Quasi-Solid Polymer Electrolyte with Multiple Lithium-Ion Transport Pathways by In Situ Thermal-Initiating Polymerization

Abstract

Solid polymer electrolytes (SPEs) are considered to be attractive candidates for rechargeable batteries on account of their high safety and flexible processability. However, the restricted polymer segmental dynamics limit the Li+ conduction of SPEs. Herein, a composite electrolyte membrane was prepared via in situ thermal-initiating polymerization of diethylene glycol diacrylate (DEGDA) in a poly(vinylidene fluoride) frameworks (PVDF FMs) electrospun in advance. As a quasi-solid polymer electrolyte (QSPE), it provides multiple transport highways for Li+ built by the CO or C–O or CO/C–O groups in poly(diethylene glycol) diacrylate (PDEGDA), respectively, proved by density functional theory calculations together with the high-resolution 7Li solid-state nuclear magnetic resonance spectra. Since the interaction between Li+ and CO is weaker than that between Li+ and C–O, Li+ tends to move along CO dominating paths in PDEGDA/PVDF FMs QSPEs, even skipping back to CO nodes from the original C–O dominating way. Multiple transport patterns facilitate Li+ migration within PDEGDA/PVDF FMs QSPEs, contributing to the ionic conductivity of 1.41 × 10–4 S cm–1 at 25 °C and the Li+ transference number of 0.454. Ascribing to the wetting capability of the monomer to the electrodes in use, compatible electrolyte/electrode interfaces with low interface resistance and compact cells were acquired by the in situ polymerization. Protective lithiated oligomers (RCOOLi) and LiF are enriched at the Li anode surface, promoting a lasting stable Li plating/stripping over 2000 h. By applying the QSPEs in LiFePO4 cell, a capacity of 157.7 mAh g–1 with almost 100% coulombic efficiency during 200 cycles is achieved at 25 °C.

Coupling Anion‐Capturer with Polymer Chains in Fireproof Gel Polymer Electrolyte Enables Dendrite‐Free Sodium Metal Batteries

“…Scanning electron microscope (SEM) image and transmission electron microscope (TEM) image in Figure S1 (Supporting Information) and Figure a shows that the morphology of M‐BNNs maintains excellent lamellar structure without agglomeration after modifying with MPS. Furthermore, atomic force microscope (AFM) image displays that the thickness of M‐BNNs is ≈5 nm (Figure S2, Supporting Information), [ 43 ] implying good exfoliation of bulk BN during ultrasonic‐assisted hydrolysis reaction process. To demonstrate the successful functionalization of M‐BNNs, Fourier transform infrared (FTIR) spectroscopy was conducted to investigate the changes in functional groups.…”

Fiber-reinforced quasi-solid polymer electrolytes enabling stable Li-metal batteries

“…It can be seen that the current Li/LFP full cell exhibits stable cycling performance with a capacity retention of 91% over 900 cycles, superior than the cell in previous reports. [53][54][55][56][57][58][59][60][61][62] Moreover, the symmetric cell with such a fiber-reinforced quasi-solid polymer electrolyte can also be stably cycling over 1800 h at 0.1 mA cm À2 .…”

LLZTO Nanoparticle- and Cellulose Mesh-Coreinforced Flexible Composite Electrolyte for Stable Li Metal Batteries

“…Recently, an in situ method that directly converts liquid precursor solution to solid-state phase has gradually come into view and is considered a desirable way to overcome these obstacles mentioned above. 31,32 Second, although many efforts have been made, their ionic conductivity and transference number are still not satisfactory, which greatly limits the charge/discharge performance of batteries at high current density. Inspired by gel polymer electrolytes, introducing highly ion-conductive liquid components can enhance ionic conductivity greatly.…”

“…Therefore, an environmentally friendly and efficient method is urgently needed. Recently, an in situ method that directly converts liquid precursor solution to solid-state phase has gradually come into view and is considered a desirable way to overcome these obstacles mentioned above. , Second, although many efforts have been made, their ionic conductivity and transference number are still not satisfactory, which greatly limits the charge/discharge performance of batteries at high current density. Inspired by gel polymer electrolytes, introducing highly ion-conductive liquid components can enhance ionic conductivity greatly. , But the incorporated liquid would further degrade the mechanical properties of polymer electrolytes. , It is well proved that the introduced inorganic particles are able to compensate for the sacrificed mechanical properties and simultaneously improve the Li + transference number by Lewis acid–base interactions between ceramics and mobile anions. − …”