Solid Polymer Electrolyte Films Research Articles

High-performance solid-state Li-ion batteries enabled by homogeneous, large-area ferroelectric PVDF-TrFE solid polymer electrolytes via horizontal centrifugal casting method

Solid polymer electrolytes (SPEs) have emerged as promising alternatives for enhancing the safety features of lithium-ion batteries (LIBs) while remaining compatible with established LIB manufacturing processes. However, a persistent challenge has been the relatively limited yield achieved via traditional fabrication techniques such as solution casting and doctor blade methods. In this study, we present a novel strategy to produce extensive and uniform films of solid polymer electrolytes using a ferroelectric polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) polymer. This approach employs horizontal centrifugal casting (HCC), a technique hitherto unutilized for SPE production. The substantial centrifugal forces generated during the HCC process yield SPE films characterized by uniform thickness across the surface and elevated ionic conductivity at ambient temperature. Compared to conventional solution casting techniques, the Li//Li cell featuring the SPE derived from HCC manifests stable electrochemical performance and increased cycle endurance. Additionally, a full cell incorporating a Li iron phosphate cathode displays consistent electrochemical behavior at room temperature. Notably, a 3 × 4 cm2 pouch cell maintains its performance attributes even under mechanical stress conditions such as folding and punching. These findings underscore the potential effectiveness of employing the HCC method in the development of high-performance SPE-based LIB systems.

To Study the Effect of Nanoparticle TiO2 on Sodium (Na+) – Ion Conducting Solid Polymer Electrolyte System: [80PEO:20NaPF6

AbstractTo study the effect of nanofiller particle TiO2 on sodium (Na+) – ion conducting solid polymer electrolyte (SPE) film: [80PEO:20NaPF6] and nanocomposite polymer electrolyte (NCPE): [80PEO:20NaPF6] + xTiO2, where x = 1–9 wt. (%) have been prepared. SPE film composition: [80PEO:20NaPF6] selects as Ist‐phase host and nano‐sized (<100 nm) filler materials TiO2 as IInd‐phase dispersoid. Both SPE and NCPE films have been prepared by the hot‐press technique. Filler particle‐dependent conductivity study reveals the NCPE system: [80PEO:20NaPF6] + 8TiO2 as the highest conducting composition with σrt − 3.53 × 10−6 S cm−1, which is approximately one order of magnitude higher than the SPE optimum conducting composition (OCC) (σrt) ≈ 7.78 × 10−7 S cm−1. Ion transport properties for both SPE and NCPE system have been evaluated in terms of ionic conductivity (σ) and total ionic (tion)/cationic (t+) transference numbers using combined AC/DC techniques in order to evaluate its usefulness in all‐solid‐state battery applications. Structural/thermal properties have been characterized using X‐ray diffraction (XRD) and differential scanning calorimetry (DSC) techniques. A cyclic voltammetry (CV) study has been performed in SPE and NCPE OCC film to evaluate the electrochemical performance for battery application.

Poly(Vinylidene Fluoride‐CO‐Hexafluoropropylene) (PVDF‐HFP) Incorporated Acetylene Black: Electrical, Optical, and Structural Studies

AbstractThe primary goal of this study is to synthesize a high‐conducting polymer electrolyte film. The PVDF‐HFP and NaSCN film are prepared which showed the highest conductivity at 30 wt% dopant of NaSCN in the Polymer PVDF‐HFP which is 1.24× 10−4 S cm−1. Therefore, here the base polymer is taken as PVDF‐HFP and NaSCN (30 wt%) and further Acetylene Black is added to check the variation in the conductivity of the polymer film. Solution casting technique is used to create solid polymer electrolyte films using poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) with salt sodium thiocyanate and Acetylene Black. Polarized optical microscopy (POM) is used to evaluate the morphology of the polymer film surface. Fourier transform infrared spectroscopy (FTIR) to check the presence of functional group is used, impedance spectroscopy is used for the measurement of the conductivity of the sample, linear sweep voltammetry for finding electrical stability window, and transference number measurements for concentration of charge carriers are done for the electrical studies of polymeric films. The 1 wt% Acetylene Black doped polymer electrolyte film is found to have the maximum ionic conductivity, which is 1.95 × 10−3 S cm−1. The solid polymer electrolyte film has an electrochemical stability window (ESW) of 4.8 V and tion value of 0.83.

Xylose- and Nucleoside-Based Polymers via Thiol-ene Polymerization toward Sugar-Derived Solid Polymer Electrolytes.

A series of copolymers have been prepared via thiol-ene polymerization of bioderived α,ω-unsaturated diene monomers with dithiols toward application as solid polymer electrolytes (SPEs) for Li+-ion conduction. Amorphous polyesters and polyethers with low Tg's (-31 to -11 °C) were first prepared from xylose-based monomers (with varying lengths of fatty acid moiety) and 2,2'-(ethylenedioxy)diethanethiol (EDT). Cross-linking by incorporation of a trifunctional monomer also produced a series of SPEs with ionic conductivities up to 2.2 × 10-5 S cm-1 at 60 °C and electrochemical stability up to 5.08 V, a significant improvement over previous xylose-derived materials. Furthermore, a series of copolymers bearing nucleoside moieties were prepared to exploit the complementary base-pairing interaction of nucleobases. Flexible, transparent, and reprocessable SPE films were thus prepared with improved ionic conductivity (up to 1.5 × 10-4 S cm-1 at 60 °C), hydrolytic degradability, and potential self-healing capabilities.

The Effect of Sodium Acetate on Biodegradable Rice Starch-Based Solid Polymer Electrolyte for Supercapacitor

This study examined the use of sodium acetate salt as an ionic dopant in biodegradable solid polymer electrolyte (SPE). In the solution casting method for making polymer electrolyte, rice starch is used as the host polymer and glycerol is used as the plasticizer. The characteristics of SPE film were investigated using X-Ray Diffraction (XRD), Fourier Transform Infrared (FT-IR), and Thermogravimetric Analysis (TGA). Salt enhances the amorphous structure by decreasing the crystallinity of the polymer. Alternatively, it decreases the temperature of thermal breakdown. In addition, the biodegradability of SPE was investigated using the soil burial method. Electrochemical Impedance Spectroscopy (EIS) was used to evaluate the ionic conductivity behavior and temperature dependent of SPE. The 35% sodium acetate salt addition makes the supercapacitor's electrolyte have the highest ionic conductivity at room temperature, which is 5.57x10-4 S/cm.

MXene nanofiller doped ion conducting polyethylene oxide for electrochemical devices

AbstractNanofiller‐doped polymer electrolyte‐based electrochemical devices are now emerged as a novel material for electrochemical devices. This paper reports a solid polymer electrolyte film doped with a new nanofiller synthesized by the solution casting technique. Electrical, optical, and photoelectrochemical characterization are presented in detail. Electrochemical impedance spectroscopy (EIS) shows with the dispersion of nanofillers conductivity increases attains maxima and decreases. The maximum conductivity was at 0.04 wt% nanofiller concentration of 2.05 × 10−4 S/cm. The calculated ionic transference value was 0.92 which shows the dormancy of the system as ionic. The linear sweep voltammetry confirms a high electrochemical stability window (ESW) of 4.01V. Sandwitched electrical double‐layer capacitors (EDLC) have been developed using carbon‐based electrodes and sandwitched nanofiller dispersed polymer electrolyte, showing a high specific capacitance value of ~200 F/g.

Amorphous Magnesium-Doped Chitosan films as solid polymer electrolytes for energy storage device applications

Magnesium ion-conducting biodegradable solid polymer electrolyte (SPE) films of magnesium perchlorate [Mg(ClO4)2] doped Chitosan [CS] were prepared using the solution casting technique at room temperature. XRD study shows that amorphous nature of the polymer matrix increases upon doping. FTIR deconvolution confirm the complexation generated between the salt and the polymer. The current–voltage measurement exhibited electrochemical stability window for all samples above 2.14 V. The ionic transference number for the highest conducting sample was 0.99. The impedance analysis was done for each SPE film, and the sample with the highest concentration (40 wt%) exhibited the highest conductivity, 5.7 × 10-4 Scm−1. The prepared primary magnesium battery using the highest conducting SPE showed open circuit potential of 2.112 V. Due to its exceptional qualities, this prepared electrolyte may be a strong contender for energy storage systems.

(Invited) Electrolytes for Next-Generation Sodium Metal Batteries

Developing reliable and cost-effective electrical energy storage systems (EESs) for portable electronics, electric vehicles, and grid storage applications is vital. Na-ion batteries are the most promising alternative technology owing to their natural abundance and low sodium cost.[1] Solid-state batteries (SSBs) have garnered extensive attention for their ability to suppress the safety hazards of organic liquid electrolytes by replacing them with solid electrolytes.[2] Among the various solid electrolytes being explored, our group mainly focuses on NASICON (Sodium superionic conductor) type silicate and solid polymer electrolytes. Sodium silicates are a class of materials with composition, NaxMxSixOx (M = rare-earth metals, x = integer (1-10)).[3] They have the advantage of low sintering temperature (~1050 °C) and 3D framework structure containing MO6 octahedra and SiO4 tetrahedra providing facile ionic movement.[4] Solid polymer electrolytes (SPE) are known for their flexibility and electrode compatibility. Highly conductive, filler-free composite solid polymer electrolyte films were prepared using poly(vinylidene fluoride), poly(vinyl pyrrolidone) (PVP), and NaPF6.[5] PVP binder played an essential role in improving Na ion conductivity and excellent plating−stripping performance. This talk will present an overview of these solid electrolytes for next-generation sodium metal batteries.

(Best Poster Award - 1st Place) Characterisation of the Li Metal|Electrolyte Interface of PEO-Based SPEs with Borate Salts, Using in Situ Li Deposition PES Measurements Aided by AIMD Simulations

Lithium metal and anode-free batteries has the potential to increase the energy density and specific energy of the batteries drastically. However, when regular electrolyte materials are tried for these concepts they are plagued with problems due to degradation of the electrolyte at the interface and processes like dendrite formation which leads to poor capacity retention.[1] A strategy to mitigate these problems is to use Solid Polymer Electrolytes (SPEs), as these have better stability towards lithium metal. In order to find appropriate chemistries to use in SPE-based cells it is important to investigate and understand their anode interface, as this is where the Solid Electrolyte Interphase (SEI) is created from the degradation products during cycling.This work investigates three polyethylene oxide (PEO)-based SPEs, using lithium tetrafluoroborate (LiBF4), lithium bis(oxalate)borate (LiBOB), and lithium difluoro(oxalate)borate (LiDFOB) as the lithium conducting salts. The interfaces of these SPEs (PEO:LiBF4, PEO:LiBOB, and PEO:LiDFOB) was studied using Photo-Electron Spectroscopy (PES) with in situ lithium deposition, where lithium atoms are evaporated on top of the SPE film. The analysis of the core-level spectra before and after lithium deposition is compared to Ab Initio Molecular Dynamics (AIMD) simulations of the interface, where lithium atoms are gradually added during the simulation. These experimental and theoretical methods are meant to mimic the electrochemical plating of lithium at the lithium|SPE interface during charging of a lithium metal or anode-less cell.The interfaces of PEO:LiBOB and PEO:LiBF4 show, among other compounds, polyethylene as a breakdown product at the interface. PEO:LiDFOB shows a much lesser degree of degradation compared to the other two systems. The degradation layer is however still effective at protecting the SPE from further breakdown, as PEO:LiDFOB has a relatively high capacity retention compared to PEO:LiBF4 and PEO:LiBOB. Suggested is that the LiF provides a better electrochemical stability, while the boron and oxalate breakdown products provides a higher mechanical stability at the interface.[1] Huang WZ, Zhao CZ, Wu P, Yuan H, Feng WE, Liu ZY, Lu Y, Sun S, Fu ZH, Hu JK, Yang SJ. Anode‐Free Solid‐State Lithium Batteries: A Review. Advanced Energy Materials. 2022 Jul;12(26):2201044. Figure 1

Effect of Sodium Iodide on Structural, Electrical and Optical Properties of Polyethylene Oxide/ Carboxymethyl Cellulose Blends

The production of highly potential Solid Polymer Electrolyte (SPE) materials has been the subject of extensive research. Due to their high flexibility, superior processability and enhanced resistance to electrodes during the charging/discharging process, they found to exhibit wide applications when compared to liquid or gel. In the present study, SPE films with 30/70 composition of Polyethylene oxide/Carboxymethyl cellulose blend, doped with Sodium Iodide (NaI) were prepared using a simple solution cast technique. The optical properties of the prepared samples were studied by UV–Vis spectroscopy technique and the results show that, the energy band gap decreases with the increase of salt concentration which is due to the enhancement of amorphous nature with the concentration of salt and is as evidenced from X-Ray diffraction studies. The electrical properties of the samples were studied using impedance analyser. The dielectric constant of the prepared samples decreases exponentially with frequency of applied electric field. In addition, the AC conductivity of the blend was found to increase with increase in salt concentration and the maximum conductivity was observed for 0.03% NaI salt doped Polyethylene oxide/Carboxymethyl cellulose blend. Thus, the said samples can be used in the preparation of SPE’s

Investigation of the electrochemical performance of Mg-ion batteries based on PVDF-HFP thin polymer electrolyte films

In the present work, poly(vinylidene fluoride-hexafluoropropylene):magnesium trifluoromethanesulfonate (PVDF-HFP:MgTf) polymer electrolytic films with a porous structure were developed using the solution-casting method. With its high performance and versatility, PVDF-HFP has been widely employed in the development of solid polymer electrolyte films (SPEFs). In this study, metal salt particles are successfully included as an inorganic filler into solid PVDF-HFP films, reducing pore size and boosting the amorphous character of the films. Fourier transform infrared spectroscopy is used to examine the chemical structure of the produced SPEFs, and scanning electron microscopy is used to evaluate the surface morphology and locate pores in the SPEFs. The surface nature of the PVDF-HFP films and the PVDF-HFP:MgTf is confirmed by X-ray diffraction. The electrochemical stability of PVDF-HFP and PVDF-HFP:MgTf films is studied through a differential scanning calorimetry experiment. Results revealed that PVDF-HFP:MgT films could be stabilized when filled with electrolytes and electrodes and made less porous by adding inorganic salt particles. Further, electrochemical impedance spectroscopy is used to measure electrical conductivity between 303 and 423 K. At room temperature, PVDF-HFP and PVDF-HFP/Mg2+ SPEFs have optimal ionic conductivities of 3.38 × 10−7 and 1.08 × 10−6 SS ccmm−1−1 respectively. Ionic conductivity was found to increase with temperature. The modulus of the imaginary part of the loss tangent (M′ and M″) was found to be related to dielectric and conductivity relaxation.

Correlations between the dopant concentration and ion transport properties of plasticized NaCMC-Pectin polyblend electrolyte membranes for electrochemical device applications

This study explores the structural and electrical properties of sodium carboxymethyl cellulose (NaCMC)–pectin (PC)–glycerol–NH4Br electrolyte films and investigates their potential applications in proton batteries. Plasticized solid polymer electrolyte (SPEs) films were fabricated using the solution casting method. The interaction between the salt and polymer blends was verified using Fourier-transform infrared (FTIR) analysis. Incorporation of various salt concentrations (up to 25 wt%) was found to enhance the amorphous phase of the polymer blend, as evidenced by X-ray diffraction (XRD) results. Additionally, the decrease in the glass transition temperature, as confirmed by DSC analysis, indicates that the inclusion of both plasticizer and salt contributed to this effect. An electrolyte with 25% wt. of NH4Br has the highest room temperature conductivity of 4.68 ×10−4 S cm−1. This electrolyte was employed to fabricate the proton battery for energy storage application.

Development and Characterization of a New Solid Polymer Electrolyte for Supercapacitor Device

In this study, solid polymer electrolytes (SPEs) are based on methylcellulose (MC) used as a polymer host and sodium iodide (NaI) as a dopant. The SPE films are developed using different contents of ethyl carbonate (EC) as a plasticizer to enhance their properties via a solution casting method. The surface morphology of SPE films is shown using polarized optical microscopy (POM), which indicates the existence of amorphous patches due to the plasticizing effect of EC. The creation of a complex between MC, NaI, and EC was confirmed by Fourier transform infrared (FTIR) spectra. A tiny amount of EC applied to the MC-NaI polymer salt matrix increases the number of charge carriers and improves ionic conductivity. The ionic conductivity of the generated polymer electrolytes is examined using electrochemical impedance spectroscopy (EIS). The high-ion conducting PE of 5.06 × 10−3 S·cm−1 was found with the mixture MC + 50 wt% NaI + 10 wt% EC (room temperature). The linear speed voltammetry (LSV) test shows that the optimized polymer electrolyte can withstand decomposition up to 2.5 V. The optimized sample transmission numbers were calculated using a TNM (transference number measurement) approach, and the results show that 99% of the ions contribute to the conductivity, compared to only 1% of the electrons. A solid-state electrical double-layer capacitor (EDLC) was fabricated using the highest ion-conductive polymer electrolyte and graphene oxide (GO)-based electrodes. The galvanostatic charge-discharge (GCD) technique was performed, and the GCD graph shows the behavior of an ideal capacitor with a less Faradic process and a low ESR value. The GO-based cell’s columbic efficiency is 100%, and the system delivers the charge for a long duration. The EDLC cell demonstrates outstanding cyclability. The specific capacitance of the EDLC cell incorporated with MC + 50 wt. % NaI + 10 wt. % EC was found to be 154.66 F/g.

Improving electrolyte performance: Nanocomposite solid polymer electrolyte films with cobalt oxide nanoparticles

AbstractThe present work gives an insight into the structural, thermal, and electrical analysis of novel nanocomposite solid polymer electrolyte films prepared using the solution casting technique by incorporating cobalt oxide nanoparticles into methyl cellulose‐magnesium acetate polymer electrolyte matrix. The impact of ceramic oxide on the complexation of the salt with the polymer chain is evident from FTIR analysis. The crystallinity of the electrolyte systems decreases upon the incorporation of nanofiller into the matrix. Electrochemical Impedance Analysis of the samples shows enhancement in the conductivity of the electrolytes. Nanocomposite electrolyte systems with 2 wt% (5.93 × 10−4 S/cm) and 3 wt% (5.77 × 10−4 S/cm) of cobalt oxide exhibit maximum room temperature ionic conductivity compared to other electrolyte systems. DSC thermogram reveals the creation of free volume in the matrix with the incorporation of the filler. A primary battery is fabricated using the nanocomposite electrolyte system with 3 wt% of the nanofiller, and its open circuit potential and discharge characteristics have been analyzed.Highlights Novel nanocomposite SPEs with cobalt oxide were prepared via solution casting. FTIR and XRD studies revealed modification in the microstructure. Cobalt oxide incorporation enhanced ionic conductivity of SPE. A primary battery fabricated using the highest conducting SPE.

Optical, vibrational, electrical, and electrochemical studies of new plasticized methylcellulose‐based solid polymer electrolytes for supercapacitor application

AbstractIn this work, new plasticized solid polymer electrolytes (SPEs) are developed using MC (methylcellulose) as a polymer host, and sodium iodide (NaI) as a dopant via the solution casting method. Ethyl carbonate (EC) is used as a plasticizing agent to improve the properties of the SPEs. Polarized optical microscopy analysis reveals that the surface morphology of the MC‐NaI‐EC films contained porous amorphous regions owing to the presence of EC. The complex formation between MC, NaI, and EC is confirmed by Fourier‐transform infrared spectra. The addition of EC in the MC‐NaI polymer salt matrix enhances the electrochemical properties of the prepared films. The highest ionic conductivity of 5.06×10−3 S/cm is achieved for the composition: MC+50 wt. % NaI +10 wt. % EC. The linear sweep voltammetry test reveals that the optimal plasticized‐SPE can withstand up to 2.5 V. The ionic transference number analysis reveals that 99% of ions contribute to the total conductivity. The optimized SPE film and graphene oxide‐based electrodes are used to manufacture a solid‐state electrical double‐layer capacitor. The coulomb efficiency of the supercapacitor cell is 100%, and the specific capacitance of the supercapacitor is found to be 18.56 F/g utilizing impedance data at low frequency.

M3+/NaTiO3/PVA–chitosan nanocomposites (M = Ga, Ce, Nd or Er): novel solid polymer electrolytes for supercapacitors

Designing flexible and thermally stable solid polymer-electrolyte (SPE) -based green materials for energy storage devices is an interesting approach from environmental and technological points of view. In this paper, NaTiO3 (ST) nanofibers of diameters in the range of 4.88–9.48 nm were hydrothermally prepared and loaded into the poly(vinyl alcohol)–chitosan (PVA–Ch) bio-blend via solution casting. Additionally, the obtained nanocomposite solution was mixed with Ga3+ and rare Earths (Ce3+, Nd3+, or Er3+) for preparing novel solid polymer electrolyte films. XRD results indicated the semicrystalline nature of all samples, and the degree of crystallinity decreased after loading these additives. FE-SEM and EDS were used to investigate the surface morphology, fracture cross-section and the elemental chemical composition. FTIR analysis confirmed the complexation and complete dissociation of the salts inside the blend. UV–vis spectroscopy showed that the optical band gap of the films was reduced from 4.4 eV to 3.5 eV, and the refractive index is in the range of 2.376–2.648. The thermo-gravimetric analysis (TGA) revealed that the samples are thermally stable until 200 °C, and the maximum decomposition occurs in the temperature range 255–300 °C. In addition, four endothermic peaks were detected in the differential scanning calorimetry thermograms. Dielectric properties were measured in the fRequency range of 100 Hz–8.0 MHz and at temperatures in the range of 30–120 °C. The dielectric constant and ac conductivity were greatly improved due to doping with ST and mixing the salts. The small dielectric loss associated with the improvements in the dielectric constant and ac conductivity suggest the use of the ST/blend and salts/ST/blend films for energy storage devices and related applications.

Structural and electrical properties of TSP: CH3COONa amorphous Biopolymer electrolytes for electrochemical cell applications

Solid biopolymer electrolytes have gained enormous attention recently due to their potential as non-toxic, biodegradable properties over their synthetic counterpart. Considering their uses in energy applications, the present investigation aims to synthesize and characterize solid biopolymer electrolytes comprising tamarind seed polysaccharide (TSP) as the host polymer and sodium acetate (CH3COONa) salt as the ionic dopant. The solution cast technique was employed to create free-standing tamarind seed polysaccharide (TSP): Sodium acetate (CH3COONa) solid polymer electrolyte films with varying weight percentages. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) studies investigated the structural and chemical correlation between TSP and CH3COONa. AC impedance spectroscopy was used to test the conductivity and dielectric properties of the prepared polymer films. The conductivity rises with increasing temperature. The maximum conductivity was found to be 1.95 × 10−4 S cm−1 for 80:20 (TSP: CH3COONa) wt.% ratio sample at room temperature (303 K), which was three orders of magnitude higher than the pure TSP (10−7 S cm−1). These polymer electrolyte films showed conductivity that altered with temperature, which follows Arrhenius's behaviour. Dielectric studies showed that dielectric constant and dielectric loss were high at low frequencies and decreased at high frequencies. Wagner's polarisation technique confirmed that charge transport in these polymer electrolyte systems was principally ionic, with the highest tion ( ̴ 0.99) and electrons having a negligible contribution. The discharge studies of the cell showed good stability and performance with OCV at 1.68 V and SCC at 0.69 mA.

Effect of lithium bromide doping on structural, dielectric, and transport properties of methylcellulose-based solid polymer electrolyte films

Effect of lithium bromide doping on structural, dielectric, and transport properties of methylcellulose-based solid polymer electrolyte films

Characterization and charge transport properties of sodium ion conducting PEO:NaBr solid polymer electrolyte films

AbstractThe study examines the effects of metal salt doping on polyethylene oxide (PEO) solid polymer electrolyte films. Sodium Bromide (NaBr) doped PEO films are prepared using a solution casting technique. The study finds that Na+ rom NaBr interacts with PEO's ether group (C–O–C) through complexation, as confirmed by Fourier Transform Infrared (FTIR) Spectroscopy. X‐ray diffraction analysis reveals that NaBr reduces PEO's degree of crystallinity. The addition of NaBr improves PEO's thermal stability, as shown by thermogravimetric analysis (TGA). Scanning electron microscopy (SEM) images show smooth surface morphology of the polymer electrolyte films. The study also finds that the polymer electrolytes are non‐Debye in nature, based on dielectric studies. The highest ionic conductivity of 1.01 × 10−5 S/cm is observed for the 12.5 wt% NaBr doped PEO, with a low activation energy of 0.246 eV. Wagner's polarization technique is used to determine the charge carrier transport numbers, and the transient ionic current technique confirmed the presence of a single ionic species in the polymer electrolyte. Overall, the study suggests that 12.5 wt% NaBr doped PEO films have appropriate electrical properties for developing charge storage devices.

Self-healing polymer electrolytes with dynamic-covalent borate for solid-state lithium metal batteries

Developing a solid polymer electrolyte (SPE) combining superior interface stability with high ionic conductivity is still a challenge in the energy storage field. Herein, a series of novel self-healing solid polymer electrolytes were prepared by free radical photopolymerization with poly(ethylene glycol) methyl ether methacrylate and monomers containing borate. The reversible reaction induced by interesterification of borate ester endows the polymer electrolytes with excellent self-healing ability. The comb-like structure based on flexible poly(ethylene glycol) provides an amorphous state, which is conducive to lithium-ion transport. Further benefiting from the strong interaction between electron capture groups and anions of electrolyte salts, the borate-containing comb-shaped solid polymer electrolytes (PPBSPE) films display optimal ionic conductivity of 0.272 mS cm−1 at 60 °C, satisfactory transfer number for lithium ion, wide working voltage window, and remarkable stability towards lithium metal. The initial discharge capacities of the cell based on PPBSPE reach 156.2 mAh g−1 at a current rate of 0.1C, and high Coulombic efficiency (CE) of 99.4 %. This enhancement is due to the introduction of borate to the comb-shaped polymer, which is beneficial to form a more suitable electrolyte that can stabilize and improve the performance of lithium metal batteries.