High performance electrospun PVdF‐HFP/SiO2 nanocomposite membrane electrolyte for Li‐ion capacitors

Electrospun poly[(vinylidene fluoride)‐co ‐hexafluoropropylene]/silica (PVdF‐HFP/SiO₂) nanocomposite polymer membranes (esCPMs) were prepared by incorporating different weight percentages of SiO₂ nanoparticles onto electrospun PVdF‐HFP by electrospinning technique. The surface morphology of electrospun PVdF‐HFP nanocomposite membranes was characterized by scanning electron microscopy. The effect of SiO₂ nanoparticles incorporation onto electrospun PVdF‐HFP polymer membranes (esPMs) has been studied by XRD, DSC, TGA, and tensile analysis. The electrospun PVdF‐HFP/SiO₂ based nanocomposite membrane electrolytes (esCPMEs) were prepared by soaking the corresponding esCPMs into 1 M LiPF₆ in EC:DMC (1:1 vol/vol %). The ionic conductivity of the esCPMEs was studied by AC‐impedance studies and it was found that the incorporation of SiO₂ nanoparticles into PVdF‐HFP membrane has improved the ionic conductivity from 1.320 × 10^?3 S cm^?1 to 2.259 × 10^?3 S cm^?1. The electrochemical stability of the esCPME was studied by linear sweep voltammetry studies and it was found to be 2.87 V. Finally, a prototype LiCo_0.2Mn_1.8O₄//C Li‐ion capacitor (LIC) cell was fabricated with esCPME, which delivered a discharge capacitance of 128 F g^?1 at the current density of 1 A g^?1 and retained 86% of its discharge capacitance even after 10,000 cycles. These results demonstrated that the esCPMEs could be used as promising polymer membrane electrolyte for LICs. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45177.     

Characterisation of [(1−x)PMMA-xPVdF] polymer blend electrolyte with Li ion

The possible use of polymeric materials in thin-film solid electrolytes for battery systems, fuel cells, sensors and other electrochemical applications has stimulated worldwide interest in metal salt solvating macromolecules. Polymer electrolyte membranes comprising of poly(methyl methacrylate) (PMMA), poly(vinylidene fluoride) (PVdF) and lithium perchlorate are prepared using a solvent casting technique. Polymer blends have been characterised by FTIR and XRD studies to determine the molecular environment for the conducting ions. The role of interaction between polymer hosts on conductivity is discussed using the results of ac impedance studies. The ionic conductivity is presented as a function of temperature and PVdF content. Room temperature conductivity of 3.14×10⁻⁵ S cm⁻¹ has been obtained for the [0.25PMMA/0.75PVdF]-LiClO₄ polymer complex.     

Preparation and characterization of poly(vinylidene fluoride)/sulfonated poly(phthalazinone ether sulfone ketone) blends for proton exchange membrane

Poly(vinylidene fluoride)/sulfonated poly(phthalazinone ether sulfone ketone) (PVdF/SPPESK) blend membranes are successfully prepared by solution blending method for novel proton exchange membrane (PEM). PVdF crystallinity, FTIR‐ATR spectroscopy, thermal stability, morphology, water uptake, dimension stability, and proton conductivity are investigated on PVdF/SPPESK blends with different PVdF contents. XRD and DSC analysis reveal that the PVdF crystallinity in the blends depends on PVdF content. The FTIR‐ATR spectra indicate that SPPESK remains proton‐conducting function in the blends due to the intactness of ? SO₃H group. Thermal analysis results show a very high thermal stability (T_d1 = 246–261°C) of the blends. PVdF crystallinity and morphology study demonstrate that with lower PVdF content, PVdF are very compatible with SPPESK. Also, with lower PVdF content, PVdF/SPPESK blends possess high water uptake, e.g., P/S 10/90 and P/S 15/85 have water uptake of 135 and 99% at 95°C, respectively. The blend membranes also have good dimension stability because the swelling ratios are at a fairly low level (e.g., 8–22%, 80°C). PVdF/SPPESK blends with low PVdF content exhibit very high proton conductivity, e.g., at 80°C, P/S 15/85 and P/S 10/90 reach 2.6 × 10^?2 and 3.6 × 10^?2 S cm^?1, respectively, which are close to or even higher than that (3.4 × 10^?2 S cm^?1) of Nafion115 under the same test condition. All above properties indicate that the PVdF/SPPESK blend membranes (particularly, with 10–20% of PVdF content) are very promising for use in PEM field. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Crystallinity, morphology, mechanical properties and conductivity study of in situ formed PVdF/LiClO4/TiO2 nanocomposite polymer electrolytes

Nanocomposite polymer electrolytes composed of poly(vinylidene fluoride) (PVdF), lithium perchlorate (LiClO₄) and TiO₂ nanoparticles were prepared by a solution-cast method. The nanosized ceramic filler, TiO₂, was synthesized in situ by a sol-gel process. Differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) analysis revealed that the crystalline phase and crystallinity were slightly decreased with the addition of TiO₂ to the PVdF/LiClO₄ system. Scanning electron microscopy (SEM) micrographs showed that the PVdF/LiClO₄/TiO₂ solid polymer electrolyte (SPE) membranes had a porous structure to a certain extent, and that the pore size decreased with increasing TiO₂ content. The overfull nanoparticles tended to aggregate on the surface and inside the pores at TiO₂ content above 15 wt.% so that the porosity decreased. Regarding mechanical properties, the strength of the PVdF/LiClO₄/TiO₂ electrolytes decreased after the uptake of EC/PC solution. In contrast to the conductive behavior of wet PVdF/LiClO₄/TiO₂ membranes relative to the uptake of EC/PC solution, the conductive mechanism of the solid membranes, after the lithium ion of LiClO₄ had already been installed in the PVdF solid polymer network, was mainly influenced by the TiO₂ nanoparticles. At a TiO₂ content of 10 wt.%, the solid and wet PVdF/LiClO₄/TiO₂ systems had the maximum conductivity values of 7.1 × 10⁻⁴ and 1.8 × 10⁻³ S/cm, respectively.     

Preparation and properties of gel‐filled PVDF separators for lithium ion cells

Polyether gel‐filled poly(vinylidene fluoride) separators (GF‐PVDF separators) were prepared by means of thermal crosslinking of poly(ethylene glycol) methyl ether acrylate (PEGMEA) and poly(ethylene glycol) diacrylate (PEGDA) as gel constituents. The intrinsic properties of GF‐PVDF and their corresponding gel polymer electrolyte (GPE) were characterized by SEM, DSC, and electrochemical methods. It was found a relatively better GPE could be got when the filled polyether content no more than 60 wt % and its ion conductivity could reach 1.3 × 10^?3 S cm^?1. The GPE is compatible with anode and cathode of lithium ion battery at high voltage and its electrochemical window is 4.6 V (vs. Li/Li⁺). The coulombic efficiency could reach 94% after 100 cycles for the cells using such GPE. The results reveal that the composite polymer electrolyte qualifies as a potential application in lithium cells. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44473.     

Physical and electrochemical characterizations of poly(vinylidene fluoride‐co‐hexafluoropropylene)/SiO2‐based polymer electrolytes prepared by the phase‐inversion technique

Highly porous poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVdF–HFP)‐based polymer membranes filled with fumed silica (SiO₂) were prepared by a phase‐inversion technique, and films were also cast by a conventional casting method for comparison. N‐Methyl‐2‐pyrrolidone as a solvent was used to dissolve the polymer and to make the slurry with SiO₂. Phase inversion occurred just after the impregnation of the applied slurry on a glass plate into flowing water as a nonsolvent, and then a highly porous structure developed by mutual diffusion between the solvent and nonsolvent components. The PVdF–HFP/SiO₂ cast films and phase‐inversion membranes were then characterized by an examination of the morphology, thermal and crystalline properties, absorption ability of an electrolyte solution, ionic conductivity, electrochemical stability, and interfacial resistance with a lithium electrode. LiPF₆ (1M) dissolved in a liquid mixture of ethylene carbonate and dimethyl carbonate (1:1 w/w) was used as the electrolyte solution. Through these characterizations, the phase‐inversion polymer electrolytes were proved to be superior to the cast‐film electrolytes for application to rechargeable lithium batteries. In particular, phase‐inversion PVdF–HFP/SiO₂ (30–40 wt %) electrolytes could be recommended to have optimum properties for the application. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 140–148, 2006     

Development of a conjugated polyaniline incorporated electrospun poly(vinylidene fluoride‐co‐hexafluoropropylene) composite membrane electrolyte for high performance dye‐sensitized solar cells

Different weight percentage (2, 3, 4, and 5 wt %) of polyaniline (PANI) were incorporated into electrospun poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVdF‐HFP) composite membranes (esCPMs). The regular morphology, molecular structure, crystallinity, porosity, electrolyte uptake, and leakage of the composite membranes were examined. The esCPMs were activated in liquid electrolyte containing 0.5 M LiI, 0.05 M I₂, and 0.5 M 4‐tert‐butylpyridine and 0.5 M 1‐butyl‐3‐methylimidazoliun iodide in acetonitrile to afford electrospun PVdF‐HFP/PANI composite membrane electrolytes (esCPMEs). The influence of different wt % of PANI on the esCPMEs was studied by electrochemical impedance measurements and Tafel polarization studies. The photovoltaic performance of a dye‐sensitized solar cell assembled using 3 wt % PANI incorporated esCPME exhibits a higher power conversion efficiency of 7.20% than that assembled using esPME (η = 6.42%). © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42777.     

Preparation of poly(vinylidene fluoride)/poly(methyl methacrylate) membranes by novel electrospinning system for lithium ion batteries

Fibrous membranes of poly(vinylidene fluoride)/poly(methyl methacrylate) (PVdF/PMMA) were fabricated by electrospinning method with different concentrations of polymer solution: 14, 16, and 18 wt %. The morphology of the electrospun membranes was observed by scanning electron microscopy. The images revealed that the nanofibers showed uniform diameter and no bead formation was observed with the concentration of 16 wt %. Also, the structure, crystallinity, ionic conduction, and electrochemical stability of the electrospun membranes were characterized. The results suggested that electrolyte uptake, ionic conduction, and electrochemical stability were improved by the addition of PMMA. Furthermore, with the 16 wt % concentration of the polymer solution, the membrane showed a high ionic conductivity of 3.5 mS cm^?1 at room temperature and electrochemical stability of up to 5.1 V. We predicted that this new method may be very promising for preparing microporous PVdF/PMMA polymer electrolytes. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Chemically Modified Polyvinyl Butyral Polymer Membrane as a Gel Electrolyte for Lithium Ion Battery Applications

A novel porous membrane of chemically modified polyvinyl butyral (mPVB), with improved thermal properties and chemical stability for lithium ion battery applications, is successfully synthesized by utilizing the chain extension reaction of the OH units from PVB. The porous mPVB membranes are obtained via the tape casting and phase inversion method. The corresponding gel polymer electrolyte (GPE) is achieved by immersing the as‐prepared membranes in the liquid electrolyte. The electrochemical performances of the GPE show that the mPVB membranes have the features of good uniformity, high porosity ( ≈ 90%), great thermal stability, and high mechanical strength. Moreover, the GPE exhibits good chemical stability, a wide electrochemical window, as well as high ionic conductivity ( ≈ 1.21 × 10^?3 S cm^?1). A test of a Li/GPE/LiFePO₄ battery cell shows a capacity of 147.7 mAh g^?1 and excellent cycling stability, demonstrating the great potential of the mPVB‐based GPE for lithium ion battery applications.     

Composite polymer electrolytes based on electrospun thermoplastic polyurethane membrane and polyethylene oxide for all‐solid‐state lithium batteries

To improve the electrochemical properties and enhance the mechanical strength of solid polymer electrolytes, series of composite polymer electrolytes (CPEs) were fabricated with hybrids of thermoplastic polyurethane (TPU) electrospun membrane, polyethylene oxide (PEO), SiO₂ nanoparticles and lithium bis(trifluoromethane)sulfonamide (LiTFSI). The structure and properties of the CPEs were confirmed by SEM, XRD, DSC, TGA, electrochemical impedance spectroscopy and linear sweep voltammetry. The TPU electrospun membrane as the skeleton can improve the mechanical properties of the CPEs. In addition, SiO₂ particles can suppress the crystallization of PEO. The results show that the TPU‐electrospun‐membrane‐supported PEO electrolyte with 5 wt% SiO₂ and 20 wt% LiTFSI (TPU/PEO‐5%SiO₂‐20%Li) presents an ionic conductivity of 6.1 × 10^?4 S cm^?1 at 60 °C with a high tensile strength of 25.6 MPa. The battery using TPU/PEO‐5%SiO₂‐20%Li as solid electrolyte and LiFePO₄ as cathode shows an attractive discharge capacity of 152, 150, 121, 75, 55 and 26 mA h g^?1 at C‐rates of 0.2C, 0.5C, 1C, 2C, 3C and 5C, respectively. The discharge capacity of the cell remains 110 mA h g^?1 after 100 cycles at 1C at 60 °C (with a capacity retention of 91%). All the results indicate that this CPE can be applied to all‐solid‐state rechargeable lithium batteries. © 2018 Society of Chemical Industry     

Effect of 1‐butyl‐3‐methylimidazolium iodide containing electrospun poly(vinylidene fluoride‐co‐hexafluoropropylene) membrane electrolyte on the photovoltaic performance of dye‐sensitized solar cells

Electrospun poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVdF‐HFP) membrane was prepared from a solution of 16 wt % of PVdF‐HFP containing acetone/N,N‐dimethyl acetamide (7:3 wt %). The prepared electrospun PVdF‐HFP membrane (esPM) was then soaked in ionic liquid electrolyte containing 0.5M LiI, 0.05M I₂ , and 0.5M 4‐tert butylpyridine, 0.5M 1‐butyl‐3‐methylimidazolium iodide (BMImI) in acetonitrile to get electrospun PVdF‐HFP membrane electrolyte (esPME). The effect of various concentrations of BMImI containing esPME on ionic conductivity was studied by AC‐impedance measurements and the diffusion co‐efficients was determined by linear sweep voltammetry. The photovoltaic performance of a DSSC fabricated using 0.5M BMImI containing electrospun PVdF‐HFP membrane electrolyte (0.5M BMImI‐esPME) has power conversion efficiency (PCE) of 6.42%. But the stability of the DSSC fabricated using 0.5M BMImI‐esPME was considerably superior to that fabricated using 0.5M BMImI containing liquid electrolyte (0.5M BMImI‐LE). © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42032.     

Review on composite polymer electrolytes for lithium batteries

This paper reviews the state of the art of composite polymer electrolytes (CPE) in view of their electrochemical and physical properties for the applications in lithium batteries. This review mainly encompasses on composite polymer electrolyte hosts namely poly(ethylene oxide) (PEO), poly(acrylonitrile) (PAN), poly(methyl methacrylate) (PMMA) and poly(vinylidene fluoride) (PVdF) studied so far. Also the ionic conductivity, transference number, compatibility and the cycling behavior of poly(vinylidene fluoride-hexafluoro propylene) (PVdF-HFP)-[AlO(OH)]_n-LiPF₆/LiClO₄ composite electrolytes have been studied and the results are discussed.     

Synthesis of transparent poly(vinylidene fluoride) (PVdF)/zirconium oxide hybrids without crystallization of PVdF chains

Transparent and homogeneous organic-inorganic hybrids with poly(vinylidene fluoride) (PVdF) could be prepared by addition of zirconium oxide nanocrystals (ZrO₂-NCs) in a polar aprotic solvent and the subsequent solvent evaporation. The polar aprotic solvents such as DMF, DMAc and DMSO would form hydrogen bonds with Zr-OH groups of the ZrO₂-NC and play a role as compatibilizers between the PVdF and ZrO₂-NCs. The interpenetration between PVdF and ZrO₂-NCs resulted in the nanometer dispersion of PVdF chains in a ZrO₂-NC matrix. High dosage of the ZrO₂-NCs as physical inhibitors between PVdF polymer chains sufficiently prevented the PVdF chain mobility in the internal of hybrids. The transparency of the PVdF/ZrO₂-NC hybrids was dramatically improved by controlling the content of ZrO₂-NCs. Novel multifunctional hybrids with high transparency, high refractive index and good mechanical property were obtained by hybridization of PVdF and ZrO₂-NCs.     

Rechargeable lithium/sulfur battery with suitable mixed liquid electrolytes

The suitability of some single/binary liquid electrolytes and polymer electrolytes with a 1 M solution of LiCF₃SO₃ was evaluated for discharge capacity and cycle performance of Li/S cells at room temperature. The liquid electrolyte content in the cell was found to have a profound influence on the first discharge capacity and cycle property. The optimum, stable cycle performance at about 450 mAh g⁻¹ was obtained with a medium content (12 μl) of electrolyte. Comparison of cycle performance of cells with tetra(ethylene glycol)dimethyl ether (TEGDME), TEGDME/1,3-dioxolane (DIOX) (1:1, v/v) and 1,2-dimethoxyethane (DME)/di(ethylene glycol)dimethyl ether (DEGDME) (1:1, v/v) showed better results with the mixed electrolytes based on TEGDME. The addition of 5 vol.% of toluene in TEGDME had a remarkable effect of increasing the initial discharge capacity from 386 to 736 mAh g⁻¹ (by >90%) and stabilizing the cycle properties, attributed to the reduced lithium metal interfacial resistance obtained for the system. Polymer electrolyte based on microporous poly(vinylidene fluoride) (PVdF) membrane and TEGDME/DIOX was evaluated for ionic conductivity at room temperature, lithium metal interfacial resistance and cycle performance in room-temperature Li/S cells. A comparison of the liquid electrolyte and polymer electrolyte showed a better performance of the former.     

Reversible photochromic nanofibrous membranes with excellent water/windproof and breathable performance

Electrospun nanofibrous membranes (NFMs) with outstanding photochromic property, waterproof, and breathability have attracted considerable interest owing to their multifunctional applications in intelligent clothing, self‐cleaning, and protection. However, great challenges still remain in creating such functional materials. A novel waterproof–breathable membrane with robust photochromic property is fabricated by introducing photochromic microcapsule (PM) into electrospun thermoplastic polyurethanes (TPU) membranes. Compared with the pristine TPU NFMs, the composite TPU/PM membranes are endowed with reversible photochromic properties. In addition, the composite membranes not only exhibited a water contact angle of 137° and a milk contact angle of 130°, but also had integrated properties of modest water vapor transmittance rate of 19,278 g m^?2 day^?1, high air permeability of 962 mm s^?1, low waterproofness of 2.813 kPa, and comparable tensile strength of 12.08 MPa. Furthermore, the convenience and efficiency of this fabrication process will allow for large‐scale production of the multifunctional NFMs. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46342.     

Thermoplastic polyurethane elastomer induced shear piezoelectric coefficient enhancement in bismuth sodium titanate – PVDF composite films

A series of ester-based thermoplastic polyurethane elastomer (TPU) and bismuth sodium titanate polycrystalline oxide (Bi_0.5Na_0.5TiO₃, BNT) co-blended poly (vinylidene fluoride) (PVDF) composite films were prepared. Mechanical test confirms the optimum BNT blending content (25 wt%) and further reveals a linear growth of tensile elongation by increasing TPU content. Microstructure modifications including strengthened hydrogen bond and valence band edge elevation are evidenced to be highly correlated to the dielectric and piezoelectric properties. Significant enhancement (7–13 times) in face shear piezoelectric coefficient (d₃₆) is achieved by adjusting the blending content of TPU. Cross-section image presents a featuring multilayer structure with improved dispersity of BNT particle under a transverse tensile force which effectively increases the interfacial contact area between BNT and polymer blends. This work reveals the significance of band structure modification and anisotropic texture construction on influencing the transfer of piezoelectric charge in TPU blended BNT-PVDF composite film.     

Preparation and properties of TPU micro/nanofibers by a laser melt‐electrospinning system

Laser melt electrospinning is a novel technology to fabricate scaffolds in the tissue engineering applications. The melt electrospinning is much safer than the conventional solution electrospinning due to without solvent effect. In this study, thermoplastic polyurethane (TPU) micro/nanofibers were successfully prepared by using this method. The effects of laser current and applied voltage on the fibers morphologies were investigated by scanning electron microscopy. The thermal behaviors and crystallization conditions of the TPU under different states were demonstrated by differential scanning calorimetry and X‐ray diffraction analysis. The mechanical property and the specific surface area of the TPU fibers membranes were also studied. All the analysis results showed that the effects of laser current and applied voltage on the average fiber diameter were complicated, the average fiber diameter ranging from 1.70 to 2.53 µm; the TPU is not an easily crystallized material; the electrospun fibers exhibited an amorphous phase; the average elongation at break laser of the electrospun TPU fiber membranes is about 134%; the average tensile strength is about 1.02 MPa and the specific surface area of the electrospun TPU fiber membrane is about 199 m²/g. POLYM. ENG. SCI., 54:1412–1417, 2014. © 2013 Society of Plastics Engineers     

Electrospun poly(lithium 2‐acrylamido‐2‐methylpropanesulfonic acid) fiber‐based polymer electrolytes for lithium‐ion batteries

Novel single‐ion conducting polymer electrolytes based on electrospun poly(lithium 2‐acrylamido‐2‐methylpropanesulfonic acid) (PAMPSLi) membranes were prepared for lithium‐ion batteries. The preparation started with the synthesis of polymeric lithium salt PAMPSLi by free‐radical polymerization of 2‐acrylamido‐2‐methylpropanesulfonic acid, followed by ion‐exchange of H⁺ with Li⁺. Then, the electrospun PAMPSLi membranes were prepared by electrospinning technology, and the resultant PAMPSLi fiber‐based polymer electrolytes were fabricated by immersing the electrospun membranes into a plasticizer composed of ethylene carbonate and dimethyl carbonate. PAMPSLi exhibited high thermal stability and its decomposition did not occur until 304°C. The specific surface area of the electrospun PAMPSLi membranes was raised from 9.9 m²/g to 19.5 m²/g by varying the solvent composition of polymer solutions. The ionic conductivity of the resultant PAMPSLi fiber‐based polymer electrolytes at 20°C increased from 0.815 × 10^?5 S/cm to 2.12 × 10^?5 S/cm with the increase of the specific surface area. The polymer electrolytes exhibited good dimensional stability and electrochemical stability up to 4.4 V vs. Li⁺/Li. These results show that the PAMPSLi fiber‐based polymer electrolytes are promising materials for lithium‐ion batteries. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Solid polymer electrolytes of blends of polyurethane and polyether modified polysiloxane and their ionic conductivity

Polymer electrolytes based on thermoplastic polyurethane (TPU) and polyether modified polysiloxane (PEMPS) blend with lithium salts were developed via an in-situ polymerization of TPU with the presence of PEMPS and salts. Morphological study of TPU/PEMPS electrolytes showed that TPU and PEMPS were immiscible and TPU/PEMPS electrolytes had a multiphase morphology. The lithium salt enhanced the interfacial compatibilization between TPU and PEMPS via the interaction of lithium ions with different phases. Three lithium salts with different interaction strengths with TPU and PEMPS were used to prepare TPU/PEMPS electrolytes with different levels of phase compatibilization: LiCl, LiClO₄, and LiN(SO₂CF₃)₂ (LiTFSI). The effect of PEMPS on ionic conductivity, dimensional stability and thermal stability of TPU/PEMPS electrolytes and their relationship with the blend morphology were investigated. TPU/PEMPS electrolytes showed good dimensional stability and thermal stability. The addition of PEMPS to TPU increased the ionic conductivity of TPU/PEMPS electrolytes. The room temperature ionic conductivity of TPU/PEMPS electrolytes with LiTFSI can reach up to 2.49 × 10⁻⁵ S/cm.     

Effect of evaporation temperature on the crystalline properties of solution-cast films of poly(vinylidene fluoride)s

The crystalline properties of poly(vinylidene fluoride) (PVdF) and its copolymer films, prepared from the solvent (N-methyl-2-pyrrolidone) evaporation at different temperatures and subsequent slow cooling to ambient temperature, were investigated by using polarized optical microscopy, differential scanning calorimetry, wide-angle X-ray diffractometry, and Fourier-transform infrared spectroscopy. The results can provide helpful data for determining the optimal processing conditions of PVdFs as the polymer binder materials in making the electrodes of rechargeable lithium batteries. The morphology analysis gives useful information that the residual solvent remaining after the evaporation shows distinguishable amounts with respect to the temperature regions dividing by the crystallization (T_c) and melting (T_m) points of original PVdF samples. It is also proved that smallest spherulitic state coexisting with dominant α- and minor γ-phase crystals, simultaneously showing the lowest heat of fusion (e.g., the lowest crystallinity), can be obtained when the solvent is evaporated at a temperature between T_c andT _m. Letting the minor γ-phase crystals exist by controlling the evaporation temperature like this can be one of the best drying (evaporation) conditions of PVdF-containing slurry in lithium rechargeable battery system.