Structural, microstructural and electrochemical properties of dispersed-type polymer nanocomposite films

Abstract

The free standing solid polymer nanocomposite (PEO-PVC)+LiPF6-TiO2 films has been prepared through standard solution cast technique. The improvement in structural, microstructural and electrochemical properties has been observed on the dispersion of nanofiller in polymer salt complex. X-Ray diffraction studies clearly reflect the formation of complex formation as no corresponding salt peak appeared in the diffractograms. The FTIR analysis suggested a clear and convincing evidence of polymer-ion, ion-ion and polymer-ion-nanofiller interaction. The highest ionic conductivity of the prepared solid polymer electrolyte films is ~5×10 -5 S cm -1 for 7 wt. % TiO2.The Linear Sweep Voltammetry provide the electrochemical stability window of the prepared solid polymer electrolyte films, which is of the order of ~3.5 V. The ion transference number has been estimated, tion =0.99 through dc polarization technique. Dielectric spectroscopic studies were performed to understand the ion transport process in polymer electrolytes. All solid polymer electrolyte possesses good thermal stability up to 300 °C. DSC analysis confirms the decrease of melting temperature and signal of glass transition temperature with addition of nanofiller which indicates the decrease of crystallinity of polymer matrix. An absolute correlation between diffusion coefficient (D), ion mobility (μ), number density (n), double layer capacitance (Cdl), glass transition temperature, melting temperature (Tm), free ion area (%) and conductivity (σ) has been observed. A convincing model to study the role of nanofiller in polymer salt complex has been proposed which supports the experimental findings. The prepared polymer electrolyte system with significant ionic conductivity, high ionic transference number, good thermal, voltage stability could be suggested as a potential candidate as electrolyte cum separator for fabrication of rechargeable lithium-ion battery system. IntroductionFrom last two decades, lithium ion batteries (LIB) are widely investigated energy source for the portable electronics because of attractive features like high energy density, shape mouldability, design flexibility, zero memory loss and high safety. The desirable characteristics of polymer electrolytes for R&D application in LIB are good compatibility with electrode materials, leakage proof, longer shelf life, high capacity and light weight [1]. The conductivity in solid state conductors was reported first time by Faraday in 1800s, and later the discovery of poly ethylene oxide (PEO) and alkali metal salts (NaI) system in the 1970s was contributed by Wright and coworkers. Then, Armand realized their technological importance due to flexibility, deformability and introduced the first new class of solid state ionic conductors (SSIC). Solid Polymer electrolytes (SPEs) comprising the high electrical conductivity along with mechanical flexibility, faster segmental motion of polymer chain makes them, best substitute over liquid electrolytes in electrochemical devices such as supercapacitor, cell ...

Optimization of salt concentration and explanation of two peak percolation in blend solid polymer nanocomposite films

“…The almost same trend is followed by the peak associated with melting temperature (Tm) where polymer gets melted. The shift of peak toward lower temperature indicates the increased ionic conductivity and both Tg & Tm supports this approach [83][84]. The crystallinity was calculated using equation 3 and it shows the crystallinity minima for the SPE 2 system.…”

Tailoring the Structural, Morphological, Electrochemical, and Dielectric Properties of Solid Polymer Electrolyte

“…It is observed that for all SPEs, the initial current decreases with time and achieved steady state in small time. The initial current is the contribution of both the ions and the electrons ( = + ) while the later one is the contribution of electrons only because of blockage of ions at the electrode-electrolyte interface [45][46][47]. The obtained ion transference number is 0.99 (close to unity).…”

“…However, SPE possesses lower ionic conductivity at ambient temperature. To overcome the poor ionic conductivity various approaches are manifested to develop new materials such as polymer blending, nanofiller dispersion, incorporation of ionic liquids/plasticizer [5][6][7][8][9][10][11][12][13][14][15][16].…”

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

“…The modification of PVB can be demonstrated by the FTIR measurements . As shown in Figure a, the peak at 1666 cm −1 in the spectrum of mPVB membrane is ascribed to the CO stretching vibration of units II and III.…”

“…The modification of PVB can be demonstrated by the FTIR measurements. [21][22][23] As shown in Figure 3a, the peak at 1666 cm −1 in the spectrum of mPVB membrane is ascribed to the CO stretching vibration of units II and III. The shift could be contributed to its overlap with the blending vibration peaks of the residual crystal water from the reaction procedures, which are not found in the FTIR spectrum of the PVB membrane.…”