藉由XRD、SEM、AC Impedance、Cyclic Voltammetry，以及毛細現象分析極板潤濕程度等五種分析技術，探討正極極板輾壓密度對鋰離子二次電池在不同放電速率下的影響。
實驗結果顯示，當電池放電速率小於1C時，極板密度越密的電池，其放電容量越高。然而，當電池放電速率高於2C時，最密極板結構的電池(3.6 g/cm3)，其放電容量將快速遞減。
這表示，極板輾壓將使鈷酸鋰活性顆粒物質推擠得更緊密並且降低電池內組抗，使反應動力學增快。因此，活性顆粒物質間的接觸品質，是電池在小於1C放電速率下的主要影響因素。此外，當電池放電速率超過2C時，電解液的離子導電度與對多孔性極板結構的潤濕程度，將會成為影響放電容量的主要因素。當然，此時活性顆粒物質間的接觸品質，仍然是重要的因素，並且極板密度至少要高於3.2 g/cm3。也就是說，在3C放電速率情況下，對於密度高於3.2 g/cm3的電池而言，其放電容量將受電解液的離子導電度與對多孔性極板結構的潤濕程度影響。

The effect of rolling positive electrodes into different densities on the performance of lithium ion batteries discharged at different rates was studied by using X-ray diffraction, SEM, AC impedance, cyclic voltammetry, and gravimetrically measured capillary liquid movement.
The results show that, as the battery discharged at lower than 1C rate, the capacity increased as electrodes density increased. However, as the discharging rate increased over 2C, the capacity of the densest electrode, 3.6 g/cm3, would drop rapidly.
This suggests that rolling positive electrode would make the active particles (LiCoO2) be compacted more closely, resulting in decreased internal impedance and faster kinetics. Therefore, the inter-particle contact quality is the main factor to determine the discharge efficiency if the discharging rate is below 1C. Moreover, as the discharging rate increases over 2C, both liquid ionic conductivity and the contact area between active particles and electrolyte, that is to say “wettability”, would govern the discharge capacity. But, the inter-particle contact quality is still important and the density should be at least denser than 3.2 g/cm3. Namely, these two factors, ionic conductivity and wettability, would become more important for battery discharge at 3C with electrode denser than 3.2 g/cm3.

1. K.S. Harris, Ph.D. Thesis UCRL-8381, University of California, Berkeley.
2. 宋金穎，「微孔性聚偏氟乙烯高分子電解質之電化學特性研究」，博士論文，國立清華大學化工系，2000
3. W. van Schalkwijk, and B. Scrosati, “Advance in Lithium-ion Batteries”, Kluwer Academic/Plenum Publishers, chap.9, 2002
4. 林振華，充電式鋰離子電池/材料與應用，全華科技圖書，2001
5. J. Newman, and W. Tiedemann, “Porous-Electrode Theory with Battery Applications”, AIChE Journal, pp.25-39 (1975)
6. O. Lanzi, and U. Landau, “Effect of Pore Structure on Current and Potential Distributions in a Porous Electrode”, Journal of The Electrochemical Society, pp.585-593 (1990)
7. J. K. Weaver and E. J. Cairns, “Experimental and Theoretical Study of Comcentration Distribution in a Model Pore Electrode”, Journal of The Electrochemical Society, pp.2579-2585 (1991)
8. J.S. Gnanaraj, Yaron S. Cohen, M.D. Levi, D. Aurbach, “The effect of pressure on the electroanalytical response of graphite anodes and LiCoO2 cathodes for Li-ion batteries”, journal of electroanalytical chemistry, pp.89-102 (2001)
9. A.D. Pasquier and T. Zheng, “Microstructure effects in plasticized electrodes based on PVDF-HFP for plastic Li-ion batteries”, journal of power sources, pp.758-761 (2001)
10. J. Fan and P. S. Fedkiw, “Electrochemical impedance spectra of full cells: relation to capacity and capacity-rate of rechargeable Li cells using LiCoO2, LiMn2O4, and LiNiO2 cathodes”, journal of power sources, pp.165-173 (1998)
11. A. Lundbland and B. Bergman, “Determination of contact angle in porous molten-carbonate fuel-cell electrodes”, journal of the electrochemical society, pp. 984-987 (1997)
12. Mao Sung Wu, Tzu Ling Liao, Yung Yun Wang, and Chi Chao Wan, “Assessment of the wettability of porous electrodes for lithium ion batteries”, Journal of applied electrochemistry, pp.797-805 (2004)
13.許樹恩，吳泰伯，X光繞射原理與材料結構分析，中國材料科學學會，第16章，民國82。
14. J. B. Bates, N. J. Dudney, and S. A. Hackney, “Preferred Orientation of Polycrystalline LiCoO2 Films ”, Journal of The Electrochemical Society, pp.59-70 (2000)
15. S.R. Narayanan, and D. H. Shen, “Electrochemical Impedance Spectroscopy of Lithium-Titanium Disulfide Rechargeable Cells”, journal of the electrochemical society, pp. 1854-1861 (1993)
16. M.G.S.R. Thomas, and P.G. Bruce, “Electrochemical Passivation of Lithium in Lithium Hexafluoroarsenate/2-Methyltetrahydrofuran Electrolyte”, journal of the electrochemical society, pp. 345-349 (1989)
17. N. Popov, and W. Zhang, “Impedance Spectroscopy as a Nondestructive Health Interrogation Tool for Lithium-BCX Cells”, journal of the electrochemical society, pp. 3097-3103 (1993)
18. R. Koksbang and I. I. Olsen, “Polymer electrolyte lithium batteries rechargeability and positive electrode degradatin: an AC impedance study”, Journal of Applied Electrochemistry, pp.301-307 (1991)
19. C. H. Chen, and J. Liu, “Symmetric cell approach and impedance spectroscopy of high power lithium ion batteies”, Journal of power sources, pp.321-328 (2001)
20. C. H. Chen, and J. Liu, “Symmetric cell approach towards simplified study of cathode and anode behavior in lithium ion batteries”, Electrochemistry Communication, pp.44-47 (2001)
21. C. H. Chen, and J. Liu, “Aluminume-doped lithium nickel cobalt oxide electrodes for high-power lithium ion batteries”, Journal of power sources, pp.278-285 (2004)
22. R.de Levie, “On porous electrodes in electrolyte solutions”, Electrochimica Acta, pp.1231-1245 (1964)