Solid Polymer Research Articles

High-Stability Composite Solid Polymer Electrolyte Composed of PAEPU/PP Nonwoven Fabric for Lithium-Ion Batteries.

Solid polymer electrolytes have attracted considerable attention, owing to their flexibility and safety. At present, poly(ethylene oxide) is the most widely studied polymer electrolyte matrix. It exhibits higher safety than the polyolefin diaphragm used in traditional lithium-ion batteries. However, it readily crystallizes at room temperature, resulting in low ionic conductivity, and the preparation process involves organic solvents. In this study, from the perspective of molecular design, solvent-free polyaspartate polyurea (PAEPU) and the cheap and easily available polypropylene (PP) nonwoven fabric were used as support materials for the PAEPU/PP composite solid polymer electrolyte (PAEPU/PP m -CPE). This CPE has good thermal stability, dimensional stability, flexibility, and mechanical properties. Among the different CPEs that were analyzed, PAEPU/PP10-CPE@20 had the highest ionic conductivity, which was reinforced with 10 g/m2 PP nonwoven fabric and the content of lithium salt was 20 wt %. Furthermore, PAEPU/PP10-CPE@20 exhibited the highest electrochemical stability with an electrochemical window value of 5.53 V. Moreover, the capacity retention rate of the Li//PAEPU/PP10-CPE@20//LiFePO4 half-cell was 96.82% after 150 cycles at 0.05 C and 60 °C, and the capacity recovery rate in the rate test reached 98.81%.

Polyester‐Polycarbonate Polymer Electrolytes Beyond LiFePO4: Influence of Lithium Salt and Applied Potential Range

AbstractRechargeable polymer‐based solid‐state batteries with metallic lithium anodes and LiNixMnyCo1−x−yO2 (NMC)‐based cathodes promise safer high‐energy‐density storage solutions than existing lithium‐ion batteries, but have shown challenging to realize. The failure mechanisms that have been suggested for these battery cells have mostly been related to the use of a metallic lithium anode and formation of dendrites during cycling. Here, we approach the issue of using solid polymer electrolytes (SPEs) vs. NMC cathodes by employing a range of materials based on poly(ϵ‐caprolactone‐co‐trimethylene carbonate) (PCL‐PTMC) with different salts under various cycling conditions. It is seen that although the ionic conductivity of the electrolyte can be improved by exchanging the lithium salt, it does not immediately correlate to better cycling performance. However, increasing the temperature during battery cycling to improve the ion transport kinetics lowers the polarization of the battery cell and full capacity can be achieved at an upper voltage cut‐off that is appropriate for the polymer electrolyte. For these electrolytes, the limit is demonstrated to be 4.4 V vs. Li+/Li, and cycling with NMC‐111 cathodes is thereby possible provided that the upper cut‐off is limited to below this limit.

Rational design of hybrid electrolyte for all-solid-state lithium battery based on investigation of lithium-ion transport mechanism

Lithium all-solid-state batteries (ASSBs) are a promising technology for achieving high energy density, long cycle life, and safe rechargeable battery systems. Among these, Li ASSBs using solid polymer electrolytes (SPEs) have gained attention owing to their processability, lightweight nature, flexibility, and favorable electrode contacts. However, SPEs have low ionic conductivity, low Li+ transference number, and lack mechanical strength, limiting cell performance. Therefore, the present study focuses on the development of hybrid polymer electrolytes (HPEs) by incorporating Li1+xAlxTi2-x(PO4)3 (LATP) of Li/Na superionic conductor-type materials into SPEs. The HPEs with LATP 10 wt% exhibited significant improvements with an ionic conductivity of 7.23 × 10−4 S cm−1 at 45 °C and a Li+ transference number of 0.61. Density functional theory calculations supported the enhanced Li-ion migration through the polymer-LATP interface achieved by the optimized LATP content. The addition of LATP particles enhanced the mechanical strength of the electrolytes, effectively suppressing dendrite growth, resulting in a 66.65 % capacity retention after 320 cycles, highlighting the crucial role of high-performance HPEs in advanced ASSBs. By addressing the limitations of SPEs, HPEs offer promising opportunities to unlock the full potential of solid-state battery technologies for various energy storage systems.

All solid-state lithium-ion batteries based on designed polyrotaxane-containing networks

Selecting the appropriate polymer structure for use as both a solid electrolyte and catholyte is essential for enhancing the electrochemical performance of all-solid-state lithium metal batteries. In this study, we are pioneering the customization of solid electrolyte and catholyte synthesis based on novel polyrotaxane (PRX)-containing polymer networks by altering the length of the polyether crosslinkers to tune the properties to meet specific needs of different components. On one hand, the modified PRX polymer networks based on the shorter crosslinker show good mechanical strength, high ionic conductivity (7.25 × 10−4 S cm−1) and high lithium ions transference number (0.54) at 60 °C, allowing their use as solid polymer electrolyte (SPE) self-supporting membranes. On the other hand, all-solid-state lithium-ion batteries with this SPE demonstrate a much higher initial capacity (above 160 mAh/g using LiFePO4 as active material at the cathode and lithium metal as anode), and better cycling performance when paired with longer cross-linked PRX as catholytes than the other non-customized combinations all solid lithium-ion batteries. Moreover, the cycling performance of the full cell can be further improved by incorporating different lithium salts in the electrolyte (LiTFSI) and cathode (LiClO4). This work highlights that the customized design of solid electrolytes and catholytes based on polymer networks is an efficient strategy to obtain high-performance all-solid-state lithium metal batteries.

Lithium iodide transport in double gyroid nanochannels formed by zwitterion‐containing solid polymer electrolytes

AbstractThe fabrication of nanostructured block copolymer (BCP) films endowed with lithium ion‐conducting gyroid (GYR) nanochannels is an appealing solution to build solid polymer electrolytes (SPEs) that combines high ionic conductivity (IC) with suitable mechanical properties. However, the formation of a well‐developed GYR structure remains challenging to achieve from the self‐assembly of polyelectrolyte BCP chains. To overcome this issue, large ion conducting gyroid grains were produced within freestanding polystyrene‐block‐poly(2‐vinylpyridine)‐block‐poly(ethylene oxide) (PS‐b‐P2VP‐b‐PEO) films by combining a solvent vapor annealing (SVA) treatment with an infiltration process. Here, the SVA treatment enabled the manufacture of SPEs entirely composed of a GYR structure while the infiltration process allowed for the incorporation of an appropriate Li salt (i.e., lithium iodoacetate, LiIAc) within the 3D‐interconected nanochannels via a Menshutkin reaction. By using this SVA‐Infiltration strategy, it has been demonstrated that the creation of ion conducting GYR nanochannels enhances the ion transportation capacity of pyridine‐containing SPEs since substantially lower ICs were measured from analog PS‐b‐P2VP‐b‐PEO/LiIAc films having a nominally disordered as‐cast state. Remarkably, zwitterionic pyridinium‐based moieties formed inside the interpenetrated nanochannels enable an efficient migration of Li+ and I3− species, leading to an IC as high as 10−4 S cm−1 at 70°C.

On the effect of strain rate during the cyclic compressive loading of liquid crystal elastomers and their 3D printed lattices

Nematic liquid crystal elastomers (LCEs) are a unique class of network polymers with the potential for enhanced mechanical energy absorption and dissipation capacity over conventional network polymers because they exhibit both conventional viscoelastic behavior and soft-elastic behavior (nematic director changes under shear loading). This additional inelastic mechanism makes them appealing as candidate damping materials in a variety of applications from vibration to impact. The lattice structures made from the LCEs provide further mechanical energy absorption and dissipation capacity associated with packing out the porosity under compressive loading.Understanding the extent of mechanical energy absorption, which is the work per unit mass (or volume) absorbed during loading, versus dissipation, which is the work per unit mass (or volume) dissipated during a loading cycle, requires measurement of both loading and unloading response. In this study, a bench-top linear actuator was employed to characterize the loading-unloading compressive response of polydomain and monodomain LCE polymers and polydomain LCE lattice structures with two different porosities (nominally, 62% and 85%) at both low and intermediate strain rates at room temperature. As a reference material, a bisphenol-A (BPA) polymer with a similar glass transition temperature (9 °C) as the nematic LCE (4 °C) was also characterized at the same conditions for comparing to the LCE polymers. Based on the loading-unloading stress-strain curves, the energy absorption and dissipation for each material at different strain rates (0.001, 0.1, 1, 10 and 90 s-1) were calculated with considerations of maximum stress and material mass/density. The strain-rate effect on the mechanical response and energy absorption and dissipation behaviors was determined. The energy dissipation ratio was also calculated from the resultant loading and unloading stress-strain curves. All five materials showed significant but different strain rate effects on energy dissipation ratio. The solid LCE and BPA materials showed greater energy dissipation capabilities at both low (0.001 s−1) and high (above 1 s−1) strain rates, but not at the strain rates in between. The polydomain LCE lattice structure showed superior energy dissipation performance compared with the solid polymers especially at high strain rates.

Development of solid-state hybrid capacitor using carbon nanotube film as current collector

Structural energy-storage devices are receiving considerable attention because they can simultaneously store electrical energy and provide structural support, thereby offering high volumetric and gravimetric capacities. Although carbon fiber–based materials have been the most popular choice for current collectors, their conductivity and specific surface area are relatively low; this limits the ability to load other active materials on to the current collector. Carbon nanotube (CNT) fiber is a promising alternative for lightweight structural materials because it has a density of less than 1 g cm−3 as well as high strength and electrical conductivity. In this study, we produced a light, strong, and porous CNT film (CNTF) via direct spinning for use as a current collector. The CNTF exhibited a high specific strength compared with Al foil. We also created an activated carbon–lithium titanium oxide hybrid capacitor with the CNTF current collector, which achieved a capacity similar to that of a capacitor having an Al current collector. Furthermore, a planar pouch cell created using a solid polymer electrolyte achieved a capacity of 74.1 mAh g−1, which is comparable to that of coin cells. Thus, our findings highlight the feasibility of CNTF as a material for current collectors and provide a foundation to develop manufacturing processes for structural batteries.

Self‐Extinguishing and Low‐Cost Quasi‐Solid Polymer Electrolyte for Room Temperature Lithium Metal Batteries

AbstractMost modification strategies of polyethylene oxide (PEO)‐based solid polymer electrolyte focus on improving the room temperature ionic conductivity, while disregarding its inherent flammability that poses substantial safety hazard. Herein, a self‐extinguishing quasi‐solid‐state polymer electrolyte (PTTF‐SPE), which combines excellent room temperature electrochemical properties and high safety, has been developed by introducing triethyl phosphate (TEP) as a low‐cost and highly effective flame retardant. The cross‐linking structure derived from −CH2−CH2−O− segments of tetramethylene glycol dimethyl ether (TEGDME) and PEO makes a contribution to a high amorphous state of polymer. A robust solid electrolyte interphase (SEI) formed by preferential decomposition of fluoroethylene carbonate (FEC) that acts as a film‐forming additive, which can prevent TEP from degradation at lithium metal anode. The optimized PTTF‐SPE exhibits high ionic conductivity (0.54×10−3 S/cm) and lithium transference number (0.71) at room temperature. The LiFePO4||Li battery demonstrates excellent cycle life over 500 cycles at 0.5 C with a high average discharge capacity of 131 mAh/g. A symmetric Li||Li battery that operating for 850 hours indicates a good compatibility of PTTF‐SPE towards lithium metal. This work provides a new idea for developing high‐energy‐density and high‐safety lithium‐metal batteries (LMBs) for room temperature.

Polyoxymethylene-based solid polymer electrolyte for high-performance room-temperature all-solid-state lithium batteries

Compared with flammable liquid electrolytes, solid state electrolytes show promising potential for lithium-ion batteries with high safety and high energy density simultaneously due to their high thermal stability, mechanical strength, excellent chemical and electrochemical stability. Solid polymer electrolytes are an attractive choice to achieve high energy density due to their thinness and good manufacturability. However, traditional solid polymer electrolytes typically need to operate at above 60 °C due to the insufficient room-temperature ionic conductivity, thereby limiting its practical application in common room temperature lithium-ion batteries. Here, we report a novel design of polyoxymethylene (POM)-based solid polymer electrolytes for high-performance room-temperature all-solid-state lithium batteries. This design includes POM and lithium bis(trifluoromethylsulfonyl)amine (LiTFSI), which offers the similar structure to polyethylene oxide based solid electrolyte while with shorter chain segments to achieve higher ionic conductivity (2.8 × 10−4S cm−1) and mechanical strength at room temperature. As a result, lithium dendrites can be efficiently suppressed, and symmetrical Li-Li cells have demonstrated more than 300 h of cycling at 0.05 mA cm−2. The wide electrochemical stability window of 4.75 V also enables broader application for full cells. All-solid-state lithium batteries fabricated with POM/LiTFSI exhibit excellent cycling stability for 150 cycles at 0.2 C rate at room temperature. The design breaks through the useable temperature limit of solid polymeric electrolytes and broaden their application in all-solid-state lithium batteries.

Studies on ionic conductivity, linear and non-linear optical properties of ecofriendly methyl cellulose: sodium bromide based solid polymer blend electrolytes

Biopolymer electrolytes based on methyl cellulose (MC) and sodium bromide(NaBr) have been prepared through solvent casting technique. Both the concentrations of MC and NaBr are varied. The prepared biopolymer electrolytes have been subjected to AC impedance and UV-Vis spectroscopic techniques. The ionic conductivity reached a maximum value of 4.84 × 10−8 Scm−1 for 0.8 g of MC and 0.2 g of NaBr. UV studies revealed that low direct and indirect band gaps have been observed for the maximum ionic conducting sample. Other optical parameters, such as refractive index, extinction coefficient, skin depth, and optical conductivity, have been estimated. The single-oscillator energy (Eo ) and dispersion energy (Ed ) for all the prepared biopolymer electrolyte samples were calculated with the help of Wemple and DiDomenico single oscillator model. The higher-order non-linear susceptibility values were also calculated. Polymer electrolytes are found to be suitable for optical and electronic devices.

Assembly of functional carboxymethyl cellulose/polyethylene oxide/anatase TiO2 nanocomposites and tuning the dielectric relaxation, optical, and photoluminescence performances

Nanocomposite films consisting of carboxymethyl cellulose, polyethylene oxide (CMC/PEO), and anatase titanium dioxide (TO) were produced by the use of sol-gel and solution casting techniques. TiO2 nanocrystals were effectively incorporated into CMC/PEO polymers, as shown by X-ray diffraction (XRD) and attenuated total reflectance fourier transform infrared (ATR-FTIR) analysis. The roughness growth is at high levels of TO nanocrystals (TO NCs), which means increasing active sites and defects in CMC/PEO. In differential scanning calorimetry (DSC) thermograms, the change in glass transition temperature (T g) values verifies that the polymer blend interacts with TO NCs. The increment proportions of TO NCs have a notable impact on the dielectric performances of the nanocomposites, as observed. The electrical properties of the CMC/PEO/TO nanocomposite undergo significant changes. The nanocomposite films exhibit a red alteration in the absorption edge as the concentration of TO NCs increases in the polymer blend. The decline in the energy gap is readily apparent as the weight percentage of TO NCs increases. The photoluminescence (PL) emission spectra indicate that the sites of the luminescence peak maximums show slight variation; peaks get wider, while their intensities decrease dramatically as the concentration of TO increases. These nanocomposite materials show potential for multifunctional applications including optoelectronics, antireflection coatings, photocatalysis, light emitting diodes, and solid polymer electrolytes.

AC Impedance Analysis of Blend Polymer Electrolyte of PVP – PPA with Magnesium Salts as an Ionic Dopant for Potential Battery Applications

Abstract Solid polymer electrolyte films containing blend polymer electrolyte of Polyvinylpyrrolidone (PVP) and Poly p - amino benzoic acid (PPA) with varying ratios of magnesium salts were synthesized by solution casting method. Their conduction and relaxation mechanisms were studied by impedance spectroscopy (AC) at room temperature. The dependence of electrical data on frequency was analyzed by Cole – Cole plot and Jonscher’s power law. The semicircle seen in the plot represents the double relaxation process and shows how bulk electrolyte and the interfacial effect contribute to non-Debye and electrical conduction. The ac and dc conductivity values were calculated and the conductivity variation for the blend polymer PVP – PPA doped with different concentrations of magnesium salts was explained by the ionic contribution of the electrolytes. The dielectric constant and dielectric loss were measured by the dielectric investigations. The relaxation phenomenon of these electrolytes is provided by the dissipation factor analysis and electric modulus value. The conductivity of the system determines the suitability of the thin film concentration for potential battery applications as a polymer electrolyte.

Piperazinium Poly(Ionic Liquid)s as Solid Electrolytes for Lithium Batteries.

Poly(ionic liquid)s combine the unique properties of ionic liquids (ILs) within ionic polymers holding significant promise for energy storage applications. It is reported here the synthesis and characterization of a new family of poly(ionic liquid)s synthesized from cationic piperazinium ionic liquid monomers. The cationic poly(acrylamide piperazinium) in combination with sulfonamide anions like bis(trifluoromethanesulfonyl) imide (TFSI) and bis(fluorosulfonyl) imide (FSI) are characterized as solid polymer electrolytes. The polymer electrolytes in combination with pyrrolidonium ILs and LiFSI show high ionic conductivity, 5×10-3 S cm-1 at 100 °C. Piperazinium polymer electrolytes show excellent compatibility with lithium metal reversible plating and stripping at high current density and low temperature 40 °C.

Polymer-based solid/semi-solid electrolytes in lithium ion batteries

Abstract The inception of lithium-ion batteries with liquid electrolytes can be traced back to the early 1980s. Nevertheless, the utilization of liquid electrolytes has many drawbacks, including its susceptibility to combustion, limited energy density, and very brief operational lifespan. Consequently, there is currently a concerted effort to substitute liquid electrolytes with solid compounds. This study investigates the electrochemical and mechanical features of solid/semi-solid electrolytes used in lithium ion batteries (LIBs) as well as their performance relative to conventional liquid electrolytes, with LIBs having unique challenges related to high flammability, electrochemical instability, and low mechanical stability posed by conventional liquid electrolytes versus solid polymer electrolytes (SPEs) which provide greater safety, mechanical stability but lower ionic conductivity than liquid counterparts. SPEs offer better safety but lack sufficient ionic conductivity which limits their potential. In order to overcome these obstacles, the implementation of gel-based and composite solid and semi-solid electrolytes is proposed as a means to improve ionic conductivity, electrochemical stability, and mechanical stability. The study suggests that a focus should be placed on solid composite electrolytes as they possess higher mechanical stability, which contributes to improved safety. Additionally, these electrolytes exhibit enhanced ionic conductivity within the range of 10−4 to 10−2 S/cm, hence enhancing the performance of LIBs.

CFD Analysis of Gas-Dynamic and Heat Transfer Processes in a Propulsion System Using Polymer Fuel

In the presented work, a computer model of thermodynamic and gas-dynamic processes in a rocket engine of a new type, which uses solid polymers as fuel is considered. The design feature is the presence of a central body - a gasification chamber, where solid polymer fuel is decomposed into volatiles. To conduct the research, a preliminary thermodynamic analysis of the combustion of gasification products was carried out. Based on the results of the thermodynamic analysis using the mathematical model of the turbulent flow of viscous compressible gas, the processes of gas dynamics and heat transfer in the chamber and nozzle of the rocket engine were simulated. Analyses are made for the geometry of a real experimental sample of a polymer-fueled rocket engine developed at Oles Honchar Dnipro National University (Ukraine), which has passed the first successful tests. As a result of CFD simulation, dynamic and thermal fields in the combustion chamber and engine nozzle were obtained, and ways of further improvement of the design were determined.

Electrochemical Performance of Supercapacitor Using Plasticised Corn Starch Polymer Electrolyte Incorporated with Lithium Iodide

An electrical double-layer capacitor (EDLC) is a supercapacitor type that offers higher energy density and capacitance than an electrolytic capacitor. EDLC bridges the energy or power gap between the batteries, fuel cells, and dielectric capacitors. Most EDLCs are fabricated using electrolytic solutions, many of which are highly corrosive, leading to heavy, bulky, and leaky devices. This research assembled an EDLC employing a plasticised solid polymer electrolyte based on lithium iodide (LiI) doped corn starch. Glycerol was used as the plasticiser. The fabricated EDLC was characterised using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge (GCD) techniques. The specific capacitance obtained from EIS was 1.74 F g–1. By analysing the Nyquist plot obtained from EIS, charge transfer resistance (Rct) and equivalent series resistance (ESR) were determined. CV of the EDLC was carried out at various sweep rates. The highest specific capacitance of 4.66 F g–1 was obtained at a 50 mV s–1 sweep rate. The EDLC was charged and discharged ten times at 1 mA constant current. From GCD, the specific capacitance was found to be in the 4.36 – 5.57 F g-1 range. From these results, starch-LiI-glycerol showed potential as a candidate for electrolyte material for energy device applications.Keywords: Electrolyte, electrical double-layer capacitor, glycerol, lithium iodide, solid polymer, starch, specific capacitance

A Dual-Bond Crosslinking Strategy Enabling Resilient and Recyclable Electrolyte Elastomers for Solid-State Lithium Metal Batteries.

Elastomeric solid polymer electrolytes (SPEs) are highly promising to address the solid-solid-interface issues of solid-state lithium metal batteries (LMBs), but compromises have to be made to balance the intrinsic trade-offs among their conductive, resilient and recyclable properties. Here, we propose a dual-bond crosslinking strategy for SPEs to realize simultaneously high ionic conductivity, elastic resilience and recyclability. An elastomeric SPE is therefore designed with hemiaminal dynamic covalent networks and Li+-dissociation co-polymer chains, where the -C-N- bond maintains the load-bearing covalent network under stress but is chemically reversible through a non-spontaneous reaction, the weaker intramolecular hydrogen bond is mechanically reversible, and the soft chains endow the rapid ion conduction. With this delicate structure, the optimized SPE elastomer achieves high elastic resilience without loading-unloading hysteresis, outstanding ionic conductivity of 0.2 mS cm-1 (25 °C) and chemical recyclability. Then, exceptional room-temperature performances are obtained for repeated Li plating/stripping tests, and stable cycling of LMBs with either LiFePO4 or 4.3 V-class LiFe0.2Mn0.8PO4 cathode. Furthermore, the recycled and reprocessed SPEs can be circularly reused in LMBs without significant performance degradation. Our findings provide an inspiring design principle for SPEs to address the solid-solid-interface and sustainability challenges of solid-state LMBs.

Compliant Solid Polymer Electrolytes (SPEs) for Enhanced Anode-Electrolyte Interfacial Stability in All-Solid-State Lithium-Metal Batteries (LMBs).

Practical application of high energy density lithium-metal batteries (LMBs) has remained elusive over the last several decades due to their unstable and dendritic electrodeposition behavior. Solid polymer electrolytes (SPEs) with sufficient elastic modulus have been shown to attenuate dendrite growth and extend cycle life. Among different polymer architectures, network SPEs have demonstrated promising overall performance in cells using lithium metal anodes. However, fine-tuning network structures to attain adequate lithium electrode interfacial contact and stable electrodeposition behavior at extended cycling remains a challenge. In this work, we designed a series of comb-chain cross-linker-based network SPEs with tunable compliance by introducing free dangling chains into the SPE network. These dangling chains were used to tune the SPE ionic conductivity, ductility, and compliance. Our results demonstrate that increasing network compliance and ductility improves anode-electrolyte interfacial adhesion and reduces voltage hysteresis. SPEs with 56.3 wt % free dangling chain content showed a high Coulombic efficiency of 93.4% and a symmetric cell cycle life 1.9× that of SPEs without free chains. Additionally, the improved anode compliance of these SPEs led to reduced anode-electrolyte interfacial resistance growth and greater capacity retention at 92.8% when cycled at 1C in Li|SPE|LiFePO4 half cells for 275 cycles.

AN INFORMATION-THEORETIC FILTER SINGLE-STEP SEQUENTIAL MONTE CARLO METHOD IN PRACTICE. AN EXPERIMENTAL CASE STUDY FOR THE PARTICLE SIZE DISTRIBUTION ESTIMATION

In this article, we implement an extended version of a Monte Carlo methodology making use of a Sampling/Mapping/Filtering (SMF) strategy, to estimate the Particle Size Distribution (PSD) of a particle system. The methodological difference is shown by the use of a filter, based on information theory, which computes a cut-off level using an optimization scheme following the principle of relevant information (PRI). The practical application of the full strategy considers the fusion between scanning electron microscope (SEM) data and static light scattering (SLS) measurements. The two models are utilized, assuming spherical particles represented as hard spheres: the so-called local monodisperse approximation (LMA) and the Vrij’s finite mixtures model (VFMM). We analyze the resulting estimates for different configurations of both prior information and SLS models, where final results are compared to those obtained in previous studies for a polymeric particle system embedded in a solid polymer matrix.

Deep Eutectic Solvent‐Based Solid Polymer Electrolytes for High‐Voltage and High‐Safety Lithium Metal Batteries

AbstractSolid‐state electrolytes (SSE) exhibit great promise in enhancing the safety of Li metal batteries by replacing flammable liquid electrolytes. However, the practical application of SSE is hampered mainly due to the poor electrode–electrolyte interface, low ion conductivity, and inferior electrochemical stability. Herein, superior nonflammable solid polymer electrolytes are elaborately designed by in situ encapsulating succinonitrile (SN)‐based deep eutectic solvent (DES) into the ethoxylated trimethylolpropane triacrylate (ETPTA) matrix (DES‐ETPTA). Benefiting from strong polarity and high anti‐oxidation capability, as‐prepared DES‐ETPTA electrolyte shows high ionic conductivity (9.55 × 10−4 S cm−1 at 30 °C), high Li+ transference number (0.68), and good electrochemical stability. As a result, the assembled LiFePO4 || Li full cells based on the designed DES‐ETPTA electrolyte deliver a high reversible capacity and capacity retention at −10 °C and room temperature. Furthermore, considering the compatibility with high‐voltage layered oxide cathode, the electrochemical stability of the ETPTA is further improved through the decoration of cyanoacrylate (CA) with strong electron‐withdrawing characteristic of C≡N. Consequently, the constructed 4.5 V LiCoO2 || Li full cells using DES‐ETPTA‐CA electrolyte deliver a high reversible capacity of 144 mAh g−1 and a superior retention rate of 93% after 200 cycles at 0.5 C. This work paves a new pathway to design high‐safety and high‐voltage solid polymer electrolytes for lithium metal batteries.