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This work focuses on the development of a composite polymer electrolyte (CPE) for all‐solid‐state lithium metal batteries (ASSLMBs), integrating LLTO nanofibers into a PEO (polyethylene oxide)‐PVDF‐HFP (poly(vinylidene fluoride‐cohexafluoropropylene)) matrix with LiClO4 as the lithium salt. The PEO has high ionic conductivity and flexibility, and the PVDF‐HFP has high mechanical strength and electrochemical stability. Therefore, the resulting composite has improved electrochemical performance and mechanical properties. Incorporating LLTO nanofibers enhances ionic conductivity due to the one‐dimensional ion transport pathways provided by the nanofibers while maintaining mechanical integrity and air stability, overcoming the challenges associated with conventional fillers. The prepared CPE demonstrates exceptional electrochemical stability up to 5.1 V versus Li/Li+, making it suitable for high‐voltage applications over traditional polymer electrolytes. The optimized CPE with 15 wt% LLTO provides the ionic conductivity of 1.1 × 10−5 S cm−1 at room temperature and reaches 1.46 × 10−4 S cm−1 at 80°C. The assembled LiNi1/3Mn1/3Co1/3PO4||PEO‐PVDF‐HFP‐LiClO₄‐LLTO||Li based 2032 coin cell worked in between 3 and 4.8 V versus Li/Li+ potential window without any electrolyte decomposition from 0.5 to 5 mV/s scan rates. Similarly, the fabricated LiFePO₄||PEO‐PVDF‐HFP (1:2)‐LiClO4‐LLTO (15 wt%)||Li cell provides an initial capacity of 149 mAh g−1 at 0.1 C and 85 mAh g−1 at 0.5 C, exploring its potential for lithium metal batteries. Overall, this work offers a promising pathway for developing advanced solid polymer electrolytes for next‐generation lithium metal batteries, which combine high ionic conductivity, excellent electrochemical performances, and robust mechanical properties. [ABSTRACT FROM AUTHOR]

Supercapacitors based on ionic liquid gel polymer electrolytes (GPEs) have attracted considerable attention as a new energy storage device due to their good specific capacitance, good cycling capacity and stability. In this work, flexible gel polymer electrolyte (GPE) films were prepared and applied using three butyl imidazole ionic liquids with different anions as additives based on polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP). The structure and the mechanical properties of the GPE films and the electrical properties of the assembled symmetrical supercapacitors have been characterized. In particular, the structure–activity relationship between the structure and properties of the gel electrolyte was revealed by combining calculations with experiments. In particular, the structure–activity relationship between the structure and properties of the GPE was revealed through the combination of calculation and experiment. The results show that the electronegativity of the anions plays an important role in improving the stability and electrochemical properties of the gel system. This work is useful to further verify the influence of the anionic component of ionic liquids on the physical and chemical properties of gel electrolytes and to prepare more excellent solid electrolytes for supercapacitors. [ABSTRACT FROM AUTHOR]

Solid polymer electrolyte (SPE) films based on poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF–HFP) with salt and ionic‐liquid (IL) are synthesized using the solution‐cast technique and summarized in this review. Doping ILs or salts increases ionic conductivity up to the device level. This is further confirmed using differential scanning calorimetry (DSC) and X‐ray diffraction (XRD) measurements. Polarized optical microscopy (POM) affirms that enhancement in ionic conductivity is due to increase in amorphous nature of film. The complex nature of polymer electrolyte films is confirmed using Fourier transform infrared (FT‐IR) spectroscopy. Overall results show that doping IL into polyether matrix is advantageous material playing a dominant role in electrochemical devices. [ABSTRACT FROM AUTHOR]

Nanocomposite solid polymer electrolytes (NSPEs) with PVDF‐HFP/Pluronic as blend polymer matrix, graphene oxide (GO) as nanofiller, and LiClO4 are reported. FTIR spectroscopy reveals the crystal phase transformation of PVDF‐HFP from nonpolar α phase to electroactive γ phase upon salt addition that suggests the ion‐dipole interaction between the salt and the matrix. Further, Pluronic not only hinders the PVDF crystallization that increases the amorphous character of the matrix but also interacts with the salt and hence assists in salt dissociation in the blend matrix. The dc conductivity of PVDF‐HFP/Pluronic/LiClO4 blend SPE improves with increasing the Pluronic content reaching 0.73 × 10−6 Scm−1 at room temperature with 60 wt.% Pluronic. The dispersion of GO in the same blend SPE leads to a significant jump in room temperature ion conductivity (≈1.2 × 10−6 Scm−1) with 0.4% GO. Temperature‐dependent ion conductivity of the NSPEs reveals an Arrhenius type thermally activated process. The dc polarization data indicates that the conductivity is predominantly due to ions. Impedance plots exhibit a distorted semicircle at higher frequency and a tilted spike at lower frequency. The spike is an indication of ion diffusion and electrode polarization effect. Further, GO also has enhanced the mechanical properties of the fabricated NSPEs. [ABSTRACT FROM AUTHOR]

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 1.06×10−3 S cm−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. [ABSTRACT FROM AUTHOR]

Benefiting from employing solid composite electrolytes (SCEs), all‐solid‐state lithium‐ion batteries (ASSLBs) are recognized to occupy with high energy density and safety. Herein, a polymer‐based SCE membrane (SCE‐66@67) with core–shell structured metal–organic frameworks (MOFs) (UiO‐66‐NH2@67) as the fillers is presented. The SCE has combined the advantages of the two kinds of MOFs and shows a satisfying ionic conductivity (2.09 × 10−4 S cm−1 at 60 °C) and a wide electrochemical stability window of ≈5.0 V. The full cell (Li/SCE‐66@67/LiFePO4) also maintains a high capacity of 120.9 mAh g−1 at 3 C. This research might help to promote the development of future SCEs for ASSLBs. [ABSTRACT FROM AUTHOR]

Solid polymer electrolytes (SPEs) represent one of the most suitable options to overcome durability and safety issues. Herein, three‐component SPEs based on poly(vinylidene fluoride‐co‐hexafluoropropylene) as a binder, the 1‐butyl‐3‐methylimidazolium thiocyanate ionic liquid as an ionic conductive component, and zeolites, to improve SPE ionic conductivity and electrochemical stability, are prepared and characterized. Different zeolite and zeolite‐like structures (clinoptilolite, ETS‐4, and ETS‐10) are used, and the effect of lithium‐ion exchange in their structures is evaluated. A clear influence of the ion exchange process on the crystallinity of the prepared samples is observed, which plays a key role in the conduction mechanisms. The ionic conductivity of the samples at room temperature is of the order of 10−3 S cm−1, making them suitable for battery applications. The assembled batteries show promising results at room temperature, proving that the ion exchange has a positive effect on battery performance. The ion‐exchanged clinoptilolite sample presents the best performance at a prolonged cycle number, with an initial discharge capacity of about 130 mAh g−1 at C/10, and a capacity retention of 70% after 50 cycles. Thus, it is proved that the ion exchange process in microporous silicates represents a suitable strategy to develop high‐performance solid‐state lithium‐ion batteries (LIBs). [ABSTRACT FROM AUTHOR]

Lithium-ion batteries are popular energy storage devices due to their high energy density. Solid electrolytes appear to be a potential replacement for flammable liquid electrolytes in lithium batteries. This inorganic/hybrid solid electrolyte is a composite of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt, (poly(vinylidene fluoride-hexafluoro propylene) (PVDF-HFP) polymer and sodium superionic conductor (NASICON)-type Li1+xAlxTi2−x(PO4)3 (LATP) ceramic powder. The structure, morphology, mechanical behavior, and electrochemical performance of this composite solid electrolyte, based on various amounts of LiTFSI, were investigated. The lithium-ion transfer and conductivity increased as the LiTFSI lithium salt concentration increased. However, the mechanical strength apparently decreased once the percentage of LITFSI was over 60%. The hybrid electrolyte with 60% LiTFSI content showed high ionic conductivity of 2.14 × 10−4 S cm−1, a wide electrochemical stability window (3–6 V) and good electrochemical stability. The capacity of the Li|60% LiTFSI/PVDF-HFP/LATP| LiFePO4 solid-state lithium-metal battery was 103.8 mA h g−1 at 0.1 C, with a high-capacity retention of 98% after 50 cycles. [ABSTRACT FROM AUTHOR]

[Display omitted] • Developed polymer solid electrolyte membrane using solution casting method. • Achieved high ionic conductivity and strong mechanical properties in BPE membrane. • Demonstrated ultra-stable cycles and high-capacity retention in ASSLMBs. Polymer electrolytes have become widely popular on account of their low expenses, reduced weight, simple processing, and excellent safety features. However, polymer electrolytes have yet to find use in commercial batteries because of their limited mechanical durability and poor ionic conductivity. In this paper, an ultra-stable cycles and interfaces blending polymer electrolyte (BPE) suitable for all solid-state Li metal batteries was prepared by blending three polymers: polymethyl methacrylate (PMMA), polyvinylidene fluoride hexafluoropropylene (PVDF-HFP), and polyethylene oxide (PEO). Microstructure characterization showed numerous amorphous areas with strong interfacial strength of the BPE. The BPE3 exhibited a maximum of 15.65 MPa in tensile strength. BPE2 have excellent electrochemical performance, such as wide electrochemical windows (up to 4.7 V vs Li/Li+), high lithium ion transference numbers (up to 0.75), high ion conductivity (up to 1.87 × 10-4 S cm−1 at 60 °C), and excellent interface stability. By assembling all state-solid LiFePO 4 /BPE2/Li batteries for electrochemical testing, BPE2 exhibit high electrochemical characteristics. BPE2 discharge specific capacity is as high as 154.7 mAh g−1 at 1C. The BPE2 underwent 200 cycles at 0.5C and 400 cycles at 1C, with capacity retention rates of 95.7 % and 96.6 %, respectively. BPE is a promising electrolyte candidate for flexible lithium metal batteries. [ABSTRACT FROM AUTHOR]

Lithium metal batteries (LMBs) show several limitations, such as high flammability and Li dendrite growth. All‐solid‐state LMBs (ASSLMBs) are promising alternatives to conventional liquid electrolyte (LE)‐based LMBs. However, it is challenging to prepare a solid electrolyte with both high ionic conductivity and low electrode–electrolyte interfacial resistance. In this study, to overcome these problems, a solid composite electrolyte (SCE) consisting of Li6.25La3Zr2Al0.25O12 and polyvinylidene fluoride‐co‐hexafluoropropylene is used, which has attracted considerable attention in recent years as a solid‐state electrolyte. To operate LMBs without an LE, optimization of the electrode–solid‐electrolyte interface is crucial. To achieve this, physical and chemical treatments are performed, i.e., direct growth of each layer by drop casting and thermal evaporation, and plasma treatment before the Li evaporation process, respectively. The optimized ASSLMB (amorphous V2O5−x (1 µm)/SCE (30 µm)/Li film (10 µm)) has a high discharge capacity of 136.13 mAh g−1 (at 50 °C and 5 C), which is 90% of that of an LMB with an LE. It also shows good cycling performance (>99%) over 1000 cycles. Thus, the proposed design minimizes the electrode–solid‐electrolyte interfacial resistance, and is expected to be suitable for integration with existing commercial processes. [ABSTRACT FROM AUTHOR]

Although gel polymer electrolytes (GPEs) have attracted tremendous attention for lithium metal batteries due to their high ionic conductivity, high safety, and excellent adaptability, it is still challenging to suppress the uncontrollable lithium dendrite growth for GPEs. Here, an organic/inorganic composite gel electrolyte (PPPL) as GPEs is proposed, which is formed by ring-opening polymerization reaction of poly(methyl vinyl ether-alt-maleic anhydride) (PMVE-MA) and polyethylene glycol (PEG) in polymer matrix of poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) embedded with Li6.4La3Zr1.4Ta0.6O12 (LLZTO) particles. The PMVE-MA participates in the formation of a stable solid electrolyte interface (SEI) and the PEG greatly improves the flexibility of PPPL. The PPPL exhibits excellent performance in terms of a wide electrochemical window (4.7 V), high lithium transference number (0.59), and satisfactory mechanical strength (11 MPa). Besides, the PPPL contributes to the formation of stable and flexible SEI containing organic components and LiF on lithium metal, and constructs fast and uniform lithium transport channels to effectively suppress the lithium dendrite growth. The Li/PPPL/Li symmetric batteries can stably cycle 800 h at the high current density of 5 mA cm-2 and capacity of 5 mAh cm-2. The outstanding electrochemical performance of the PPPL will provide important insights for design of advanced GPEs. [ABSTRACT FROM AUTHOR]

Lithium (Li) metal has been considered as a potential substitute for the graphite anode in Li-ion batteries to further boost their energy density. Polymer electrolytes (PEs) are expected to be applied in Li metal batteries (LMB) to replace liquid electrolytes due to safety concerns. Among others, poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)-based electrolytes offer clear advantages such as improved processability and chemical/electrochemical stability. However, Li dendrite growth in LMBs and the low Li-ion conductivity of solid polymer electrolytes (SPEs) still hinder their practical applications. To address this issue, it has been proposed that solvent-enhanced PVDF-HFP-based polymer electrolytes (SPPEs) with a tuned amount of residual N-methyl-2-pyrrolidone (NMP) could provide improved ionic conductivity and outstanding chemical/electrochemical stability. We report herein the effects of different salts, polymer, and additives on the electrochemical performance and interface stability of SPPEs. We demonstrate that lithium salts and blended polymers play a pivotal role in the electrochemical performance of SPPEs. In addition, additives exert a remarkable effect on the stripping/plating behaviors of metallic lithium anode in SPPEs. SPPEs with adequate LiNO3 are found to be stable with lower overpotentials at 0.5 mA cm−2 on cycling of symmetrical Li cells. These results highlight novel SPPE strategies for optimizing the ionic conductivity and stabilizing the lithium metal anodes. [ABSTRACT FROM AUTHOR]

Summary: Lithium (Li) metal anodes can be inevitably corroded and destructed due to the direct contact with the liquid electrolyte. Here, a precast solid electrolyte interface (SEI) film is constructed based on poly(vinylidene‐co‐hexafluoropropylene) (PVDF‐HFP) matrix on a copper current collector to avoid side reactions between Li and electrolytes and further prevent dendrites growth. Lithium bis(oxalato)borate (LiBOB), SiC, and polyethylene oxide (PEO) are rationally hybridized, and their effects on the morphology, composition, strength, and other properties of the precast SEI film are studied through both physical and electrochemical characterizations. Due to the addition of LiBOB, SiC, and PEO, the structure and properties of the PVDF–HFP matrix have undergone a distinct change, which affects the cycle stability of the substrate. As a result, the cycling lifetime of the SEI film is increased from 61 to 295 cycles after adding an appropriate amount of LiBOB to the PVDF–HFP. Furthermore, the Li metal anode delivers a significantly improved life‐span of 452 cycles at 1.0 mA·cm−2, 1.0 mAh·cm−2 by virtue of the robust SEI with SiC and PEO added. Meantime, the Coulombic efficiency of the cell has also increased from 95.0% to more than 99.0%. The morphology and composition characterization results show that the SEI structure gradually collapses during cycling, which are found to arise from the formation of loosely connected Li2CO3, LiF, and dilapidated PVDF–HFP mixture. The deteriorative artificial SEI also induces the disconnected electrical contact, and as such the impedance significantly increases, resulting in eventual failure of the Li metal anode. [ABSTRACT FROM AUTHOR]

The dendrite growth of Li anodes severely degrades the performance of lithium-oxygen (Li-O2) batteries. Recently, hybrid solid electrolyte (HSE) has been regarded as one of the most promising routes to tackle this problem. However, before this is realized, the HSE needs to simultaneously satisfy contradictory requirements of high modulus and even, flexible contact with Li anode, while ensuring uniform Li+ distribution. To tackle this complex dilemma, here, an HSE with rigid Li1.5Al0.5Ge1.5(PO4)3 (LAGP) core@ultrathin flexible poly (vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) shell interface has been developed. The introduced large amount of nanometer-sized LAGP cores can not only act as structural enhancer to achieve high Young's modulus but can also construct Li+ diffusion network to homogenize Li+ distribution. The ultrathin flexible PVDF-HFP shell provides soft and stable contact between the rigid core and Li metal without affecting the Li+ distribution, meanwhile suppressing the reduction of LAGP induced by direct contact with Li metal. Thanks to these advantages, this ingenious HSE with ultra-high Young's modulus of 25 GPa endows dendrite-free Li deposition even at a deposition capacity of 23.6 mAh. Moreover, with the successful inhibition of Li dendrites, the HSE-based quasi-solid-state Li-O2 battery delivers a long cycling stability of 146 cycles, which is more than three times that of gel polymer electrolyte-based Li-O2 battery. This new insight may serve as a starting point for further designing of HSE in Li-O2 batteries, and can also be extended to various battery systems such as sodium-oxygen batteries. [ABSTRACT FROM AUTHOR]

Polyethylene oxide (PEO)-based electrolytes are considered to be promising for all-solid-state battery, benefiting from the superior flexibility, excellent processability and well compatibility. However, the low ionic conductivity at room temperature and poor stability under high voltage limit their further application. Herein, ZIF-8@PVDF-HFP/PEO (PPZ) solid electrolyte was successfully prepared by facial electrospinning process. On one side, the cooperation of PVDF-HFP and ZIF-8 was benefit to decrease the crystallization degree of PEO and thus promoted the Li+ transfer. Moreover, the in-situ formed LiF layer derived from the decomposition of PVDF-HFP protected the electrolyte from contacting directly with the electrode, contributing to a stable electrode/electrolyte interface. The results demonstrated that the electrochemical stability and mechanical property of PPZ electrolyte were significantly improved when compared to the bare PEO electrolyte. The tensile strength increased from 0.5 to 6.7 MPa and the Li+ transference number enlarged from 0.17 to 0.48. More importantly, the assembled LCO(LiCoO 2)||PPZ||Li all-solid-state battery delivered a discharge specific capacity of 144.7 mAh g-1 at 0.2 C, nearly 1.6 times than that of the LCO||PEO||Li (90.7 mAh g-1). Besides that, the retention maintained at 86.3 % even after 200 cycles, manifesting a long-term cycling stability. This work provides a new idea for the practical application of PEO under high voltage. [ABSTRACT FROM AUTHOR]

Solid-state batteries (SSBs) are regarded as favorable future technology as they promise to deliver high energy density and improved safety. However, despite extensive research efforts, the development of SSBs still fall short of expectations mainly because of suitable solid electrolyte which can provide high ionic conductivity as well as good flexibility to enhance interface contact between electrolyte and electrodes. In this work, we have prepared free-standing, flexible composite solid polymer electrolyte (CSPE) membranes by incorporating LLZTO ceramic particles in PVDF-HFP/LiTFSI based solid polymer electrolyte (SPE). Addition of 20 wt% LLZTO has shown to improve the electrochemical properties of the solid electrolyte such as ionic conductivity (8.2 × 10−4 S cm−1 at 60 °C), transference number, electrochemical stability and long-term interface stability with the lithium-metal also showed significant improvement. Furthermore, solid-state LiFePO 4 /SPE/Li and LiFePO 4 /CSPE/Li batteries were fabricated, and charge/discharge cycling was performed, where battery with SPE and CSPE exhibited discharge capacity of 119 mA h g−1 and 131 mA h g−1 respectively at 0.1C rate, 60 °C. [Display omitted] • Composite solid polymer electrolytes (CSPEs) based on LLZTO incorporated in PVDF-HFP/LiTFSI solid polymer electrolyte. • Addition of LLZTO increases the ionic conductivity of the solid electrolyte reaching up to 8.2 × 10−4 S cm−1 at 60 °C. • LiFePO 4 /CSPE/Li battery delivers discharge capacity of 131 mAh.g−1 at 0.1C, 60 °C. • Enhanced interface stability between solid electrolyte and lithium metal anode is achieved by incorporating LLZTO. [ABSTRACT FROM AUTHOR]

Polymer electrolytes possess good flexibility and processability, and have wide application prospects in the field of battery. However, polymer electrolytes have the disadvantages of low ionic conductivity, narrow electrochemical window and poor mechanical properties. Herein, we designed a PVDF-HFP based composite electrolyte filled with lithium magnesium silicate. The addition of lithium magnesium silicate can disrupt the ordered arrangement of polymer chain segments, promote the dissociation of lithium salts, increase the content of [NMP-Li+], reduce the gap on the surface of PVDF-HFP electrolyte membrane, inhibit the migration of anions and improve the electrochemical stability of the electrolyte membrane. To improve the mechanical properties of the electrolyte membrane, polyethylene membrane with excellent mechanical property was added into the electrolyte membrane. The modified PVDF-HFP based polymer composite electrolyte membrane has high ionic conductivity (2.56 × 10−4 S·cm−1) under room temperature and high lithium ion migration number (0.41). Due to its good lithium ion transmission ability, the oxidation potential (4.8 V) and the ability to restrain lithium dendrite growth of the modified PVDF-HFP based composite electrolyte have been effectively boosted. The whole battery assembled with this electrolyte membrane and NCM622 can stably cycle for 50 cycles at 0.5 C (capacity retention rate is 89.6%). [Display omitted] • Lithium magnesium silicate is introduced into solid electrolyte to boost its properties. • Lithium magnesium silicate contributes to the formation of [NMP-Li+]. • Lithium magnesium silicate contributes to the dissociation of more LiTFSI. • The NCM622/PSSE2/Li battery delivers good electrochemical performance. [ABSTRACT FROM AUTHOR]

Solid polymer electrolytes (SPEs) are the necessary step towards solid-state lithium-ion batteries (LIBs). Their function as separator and electrolyte allows to increase the safety of energy storage devices by the elimination of the liquid components. In this work, three-component SPEs based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) as host polymer, clinoptilolite zeolite, and different ionic liquids (ILs) (1-ethyl-3-methylimidazolium thiocyanate ([EMIM][SCN]), 1-butyl-3-methylimidazolium thiocyanate ([BMIM][SCN]), 1-ethyl-3-methylimidazolium dicyanamide ([EMIM][NCN 2 ]) and 1-butyl-3-methylimidazolium dicyanamide ([BMIM][NCN 2 ]) were produced and characterized. The influence of the nature of the IL anion and cation on the morphology, degree of crystallinity, mechanical properties, ionic conductivity, and battery cycling performance were studied. It is demonstrated that the [SCN]- anion is the most suitable if SPE applications are envisaged. The ionic conductivity depends on the IL type. At room temperature, a maximum value of 1.3 × 10−5 S cm−1 was obtained for the SPE doped with [BMIM][NCN 2 ]. Regarding battery performance, the best value of discharge capacity was observed for the SPE based on [BMIM][SCN], which for an initial discharge capacity of 135 mAh.g−1 yielded a capacity loss below 30% after 30 cycles at room temperature. Thus, it is concluded that proper selection of the IL (cation chain length and anion size) allows tailoring battery performance of solid-state batteries based on three-component SPEs. [Display omitted] • Solid polymer electrolytes (SPE) based on PVDF-HFP with clinoptilolite and different ionic liquids have been prepared. • The influence of the different anions and cations of the IL in the SPE properties is demonstrated. • The ionic conductivity and battery behavior of the SPE depends on the anion and cation type. • The best ionic conductivity value of 1.3 × 10−5 S cm−1 has been obtained for the SPE with [BMIM][NCN 2 ]. • Excellent performance at room temperature (135 mAh.g−1) is achieved for the SPE based on [BMIM][SCN]. [ABSTRACT FROM AUTHOR]

Solid electrolytes for Li transport have been prepared by melt-compounding in one single step. Electrolytes are composed of polyvinylidene fluoride–hexafluoropropylene (PVDF–HFP) with PYR13TFSI on its own or with varying concentration of LiTFSI. While the extrusion of PVDF–HFP with PYR13TFSI is possible up to relatively high liquid fractions, the compatibility of PVDF–HFP with LiTFSI/PYR13TFSI solutions is much lower. An organo-modified sepiolite with D-α-tocopherol polyethylene glycol 1000 succinate (TPGS-S) can be used to enhance the compatibility of these blends and allows to prepare homogeneous PYR13TFSI/LiTFSI/PVDF–HFP electrolytes with controlled microphase separations by melt-compounding. The structure and morphology of the electrolytes has been studied by FTIR, differential scanning calorimetry (DSC), SEM, and AFM. Their mechanical properties have been studied by classical strain–stress experiments. Finally, ionic conductivity has been studied in the −50 to 90 °C temperature range and in diffusivity at 25 °C by PFG-NMR. These electrolytes prove to have a microphase-separated morphology and ionic conductivity which depends mainly on their composition, and a mechanical behavior typical of common thermoplastic polymers, which makes them very easy to handle. Then, in this solvent-free and scalable fashion, it is possible to prepare electrolytes like those prepared by solvent casting, but in few minutes instead of several hours or days, without solvent evaporation steps, and with ionic conductivities, which are very similar for the same compositions, above 0.1 mS·cm−1 at 25 °C. In addition, some of the electrolytes have been prepared with high concentration of Li ion, what has allowed the anion exchange Li transport mechanism to contribute significantly to the overall Li diffusivity, making DLi become similar and even clearly greater than DTFSI.

[Display omitted] • The SEI with rich organic and inorganic components exhibits high Li+ conductivity and mechanical strength. • The organic-inorganic interlayer prevents the serious reaction between Li metal and PVDF-HFP which maintains as the compact coating layer. • The organic-inorganic interlayer favor the stable Li+ plating/stripping in long-term. • The PVDF-HFP assisted by organic-inorganic interlayer enable high performance of Li-oxygen battery. PVDF-HFP layer has been used in lithium (Li) metal-based batteries for its high Li-ion conductivity, excellent mechanical strength and water-proof property. Moreover, the layer reacts with Li metal and improves the performance of solid electrolyte interphase (SEI) by introducing the additional component of LiF. Herein, we further allow an organic molecular (11-mercaptoundecanoic acid, MUA) to involve in the reaction between the PVDF-HFP layer and Li metal, which results in an organic–inorganic SEI interlayer consisting of Li 2 S, LiF, lithium alkyl carbonate (RCOOLi), and MUA-Li etc. This interlayer shows the high Li+ transfer number (0.62) and Young's modulus (6.17 GPa), which also serves to increase the adhesion between PVDF-HFP and Li metal. By using the organic–inorganic interlayer enhanced PVDF-HFP coated Li metal, the Li/Li symmetric cells can run for at least 2190 h steadily, and the Li-oxygen batteries can operate for 214 cycles, demonstrating the improved protection and ionic conductivity of Li metal anodes. [ABSTRACT FROM AUTHOR]

Solid polymer electrolyte (SPE) is routinely regarded as core component to tackle the potential safety hazards and energy density of conventional lithium-ion batteries. However, it is still beset by low ionic conductivity and poor interface compatibility. Currently, the utilization of SPEs to replace flammable and leaky liquid electrolytes is regarded as a powerful method to promote battery security. However, it is still an arduous task to develop a SPE with a wider electrochemical window and higher ionic conductivity. Herein, graphitic carbon nitride (g-C 3 N 4) nanosheets were prepared by thermal oxidative exfoliation and introduced into PVDF-HFP based SPEs to prepare solid composite electrolyte for the first time. The introduction of g-C 3 N 4 nanosheets effectively disrupts the orderly arrangement of polymer segments in the SPE, thereby diminishing the crystallinity of the solid electrolyte. The results prove that the presence of g-C 3 N 4 nanosheets efficiently reduces the bulk impedance of the solid electrolyte membrane, enhance the ionic conductivity and ion transport number, and boost the oxidation potential and stability of the electrolyte membrane to the lithium anode. The ionic conductivity of SPE with 15 wt% g-C 3 N 4 nanosheets is 1.67 × 10−4 S·cm−1 at 25 °C, and its oxidation potential reaches 4.7 V. The NCM622/PCSE3/Li battery delivered a specific discharge capacity of 122.8 mAh·g−1 after 100 cycles at 0.5 C. [Display omitted] [ABSTRACT FROM AUTHOR]

• A three-component solid composite electrolyte is designed. • PVDF-HFP is difficult to be oxidized by high-voltage cathodes. • The controlled degradation of PPC can wet and stabilize the interface. • The NCM622/SCE/Li battery delivers good electrochemical performance Substituting flammable and leaky liquid electrolytes with advanced solid composite electrolytes considered as one of the most hopeful strategy to develop solid-state lithium metal batteries with high security and high energy density. However, it is still an arduous task to develop a solid electrolyte with high ionic conductivity and wide electrochemical window. To this end, we designed three-component solid poly(vinylidene fluoride- co -hexafluoropropylene) (PVDF-HFP)/poly(propylene carbonate) (PPC)/Li 0.33 La 0.557 TiO 3 (LLTO) nanorods composite electrolyte. Oxidation-resistant PVDF-HFP can stabilize the cathode of lithium metal batteries and widen the electrochemical window. The controlled degradation of PPC can wet and stabilize the interface between the electrolyte and the lithium metal anode to a certain extent. The introduction of LLTO nanorods not only decreases the crystallinity of the composite solid electrolyte, but also provides an additional path for the transmission of lithium ions, and improves the ionic conductivity of the electrolyte membrane (2.18×10−4 S·cm−1 at room temperature). The Li/PPLSE3/Li symmetric cell assembled with this electrolyte has a long cycling life of 2000 h at a current density of 0.1 mA·cm−2 at room temperature. The assembled NCM622/PPLSE3/Li full battery has a specific discharge capacity of 142 mAh·g−1 and a capacity retention rate of 84.6% after 100 cycles at room temperature. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • PVB additives were firstly introduced to the solid composite electrolytes (SCEs). • The SCE has a high lithium-ion transference number (t+ =0.72). • At 3C, a capacity of around 100 mAh g−1 was also achieved. All solid-state lithium-ion batteries (ASSLBs) are thought to benefit from using solid composite electrolytes (SCEs) to increase their energy density and safety. In this study, we firstly introduce the PVB additives to SCEs and prepared a SCE composed of a mixture of nanostructured MOFs (UiO-67), PVDF-HFP, PVB, and LiTFSI. Electrochemical characterizations of the SCEs (EIS, LSV, CV and battery test) were also conducted. The SCE UBP-2 (PVB:PVDF-HFP = 1:10) shows a high lithium-ion transference number (t Li + =0.72) and good ionic conductivity (3.27×10−4 S cm−1 at 60 °C). A symmetric Li cell with SCE UBP-2 can be continuously cycled at 0.1 mA cm−2 for more than 2500 h without experiencing a short circuit. The full cell (LiFePO 4 /UBP-2/Li) also maintained a high reversible discharge capacity of 154.9 mAh g−1 at 0.1C after 200 cycles at 60 °C. At 3C, a capacity of around 100 mAh g−1 was also achieved. This work might help to enhance the development of the forthcoming all solid-state batteries. [ABSTRACT FROM AUTHOR]

Solid-state batteries (SSBs) are gaining attention as they promise to provide better safety and a higher energy density than conventional liquid electrolyte batteries. Solid polymer electrolytes (SPEs) are promising candidates due to their flexibility providing better interfacial contact between electrodes and the electrolyte. However, SPEs exhibit very low ionic conductivity at ambient temperatures, which prevents their practical use in batteries. Herein, a simple and effective technique of hot press rolling is demonstrated to improve ionic conductivity and, hence, the performance of polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP)-based solid polymer electrolyte. Applying hot press rolling to the electrolyte membrane induced structural changes in the grain boundaries, which resulted in a reduction in the crystallinity of the material and, hence, an increase in the amorphous phase of the material, which eased the movement of the lithium ions within the material. This technique also improved the surface of the membrane, making it homogeneous and smoother, which resulted in better interfacial contact between the electrodes and electrolyte. Electrochemical tests were carried out on electrolyte membranes treated with and without hot press rolling to evaluate the effect of the treatment. The hot pressed electrolyte membrane showed significant improvements in its ionic conductivity and transference number. The cycling performance of the LFP/Li batteries using a hot press rolled electrolyte was also evaluated, which gave a specific discharge capacity of 134 mAh/g at 0.1 C. These results demonstrate that hot press rolling can have a significant effect on the electrochemical performance of solid polymer electrolytes. [ABSTRACT FROM AUTHOR]

Solid polymer electrolytes are potential replacement of liquid electrolytes due to their much less flammability and leakage. Among them, poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)-based electrolytes have several advantages including improved processability and electrochemical stability. Unfortunately, poor ionic conductivity and mechanical properties due to high plasticizer concentration hinder their practical applications. Herein, we address these issues by exploiting the solvation effect in the electrolyte through tuning the amount of residual N-methyl-2-pyrrolidone (NMP) and lithium salts. Moreover, by blending with porous carbon (PC) the mechanical integrity of the PVDF-HFP electrolytes is substantially enhanced due to improved interfacial bonding and specific surface area. The appropriate value of electrical conductivity and highly porous morphology of PC also meet the ionic transport and electronic insulation requirements. With the absorbed residual NMP as plasticizer and complexed with Li ions to form L i [ N M P ] 3 + , ionic conductivity and amorphicity are improved. By elucidating the solvent and salt concentration interplay, Li-ion conductivity of up to 0.56 mS cm−1, wide electrochemical window of 5 V versus Li/Li+ and 1000 h of cycling stability (versus Li, 0.2 mA/cm2) are obtained. These findings afford a novel electrolyte design guideline for enhancing interfacial compatibility and cycling through hybridization and ion solvation to develop practical lithium batteries. [Display omitted] • Solvation and plasticizer effect of NMP improve electrochemical performance. • Better performance is achieved due to the synergistic effect with porous carbon. • Composite polymer electrolyte with high ionic conductivity of 0.56 mS cm−1 at RT. • Symmetric lithium system shows good cycling stability and long life (over 1000 h). • Transfer number measured accurately via regulating the interfacial impedance. [ABSTRACT FROM AUTHOR]

Gel polymer electrolytes have the advantages of both a solid electrolyte and a liquid electrolyte. As a transitional product before which a solid electrolyte can be comprehensively used, gel polymer electrolytes are of great research value. They can reduce the risk of spontaneous combustion and explosion caused by leakage during the use of conventional liquid electrolytes. Poly(vinylidene-fluoride-co-hexafluoropropylene) (PVDF–HFP), a material with excellent performance, has been widely utilized in the preparation of gel polymer electrolytes. Here, PVDF–HFP-based gel polymer membranes with polyvinyl pyrrolidone (PVP) pores were prepared using a phase inversion method, and Octavinyl-polyhedral oligomeric silsesquioxane (OVAPOSS) was doped to improve its temperature resistance as well as its ionic conductivity, to enhance its safety and electrochemical performance. The final prepared polymer membrane had a porosity of 85.06% and still had a certain mechanical strength at 160 °C without any shrinkage. The gel polymer electrolyte prepared with this polymer membrane had an ionic conductivity of 1.62 × 10−3 S·cm−1 at 30 °C, as well as an electrochemical window of about 5.5 V. The LiCoO2-Li button half-cell prepared therefrom had a specific capacity of 141 mAh·g−1 at a rate of 1C. The coulombic efficiency remained above 99% within 100 cycles and the capacity retention rate reached 99.5%, which reveals an excellent cycling stability. [ABSTRACT FROM AUTHOR]

Sulfide-based composite solid-state electrolyte has been deemed as "Holy Grail" for unlocking solid-state lithium metal batteries (SSLMBs) with high-energy density, combining the extremely high ionic conductivity of sulfide and machinability of organic polymer. However, this appealing system is hitherto stymied by two hindrances, difficult to synthesize due to the chemical incompatibility of sulfide with moisture and polar solvents, moreover, interfacial instability with lithium (Li) anode inducing severe Li dendrite grown. Herein, by utilizing perfluoropolyethers as bifunctional adjuvant, we initiatively fabricate sulfide-based composite electrolyte, Poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)/Li 10 GeP 2 S 12 and assemble SSLMBs. Perfluoropolyethers with low molecular weight facilitate the stable dispersion of Li 10 GeP 2 S 12 in casting solution, ascribed to their strong electronegativity of C–F bonds. In addition, high molecular weight perfluoropolyethers function as interfacial stabilizer, dramatically improving the interfacial compatibility with Li anode by in-situ forming a LiF-rich solid electrolyte interphase layer. This composite electrolyte exhibits high room temperature ionic conductivity (0.18 mS cm−1), outstanding lithium ion transfer number (0.68), good mechanical strength and nonflammability. The solid-state LiFePO 4 ǁLi battery presents superior long-term cycling stability and rate capability. Our study paves a new way for fabricating the sulfide-based composite electrolyte, provides an effective strategy for constructing compatible solid-state electrolyteǁLi interface. Image 1 • PVDF-HFP/Li 10 GeP 2 S 12 electrolyte is prepared by binary solution casting method. • PFPE 500 as dispersing solvents exhibit good chemical compatibility with Li 10 GeP 2 S 12. • A high ion conductivity (σ RT = 10−4 S cm−1) and Li+ transfer number (0.68) are obtained. • PFPEs as interfacial stabilizers enhance the compatibility of Li 10 GeP 2 S 12 with Li. • LiFePO 4 ‖Li battery shows good cycling stability and rate capability. [ABSTRACT FROM AUTHOR]

Solid electrolytes for Li transport have been prepared by melt-compounding in one single step. Electrolytes are composed of polyvinylidene fluoride–hexafluoropropylene (PVDF–HFP) with PYR13TFSI on its own or with varying concentration of LiTFSI. While the extrusion of PVDF–HFP with PYR13TFSI is possible up to relatively high liquid fractions, the compatibility of PVDF–HFP with LiTFSI/PYR13TFSI solutions is much lower. An organo-modified sepiolite with D-α-tocopherol polyethylene glycol 1000 succinate (TPGS-S) can be used to enhance the compatibility of these blends and allows to prepare homogeneous PYR13TFSI/LiTFSI/PVDF–HFP electrolytes with controlled microphase separations by melt-compounding. The structure and morphology of the electrolytes has been studied by FTIR, differential scanning calorimetry (DSC), SEM, and AFM. Their mechanical properties have been studied by classical strain–stress experiments. Finally, ionic conductivity has been studied in the −50 to 90 °C temperature range and in diffusivity at 25 °C by PFG-NMR. These electrolytes prove to have a microphase-separated morphology and ionic conductivity which depends mainly on their composition, and a mechanical behavior typical of common thermoplastic polymers, which makes them very easy to handle. Then, in this solvent-free and scalable fashion, it is possible to prepare electrolytes like those prepared by solvent casting, but in few minutes instead of several hours or days, without solvent evaporation steps, and with ionic conductivities, which are very similar for the same compositions, above 0.1 mS·cm−1 at 25 °C. In addition, some of the electrolytes have been prepared with high concentration of Li ion, what has allowed the anion exchange Li transport mechanism to contribute significantly to the overall Li diffusivity, making DLi become similar and even clearly greater than DTFSI. [ABSTRACT FROM AUTHOR]