In order to improve the safety and reduce interface impedance of lithium-ion batteries, the star-shaped polyhedral POSS-poly(methyl methacrylate) (POSS-(PMMA46)8), which has both excellent heat resistance and good compatibility with the polymer material, was selected as a modifier to modify the separator of commercial polypropylene (PP) by the method of impregnation. The micromorphology of the composite separator was studied by scanning electron microscope (SEM). The mechanical property of the separator was measured by a tensile tester. The thermal stability of the separator was studied at a high temperature. The wettability of the separator was tested by a contact angle tester. The AC impedance was used to obtain the bulk impedance of the composite separator and then its ionic conductivity was studied. The electrochemical stability of the separator was measured by linear sweep voltammetry (LSV). The results show that when the mass fraction of POSS-(PMMA46)8 is 40%, the pore distribution of the composite membrane is homogeneous, and the wettability is the best. The tensile strength is 5.34 times that of the original film, and the thermo-stability is ideal at 160℃/1h. The conductivity of the composite membrane is 1.35×10-3 S/cm. The interface resistance between the composite separator and the electrode is reduced from 743Ω to 152Ω, and which is 79.5% higher than that of the original film; for Li/Separator/LiFePO4 cell, the charge-discharge cycling stability is better and the battery capacity at low magnification is comparable to commercial PP separator.
YANG K Q , MA X Y , SUN K , et al. Electrospun octa(3-chloropropyl)-polyhedral oligomeric silsesquioxane-modified polyvinylidene fluoride/poly(acrylonitrile)/poly(methylmethacr-ylate) gel polymer electrolyte for high-performance lithium ion battery[J]. Journal of Solid State Electrochemistry, 2018, 22 (2): 441- 452.
YU L H , JIN Y , LIN Y S . Ceramic coated polypropylene separators for lithium-ion batteries with improved safety:effects of high melting point organic binder[J]. RSC Advances, 2016, 6 (46): 40002- 40009.
CHENG Q H , HE W , ZHANG X D , et al. Recent advances in composite membranes modified with inorganic nanoparticles for high-performance lithium ion batteries[J]. RSC Advances, 2016, 6 (13): 10250- 10265.
YU L H , MIAO J S , JIN Y , et al. A comparative study on polypropylene separators coated with different inorganic materials for lithium-ion batteries[J]. Frontiers of Chemical Science and Engineering, 2017, 11 (3): 346- 352.
MA J Y , SUN K , MA X Y , et al. Structure and property of electrospinning POSS-(C3H6Cl)8 composite PVDF polymer separators[J]. Polymer Materials Science & Engineering, 2018, 34 (6): 54- 59.
SHI C , DAI J H , SHEN X , et al. A high-temperature stable ceramic-coated separator prepared with polyimide binder/Al2O3 particles for lithium-ion batteries[J]. Journal of Membrane Science, 2016, 517, 91- 99.
XIONG Q Q , ZHENG C , CHI H Z , et al. Reconstruction of TiO2/MnO2-C nanotube/nanoflake core/shell arrays as high-performance supercapacitor electrodes[J]. Nanotechnology, 2017, 28 (5): 055405.
LI Z G , MA X Y , GUAN X H , et al. Aggregation behavior of star-shaped fluoropolymers containing polyhedral oligomeric silsesquioxane (POSS) at the air-water interface[J]. Colloid and Polymer Science, 2017, 295 (1): 157- 170.
ZHANG F , GUAN X H , MA X Y , et al. Effect of POSS star-shaped polymers on the properties of PMMA-based GPE[J]. Acta Polymeric Sinica, 2015, (7): 852- 857.
LIU Y , MA X , SUN K , et al. Preparation and characterization of gel polymer electrolyte based on electrospun polyhedral oligomeric silsesquioxane-poly(methyl methacrylate)8/polyvin-ylidene fluoride hybrid nanofiber membranes for lithium-ion batteries[J]. Journal of Solid State Electrochemistry, 2017, 22 (4): 1- 10.
QIANG X , MA X Y , LI Z G , et al. Synthesis of star-shaped polyhedral oligomeric silsesquioxane (POSS) fluorinated acrylates for hydrophobic honeycomb porous film application[J]. Colloid and Polymer Science, 2014, 292 (7): 1531- 1544.
DONG X , MI W , YU L , et al. Zeolite coated polypropylene separators with tunable surface properties for lithium-ion batteries[J]. Microporous and Mesoporous Materials, 2016, 226, 406- 414.
LI X , ZHANG M , HE J , et al. Effects of fluorinated SiO2 nanoparticles on the thermal and electrochemical properties of PP nonwoven/PVDF-HFP composite separator for Li-ion batteries[J]. Journal of Membrane Science, 2014, 455, 368- 374.
LEE J Y , YONG M L , BHATTACHARYA B , et al. Solid polymer electrolytes based on crosslinkable polyoctahedral silsesquioxanes (POSS) for room temperature lithium polymer batteries[J]. Journal of Solid State Electrochemistry, 2010, 14 (8): 1445- 1449.
PARK J H , CHO J H , PARK W , et al. Close-packed SiO2/poly(methyl methacrylate) binary nanoparticles-coated polye-thylene separators for lithium-ion batteries[J]. Journal of Power Sources, 2010, 195 (24): 8306- 8310.
KIM K M , HEPOWIT L R , KIM J C , et al. Enhanced separator properties by coating alumina nanoparticles with poly(2-acrylamido-2-methyl-1-propanesulfonic acid) binder for lithium-ion batteries[J]. Korean Journal of Chemical Engin-eering, 2015, 32 (4): 717- 722.