A boron nitride-polyvinylidene fluoride-co-hexafluoropropylene composite gel polymer electrolyte for lithium metal batteries

A modified gel polymer electrolyte (GPE) with boron nitride (BN) additive was designed to boost the electrochemical performance of rechargeable lithium metal battery, which consists of Li-rich layered cathode and possesses a high energy density. BN, electron insulator and ion conductor, has excellent thermodynamic and electrochemical stability. BN particles were well dispersed in polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) polymer matrices and thus substantially enhanced the electrochemical and physical properties of the GPEs. With only 0.5 wt% BN additive, it remarkably improved the mechanical modulus and ionic conductivity (to 4.1 × 10−4 S∙cm−2) of GPEs, which was beneficial for suppressing lithium dendrite formation and fast ion transportation, respectively, thereby enabling high-performance lithium metal batteries with ultra-long cycle life and high safety at ambient temperature (25 °C) and high temperature (55 °C). A modified GPE with a multifunctional BN additive can revitalize LMBs to readily obtain a comparative ionic conductivity and remarkably improve mechanical modulus, which is beneficial for suppressing Li dendrite formation. [Display omitted] •We have successfully incorporated 2D BN fillers into a gel polymer electrolyte based on PVDF-HFP.•Only 0.5 wt% addition of BN can readily obtain a comparative ionic conductivity and improved mechanical modulus.•The Li1.18Ni0.15Co0.15Mn0.52O2/0.5 wt% BN-(PVDF-HFP)/Li cell performs a superior stability and rate capability.