Composite Solid Polymer Electrolyte Research Articles

Solid electrolytes reinforced by infinite coordination polymer nano-network for dendrite-free lithium metal batteries

As the demand for high energy-density and safe Li-based batteries, the development of composite solid polymer electrolytes (CSPEs) with high ionic conductivity and high electrochemical stability are significant. Herein, the amorphous infinite coordination polymer (ICP) nano-network of Ce-coordinate polyphenol ellagic acid (EACe2) is introduced into PEO matrix to achieve highly endurable Li metal batteries (LMBs). Different from conventional metal-organic frameworks (MOFs) with discrete crystalline grains, ICP network with high interconnectivity and self-assembly capability enables the better penetration effect and multi-scale interaction of filler in PEO. EACe2 nano-filler promotes the improvement of ionic conductivity and Li-ion transference number of CSPEs, as well as the construction of robust solid-electrolyte interphase (SEI) with the concentration of LiF, Li2O and Li2S, leading to ultrastable and kinetically favorable Li/Li cells with dendrite-mitigated cycling over 8800 h. The low interfacial resistances (16 Ω cm2 and 20.5 Ω cm2 for CSPE-EACe2/Li and CSPE-EACe2/LiFePO4 respectively) can achieve highly reversible Li/LiFePO4 cells (with capacities of 102.6 mAh g−1 after 2000 cycles at 0.5 C and 103.2 mAh g−1 after 1200 cycles at 1 C). This CSPE-EACe2 membrane also enables the tolerance of high-voltage cathode (LiNi0.8Co0.1Mn0.1O2, up to 4.3 V), room temperature operation, and ultrathin thickness (25-μm-thick). [Display omitted]

Effect of Different Lithium Salts on the Structure and Morphology of Polystyrene-co-acrylonitrile Based Composite Solid Polymer Electrolytes

In the present study, a series of poly(styrene-co-acrylonitrile) (SAN) polymer electrolytes and SAN- poly(vinyl alcohol) (PVA) polymer blend electrolytes were prepared with different lithium salts using a solvent casting technique. The morphology of prepared polymer blend electrolytes was studied by XRD studies. FT-IR spectroscopy studies reveal the interaction between polymer host and the lithium salt.

Study of the Thermal Stability and Ionic Conductivity of Polystyrene-Co-Acrylonitrile Based Composite Solid Polymer Electrolytes Incorporated with different Lithium Salts

In the present study, a series of poly(styrene-co-acrylonitrile) (SAN) polymer electrolytes and SAN- poly(vinyl alcohol) (PVA) polymer blend electrolytes were prepared with different lithium salts using a solvent casting technique. TG & DSC studies were carried out to investigate the thermal stability of the polymer blend electrolytes. Ionic conductivities of these electrolytes were measured by AC impedance spectroscopy. Results for conductivity studies have shown that the polymer with SAN/PVA complex with 5 % LiBr exhibits the highest conductivity of 8.7 × 10−5 S/cm at 70°C. The temperature dependence of the polymer electrolyte films obeys Arrhenius relation.

Polyethylene glycol functionalized polyhedral cage silsesquioxane as all solid-state polymer electrolyte for lithium metal batteries

Polyethylene oxide (PEO) based solid polymer electrolyte is expected to be the safe and high energy density lithium-ion batteries owing to leakage-free and good flexibility, but high crystallinity results in low ionic conductivity at room temperature. In this paper, different molecular weights of the polyhedral oligomeric silsesquioxane-polyethylene glycol (POSS-(PEGw)8, w = 1 K g/mol and 2 K g/mol) is synthesized by click reaction between azido polyhedral oligomeric silsesquioxane (POSS-N3) and different weight of alkynyl methoxy polyethylene glycol (Alkynyl-PEG) are used as doped fillers to reduce the crystallinity of the PEO and enhance the ion conductivity of the electrolyte. The effect of the molecular weight of PEG in POSS-(PEGw)8 on the crystallinity and conductivity of composite solid polymer electrolytes (CSPEs) is analyzed and the result shows that PEO/POSS-(PEG1K)8 exhibits higher ionic conductivity (0.9 × 10−3 S·cm−1 at 50 °C) and Li+ transference number (0.47) than PEO/POSS-(PEG2K)8. Simultaneously, PEO/POSS-(PEG1K)8 presents a superior electrochemical window of 5.08 V. The LiFePO4‖PEO/POSS-(PEG1K)8–60%‖Li cell assembly reaches 133 mAh·g−1 after 100 cycles. The high capacity and good cycle performance prove the feasibility of applying POSS-(PEGw)8 to CSPEs, which contributes to the practical application of lithium metal batteries.

Enabling safer, ultralong lifespan all-solid-state Li-organic batteries

Organic cathode materials have attracted widespread attention due to their diverse structures, abundant raw materials, low cost, and eco-friendliness. However, their practical applications are restricted because of the poor cycling stability and lifespan owing to the dissolution and shuttle effect of the organic cathode in the liquid electrolyte. In this work, a novel all-solid-state Li-organic battery with ultralong lifespan is developed by using perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) as the organic cathode, composite solid polymer electrolyte (hybrid polymer-LiTFSI-LLZTO, HLL) as the electrolyte, and Li metal as the anode. The as-prepared HLL electrolyte exhibits high ionic conductivity (1.46 × 10-4 S cm−1 at 30 °C), superior thermal stability (~202 °C), outstanding electrode/electrolyte interfacial compatibility, and significant suppression to the dissolution/shuttle of PTCDA and the growth of Li dendrite. Ascribing to these advantages, the solid-state PTCDA|HLL|Li battery delivers a reversible capacity of 60 mAh g−1 after 1000 cycles at a high current density of 500 mA g−1, corresponding to an outstanding capacity retention of 91%. Moreover, the solid-state PTCDA|Li battery presents an elevated thermal stable window (178 °C) and less heat release (430 J g−1) compared with the analogous battery using liquid electrolyte (151 °C and 486 J g−1). Furthermore, the solid-state battery exhibits desirable flexibility and satisfactory safety under various abuse conditions (bending, cutting, and punching), demonstrating its outstanding safety in practical environments. This work offers a new pathway toward safer, longer lifespan solid-state Li-organic batteries.

An advanced solid polymer electrolyte composed of poly(propylene carbonate) and mesoporous silica nanoparticles for use in all-solid-state lithium-ion batteries

Composite solid polymer electrolytes (CSPEs) are promising candidates for replacing potentially hazardous organic liquid electrolytes used in Li ion batteries (LIBs). CSPEs are easy to process, have the ability to form films, and make better interfacial contact. However, their poor mechanical strength, low ionic conductivity, and long cycling stability limit their practical applications. Here, we demonstrate the fabrication of a cost-effective, flexible, self-standing, and highly stable CSPE using poly(propylene carbonate) (PPC) as the host matrix and highly mesoporous silica nanoparticles (MSNs) as the filler. The fabricated CSPE had a high ionic conductivity of approximately 8.5 × 10−4 S cm−1 at 60°C, electrochemical potential stability up to approximately 4.8 V vs. Li/Li+, an ultra-high lithium transference number of approximately 0.86, impressive stability over 1000 h of Li stripping/plating, and an excellent electrode compatibility. With cyclability over 200 cycles and a negligible overpotential, the Li/CSPE/LFP cell delivered a reversible capacity of 171 and 103 mAh g−1 at 0.1 C and 1 C, respectively, with a good rate capability up to 5 C. The interaction of Li+ with PPC and the MSNs is demonstrated by solid-state magic angle spinning nuclear magnetic resonance (MAS-NMR) and X-ray photoelectron spectroscopy (XPS) studies. The enhanced physico-electrochemical properties of the CSPE were attributed to the large MSNs-related surface area, which enables firm interaction with the PPC matrix and provides a less-tortuous polymer-ceramic phase for fast lithium ion transportation. The proposed MSNs-reinforced CSPE thus opens new possibilities for the fabrication and engineering of solid-state batteries.

Synthesis and characterization of LAGP-glass-ceramics-based composite solid polymer electrolyte for solid-state Li-ion battery application

Solid State Electrolytes (SSEs) are the future alternatives of the present conventional liquid electrolytes in terms of safety, high temperature stability and also good electrochemical performance. Glass (G), based on Lithium Aluminium Germanium Phosphate (LAGP) was prepared and converted into glass-ceramics (GC) by optimized heating schedule. The crystalline LAGP has Na Super Ionic CONductor (NASICON) type unit cell where the lithium ions hop between two different positions providing long range ionic motion. To improve the inter-electrode surface resistance and cell performance, Composite Solid Electrolyte (CSE) was prepared with poly(vinylidene fluoride-co-hexaflurophoaphate) (P(VDF-HFP)), 20wt% LAGP, Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and 1-Ethyl-3-methylimidazolium bis-(trifluoromethylsulfonyl)-imide (EMITFSI). X-ray diffraction patterns confirm the formation of the NASICON phase in LAGP GC and the amorphous nature of the CSE. NMR studies confirm formation of the Ge/AlO6 octahedra and PO4 tetrahedra inside the crystal. 7Li NMR also confirmed two different Lithium sites in LAGP crystal. The ionic conductivity values of CSE and LAGP GC are (4.49±0.31) × 10−3Scm−1 and (2.70±0.04) × 10−4Scm−1, respectively. The thermal stability of the prepared CSE is tested upto 315°C without any degradation. Two cells (Cell-I & Cell-II) were fabricated using the LAGP GC and CSE respectively. Cell-II shows the specific discharge capacity of 151mAhg−1 at 50th cycle which is higher as compared to Cell-I (129mAhg−1) when tested at the C-rate of 0.05C.

Composite solid polymer electrolyte with silica filler for structural supercapacitor applications

Structural supercapacitors are energy storage devices that can function as structural materials. We synthesized composite solid polymer electrolytes (CSPEs) from 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([EMIm][OTF]), poly (ethylene glycol) monomethyl ether acrylate (PEGA) and functionalized silica filler. Two types of fumed silica were used: one had an unmodified surface, and the other an organically modified surface. The CSPEs were prepared by adding ionic liquids (IL) to the PEGA and the ratios between PEGA and IL were 7: 3 and 5: 5, respectively. The functionalized silica was synthesized by the sol-gel method under acidic conditions using methacryloxypropyl trimethoxysilane (MAPTMS), whereas the effects of silica filler on the electrochemical and thermal properties of CSPEs were investigated using electrochemical impedance spectroscopy, cyclic voltammetry, and differential scanning calorimetry. The ionic conductivity of CSPEs based on PEGA/[OTF]_SiO2 at various concentrations of [EMIm][OTF] was 5.7×10−4 and 4.8×10−4S/cm, and their specific capacitance was 10.0 and 9.5 F/g, respectively. With the addition of silica filler, the ionic conductivity and specific capacitance of the synthesized CSPEs were lower than those of the neat CSPEs.

Reactivity-guided formulation of composite solid polymer electrolytes for superior sodium metal batteries

The ionic conductivity and interfacial impedance can be simultaneously improved by the reactivity-guided formulation of a composite solid polymer electrolyte with the polyethylene oxide host, PPC additive and ceramic filler.

A Metal–Organic Framework‐5‐Incorporated All‐Solid‐State Composite Polymer Electrolyte Membrane with Enhanced Performances for High‐Safety Lithium‐Ion Batteries

Solid polymer electrolytes (SPEs) have been one of the most promising candidates to replace nonaqueous liquid electrolyte for achieving high‐safety lithium‐ion batteries (LIBs). However, the extremely low ionic transport capacities of SPEs have seriously hindered their applications in LIBs. Herein, a metal–organic framework (MOF) material MOF‐5 is applied to polymer electrolyte for enhancing electrochemical performances of SPEs. Specifically, a polymer matrix is first obtained via a strategy of random copolymerization of trifluoroethyl methacrylate (TFEMA) and poly(ethylene glycol) methacrylate (PEGMA). Then, a free‐standing flexible composite SPE (CSPE) membrane composed of P(TFEMA‐ran‐PEGMA) polymer, lithium salt, and MOF‐5 (nanofillers) is prepared by the solution casting technique. The results indicate that the room temperature ionic conductivity of the CSPE is 1.5 times higher than that of neat SPEs and lithium‐ion transference number of CSPE remarkably enhances from 0.25 to 0.51. In addition, the as‐prepared CSPE has a very wide electrochemical window of 5.38 V. Moreover, the assembled solid cell LiFePO4/CSPE/Li presents an outstanding specific discharge capacity retention of 92.2% after 25 cycles. Thus, the superior comprehensive properties of the MOF‐incorporated composite polymer electrolyte exhibit a promising potential application in solid electrolyte for high‐safety solid LIBs.

A novel ceramic/polyurethane composite solid polymer electrolyte for high lithium batteries

Compared with the organic electrolyte, the solid electrolyte is more stable and non-volatile at high potential, which solves the decomposition problem of organic electrolyte and the potential safety hazard of flammability and explosion. Based on the advantages of inorganic solid electrolyte and polymer solid electrolyte, a ceramic/polyurethane composite polymer electrolyte (CPPE) based on Li0.35La0.55TiO3 (LLTO) and polyurethane (LPU) was prepared in this work. First, a linear polyurethane (LPU) was synthesized via 2,4-toluene diisocyanate (TDI) and poly(propylene oxide) (PPO), owing to the high ionic conductivity of LLTO and good mechanical property of LPU. The CPPE has a satisfactory lithium ion conductivity (3.8 × 10−4 S cm−1) at room temperature. Furthermore, the assembled LiFePO4|CPPE|Li battery exhibit excellent cycle performance at room temperature, the discharge capacity was still 149.8 mAh g−1 after 200 cycles and with a superior capacity retention of 97.8% at 0.5 °C. Additionally, the LiNi0.8Co0.1Mn0.1O2|CPPE|Li exhibited remarkable rate capacity that the initial capacity reached to 216.4 mAh g−1 at 0.1 °C and maintains the excellent specific capacity of 138 mAh g−1 at 1 °C. These findings suggest that CPPE provides a viable idea for the development of high-performance lithium batteries.

Hyperbranched Poly(Glycidol)‐Grafted Silica Nanoparticles for Enhancing Li‐Ion Conductivity of Poly(Ethylene Oxide)

AbstractSilica nanoparticles bearing hyperbranched polyglycidol (hbP) grafts are synthesized and blended with poly(ethylene oxide) (PEO) for the fabrication of composite solid polymer electrolytes (SPEs) for enhancing Li‐ion conductivity. Different batches of hbPs are prepared, namely, the 5th, 6th, and 7th with increasing molecular weights using cationic ring‐opening polymerization and grafted the hbPs onto the silica nanoparticles using quaternization reaction. The effect of end functionalization of hbP‐grafted silica nanoparticles with a nitrile functional group (CN–hbP–SiO2) on the ionic conductivity of the blends with PEO is further studied. High dipole moments indicate polar nature of nitriles and show high dielectric constants. Among all the hbPs, the 6th‐batch CN–hbP–SiO2 nanoparticles exhibit better ionic conductivity on blending with PEO showing ionic conductivity of 2.3 × 10−3 S cm−1 at 80 °C. The blends show electrochemical stability up to 4.5 V versus lithium metal.

Free-standing, high Li-ion conducting hybrid PAN/PVdF/LiClO4/Li0.5La0.5TiO3 nanocomposite solid polymer electrolytes for all-solid-state batteries

The free-standing PAN/PVdF/LiClO4/Li0.5La0.5TiO3 nanocomposite solid polymer electrolytes have been prepared by solution casting technique. The thermal stability of composite solid polymer electrolytes is evaluated by TG/DSC analysis, which reveals that the filler incorporated composite samples exhibit high thermal stability up to 500 °C. The XRD analysis demonstrated that the Li0.5La0.5TiO3 nanoparticles significantly reduced the crystallinity of the hybrid PAN/PVdF/LiClO4 polymer films. The FTIR spectra of PAN/PVdF/LiClO4/Li0.5La0.5TiO3 composites show the vibrational band of –CN stretching, CF2 asymmetric stretching, and Ti-O-La stretching which confirmed the complexation between polymer host matrices and Li0.5La0.5TiO3 nanoparticles. The 10 wt% Li0.5La0.5TiO3 nanoparticles embedded PAN/PVdF/LiClO4 solid polymer electrolyte possessed an excellent ionic conductivity of 1.43 × 10−3 S cm−1 at room temperature, which is far better than the filler-free samples (~ 10−5 S cm−1). The incorporation of Li0.5La0.5TiO3 nanoparticles into the PAN/PVdF/LiClO4 polymer electrolyte improves the concentration of free mobile lithium ions and develops Li-ion conduction channels within the crystalline framework. The PAN/PVdF/LiClO4/Li0.5La0.5TiO3 (10 wt%) composite electrolyte exhibited high thermal stability, good discharge capacities of 122, 105, 94, and 80 mAh g−1 at 0.1, 0.5, 1, and 2C rates, and good cycling stability.

A Comparative Study on Printable Solid Electrolytes toward Ultrahigh Current and Environmentally Stable Thin Film Transistors

AbstractPrinted oxide thin film transistors (TFTs) have outperformed their organic counterparts in the recent past; printable solid electrolytic insulators have also emerged as a suitable alternative to oxide dielectrics. In the present study, multiple composite solid polymer electrolytes (CSPEs) and an easy‐to‐formulate ion gel are fabricated and characterized for their double‐layer capacitance (CDL) values and the quality of electrostatic coupling. In the next step, alongside printed In2O3 as the semiconductor channel, the performance of the solid electrolytes is evaluated using printed top‐gate TFTs. The semiconductor ink formulation and the device architecture are optimized to ensure unsurpassed device performance. In effect, unprecedented transistor performance is observed for all the three electrolytic insulators, with drive currents >10 mA and linear mobility >100 cm2 V−1 s−1; a rigorous discussion on the reliability factors and the merit/demerit of the linear versus saturation mobility values suggests reporting of only the linear mobility, henceforth. Next, the lifetime studies on the electrolyte‐gated TFTs have shown superior environmental stability of the CSPE‐gated devices. The present study not only provides a recipe to formulate a set of high‐performance electrolytic gate insulators, but also offers a method to fabricate high‐current power transistors, using the standard printing techniques.

Plasticizer ethylene carbonate facilitates new ion coordination site in blend polymer electrolyte: Dielectric relaxation through two-parameter Mittag-Leffler function

A solid polymer electrolyte (SPE) film with improved mechanical and thermal stability has drawn significant attention in the field of polymer research due to their technological applications in energy storage devices. We have explored the electrical properties of the blend SPE composed of 20 wt. % poly(ethylene oxide), 80 wt. % polyvinylidene fluoride, and 35 wt. % NH4I by introducing a plasticizer ethylene carbonate (EC). A significant enhancement of electrical conductivity has been found in the composite SPE containing 80 wt. % of EC. We have confirmed the formation of a hydrogen bonding network between the carbonyl group (C=O) of EC and the cations NH4+. Therefore, EC facilitates the new coordination sites via the hydrogen bonding network with the cations NH4+, which eventually leads to the enhancement of conductivity up to a maximum value of 1.2 × 10−4 S/cm at 80 wt. % of EC. The increase in the relative percentage of contact ions over free ions at 80% of EC, as estimated from the FTIR study, is thus intriguing. Therefore, we have proposed an ion transport mechanism based on ion hopping through different coordinating sites mediated by EC. Dielectric relaxation of the composite SPE has been best delineated by a two-parameter Mittag-Leffler function. The exponents obtained from the fit of the experimental decay function with the two-parameter Mittag-Leffler function in the entire time domain are positive and less than one, suggesting non-Debye relaxation in the polymer composite system under investigation.

Nanocomposite with fast Li+ conducting percolation network: Solid polymer electrolyte with Li+ non-conducting filler

Solid polymer electrolytes (SPEs) have attracted considerable research interest because they are expected to solve the safety problems caused by the liquid electrolytes. However, the low ionic conductivity limits their practical applications. Constructing Li + fast conducting network in SPEs with Li + highly conducting ceramic fillers following the mixed matrix membrane concept have shown their limits in raising the Li + conductivity. Herein, a new strategy using Li + non-conducting fillers like CeO 2 nanowires, is proposed to construct a Li + fast conducting network through SPEs. CeO 2 nanowires can dissociate LiTFSI, which results in a high Li + conductivity through the SPEs near to the fiber surface. This experimental finding is confirmed by analytics (FT-IR, Raman and NMR) and theoretical calculations (DFT-MD and COHP). As a result, the network of interwoven CeO 2 nanowires helps form a continuous Li + fast conducting percolation network through the SPEs. The ionic conductivity of the composite SPEs with 10 wt% CeO 2 nanowires is greatly improved (1.1 × 10 −3 S cm −1 at 60 °C). The Li symmetric cells with this composite electrolyte exhibit good cyclic stability (without short circuiting after 2000 h), and the all-solid-state LiFePO 4 /Li cells present a superior cycling performance (remained 140 mA h g −1 after 100 cycles at 1 C). • Li + non-conducting nanofillers are used to construct Li + fast conducting network. • Dissociation process of LiTFSI on the CeO 2 surface is theoretically simulated. • Novel mechanism for the enhancement of Li + conductivity is proposed.

Bacterial Cellulose Composite Solid Polymer Electrolyte With High Tensile Strength and Lithium Dendrite Inhibition for Long Life Battery

The development of metallic lithium anode is restrained by lithium dendrite growth during cycling. The solid polymer electrolyte with high mechanical strength and lithium ion conductivity could be applied to inhibit lithium dendrite growth. To prepare the high‐performance solid polymer electrolyte, the environment‐friendly and cheap bacterial cellulose (BC) is used as filler incorporating with PEO‐based electrolyte owing to good mechanical properties and Li salts compatibility. PEO/LiTFSI/BC composite solid polymer electrolytes (CSPE) are prepared easily by aqueous mixing in water. The lithium ion transference number of PEO/LiTFSI/BC CSPE is 0.57, which is higher than PEO/LiTFSI solid polymer electrolyte (SPE) (0.409). The PEO/LiTFSI/BC CSPE exhibits larger tensile strength (4.43 MPa) than PEO/LiTFSI SPE (1.34 MPa). The electrochemical window of composite electrolyte is widened 1.43 V by adding BC. Density functional theory calculations indicate that flex of PEO chains around Li atoms is suppressed, suggesting the enhanced lithium ion conductivity. Frontier molecular orbitals results suggest that an unfavorable intermolecular charge transfer lead to achieve higher potential for BC composite electrolyte. All solid‐state Li metal battery with PEO/LiTFSI/BC CSPE delivers longer cycle life for 600 cycles than PEO/LiTFSI SPE battery (50 cycles). Li symmetrical battery using PEO/LiTFSI/BC CSPE could be stable for 1160 h.

Structural, optical and electrical properties of copper chloride filled polyvinyl chloride/polystyrene blend and its antifungal properties against Aspergillus avenaceus and Aspergillusterreus

Composite samples of polyvinyl chloride/polystyrene (PVC/PS) blend filled with copper chloride (CuCl2) were synthesized by the solution casting technique. The XRD and SEM analyses implied the presence of CuCl2 crystallites in PVC/PS polymeric blend. The FTIR spectra depicted the compatibility of the blend components and the formation of interactions between the functional groups of PVC/PS matrix and the Cu2+ ions. In the UV region, the UV/Vis. spectrum of PVC/PS showed the CUT-OFF range that was largely increased after the filler addition. Further, the optical parameters were determined. The dielectric and alternating current electrical conductivity spectra of polymer composites had been investigated at room temperature in the frequency range from 100 Hz to 1 MHz. The effect of prepared composite samples on the antifungal properties of Aspergillus avenaceus and Aspergillusterreus is scrutinized and has been tested by the agar disk diffusion technique. Further, the fungal biomass, catalase activity, and protein content were investigated. Moreover, SEM revealed that blend surfaces with 8% CuCl2 displayed a noticeable diminishing in fungal hyphal net framework, reduced density and inhibition on hyphal growth. The results indicated that composite samples with the highest CuCl2 concentration are more toxic to both fungal species. The multifunctional properties of these prepared samples depict their suitability as a base matrix for composite solid polymer electrolytes, dielectric substrate for the optoelectronic/microelectronic devices. Also, it can be utilized as a promising material for excellent UV/Vis. optical limiting and UV-protector and a novel antifungal agent to control the pathogenic fungi.

Study of a composite solid electrolyte made from a new pyrrolidone-containing polymer and LLZTO

Improving the safety and performance of lithium ion batteries (LIB) sparked the idea of using a solid electrolyte to construct all-solid-state ones. In this study, a composite solid polymer electrolyte based on Li6.40La3Zr1.40Ta0.60O12 (LLZTO) nanoparticles and a random copolymer, poly(vinyl pyrrolidone-co-poly(oligo(ethylene oxide) methyl ether methacrylate) (PPO), was successfully prepared and investigated in detail. The copolymer PPO is mixed with LiTFSI and LLZTO at different ratios and the Li conductivity and other electrochemical properties were studied. The copolymer matrix shows the highest ionic conductivity, 2.43 × 10−5 S/cm at 60 °C, at the content of 20 wt% LiTFSI, the highest lithium ion transference number is determined to be 0.33 at room temperature, and the electrochemical stability reaches 4.3 V vs. Li+/Li. Interestingly, when compounded with LLZTO nanoparticles, the ionic conductivity is not improved much. For example, the highest ionic conductivity increases a little to 2.74 × 10−5 S/cm at 60 °C when 5 wt% LLZTO is added. However, a large increase in electrochemical stability to 5.0 V is obtained for the sample of PPO-20%-10LLZTO. Both PPO and the composite electrolyte show good cycling performance during a plating/stripping experiment at a current density of 0.01 mA/cm2. The limited improvement of properties is possibly due to the poor interface contact between PPO and LLZTO nanoparticles. The result may shed light on the complexity of fabricating composite electrolytes using mixtures of polymer and lithium-conducting ceramics.

Room-temperature, high-voltage solid-state lithium battery with composite solid polymer electrolyte with in-situ thermal safety study

The low room-temperature ionic conductivity, narrow voltage window, and poor thermal stability of solid polymer electrolyte hinder the application of high energy density, safer solid-state lithium batteries (SLBs). Hence, we developed a novel composite solid polymer electrolyte (CSPE) with high room-temperature ionic conductivity (2.4 × 10−4 S cm−1), wide voltage window (~4.8 V), and excellent thermal stability (~330 °C) by combining Li6.4La3Zr1.4Ta0.6O12 ceramic filler with poly(vinylidene fluoride) (PVDF) polymer and bis(trifluoromethane)sulfonimide lithium (LiTFSI) salt. Free-standing, scalable, and mechanically robust CSPE separately coupled with LiFePO4 and high-voltage LiNi1/3Co1/3Mn1/3O2 cathodes vs lithium anode demonstrated stable cycling. More importantly, we in-situ measured the thermal stable window (177 °C) with a small heat release (189 J g−1) during the thermal runaway of the entire CSPE coin cell. In contrast, the liquid electrolyte cell delivered a depressing thermal stable window (157 °C) and release a significant amount of heat (812 J g−1). The superior thermal safety of CSPE cell can be ascribed to the solid-state property and outstanding thermal stability of the CSPE. Most notably, this work not only proposes a promising CSPE but also highlights a reference for in-situ quantitative study on the thermal safety of entire SLBs.