Unveiling the enhancement essence on Li2S deposition by the polarized topological β-polyvinylidene fluoride: Beyond built-in electric field effect

Herein, we elucidate a novel strategy to introduce the electrostatic interaction by adding the ferroelectric phase PVDF through the thermal assisted polarization process. Benefitting from strong electrostatic force from β phase PVDF to PS - and Li + ions, the LSBs show outstanding rate and cycling stability. To our knowledge, rarely reported about introducing electrostatic forces in binders to inhibit the shuttling of polysulfides. Furthermore, the enhancement mechanism for the cathodes’ electrochemical performances was also discussed in details. • Ferroelectric effect was introduced by converting α-PVDF to β one via thermal polarization. • The polarized β-PVDF has an improved conductance and an enhanced chemisorption to LiPSs. • The electric field from β-PVDF can help the anchoring of the PS - ions and the diffusing of Li + ions. • The LSBs can show a highly-improved rate capability, as well as an ultrahigh cycling stability. Electric field from ferroelectric materials was often applied to energy-storage devices to enhance their electrochemical reaction kinetics via the electrostatic interaction. However, traditional ferroelectric materials are difficult to be used commercially for their insulation. Herein, we elucidate a novel strategy to introduce the electrostatic interaction by polarizing the polyvinylidene fluoride (PVDF) binder used in the C/S cathodes for lithium-sulfur batteries. In particular, we show both experimentally and theoretically how an external electric field from β -phase PVDF induces unprecedented performance and stabilities. Density functional theory calculation results indicate that the polarized topological β -phase PVDF possesses not only an strong built-in electric field and an improved conductance that benefits both the deposition of LiPSs and the transport of Li + ions, but also an enhanced adsorption capability to polysulfide ions. As a result, the specific capacity was improved by over 60%, the rate capability (from 0.1 to 2.0 C) was enhanced by 138%, and the capacity decay rate (1000 cycles at 1.0 C) largely decreases from 0.059% to 0.038% per cycle. Besides, the enhancement mechanism of Li 2 S deposition by electrostatic interaction has also been explored. This research would provide some new insight into the ferroelectric enhanced design of high-performance energy-storage devices.