PVDF-HFP-Based Composite Electrolyte Membranes having High Conductivity and Lithium-Ion Transference Number for Lithium Metal Batteries

Abstract

Lithium metal batteries (LMBs) with liquid-based electrolytes usually suffer from safety problems such as the growth of Li dendrites and the leakage and volatilization of organic solvents. Replacing liquid-based electrolytes using solid polymer electrolytes may resolve these problems. In this study, sulfonated polyvinylidene fluoride lithium-hexafluoropropylene (SPVDFLi-HFP), a single-ion conductive polymer, is synthesized from polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) and chlorosulfonic acid, and a series of LMBs are fabricated using SPVDFLi-HFPx/PVDF-HFP composite electrolyte membranes and characterized. The as-prepared SPVDFLi-HFPx/PVDF-HFP composite electrolyte membranes possess high conductivity (2.84 × 10 −4 S cm −1 ), a wide electrochemical window (5.4 V, vs Li/Li + ), and high interface compatibility with lithium metal anodes. Benefiting from the single-ion conductive nature of SPVDFLi-HFP, SPVDFLi-HFP50/PVDF-HFP exhibits a high lithium-ion transference number of 0.81. A solid-state LiFePO 4 |SPVDFLi-HFP50/ PVDF-HFP|Li battery exhibits an initial capacity of 147.9 mA h g −1 , a capacity retention of 89.1% at the end of 200 cycles, and an average Coulombic efficiency exceeding 99% at 0.2 C, demonstrating strong application potential in LMBs.

Two‐Dimensional Fluorinated Graphene Reinforced Solid Polymer Electrolytes for High‐Performance Solid‐State Lithium Batteries

“…designed and synthesized SPVDFLi‐HFP/PVDF‐HFP composite electrolyte, which shows enhanced mechanical properties and a high Li‐ion transference number. [ 54 ] Sui et al. designed a self‐enhancing gel polymer electrolyte (GPE) by in situ polymerizing 1,3‐dioxolane (DOL) in the PDA/PVDF‐HFP skeleton.…”

“…[48][49][50][51][52][53] Ren et al designed and synthesized SPVDFLi-HFP/PVDF-HFP composite electrolyte, which shows enhanced mechanical properties and a high Li-ion transference number. [54] Sui et al designed a self-enhancing gel polymer electrolyte (GPE) by in situ polymerizing 1,3-dioxolane (DOL) in the PDA/PVDF-HFP skeleton. Hydrogen bonds between the PDOL and skeleton effectively increase the mechanical strength of the GPE and improve ionic conductivity.…”

An organic additive assisting with high ionic conduction and dendrite resistance of polymer electrolytes

“…2d and Table S2 (ESI†) summarize the areal conductance values of the reported PVDF-based electrolytes. 16,17,19,25–27,29,33,51–60 It is worth noting that the areal conductance of our AP-PE is the highest among the electrolytes without adding inorganics. Even in comparison with the electrolytes with inorganics, our AP-PE has an outstanding areal conductance and an advantage of facile synthesis.…”

A New In Situ Prepared MOF‐Natural Polymer Composite Electrolyte for Solid Lithium Metal Batteries with Superior High‐ Rate Capability and Long‐Term Cycling Stability at Ultrahigh Current Density

“…LA is a natural polymer, it is relatively inexpensive, easily available, and environmentally friendly compared with many reported electrostatic spinning substrate materials including polyacrylonitrile (PAN) [ 2 , 9 ] and polyvinylidene difluoride‐hexafluoro propylene copolymer (PVDF‐HFP). [ 10 ] Besides, the modified LA‐based electrolyte matrix obtained by electrospinning method has a 3D network structure, which is conducive to providing the required mechanical strength of electrolyte. Moreover, ZIF‐67 can uniformly disperse on LA‐PAM electrostatic spinning membrane by the hydrogen bond interaction between imidazole groups of ZIF‐67 and the functional groups of the spinning membrane.…”

“…Particularly, the rich ion transport pathways offered by ZIF‐67 and porous electrospinning membrane is not only beneficial to fast ion conduction to the uniform deposition of lithium‐ion, but also strong hydrogen bond interaction among the abundant polar functional groups in modified LA can further provide enough high mechanical strength to suppress the lithium dendrites. [ 10 , 11 ] Consequently, the assembled battery can be stably cycled at a current density of 40, 80, and even 100 mAh cm −2 . It is worth noting that LFP cells with the MOF‐polymer composite membrane (ZIF‐67‐LA‐PAM) run steadily for 1000 cycles at 10 C, 1600 cycles at 20C for LFP cells, and 3000 h at a current density of 40 mA cm −2 , 1300 h at 100 mA cm −2 for symmetric cells and the same applies to NCM 811 positive electrode and pouch cells.…”