrid Capacitors," Electrochim. Acta, 107, 59-65(2013). https://doi.org/10.1016/j.electacta.2013.06.051
  11. Aravindan, V., Sundaramurthy, J., Kumar, P. S., Lee, Y. S., Ramakrishna S. and Madhavi, S., "Electrospun Nanofibers: A Prospective Electroactive Material for Constructing High Performance Li-ion Batteries," Chem. Commun., 51, 2225-2234(2015). https://doi.org/10.1039/C4CC07824A
  12. Kim, S., Kim, S., Kim, J., Kim, U., Hwang, H. and Cho, W., "Synthesis and Electrochemical Properties of $LiFePO_4$ by Citrate Process," Trans. of the Korean Hydrogen and New Energy Society, 22(5), 728-734(2011).
  13. Wang, J., Yao, X., Zhou, X. and Liu, Z., "Synthesis and Electrochemical Properties of Layered Lithium Transition Metal Oxides," J. Mater. Chem., 21, 2544-2549(2011). https://doi.org/10.1039/C0JM03388J