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

Abstract

Gel polymer electrolytes (GPEs) incorporate both the high ionic conductivity of organic liquid electrolyte and the high safety performance of all-solid-state electrolytes (ASSEs), greatly improving the electrochemical performance of solid polymer electrolytes (SPEs). However, the practical application of GPEs is still limited by inferior interface compatibility, lithium dendrites, etc. Herein, we prepared GPEs based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) further co-blended the two-dimensional sheet inorganic filler hectorite and poly(methyl methacrylate) (PMMA) to improve the mechanical and electrochemical properties of the GPEs. When the content of PMMA and hectorite is optimal, this GPEs have an ionic conductivity of 1.06 × 10 À 3 S cm À 1 and outstanding lithium symmetric cells cycle time of more than 3000 h, indicating that the introduction of filler effectively inhibits the growth of lithium dendrites at room temperature. Moreover, the GPEs adopt a relatively simple solution casting method to provide a fresh idea for the synthesis of high-performance GPEs.

Inert Filler Selection Strategies in Li-Ion Gel Polymer Electrolytes

“…Consequently, the mechanical strength of the system is improved. Among them, the PVDF-HFP-LiTFSI-PC-Al 2 O 3 film shows the best mechanical strength because the intermolecular hydrogen bonding effect between Al 2 O 3 nanofillers and PVDF-HFP makes the PVDF-HFP framework more mechanically robust. − Although the electrolyte membrane can withstand voltages greater than 4 V (Figure S7), interfacial side reactions still occur during the electrochemical reaction with the electrodes . Furthermore, the interfacial properties were tested in NCM811//GPEs//Li using EIS spectroscopy.…”

“…38−40 Although the electrolyte membrane can withstand voltages greater than 4 V (Figure S7), interfacial side reactions still occur during the electrochemical reaction with the electrodes. 41 Furthermore, the interfacial properties were tested in NCM811//GPEs//Li using EIS spectroscopy. As shown in Figure 1d, the semicircle (R) represents the sum of the charge transfer resistance (R ct ) and the interfacial resistance (R f ).…”

A Sustainable Gel Polymer Electrolyte for Solid-State Electrochemical Devices

“…The criteria to obtain a good polymer skeleton are: a (i) high molecular weight (10 4 –10 6 g mol −1 ) for mechanical stability, (ii) low glass transition temperature (T g < −30 °C) for fast segmental motion of the polymer chains, (iii) the presence of atoms or substituent groups promoting the dissolution of salts for ionic conductivity, (iv) a high degradation temperature (>200 °C), and (v) a wide electrochemical window for chemical and electrochemical stability (up to 5 V, depending on the solvent) [ 8 ]. Examples of host polymers include poly(ethylene oxide) (PEO), poly(vinylidene difluoride (PVdF) [ 15 ], poly(vinyl pyrrolidone) (PVP) [ 16 ], poly(acrylonitrile) (PAN) [ 17 ], poly(methyl methacrylate) (PMMA) [ 18 ] and poly(vinyl alcohol) (PVA) [ 19 ]. The salts are the source of charge carriers in GPEs and must have low dissociation energy to avoid ion pairs or aggregation.…”