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چکیده
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The development of solid-state lithium-ion batteries (LIBs) with high energy density and safety is urgently needed nowadays. A solid-state electrolyte is the fundamental component of solid-state batteries and controls their performance. Composite polymer electrolytes (CPEs) have been identified as one of the most promising options among all the existing solid electrolytes due to their inclusive performance in terms of oxidative stability and ionic conductivity. Because of its advantageous characteristics, PVDF, a semi-crystalline polymer, is a viable candidate for creating polymer electrolytes. The PVDF exhibits numerous crystalline phases, including α-, β-, γ-, δ-, and ε-phases. Among these, the polar β-phase seems more favorable due to the substantial ferroelectric polarization and piezoelectric response. Therefore, it is necessary from a technological standpoint to increase the PVDF's fraction of the β-phase by either transforming the α-phase through different physical processing treatments or by incorporating various nanofillers (inorganic or organic) during the matrix-based composite film preparation process. In this study, we used a solution-casting method to synthesize a freestanding nanocomposite solid-state electrolyte membrane from a suspension of Phosphotungstic acid (H3PW12O40 (HPW) as the nanofiller), poly(vinylidene fluoride) (PVDF), and Lithium hexafluorophosphate (LiPF6, as salt). The effect of Phosphotungstic acid as a nanofiller is studied on the fraction of β-phase, ionic conductivity, and electrochemical stability of the PVDF through XRD, FT-IR, EIS, and LSV techniques. The ionic conductivity of PVDF is improved by increasing the percentage of β-phase in PVDF through nanofiller (2.6×10-5 S/cm to 8.56×10-5 S/cm for PVDF, and 3% wt HPW, respectively).
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