Solid Electrolyte Films Research Articles

Polyvinyl Butyral Solid Electrolyte Film and Its Electrochromic Laminated Safety Glass.

In recent years, the application of electrochromic laminated safety glass has attracted more and more attention, relying on polyvinyl butyral (PVB) solid electrolyte film. Herein, the ionic conductivity (σ) of the PVB film has been improved by a cross-linked structure and blended with LiClO4, which can reach as high as 1.78 × 10-4 S cm-1 at room temperature. In addition, their excellent comprehensive characteristics have been confirmed, such as mechanical strength, high visible light transmittance (>90%), high bond strength (4.2 MPa), and excellent thermal stability. Based on the PVB film above, WO3-laminated electrochromic devices with 5 × 5 cm2 and 10 × 10 cm2 areas are constructed. They can remain stable after 20 000 cycles monitored by cyclic voltammetry curves, indicating the PVB solid polymer electrolyte (PSPE) with a cross-linked structure has the potential commercial viability of large-area electrochromic devices (ECDs).

In situ synthesis and structural morphology analysis of 3D porous hierarchical V2O5 films for transmissive-to-black all-solid-state electrochromic devices

3D, porous, low-dimensional, and nanostructured V2O5 films have significant potential for application in ECDs, but their development is still in its nascency. This paper reports a facile strategy of using PEG as a structure-directing agent and short-time heat treatments to obtain 3D, porous, and hierarchical V2O5 films comprising interpenetrating stacked ultra-long nanowire surfaces and nanorod/nanosheet mixed interiors deposited on ITO-glass substrates. The mechanism of morphological transformation was studied in detail, and the analysis shows that the formation of such special structured films is a synergetic result of the guided intercalation of PEG, atomic rearrangement, Ostwald ripening, anisotropy of crystal growth, and orientation attachment mechanism. Among them, the preferred PEG addition amount of 25 % for the 350-3-V2O5 film was applied in two types of all-solid-state ECDs: one using a gel quasi-solid electrolyte and the other using a solid-film electrolyte. The 350-3-V2O5 film served as an ion storage coating and WO3 was the electrochromic layer. These devices achieved ideal reversible switching of transmissive-to-black electrochromic characteristics. Notably, the ‘Integrated-Type’ ECD, composed of inorganic all-solid-state films, has a large optical modulation range ΔT = 72.0 %, rapid switching responses (colouration 25.4 s and bleaching 20.8 s), and sustained electrochromic performance.

Ion Conduction Mechanism in Polymer Blend Electrolyte Films

AbstractThis paper presents the development of the blend polymer solid electrolyte films (BPSE) for potential applications in electrochemical devices. Two host polymers, polyvinyl alcohol (PVA) and polymethyl methacrylate (PMMA), along with the salt KI, are employed to create the solid polymer electrolytes (SPEs). The synthesis involves varying the weight percentage of salt within the SPEs to investigate its impact on the material properties. Conductivity measurements are conducted using AC impedance spectroscopy, unveiling the conductivity behavior of the BPSEs. Additionally, surface morphology is characterized using polarized optical microscopy (POM) at 10 pixel resolution, offering a detailed examination of the film's microstructure. This comprehensive study not only contributes to the understanding of the fundamental properties of BPSEs but also opens avenues for their utilization in various electrochemical applications.

Binary Biomass-Based Electrolyte Films for High-Performance All-Solid-State Supercapacitor.

Solid-state electrolytes have received widespread attention for solving the problem of the leakage of liquid electrolytes and effectively improving the overall performance of supercapacitors. However, the electrochemical performance and environmental friendliness of solid-state electrolytes still need to be further improved. Here, a binary biomass-based solid electrolyte film (LSE) was successfully synthesized through the incorporation of lignin nanoparticles (LNPs) with sodium alginate (SA). The impact of the mass ratio of SA to LNPs on the microstructure, porosity, electrolyte absorption capacity, ionic conductivity, and electrochemical properties of the LSE was thoroughly investigated. The results indicated that as the proportion of SA increased from 5% to 15% of LNPs, the pore structure of the LSE became increasingly uniform and abundant. Consequently, enhancements were observed in porosity, liquid absorption capacity, ionic conductivity, and overall electrochemical performance. Notably, at an SA amount of 15% of LNPs, the ionic conductivity of the resultant LSE-15 was recorded at 14.10 mS cm-1, with the porosity and liquid absorption capacity reaching 58.4% and 308%, respectively. LSE-15 was employed as a solid electrolyte, while LNP-based carbon aerogel (LCA) served as the two electrodes in the construction of a symmetric all-solid-state supercapacitor (SSC). The SSC device demonstrated exceptional electrochemical storage capacity, achieving a specific capacitance of 197 F g-1 at 0.5 A g-1, along with a maximum energy and power density of 27.33 W h kg-1 and 4998 W kg-1, respectively. Furthermore, the SSC device exhibited highly stable electrochemical performance under extreme conditions, including compression, bending, and both series and parallel connections. Therefore, the development and application of binary biomass-based solid electrolyte films in supercapacitors represent a promising strategy for harnessing high-value biomass resources in the field of energy storage.

Flexible magnesium-ion-conducting solid poly-blend electrolyte films for magnesium-ion batteries

Solid biodegradable polymer electrolyte systems are considered the optimal choice for energy storage devices because they are both cost-effective and energy-efficient. A solid blend polymer electrolyte (SBPE) membrane capable of transporting magnesium ions was prepared using a mixture of 70 wt% methylcellulose, 30 wt% chitosan, and varying wt% magnesium perchlorate salt. X-ray diffraction analysis revealed an increase in the amorphous nature caused by the inclusion of Mg(ClO4)2 salt in the polymer blend matrix. A Fourier transform infrared spectroscopy study of samples containing varying salt concentrations revealed secondary interactions between polymer segments and salt, which provides the basis for energy density. Moreover, through impedance analysis, it was determined that the bulk resistance decreased with increasing salt concentration. The SBPE containing 30 wt% magnesium perchlorate exhibited the highest ionic conductivity, with a value of 2.49 × 10–6 S cm−1. A comprehensive evaluation of the ion transport parameters, including mobility, carrier density, and diffusion, was conducted for the prepared electrolyte samples. Notably, an ionic transference number (tion) of approximately 0.83 was observed for the SBPE sample with 30 wt% magnesium salt, indicating ions’ prevalence as the system’s primary charge carriers. Electrochemical analyses demonstrated that the SBPE with the highest ion conductivity possessed an electrochemical stability window (ESW) of 1.92 V. Additionally, the thermal characteristics of the samples were evaluated using thermogravimetric analysis (TGA) to assess the thermal stability of the electrolyte. Finally, the highest conducting polymer electrolyte was employed to construct a primary magnesium battery, and its discharge profile with different cathode materials was studied. Based on these findings, the current study suggests an environmentally friendly, biodegradable, and economically viable electrolyte option suitable for separator cum electrolytes in magnesium-ion batteries.

Synthesis and Characterization of a Biocompatible, and Flexible Solid-Electrolyte for Zn-MnO2 Batteries

The new generation of flexible wearable electronics is becoming one of the most in-demand wearable tech in most parts of the world, be it for regular use or for medical reasons, which gives rise to the need for the development of safe and flexible rechargeable batteries. Some of the most basic requirements for such batteries constitute the ease of use, flexibility, mechanical strength, and environmental friendliness. This can be achieved by carefully designing the electrolyte for the battery such that it fulfills the mentioned properties without compromising the electrochemical performance of the battery. This study sheds light on the development of a safe, flexible, and environmentally friendly solid electrolyte film based on a biopolymer. The electrolyte film derived from Chitosan, which is a biocompatible biopolymer, offers various advantages over the conventional liquid electrolytes. When soaked in an alkaline liquid, KOH, this Chitosan-film can be used as an efficient electrolyte for Zn-MnO2 battery chemistry. According to optical imaging, the incorporation of freeze drying for the preparation of the solid electrolyte films provided a lamellar structure with a microporous morphology. Higher concentrations of Chitosan enabled the film to absorb and retain increased amount of KOH because of the hydrogen bonds present between the Chitosan molecules and KOH, which helped in enhancing the ionic conductivity (IC) of the freeze-dried electrolyte, i.e., 300-600 mS/cm, at a thickness of 150-170µm. Additionally, the obtained electrolyte demonstrated exceptional mechanical strength and flexibility which also makes it a promising solid electrolyte for Zinc metal batteries, as it has a potential to impede the progression of Zn dendrites during cycling, thereby improving the stability and lifespan of the battery.

Interfacial Stability and Dry Room Compatibility of Na3PS4 Solid-State Electrolyte Dry Films

Sodium solid-state batteries (NaSSBs) employing nonflammable sulfide solid-state electrolytes (SSEs) are a promising solution for large-scale energy storage due to their safety, low cost, and high volumetric energy density. However, the state-of-the-art pellet type NaSSBs face challenges such as inadequate humidity stability and poor mechanical properties, resulting in nonnegligible ohmic losses, limited crucial current density, and low energy density. Reducing the thickness of the SSE layer and improving the anti-moisture stability is crucial to realize the scalable production and practical applications of NaSSBs. To address these challenges, a dry process was developed to fabricate Na3PS4 (NPS) solid electrolyte film with high retention of intrinsic ionic conductivity, and increased flexibility by incorporating only 0.2wt% of polytetrafluoroethylene (PTFE) binders. Notably, it is found that PTFE with hydrophobic groups improves moisture stability by reducing the available adsorption sites for H2O on the surface. After 24 hours exposure in a dry room condition (RH 0.1%), the NPS film exhibits more than 90% conductivity retention and stable cycling for up to 100 cycles, representing a significant step towards the scalable production and practical use of low-cost NaSSBs. Our findings may also guide the development of robust lithium-based sulfide electrolyte films, such as Li6PS5Cl.

Fabrication of 60μm-Thick Free-Standing Bilayer Solid Electrolytes for Solid-State Batteries Using Solution Processing and Lamination

Development of solid-state batteries with a high voltage cathode and lithium metal anode could enable high energy density while avoiding safety issues of flammable liquid electrolytes. However, the solid electrolyte (SE) should meet multiple requirements, including 1) electrochemical stability at both the cathode and anode side interfaces, 2) small thickness (tens of μm) to maximize energy density of the cell, and 3) fabrication with a scalable manufacturing method. Using bilayer SEs with different electrochemical stability windows could enable stability at both cathode|SE and anode|SE interfaces. In this work, we developed a manufacturing process to fabricate thin (60 μm) free-standing bilayer SE films from slurry casting and lamination, which can be used for large scale manufacturing of SSBs.Halide SE (Li3InCl6) and sulfide SE (Li6PS5Cl) were slurry casted on different substrates, and then were dried in vacuum before being laminated onto each other to make a free-standing bilayer film. The parallel slurry casting approach eliminates cross-compatibility requirements of the solvents used for slurry preparation. The resulting bilayer films after densification were pin-hole free without intermixing between the two phases. The ionic conductivity of the bilayer SE film was ~70% of the bilayer SE pellet (1 mm thickness in total) made with a conventional powder pressing method. However, because the thickness of bilayer SE film (60 μm) was much smaller than the bilayer SE pellet (1 mm), the bilayer SE film had ~10x lower area-specific resistance (ASR) compared to the bilayer SE pellet. Because of the lower total cell resistance, the cell made with the bilayer SE film had a better rate capability compared to the reference cell in pellet geometry.The strategy developed in this work could be integrated into current manufacturing infrastructure of battery fabrication as it is based on slurry casting, which is already a well-established fabrication method for lithium-ion batteries. Moreover, it could be used to fabricate multi-layered solid-state architectures in general, which are challenging to manufacture due to solvent compatibility issues during slurry casting. The study will assist the progress of solid-state battery manufacturing by providing a scalable manufacture method to prepare thin free-standing bilayer SEs.

Influence of Lithium Triflate Salt Concentration on Structural, Thermal, Electrochemical, and Ionic Conductivity Properties of Cassava Starch Solid Biopolymer Electrolytes.

Cassava starch solid biopolymer electrolyte (SBPE) films were prepared by a thermochemical method with different concentrations of lithium triflate (LiTFT) as a dopant salt. The process began with dispersing cassava starch in water, followed by heating to facilitate gelatinization; subsequently, plasticizers and LiTFT were added at differing concentrations. The infrared spectroscopy analysis (FTIR-ATR) showed variations in the wavenumber of some characteristic bands of starch, thus evidencing the interaction between the LiTFT salt and biopolymeric matrix. The short-range crystallinity index, determined by the ratio of COH to COC bands, exhibited the highest crystallinity in the salt-free SBPEs and the lowest in the SBPEs with a concentration ratio (Xm) of 0.17. The thermogravimetric analysis demonstrated that the salt addition increased the dehydration process temperature by 5 °C. Additionally, the thermal decomposition processes were shown at lower temperatures after the addition of the LiTFT salt into the SBPEs. The differential scanning calorimetry showed that the addition of the salt affected the endothermic process related to the degradation of the packing of the starch molecules, which occurred at 70 °C in the salt-free SBPEs and at lower temperatures (2 or 3 °C less) in the films that contained the LiTFT salt at different concentrations. The cyclic voltammetry analysis of the SBPE films identified the redox processes of the glucose units in all the samples, with observed differences in peak potentials (Ep) and peak currents (Ip) across various salt concentrations. Electrochemical impedance spectroscopy was used to establish the equivalent circuit model Rf-(Cdl/(Rct-(CPE/Rre))) and determine the electrochemical parameters, revealing a higher conduction value of 2.72 × 10-3 S cm-1 for the SBPEs with Xm = 17 and a lower conduction of 5.80 × 10-4 S cm-1 in the salt-free SBPEs. It was concluded that the concentration of LiTFT salt in the cassava starch SBPE films influences their morphology and slightly reduces their thermal stability. Furthermore, the electrochemical behavior is affected in terms of variations in the redox potentials of the glucose units of the biopolymer and in their ionic conductivity.

Towards a scalable production of β-Li3PS4-based all-solid-state batteries: Optimizing pressing parameters of the tape-casted solid electrolyte and composite cathode films

Pressing of all-solid-state batteries (ASSBs) components is one of the most important processes for scalable production. Henceforth, pressing parameters (pressure and temperature) for β-Li3PS4 (β-LPS) solid electrolyte (SE) separator films and LiNi0.6Co0.2Mn0.2 (NCM622)/β-LPS composite cathode films prepared by a slurry-based process were investigated and optimized. Compression of the β-LPS film at a temperature of 100 °C led to higher ionic conductivity than cold-pressed films. Raman and X-ray photoelectron spectroscopic analyses revealed no changes in the chemical nature of β-LPS material after hot pressing. Interestingly, time-of-flight secondary ion mass spectrometric (ToF-SIMS) analyses indicated a binder enrichment in the upper layers of the hot-pressed film. In a similar trend, increasing compression and temperature resulted in higher densification of NCM622/β-LPS composite cathode films. Based on galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectroscopy (EIS) measurements, hot-pressed composite cathode at 200 MPa/100 °C exhibited a higher coverage percent of catholyte on cathode active material and a greater Li+ diffusion coefficient (DLi+) than cold-pressed one at 200 MPa/20 °C. Cycling tests of “Li–In│β-LPS│NCM/β-LPS” ASSBs with hot-pressed films displayed better cycling performance than that with cold-pressed ones, attributed to the higher concentration of electrochemically active NCM in close contact with β-LPS catholyte.

A Multifunctional Additive Based on the Cation-Anion Synergistic Effect for Highly Stable Zinc Metal Anodes.

The Zn dendrite and hydrogen evolution reaction have been a "stubborn illness" for the life span of zinc anodes, which significantly hinders the development of aqueous zinc batteries (AZBs). Herein, considering the ingenious molecular structure, a multifunctional additive based on the synergistic regulation of cations and anions at the interface is designed to promote a dendrite-free and stable Zn anode. Theoretical calculations and characterization results verified that the electrostatic shield effect of the cation, the solvation sheath structure, and the bilayer structural solid electrolyte film (SEI) jointly account for the uniform Zn deposition and side reaction suppression. Ultimately, a remarkably high average Coulombic efficiency (CE) of 99.4% is achieved in the Zn||Cu cell for 300 cycles, and a steady charge/discharge cycling over 3000 and 300 h at 1.0 mA cm-2/1.0 mAh cm-2 and 10 mA cm-2/10 mAh cm-2 is obtained in the Zn||Zn cell. Furthermore, the assembled full battery demonstrates a prolonged cycle life of 2000 cycles.

ARJUNA: An Electrochemical Interface Mapping Probe for Solid-State Batteries

Solid-state batteries (SSBs) are promising candidates for next-generation energy storage, although their performance can be compromised by interfacial heterogeneity within the electrolyte. Furthermore, ensuring the quality of large form-factors electrolyte film is crucial for establishing a robust manufacturing platform for solid-state batteries. Herein, we report on the use of ARJUNA, an electrochemical interface mapping system, to characterize heterogeneities at solid electrolyte interfaces and to serve as a quality control system for SSB manufacturing. In addition to spatial mapping, the proposed system can also probe the interface behavior as a function of pressure and temperature. We present the operating principle, design, instrumentation, and evaluation of the system alongside a typical hybrid solid electrolyte produced using two common manufacturing processes. This report showcases the capability of ARJUNA to probe the heterogeneity and quality of processed solid electrolyte films.

Characterization of lithium phosphorus oxide thin film libraries by laser-induced breakdown spectroscopy imaging: A step towards high-throughput quantitative analyses

Elemental analysis is a challenge for the development of High Throughput Experimentation (HTE) on thin film materials, and an even greater one when it comes to screening lithium-containing battery materials. In this regard, Laser-Induced Breakdown Spectroscopy has been evaluated here for the quantitative analysis of lithium in libraries of Li2.3PO3.65 amorphous solid electrolyte films. The LIBS analysis of multiple samples with the same composition, but with thicknesses ranging from 50 to 700 nm, has revealed a linear trend in the intensity ratio of the Li I 610.35 nm and P I 214.91 nm emission lines, opening the way to rapid quantitative analysis of material libraries. The sensitivity of the technique finally allowed the detection of the Li I 670.79 nm emission line for film thicknesses down to 4 nm, corresponding to 0.2% of the ablated volume, or about 0.15 pg of Li.

High Ionic Conductive, Mechanical Robust Sulfide Solid Electrolyte Films and Interface Design for All‐Solid‐State Lithium Metal Batteries

AbstractAll‐solid‐state lithium batteries (ASSLBs) are considered a promising technology for next‐generation energy storage systems due to their inherent safety. However, the conventional laboratory‐scale ASSLBs reported to date are based on pellet‐type structures with thick solid electrolyte layers, leading to challenges related to low energy densities and poor electrochemical performance. In this study, porous adhesive poly(ethylene vinyl acetate) (PEVA) scaffolds and polytetrafluoroethylene (PTFE) binders are utilized to interweave sulfide solid electrolytes into freestanding films with an ultra‐low thickness of 40 µm, high ionic conductivity of 1.1 mS cm−1, and a high tensile strength of 74 MPa. To mitigate the reduction reaction between the PTFE binder and the lithium metal anode, a Li3N‐rich solid electrolyte interphase (SEI) in situ on lithium metal is formed, and the assembled symmetric cell shows excellent cycling stability within 800 h at the current density of 0.2 mA cm−2 and room temperature. Additionally, the ASSLBs using oxidatively stable Li2ZrCl5F in the composite cathode and the prepared solid electrolyte film demonstrate exceptional cycling performance and fast‐charging capability, with a high cell‐level energy density of 354.4 Wh kg−1. The ASSLBs prepared by coupling E‐LPSCl film and stable interface design exhibit excellent electrochemical performance and a high cell‐level energy density.

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.

Built‐In Electric Field of In Situ Formed Artificial Interface Layer Induces Fast and Uniform Sodium‐Ions Transmission to Achieve a Long‐Term Stable Sodium Metal Battery Under Harsh Conditions

AbstractSodium metal batteries have emerged as potential rivals to lithium‐ion batteries. Nevertheless, maintaining a stable sodium metal anode under harsh conditions (current density >10 mA cm−2) is extremely challenging. The primary issue is the highly reactive sodium metal continuously reacts with the electrolyte to form a thick and loose solid electrolyte film. The tip effect causes sodium ions (Na+) accumulated in the bulge resulting in uneven deposition. In this paper, a unique artificial interfacial layer (Ag nanoparticles distributed in NaClO4‐based matrix) is prepared on the surface of a metallic sodium anode using in situ displacement reaction. Ag particles arranged at the bottom of the artificial layer act as effective nucleation sites helping Na+ deposit uniformly, while the built‐in electric field formed between Ag in the middle/top of the artificial layer and the sodium accelerates the migration of Na+ in the interfacial layer during the deposition and reduce the polarization. Such important properties further allow the steady operation of modified sodium metal batteries in very harsh conditions. The symmetric battery achieves reversible stripping/plating for over 1000 h under high current density (10 mA cm−2). Moreover, the full cell coupled with a high‐loading Na3V2(PO4)3 cathode (20 mg cm−2) presents a stable cycle performance.

Room-temperature fabrication of garnet-type solid-electrolyte: Optimizing particle size for high ionic conductivity

Dense and uniform Li6.25Al0.25La3Zr2O12 (Al-doped LLZO) solid-electrolyte film of ∼24 µm thickness is successfully fabricated by room temperature aerosol deposition (AD) method. The process optimization study revealed that careful control of particle size and morphology is one of critical determinants in the development of a compact AD membrane. Notably, our method facilitated an impressive ionic conductivity of approximately 10−5 S cm−1, bypassing the necessity for post-annealing processes, a milestone in itself. However, it is hypothesized that the attained conductivity is somewhat restrained by factors such as smaller grain size and potential surface degradation due to moisture exposure during fabrication, indicating avenues for further research. Looking forward, detailed investigations into the film's microstructure and its impact on transport properties will be a focal point, alongside potential enhancements through post-annealing and particle coating strategies. This research hints at a promising trajectory for the development of high-efficiency solid-state battery technology.

Investigation on the properties of PVDF matrix composite porous gel polymer electrolyte doped with lithium silicon gel

Gel polymer electrolytes are safer because they do not contain liquid phase components. On this basis, the introduction of inorganic fillers effectively overcame the problem of low ionic conductivity of polymer electrolyte at room temperature, and the constructed composite polymer electrolyte (CPEs) combined the advantages of inorganic fillers and polymer segments. In this paper, lithium silicon gel SiO2(Li+) was prepared by in-situ polymerization and sol-gel method, and doped in PVDF composite porous gel polymer electrolyte film prepared by immersion precipitation method. The electrochemical properties and surface topography of lithium iron phosphate were investigated by mounting a bonded lithium iron phosphate quasisolid lithium-ion battery. The experimental results show that the solid electrolyte film modified by SiO2(Li+) has good electrochemical and a certain reference value.

(Digital Presentation) Fabrication and Characterization of 4Sc4YSZ/LSM-4Sc4YSZ Novel Electrode-Supported Half-Cell Composition for Solid Oxide Electrochemical Cells

Scandium and Yttrium co-doped ZrO2 (4Sc4YSZ) thin film solid electrolyte has exhibited improved conductivities and phase stability by considering advantages of both Y-doped zirconia (YSZ) and Sc-doped zirconia (ScSZ). To further investigate the promising properties of this co-doped composition, a solid electrolyte thin film of 4Sc4YSZ deposited on a new LSM-4Sc4YSZ composite electrode was conducted. In this study, the effect of pre-sintering temperature (1000°C, 1150°C, and 1300°C) of the LSM-4Sc4YSZ electrode substrate in the deposition of a dense solid electrolyte film was studied. X-ray diffraction (XRD) analysis of all the LSM-4Sc4YSZ composite electrodes revealed distinct phases of rhombohedral LSM and cubic 4Sc4YSZ. Also, the thin film electrolytes exhibited cubic 4Sc4YSZ with calculated lattice parameters of a equal to 5.10 Å, 5.10 Å, and 5.09 Å deposited on the electrode substrate pre-sintered at 1000°C, 1150°C, and 1300°C, respectively. The obtained lattice parameters were comparable with the reference LSM (PDF card no. 000-053-0058) and 4Sc4YSZ (PDF card no. 01-080-4524). Morphological characterization via scanning electron microscopy (SEM) showed that the thin film solid electrolyte with LSM-4Sc4YSZ electrode pre-sintered at 1300°C has a relatively dense microstructure than those with lower pre-sintering electrode temperatures. In addition, the thin film deposited on the 1300°C LSM-4Sc4YSZ obtained the lowest average thickness of 12.81 µm as compared to the 1000°C and 1150°C LSM-4Sc4YSZ with thickness values of 38.32 µm and 27.99 µm, respectively. The electrochemical performance of the fabricated half-cell was analyzed using electrochemical impedance spectroscopy (EIS). The total conductivity, as calculated from the EIS results, of 4Sc4YSZ/LSM-4Sc4YSZ half-cell pre-sintered at 1300°C is 0.0726 S/cm at 700°C under oxygen gas flow environment.

High-performance lithium metal batteries enabled by a nano-sized garnet solid-state electrolyte modified separator

Lithium metal batteries, as one of high-energy-density batteries, have become the hot spot for numerous researchers. However, serious safety problems caused by lithium dendrites need to be urgently addressed. In this work, we introduce nano-sized garnet solid-state electrolyte Li6.75La3Zr1.75Ta0.25O12 (LLZTO) to fabricate a high-safety thin composite solid electrolyte membrane (20 μm) that is simple in process and facile in preparation conditions. The thin composite solid electrolyte film has better wrinkle resistance than ordinary polyethylene (PE) films and can guide the uniform deposition of lithium ions and suppress the growth of lithium dendrites. The thermal stability of the PE separator modified by double-coated nano-sized LLZTO is enhanced, which exhibits only 30 % shrinking percentage at 140 °C in comparison with 90 % of ordinary PE. The lithium symmetric cell with the nano-sized garnet solid-state electrolyte modified separator is relatively stable after 1000 h cycling at the current density of 1 mA cm−2. More importantly, after adding the adaptable electrolyte, the lithium metal battery assembled with modified separator can be maintained for 150 cycles (0.2C) stably with a high cathode active material loading of NCM811 (18 mg cm−2), and can maintain above 95 % Coulombic efficiency on average. Our work provides a pathway for the preparation of superior thermal stability and high safety garnet-based composite membranes towards lithium metal batteries.