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Characterization and performance evaluation of lithium-ion battery separators

Abstract

Lithium-ion batteries (LIBs) with liquid electrolytes and microporous polyolefin separator membranes are ubiquitous. Though not necessarily an active component in a cell, the separator plays a key role in ion transport and influences rate performance, cell life and safety. As our understanding of separator properties and the interactions between the separator and the electrolyte deepens, it becomes evident that there are opportunities for improving separators to help meet the greater demands that new applications place on LIB technology. Here, we review the impact of the separator structure and chemistry on LIB performance, assess characterization techniques relevant for understanding structure–performance relationships in separator membranes, and provide an outlook on next-generation separator technology. Insights from this Review indicate that LIB performance can be improved by taking into account the interplay of the separator with its surroundings and indicate that, in the future, separators will be designed to play a more active role in LIB operation. Current and emerging characterization techniques will play an important role in guiding this evolution in separator technology.

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Fig. 1: Separators in LIBs.
Fig. 2: Links between properties and performance.
Fig. 3: Separator structure and degradation.

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References

  1. Palacín, M. R. & De Guibert, A. Why do batteries fail? Science 351, 1253292 (2016).

    Google Scholar 

  2. Arora, P. & Zhang, Z. Battery separators. Chem. Rev. 104, 4419–4462 (2004).

    Google Scholar 

  3. Lee, H., Yanilmaz, M., Toprakci, O., Fu, K. & Zhang, X. A review of recent developments in membrane separators for rechargeable lithium-ion batteries. Energy Environ. Sci. 7, 3857–3886 (2014). A review describing lithium-ion battery separator types, manufacturing routes and separator performance.

    Google Scholar 

  4. Deimede, V. & Elmasides, C. Separators for lithium-ion batteries: a review on the production processes and recent developments. Energy Technol. 3, 453–468 (2015).

    Google Scholar 

  5. Zhang, H., Zhou, M.-Y., Lin, C.-E. & Zhu, B.-K. Progress in polymeric separators for lithium ion batteries. RSC Adv. 5, 89848–89860 (2015).

    Google Scholar 

  6. Nunes-Pereira, J., Costa, C. M. & Lanceros-Méndez, S. Polymer composites and blends for battery separators: state of the art, challenges and future trends. J. Power Sources 281, 378–398 (2015).

    Google Scholar 

  7. Pintauro, P. N. Perspectives on membranes and separators for electrochemical energy conversion and storage devices. Polym. Rev. 55, 201–207 (2015).

    Google Scholar 

  8. Chandrasekaran, R. Quantification of contributions to the cell overpotential during galvanostatic discharge of a lithium-ion cell. J. Power Sources 262, 501–513 (2014).

    Google Scholar 

  9. Müller, S. et al. Quantifying inhomogeneity of lithium ion battery electrodes and its influence on electrochemical performance. J. Electrochem. Soc. 165, A339–A344 (2018).

    Google Scholar 

  10. Bandhauer, T. M., Garimella, S. & Fuller, T. F. A critical review of thermal issues in lithium-ion batteries. J. Electrochem. Soc. 158, R1–R25 (2011).

    Google Scholar 

  11. Liu, Q. Q., Petibon, R., Du, C. Y. & Dahn, J. R. Effects of electrolyte additives and solvents on unwanted lithium plating in lithium-ion cells. J. Electrochem. Soc. 164, A1173–A1183 (2017).

    Google Scholar 

  12. Valøen, L. O. & Reimers, J. N. Transport properties of LiPF6-based Li-ion battery electrolytes. J. Electrochem. Soc. 152, A882–A891 (2005).

    Google Scholar 

  13. Erickson, E. M. et al. Review-development of advanced rechargeable batteries: a continuous challenge in the choice of suitable electrolyte solutions. J. Electrochem. Soc. 162, A2424–A2438 (2015).

    Google Scholar 

  14. Doyle, M., Fuller, T. F. & Newman, J. The importance of the lithium ion transference number in lithium/polymer cells. Electrochim. Acta 39, 2073–2081 (1994).

    Google Scholar 

  15. Zugmann, S. et al. Measurement of transference numbers for lithium ion electrolytes via four different methods, a comparative study. Electrochim. Acta 56, 3926–3933 (2011).

    Google Scholar 

  16. Gores, H. J. et al. in Handbook of Battery Materials (eds Daniel, C. & Besenhard, J. O.) 525–626 (Wiley-VCH Verlag, Weinheim, 2011).

  17. Djian, D., Alloin, F., Martinet, S., Lignier, H. & Sanchez, J. Y. Lithium-ion batteries with high charge rate capacity: influence of the porous separator. J. Power Sources 172, 416–421 (2007).

    Google Scholar 

  18. Harris, S. J. & Lu, P. Effects of inhomogeneities — nanoscale to mesoscale — on the durability of Li-ion batteries. J. Phys. Chem. C 117, 6481–6492 (2013).

    Google Scholar 

  19. Ramadass, P., Haran, B., White, R. & Popov, B. N. Capacity fade of Sony 18650 cells cycled at elevated temperatures: Part II. Capacity fade analysis. J. Power Sources 112, 614–620 (2002).

    Google Scholar 

  20. Lagadec, M. F., Ebner, M., Zahn, R. & Wood, V. Communication — Technique for visualization and quantification of lithium-ion battery separator microstructure. J. Electrochem. Soc. 163, A992–A994 (2016).

    Google Scholar 

  21. Cannarella, J. et al. Mechanical properties of a battery separator under compression and tension. J. Electrochem. Soc. 161, F3117–F3122 (2014). Compression experiments and simulations of separators; systematic analysis of strain rate-dependent mechanical properties of dry and immersed separators.

    Google Scholar 

  22. Cannarella, J. & Arnold, C. B. The effects of defects on localized plating in lithium-ion batteries. J. Electrochem. Soc. 162, A1365–A1373 (2015).

    Google Scholar 

  23. Wood, D. L., Li, J. & Daniel, C. Prospects for reducing the processing cost of lithium ion batteries. J. Power Sources 275, 234–242 (2015).

    Google Scholar 

  24. l’Abee, R., DaRosa, F., Armstrong, M. J., Hantel, M. M. & Mourzagh, D. High temperature stable Li-ion battery separators based on polyetherimides with improved electrolyte compatibility. J. Power Sources 345, 202–211 (2017).

    Google Scholar 

  25. Gor, G. Y., Cannarella, J., Leng, C. Z., Vishnyakov, A. & Arnold, C. B. Swelling and softening of lithium-ion battery separators in electrolyte solvents. J. Power Sources 294, 167–172 (2015).

    Google Scholar 

  26. Xu, J., Wang, L., Guan, J. & Yin, S. Coupled effect of strain rate and solvent on dynamic mechanical behaviors of separators in lithium ion batteries. Mater. Des. 95, 319–328 (2016).

    Google Scholar 

  27. Cannarella, J. & Arnold, C. B. Stress evolution and capacity fade in constrained lithium-ion pouch cells. J. Power Sources 245, 745–751 (2014).

    Google Scholar 

  28. Barai, A. et al. The effect of external compressive loads on the cycle lifetime of lithium-ion pouch cells. J. Energy Storage 13, 211–219 (2017).

    Google Scholar 

  29. Xu, J. et al. Deformation and failure characteristics of four types of lithium-ion battery separators. J. Power Sources 196, 137–145 (2016).

    Google Scholar 

  30. Peabody, C. & Arnold, C. B. The role of mechanically induced separator creep in lithium-ion battery capacity fade. J. Power Sources 196, 8147–8153 (2011).

    Google Scholar 

  31. Orendorff, C. J. The role of separators in lithium ion cell safety. Electrochem. Soc. Interface 21, 61–65 (2012).

    Google Scholar 

  32. Chandrasekaran, R. Quantification of bottlenecks to fast charging of lithium-ion-insertion cells for electric vehicles. J. Power Sources 271, 622–632 (2014).

    Google Scholar 

  33. Bach, T. C. et al. Nonlinear aging of cylindrical lithium-ion cells linked to heterogeneous compression. J. Energy Storage 5, 212–223 (2016).

    Google Scholar 

  34. Ecker, M., Shafiei Sabet, P. & Sauer, D. U. Influence of operational condition on lithium plating for commercial lithium-ion batteries — electrochemical experiments and post-mortem-analysis. Appl. Energy 206, 934–946 (2017).

    Google Scholar 

  35. Zhang, X., Zhu, J. & Sahraei, E. Degradation of battery separators under charge–discharge cycles. RSC Adv. 7, 56099–56107 (2017).

    Google Scholar 

  36. Whitaker, S. Flow in porous media I: a theoretical derivation of Darcy’s law. Transp. Porous Media 1, 3–25 (1986).

    Google Scholar 

  37. Torquato, S. Random Heterogeneous Materials (Springer Science+Business Media, New York, 2002).

  38. Gor, G. Y., Cannarella, J., Prevost, J. H. & Arnold, C. B. A model for the behavior of battery separators in compression at different strain/charge rates. J. Electrochem. Soc. 161, F3065–F3071 (2014).

    Google Scholar 

  39. Finegan, D. P. et al. Characterising the structural properties of polymer separators for lithium-ion batteries in 3D using phase contrast X-ray microscopy. J. Power Sources 333, 184–192 (2016).

    Google Scholar 

  40. Lagadec, M. F., Zahn, R., Müller, S. & Wood, V. Topological and network analysis of lithium ion battery components: the importance of pore space connectivity for cell operation. Energy Environ. Sci. 11, 3194–3200 (2018). Transport simulations for different separator pore structures demonstrate the importance of non-traditional network parameters for describing separator performance.

  41. Müllner, T., Unger, K. K. & Tallarek, U. Characterization of microscopic disorder in reconstructed porous materials and assessment of mass transport-relevant structural descriptors. New J. Chem. 40, 3993–4015 (2016).

    Google Scholar 

  42. Gering, K. L. Prediction of electrolyte conductivity: results from a generalized molecular model based on ion solvation and a chemical physics framework. Electrochim. Acta 225, 175–189 (2017).

    Google Scholar 

  43. Saito, Y., Morimura, W., Kuratani, R. & Nishikawa, S. Factors controlling the ionic mobility of lithium electrolyte solutions in separator membranes. J. Phys. Chem. C 120, 3619–3624 (2016). NMR measurements of diffusion coefficients of ions and solvent molecules in separator pores; discussion of how ion diffusion and electrolyte properties are influenced by separator geometry and surface interactions.

    Google Scholar 

  44. Saito, Y., Morimura, W., Kuse, S., Kuratani, R. & Nishikawa, S. Influence of the morphological characteristics of separator membranes on ionic mobility in lithium secondary batteries. J. Phys. Chem. C 121, 2512–2520 (2017).

    Google Scholar 

  45. Zahn, R., Lagadec, M. F., Hess, M. & Wood, V. Improving ionic conductivity and lithium-ion transference number in lithium-ion battery separators. ACS Appl. Mater. Interfaces 8, 32637–32642 (2016).

    Google Scholar 

  46. Lagadec, M. F., Zahn, R. & Wood, V. Designing polyolefin separators to minimize the impact of local compressive stresses on lithium ion battery performance. J. Electrochem. Soc. 165, A1829–A1836 (2018).

    Google Scholar 

  47. Bierenbaum, H. S., Isaacson, R. B., Druin, M. L. & Plovan, S. G. Microporous polymeric films. Ind. Eng. Chem. Prod. Res. Dev. 13, 2–9 (1974).

    Google Scholar 

  48. Sarada, T., Sawyer, L. C. & Ostler, M. I. Three dimensional structure of Celgard microporous membranes. J. Memb. Sci. 15, 97–113 (1983). Visualization of the three-dimensional microstructure of polypropylene separators using electron microscopy.

    Google Scholar 

  49. Lagadec, M. F., Ebner, M. & Wood, V. Microstructure of Targray PE16A Lithium-Ion Battery Separator (ETH Zurich, 2016); https://doi.org/10.5905/ethz-1007-32

  50. Lagadec, M. F. & Wood, V. Microstructure of Celgard PP1615 Lithium-Ion Battery Separator (ETH Zurich, 2018); https://doi.org/10.3929/ethz-b-000265085

  51. Ferguson, J. C., Panerai, F., Borner, A. & Mansour, N. N. PuMA: the porous microstructure analysis software. SoftwareX 7, 81–87 (2018).

    Google Scholar 

  52. Cooper, S. J., Bertei, A., Shearing, P. R., Kilner, J. A. & Brandon, N. P. TauFactor: an open-source application for calculating tortuosity factors from tomographic data. SoftwareX 5, 203–210 (2016).

    Google Scholar 

  53. Hantel, M. M., Armstrong, M. J., DaRosa, F. & l’Abee, R. Characterization of tortuosity in polyetherimide membranes based on Gurley and electrochemical impedance spectroscopy. J. Electrochem. Soc. 164, A334–A339 (2017).

    Google Scholar 

  54. Abraham, K. M. & Alamgir, M. Polymer electrolytes reinforced by Celgard membranes. J. Electrochem. Soc. 142, 683–687 (1995).

    Google Scholar 

  55. Martinez-Cisneros, C., Antonelli, C., Levenfeld, B., Varez, A. & Sanchez, J. Y. Evaluation of polyolefin-based macroporous separators for high temperature Li-ion batteries. Electrochim. Acta 216, 68–78 (2016).

    Google Scholar 

  56. Song, J. Y., Wang, Y. Y. & Wan, C. C. Conductivity study of porous plasticized polymer electrolytes based on poly(vinylidene fluoride): a comparison with polypropylene separators. J. Electrochem. Soc. 147, 3219–3225 (2000).

    Google Scholar 

  57. Tung, K. L. et al. Recent advances in the characterization of membrane morphology. Curr. Opin. Chem. Eng. 4, 121–127 (2014).

    Google Scholar 

  58. Dahbi, M. et al. Interfacial properties of LiTFSI and LiPF6-based electrolytes in binary and ternary mixtures of alkylcarbonates on graphite electrodes and Celgard separator. Ind. Eng. Chem. Res. 51, 5240–5245 (2012).

    Google Scholar 

  59. Cheng, Q., He, W., Zhang, X., Li, M. & Song, X. Recent advances in composite membranes modified with inorganic nanoparticles for high-performance lithium ion batteries. RSC Adv. 6, 10250–10265 (2016).

    Google Scholar 

  60. Huang, C., Lin, C. C., Tsai, C. Y. & Juang, R. S. Tailoring surface properties of polymeric separators for lithium-ion batteries by cyclonic atmospheric-pressure plasma. Plasma Process. Polym. 10, 407–415 (2013).

    Google Scholar 

  61. Li, B. et al. Facile and nonradiation pretreated membrane as a high conductive separator for Li-ion batteries. ACS Appl. Mater. Interfaces 7, 20184–20189 (2015).

    Google Scholar 

  62. Xu, W. et al. Layer-by-layer deposition of organic-inorganic hybrid multilayer on microporous polyethylene separator to enhance the electrochemical performance of lithium-ion battery. ACS Appl. Mater. Interfaces 7, 20678–20686 (2015).

    Google Scholar 

  63. Stephan, A. M. Review on gel polymer electrolytes for lithium batteries. Eur. Polym. J. 42, 21–42 (2006).

    Google Scholar 

  64. Landesfeind, J., Hattendorff, J., Ehrl, A., Wall, W. A. & Gasteiger, H. A. Tortuosity determination of battery electrodes and separators by impedance spectroscopy. J. Electrochem. Soc. 163, A1373–A1387 (2016).

    Google Scholar 

  65. Huang, X. Separator technologies for lithium-ion batteries. J. Solid State Electrochem. 15, 649–662 (2011).

    Google Scholar 

  66. Thorat, I. V. et al. Quantifying tortuosity in porous Li-ion battery materials. J. Power Sources 188, 592–600 (2009).

    Google Scholar 

  67. Ehrl, A., Landesfeind, J., Wall, W. A. & Gasteiger, H. A. Determination of transport parameters in liquid binary electrolytes: I. Diffusion coefficient. J. Electrochem. Soc. 164, A826–A836 (2017).

    Google Scholar 

  68. Devaux, D. et al. Conductivity of carbonate- and perfluoropolyether-based electrolytes in porous separators. J. Power Sources 323, 158–165 (2016).

    Google Scholar 

  69. Zahn, R., Lagadec, M. F. & Wood, V. Transport in lithium ion batteries: reconciling impedance and structural analysis. ACS Energy Lett. 2, 2452–2453 (2017).

    Google Scholar 

  70. Plaimer, M. et al. Evaluating the trade-off between mechanical and electrochemical performance of separators for lithium-ion batteries: methodology and application. J. Power Sources 306, 702–710 (2016).

    Google Scholar 

  71. Xiao, X., Wu, W. & Huang, X. A multi-scale approach for the stress analysis of polymeric separators in a lithium-ion battery. J. Power Sources 195, 7649–7660 (2010).

    Google Scholar 

  72. Shi, D., Xiao, X., Huang, X. & Kia, H. Modeling stresses in the separator of a pouch lithium-ion cell. J. Power Sources 196, 8129–8139 (2011).

    Google Scholar 

  73. Cannarella, J. & Arnold, C. B. The effects of defects on localized plating in lithium-ion batteries. J. Electrochem. Soc. 162, A1365–A1373 (2015).

    Google Scholar 

  74. Pan, Y. & Zhong, Z. Modeling the ion transport restriction in mechanically strained separator membranes. J. Electrochem. Soc. 161, A583–A586 (2014).

    Google Scholar 

  75. Sheidaei, A., Xiao, X., Huang, X. & Hitt, J. Mechanical behavior of a battery separator in electrolyte solutions. J. Power Sources 196, 8728–8734 (2011).

    Google Scholar 

  76. Yan, S., Xiao, X., Huang, X., Li, X. & Qi, Y. Unveiling the environment-dependent mechanical properties of porous polypropylene separators. Polymer 55, 6282–6292 (2014).

    Google Scholar 

  77. Forgez, C., Vinh Do, D., Friedrich, G., Morcrette, M. & Delacourt, C. Thermal modeling of a cylindrical LiFePO4/graphite lithium-ion battery. J. Power Sources 195, 2961–2968 (2010).

  78. Love, C. T. Perspective on the mechanical interaction between lithium dendrites and polymer separators at low temperature. J. Electrochem. Energy Convers. Storage 13, 031004 (2016). Analysis of the temperature- and shape-dependent mechanical interactions between lithium dendrites and separators.

  79. Development of an Advanced Microporous Separator for Lithium Ion Batteries Used in Vehicle Applications (United States Advanced Battery Consortium, 2018).

  80. Xu, H., Zhu, M., Marcicki, J. & Yang, X. G. Mechanical modeling of battery separator based on microstructure image analysis and stochastic characterization. J. Power Sources 345, 137–145 (2017).

    Google Scholar 

  81. Dai, J. et al. A rational design of separator with substantially enhanced thermal features for lithium-ion batteries by the polydopamine–ceramic composite modification of polyolefin membranes. Energy Environ. Sci. 9, 3252–3261 (2016).

    Google Scholar 

  82. Jana, A., Ely, D. R. & García, R. E. Dendrite–separator interactions in lithium-based batteries. J. Power Sources 275, 912–921 (2015).

    Google Scholar 

  83. Liu, X. M., Fang, A., Haataja, M. P. & Arnold, C. B. Size dependence of transport non-uniformities on localized plating in lithium-ion batteries. J. Electrochem. Soc. 165, 1147–1155 (2018). Experimental and theoretical analysis of how structural separator inhomogeneities affect ion transport.

    Google Scholar 

  84. Sun, F. et al. Morphological evolution of electrochemically plated/stripped lithium microstructures investigated by synchrotron X-ray phase contrast tomography. ACS Nano 10, 7990–7997 (2016).

    Google Scholar 

  85. Kerman, K., Luntz, A., Viswanathan, V., Chiang, Y.-M. & Chen, Z. Practical challenges hindering the development of solid state Li ion batteries. J. Electrochem. Soc. 164, A1731–A1744 (2017).

    Google Scholar 

  86. Xu, C., Ahmad, Z., Aryanfar, A., Viswanathan, V. & Greer, J. R. Enhanced strength and temperature dependence of mechanical properties of Li at small scales and its implications for Li metal anodes. Proc. Natl Acad. Sci. USA 114, 57–61 (2017).

    Google Scholar 

  87. Hallinan, D. T. & Balsara, N. P. Polymer electrolytes. Annu. Rev. Mater. Res. 43, 503–525 (2013).

    Google Scholar 

  88. Feng, X. et al. Thermal runaway mechanism of lithium ion battery for electric vehicles: a review. Energy Storage Mater. 10, 246–267 (2018).

    Google Scholar 

  89. Etacheri, V., Marom, R., Elazari, R., Salitra, G. & Aurbach, D. Challenges in the development of advanced Li-ion batteries: a review. Energy Environ. Sci. 4, 3243–3262 (2011).

    Google Scholar 

  90. Nitta, N., Wu, F., Lee, J. T. & Yushin, G. Li-ion battery materials: present and future. Mater. Today 18, 252–264 (2015).

    Google Scholar 

  91. Hassoun, J. & Scrosati, B. Advances in anode and electrolyte materials for the progress of lithium-ion and beyond lithium-ion batteries. J. Electrochem. Soc. 162, A2582–A2588 (2015).

    Google Scholar 

  92. Bauer, I., Thieme, S., Brückner, J., Althues, H. & Kaskel, S. Reduced polysulfide shuttle in lithium-sulfur batteries using Nafion-based separators. J. Power Sources 251, 417–422 (2014).

    Google Scholar 

  93. Zhu, W. et al. Improving the electrochemical performance of polypropylene separator through instantaneous photo-induced functionalization. J. Electrochem. Soc. 165, A1909–A1914 (2018).

    Google Scholar 

  94. Ryou, M. H. et al. Excellent cycle life of lithium-metal anodes in lithium-ion batteries with mussel-inspired polydopamine-coated separators. Adv. Energy Mater. 2, 645–650 (2012).

    Google Scholar 

  95. Sun, Y. Lithium ion conducting membranes for lithium-air batteries. Nano Energy 2, 801–816 (2013).

    Google Scholar 

  96. Kirchhöfer, M., Von Zamory, J., Paillard, E. & Passerini, S. Separators for Li-ion and Li-metal battery including ionic liquid based electrolytes based on the TFSI- and FSI- anions. Int. J. Mol. Sci. 15, 14868–14890 (2014).

    Google Scholar 

  97. Bruce, P. G. & Vincent, C. A. Steady state current flow in solid binary electrolyte cells. J. Electroanal. Chem. 225, 1–17 (1987).

    Google Scholar 

  98. Wood, V. X-ray tomography for battery research and development. Nat. Rev. Mater. 3, 293–295 (2018).

    Google Scholar 

Download references

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The authors gratefully acknowledge support from an ETH research grant (0-20978-14) and the European Research Council (project 680070).

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Lagadec, M.F., Zahn, R. & Wood, V. Characterization and performance evaluation of lithium-ion battery separators. Nat Energy 4, 16–25 (2019). https://doi.org/10.1038/s41560-018-0295-9

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