A Model for the Behavior of Battery Separators in Compression at Different Strain/Charge Rates

During charge and discharge of a lithium battery, intercalation of lithium ions into the electrodes can cause their noticeable expansion, compressing the soft separator between them. To assess the role of these effects on the battery performance, it is necessary to know the response of the battery separator under compressive loading. Here we develop a model for predicting the elastic response of a commercial separator immersed in fluid to compression at different strain rates. We show that the response of the separator is determined by combination of viscoelastic behavior of the polymer skeleton and poroelastic behavior, due to the flow of the fluid in the pores. Poroelastic behavior causes effective stiffening of the separator, which increases with the strain rate. For a sample of ca. 1 cm in diameter these effects become pronounced at strain rates 10−3 s−1 and have to be taken into account

[1]  Tao Sun,et al.  Deformation and fracture behaviors of microporous polymer separators for lithium ion batteries , 2014 .

[2]  J. Rice,et al.  Some basic stress diffusion solutions for fluid‐saturated elastic porous media with compressible constituents , 1976 .

[3]  Chunsheng Wang,et al.  Nano- and bulk-silicon-based insertion anodes for lithium-ion secondary cells , 2007 .

[4]  Shengbo Zhang.  A review on the separators of liquid electrolyte Li-ion batteries , 2007 .

[5]  Henry Eyring,et al.  Mechanical Properties of Polymeric Materials , 1943 .

[6]  Jianguo Zhou,et al.  Densities, Excess Molar Volumes, Isothermal Compressibilities, and Isobaric Expansivities of Dimethyl Carbonate + Cyclohexane Systems at Temperatures from (293.15 to 313.15) K and Pressures from (0.1 to 40) MPa , 2010 .

[7]  Azadeh Sheidaei,et al.  Mechanical behavior of a battery separator in electrolyte solutions , 2011 .

[8]  K. Terzaghi.  Theoretical Soil Mechanics , 1943 .

[9]  A. Francis,et al.  Rate- and Temperature-Dependent Material Behavior of a Multilayer Polymer Battery Separator , 2013, Journal of Materials Engineering and Performance.

[10]  M. Anouti,et al.  Viscosity and carbon dioxide solubility for LiPF6, LiTFSI, and LiFAP in alkyl carbonates: lithium salt nature and concentration effect. , 2014, The journal of physical chemistry. B.

[11]  M. Biot.  General Theory of Three‐Dimensional Consolidation , 1941 .

[12]  I. Halalay,et al.  Nanoindentation testing of separators for lithium-ion batteries , 2013 .

[13]  J. Mandel.  Consolidation Des Sols (Étude Mathématique) , 1953 .

[14]  A. Rodríguez,et al.  Viscosities of Dimethyl Carbonate or Diethyl Carbonate with Alkanes at Four Temperatures. New UNIFAC−VISCO Parameters , 2003 .

[15]  C. Love.  Thermomechanical analysis and durability of commercial micro-porous polymer Li-ion battery separator , 2011 .

[16]  I. M. Ward,et al.  Mechanical Properties of Solid Polymers: Third Edition , 2012 .

[17]  P. R. Pinnock,et al.  The mechanical properties of solid polymers , 1966 .

[18]  Siegfried Schmauder,et al.  Comput. Mater. Sci. , 1998 .

[19]  H. Eyring.  Viscosity, Plasticity, and Diffusion as Examples of Absolute Reaction Rates , 1936 .

[20]  Craig B. Arnold,et al.  Ion transport restriction in mechanically strained separator membranes , 2013 .

[21]  Yue Qi,et al.  Threefold Increase in the Young’s Modulus of Graphite Negative Electrode during Lithium Intercalation , 2010 .

[22]  Xiaosong Huang,et al.  A multiphysics model for the in situ stress analysis of the separator in a lithium-ion battery cell , 2014 .

[23]  Craig B. Arnold,et al.  Stress evolution and capacity fade in constrained lithium-ion pouch cells , 2014 .

[24]  J. Christensen,et al.  Thermoelectrochemical simulations of performance and abuse in 50-Ah automotive cells , 2014 .

[25]  Craig B. Arnold,et al.  The role of mechanically induced separator creep in lithium-ion battery capacity fade , 2011 .

[26]  O. Coussy.  Poromechanics: Coussy/Poromechanics , 2005 .

[27]  Z. Zhong,et al.  Modeling the Ion Transport Restriction in Mechanically Strained Separator Membranes , 2014 .