Performance Improvement of PVDF–HFP-Based Gel Polymer Electrolyte with the Dopant of Octavinyl-Polyhedral Oligomeric Silsesquioxane

Abstract

Gel polymer electrolytes have the advantages of both a solid electrolyte and a liquid electrolyte. As a transitional product before which a solid electrolyte can be comprehensively used, gel polymer electrolytes are of great research value. They can reduce the risk of spontaneous combustion and explosion caused by leakage during the use of conventional liquid electrolytes. Poly(vinylidene-fluoride-co-hexafluoropropylene) (PVDF–HFP), a material with excellent performance, has been widely utilized in the preparation of gel polymer electrolytes. Here, PVDF–HFP-based gel polymer membranes with polyvinyl pyrrolidone (PVP) pores were prepared using a phase inversion method, and Octavinyl-polyhedral oligomeric silsesquioxane (OVAPOSS) was doped to improve its temperature resistance as well as its ionic conductivity, to enhance its safety and electrochemical performance. The final prepared polymer membrane had a porosity of 85.06% and still had a certain mechanical strength at 160 °C without any shrinkage. The gel polymer electrolyte prepared with this polymer membrane had an ionic conductivity of 1.62 × 10−3 S·cm−1 at 30 °C, as well as an electrochemical window of about 5.5 V. The LiCoO2-Li button half-cell prepared therefrom had a specific capacity of 141 mAh·g−1 at a rate of 1C. The coulombic efficiency remained above 99% within 100 cycles and the capacity retention rate reached 99.5%, which reveals an excellent cycling stability.

Perspective of polymer-based solid-state Li-S batteries

“…The improvement in ionic conductivity originates from the enhanced segmental mobility of polymer backbones in the presence of plasticizing agents, thus offering rapid ionic transport. The significant research efforts carried out in recent years have led to substantial scientific progress in improving the performance of QSSPE-based Li-S cells, such as their mechanical properties [56] , Li-ion transference number [57,58] and/or thermal stability [Table 1] [59] .…”

Enhanced electroactive β‐phase and dielectric properties in P(VDF‐HFP) composite flexible films through doping with three calcium chloride salts: CaCl2, CaCl2·2H2O, and CaCl2·6H2O

“…Furthermore, the values for tensile strength and elongation at break of the composites consistently decline with an increase in calcium salt concentrations, regardless of the type of salt. This can be attributed to the interaction between the salt filler and the polymer matrix, which restricts the mobility of polymer chains, leading to a decrease in tensile strength and elongation at break with increased filler loading 62,63 …”

“…This can be attributed to the interaction between the salt filler and the polymer matrix, which restricts the mobility of polymer chains, leading to a decrease in tensile strength and elongation at break with increased filler loading. 62,63 The enhancement in the mechanical properties of the nanocomposite films, associated with enhanced salt loading, is attributed to the homogeneous dispersion of salts in the polymer matrix, as depicted in the SEM image in Figure 3. Additionally, the constrained mobility of the P(VDF-HFP) polymer chains, coupled with the ongoing increase in salt molecular weight, likely results in a reduction in the crystallinity of the composites, as elucidated in the subsequent XRD results.…”

A Gel Polymer Electrolyte with 2D Filler‐reinforced for Dendrite Suppression Li‐Ion Batteries

“…This interesting phenomenon may be attributed to the fact that the 2D Ht enhances the thermal stability of the separators, making the separators more resistant to combustion [50]. The normal operating temperature of LIBs is below 80 °C [51], indicating that the Ph/0.2Pm/ 0.04Ht separators are safe to operate.…”