Reduction Of Interfacial Resistance Research Articles

Ionic Conductivity Analysis of NASICON Solid Electrolyte Coated with Polyvinyl-Based Polymers

The global environmental crisis necessitates reliable, sustainable, and safe energy storage solutions. The current systems are nearing their capacity limits due to the reliance on conventional liquid electrolytes, which are fraught with stability and safety concerns, prompting the exploration of solid-state electrolytes, which enable the integration of metal electrodes. Solid-state sodium-ion batteries emerge as an appealing option by leveraging the abundance, low cost, and sustainability of sodium. However, low ionic conductivity and high interfacial resistance currently prevent their widespread adoption. This study explores polyvinyl-based polymers as wetting agents for the NASICON-type NZSP (Na3Zr2Si2PO12) solid electrolyte, resulting in a combined system with enhanced ionic conductivity suitable for Na-ion solid-state full cells. Electrochemical impedance spectroscopy (EIS) performed on symmetric cells employing NZSP paired with different wetting agent compositions demonstrates a significant reduction in interfacial resistance with the use of poly(vinyl acetate)—(PVAc-) based polymers, achieving an impressive ionic conductivity of 1.31 mS cm−1 at room temperature, 63.8% higher than the pristine material, notably reaching 7.36 mS cm−1 at 90 °C. These results offer valuable insights into the potential of PVAc-based polymers for advancing high-performance solid-state sodium-ion batteries by reducing their total internal resistance.

A review on “Growth mechanisms and optimization strategies for the interface state of solid‐state lithium‐ion batteries”

AbstractAt present, the basic structural mechanisms and improvement methods of solid electrolyte interfaces (SEIs) are still in the research stage. Although many researchers have observed the problems of SEIs by various characterization methods, they still cannot analyze the subtle mechanisms. In this paper, we summarize the formation of SEIs, surface morphology, carrier transport, factors leading to interface challenges, and the progress of research to build better interfaces. Among them, strategies to inhibit the formation and growth of lithium dendrites are one of the focuses of this paper. In addition, another research focus of this paper is to reduce the interfacial resistance by constructing interfacial layers, electrolyte additives, and solid electrolytes. From the current development of battery interface improvement, the inhibition of lithium dendrites and the reduction of interfacial resistance are the most effective methods to improve the interfacial stability. Finally, the article also summarizes the research progress in solving the SEI, analyzes the future research trends for improving the SEI, and gives the research directions.

Self‐Formed Fluorinated Interphase with Fe Valence Gradient for Dendrite‐Free Solid‐State Sodium‐Metal Batteries

AbstractThe poor anode/electrolyte compatibility and dendrite growth have discouraged the development of solid‐state sodium‐metal batteries (SSSMBs). Here, a self‐formed interphase with a unique Fe valence gradient is designed to stabilize the anode interface of Na3Zr2Si2PO12 solid electrolyte. This interphase consists of a Fe‐ and NaF‐containing outer layer near the Na anode and a Fe2+/Fe3+‐rich inner layer, which are in situ formed upon contacting Na with a sodiophilic α‐Fe2O3‐xFx interlayer specially coated on Na3Zr2Si2PO12. The NaF and Fe prevents continuous reduction reactions and homogenize the electric filed, while the iron oxide gradient layer offers buffering Na storage during plating, further suppressing dendrite growth. Benefiting from the dynamically stable, low‐impedance and dendrite‐free interface, the symmetric cells achieve a 20‐fold reduction in interfacial resistance and a fourfold enhancement in critical current density (CCD) at 25 °C, and powered a high CCD of 1.9 mA cm‐2 and a 1000‐h cycle life at 1 mA cm‐2 at 80 °C. The corresponding SSSMBs based on Na3V2(PO4)3 cathodes deliver a capacity retention rate of 96% over 120 cycles at 1 C. This robust interface design supports one of the best electrochemical performances ever reported and offers a comprehensive solution to stabilize the Na3Zr2Si2PO12/Na interface toward practical SSSMBs.

Rapid sintering of Li6.5La3Zr1Nb0.5Ce0.25Ti0.25O12 for high density lithium garnet electrolytes with current induced in situ interfacial resistance reduction

In this paper, a high-entropy type lithium garnet is presented that rapidly sinters/densifies from the precursors, with favourable electrochemical properties in terms of both conductivity and limiting dendrite propagation.

Interface Stability between Na3Zr2Si2PO12 Solid Electrolyte and Sodium Metal Anode for Quasi-Solid-State Sodium Battery

Solid electrolytes are renowned for their nonflammable, dendrite-blocking qualities, which also exhibit stability over large potential windows. NASICON-type Na1+xZr2SixP3-xO12 (NZSP) is a well-known solid electrolyte material for sodium metal batteries owing to its elevated room temperature sodium-ion (Na+) conductivity and good electrochemical stability. Nevertheless, the strong electrode–electrolyte interfacial resistance restricts its implementation in sodium metal batteries and remains a significant challenge. In this work, we present an efficacious process to enhance the sodium wettability of Na3Zr2Si2PO12 by sputtering a thin gold (Au) interlayer. Our experimental investigation indicates a substantial reduction in interfacial resistance, from 2708 Ω cm2 to 146 Ω cm2, by employing a fine Au interlayer between the Na metal and the NZSP electrolyte. The symmetrical Na||NZSP||Na with a gold interlayer cell shows a steady Na stripping/plating at a high current density of 320 µA cm−2. A quasi-solid-state battery, with NaFePO4 (NFP) as a cathode, metallic sodium as an anode, and a Au-sputtered NZSP electrolyte with polypropylene (PP) soaked in electrolyte as an intermediate layer on the cathode, exhibited a discharge capacity of 100 mAh g−1 and a ~100% Coulombic efficiency at 50 μA cm−2 after the 50th charge/discharge cycle at room temperature (RT).

Immense Reduction in Interfacial Resistance between Sulfide Electrolyte and Positive Electrode.

Low interfacial resistance between the solid sulfide electrolyte and the electrode is critical for developing all-solid-state Li batteries; however, the origin of interfacial resistance has not been quantitatively reported in the literature. This study reports the resistance values across the interface between an amorphous Li3PS4 solid electrolyte and a LiCoO2(001) epitaxial thin film electrode in a thin-film Li battery model. High interfacial resistance is observed, which is attributed to the spontaneous formation of an interfacial layer between the solid electrolyte and the positive electrode upon contact. That is, the interfacial resistance originates from an interphase mixed layer instead of a space charge layer. The introduction of a 10 nm thick Li3PO4 buffer layer between the solid electrolyte and positive electrode layers suppresses the formation of the interphase mixed layer, thereby leading to a 2800-fold decrease in the interfacial resistance. These results provide insight into reducing the interfacial resistance of all-solid-state Li batteries with sulfide electrolytes by utilizing buffer layers.

Super-lubricating hybrid elastomer with rapid photothermal sterilization and strong anti-cell adhesion

Silicone elastomer has been widely used as raw materials for manufacturing medical soft catheters. The surface properties of silicone elastomer, such as bactericidal performance, anti-cell adhesion and surface lubrication, are essential features to determine whether the catheters can fully play the role in transporting liquid or gas to organisms. To realize the integration of interfacial functions, we develop a super-lubricating hybrid elastomer with rapid photothermal sterilization and strong anti-cell adhesion capacities. Specifically, a hybrid elastomer is prepared by grafting one kind of lubricating polymers with anti-cell adhesion onto near-infrared (NIR) photothermal Fe3O4 nanoparticles-loaded polydimethylsiloxane substrate. Through the hydration lubrication, a super-low friction is realized on the surface of this hybrid elastomer. More importantly, this elastomer achieves a rapid photothermal bactericidal performance by local heating triggered by NIR irradiation. In addition, this hybrid elastomer shows a strong anti-adhesion effect against HepG2 cells. Based on these merits, this hybrid elastomer shows great potential for producing biomedical catheters that may realize anti-tissue adhesion, rapid sterilization, and reduction of interfacial resistance between catheters and biological tissues.

STEM-EELS Spectrum Imaging of an Aerosol-Deposited NASICON-Type LATP Solid Electrolyte and LCO Cathode Interface

All-solid-state batteries (ASSBs) are promising candidates for application as next-generation high-power supply and storage devices in electric vehicles. ASSBs offer excellent safety and a high energy density; however, the high interfacial resistance between the positive electrode and solid electrolyte due to solid–solid contact reactions at elevated temperatures limits their applications. To address these issues, the effect of thermal annealing on the interfacial structure between a sodium super ionic conductor (NASICON)-type Li1.3Al0.3Ti1.7(PO4)3 (LATP) solid electrolyte and a LiCoO2 (LCO) cathode in an ASSB fabricated by aerosol deposition was investigated experimentally. Specifically, spectrum imaging was conducted by combining scanning transmission electron microscopy and electron energy loss spectroscopy. Metastable degraded low-density transition layers were formed between LATP and LCO in the as-deposited sample. A significant reduction in interfacial resistance was achieved after thermal annealing at 250–300 °C, which was mainly attributed to structural recovery in this temperature range. However, thermal annealing at 400 °C resulted in increased interfacial resistance due to the formation of a Co3O4-like spinel blocking layer at the LATP/LCO interface. These findings provided valuable insights into the electronic properties of the ASSB composite under investigation and were consistent with theoretical predictions of Li and O transfer between the layers due to thermal annealing.

The electrochemical performance of Li2CuO2–CuO composite-treated LiNi0.6Co0.2Mn0.2O2 cathode for all-solid-state lithium batteries

All-solid-state lithium batteries (ASSLB) are promising candidates for next-generation devices thanks to their safety and high energy density. However, there is an important problem at the interface between the cathode and solid electrolyte which must be addressed for ASSLB. To overcome this problem, the Li2CuO2–CuO composite-treated Li(Ni0.6Co0.2Mn0.2)O2 (NCM) was used as the cathode with a sulfide-based solid electrolyte for ASSLB. However, the sulfide-based electrolyte has high interfacial resistance because of the side reaction caused by the interfacial instability between sulfide electrolytes and oxide cathodes. Li2CuO2–CuO composite is an effective material for treatment of ASSLB cathodes. In particular, the 1 wt.% Li2CuO2–CuO-treated NCM material showed higher capacity and better cycle retention than the bare NCM cathode material. Electrochemical impedance spectroscopy (EIS) analysis confirmed the reduction in interfacial resistance between the cathode and solid electrolyte. These indicators of the electrochemical performance demonstrate that Li2CuO2–CuO composite treatment is effective for the ASSLB cathode material.

Preparing Microstructured Porous Garnet Electrodes By a Novel Method for All-Solid-State Batteries

High interfacial resistance is a bottleneck for all-solid-state batteries. Tremendous effort has been made to enhance the physical contact between the electrode (anode and cathode) and solid-state electrolyte. For example, by inserting a thin buffer layer of metal oxides, metals, polymers, or some other Li+ conductor, intimate physical contact can be achieved, resulting in a substantial reduction in interfacial resistance. However, this is only effective on Li metal anode side and the interfacial resistance on the cathode side is still high. A strategy to overcome this barrier is adoption of a porous-dense-porous tri-layer structure. The electrode-electrolyte interfacial surface area can be increased more than ten times, achieving low area-specific resistance. Microstructured porous layers, serving as electrode supports, are prepared with PMMA poreformer. In this work, a new water-based method is deployed to prepare vertical-direction pores aligned with the Li+ transfer path, in electrode supports based on LLZO garnet material. This method is environment-friendly, low-cost, and anticipated to be scalable. The pore size, volume, and depth is optimized and characterized with synchrotron tomography. The impact of the tri-layer structure on interfacial resistance on both anode and cathode is analyzed during full cell operation.

Interface engineering of Li1.3Al0.3Ti1.7(PO4)3 ceramic electrolyte via multifunctional interfacial layer for all-solid-state lithium batteries

Li1.3Al0.3Ti1.7(PO4)3 (LATP) suffers from high interfacial resistance and instability with Li which hinder its application in all-solid-state lithium batteries. Herein, we propose an effective method to overcome these obstacles by introducing a LATP nanoparticle-reinforced composite polymer electrolyte (CPE) at LATP/Li interface. The multifunctional CPE interfacial layer can not only avoid side reactions between LATP and Li, but also ensure intimate contact at LATP/Li interface to reduce interfacial resistance. Moreover, the soft CPE layer can mitigate the large volume change of Li anode during cycling due to its high viscosity and flexible features. With the assistance of LATP fillers, the CPE interfacial layer can inhibit the formation and penetration of Li dendrites with enhanced mechanical strength and uniform Li deposition. After the modification of CPE interfacial layer, solid-state electrolyte with the sandwiched structure of CPE/LATP/CPE possesses satisfactory features such as high ionic conductivity, high interfacial stability and wide electrochemical window. Symmetric Li cell exhibits significant reduction in interfacial resistance (from 2852 Ω cm2 to 505 Ω cm2) and overpotential (from 2.03 V to 0.04 V), which ensures a stable galvanostatic cycle for more than 400 h at 0.05 mA cm−2. Solid-state LiFePO4/LATP/CPE/Li batteries deliver remarkable cycling ability and high coulombic efficiency.

Core–shell structured graphene sphere-silver nanowire hybrid filler embedded polydimethylsiloxane nanocomposites for stretchable conductor

Three-dimensional (3D) core–shell structured graphene-silver nanowire (AgNW) hybrid fillers are prepared through facile spray drying and an optical welding process. The spray drying process enables formation of a core–shell structure with AgNWs attached onto the spherical graphene surface by van der Waals force and surface tension during evaporation. AgNW shell is optically welded for enhanced mechanical stability and interfacial resistance reduction. 3D core–shell structured graphene-AgNW hybrid fillers are partially embedded into polydimethylsiloxane (PDMS) to fabricate highly stretchable and conductive nanocomposites. The electrical conductivity of nanocomposites largely increases up to ∼116 S cm−1 and the electrical properties are well maintained under high stretchability of ∼140% strain with 100 stretching cycles despite small amount of AgNW. These enhancements are attributed to the formation of electrically conducting network by excellent dispersion property of spherical graphene core in PDMS matrix and low contact resistance of AgNW shell. We anticipate that 3D core–shell structured graphene-AgNW/PDMS nanocomposites have great potential for application in various stretchable electronic devices.

Electrodes-electrolyte interfacial engineering for realizing room temperature lithium metal battery based on garnet structured solid fast Li+ conductors

Li7La3Zr2O12 (LLZ) is one of the most promising solid electrolyte for all-solid-state batteries, owing to its high Li + conductivity and stability when in contact with lithium metal. However, LLZ has its own challenges in realizing high performance due to its high electrode/electrolyte interfacial resistance. To address this issue, we report a systematic investigation of interfacial resistance, with a metallic Li strip and a thin layer of Li deposition by thermal evaporation (TE) over dense and high Li + conductive pristine Al-LLZ (Li6.28Al0.24La3Zr2O12) and Au||Al-LLZ. Thermal treatment of Li (TE)||Au||Al-LLZ||Au||Li (TE) at 180 °C for 1-h exhibits a dramatic reduction in interfacial resistance along with stable Li platting/stripping at room temperature (25 °C). Scanning Electron Microscopic (SEM) investigation on the interface of the Li (TE)||Au||Al-LLZ||Au||Li (TE) reveals the formation of a favorable thin layer of Li-Au alloy through the heat treatment at 180 °C. A room temperature working cell with LiCoO2 as a cathode, metallic Li (TE) as anode and Al-LLZ as a solid electrolyte is possible by introducing a thin layer of Au at anode interface and a soft polypropylene interlayer at cathode interface.

Effect of lithium-ion diffusibility on interfacial resistance of LiCoO2 thin film electrode modified with lithium tungsten oxides

To investigate the contribution of lithium-ion diffusibility of lithium tungsten oxides (LWOs) to low interfacial resistance, we fabricate thin-film electrodes of 6Li-enriched LiCoO2 (6LCO) modified with various structure-types of 6Li-enriched LWOs by pulsed laser deposition. The electrodes are subjected to X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS), and secondary-ion mass spectrometry (SIMS) analyses. XRD reveals that the LWO layers have Li2WO4 structure with rhombohedral and tetragonal symmetries and amorphous states. EIS shows that the lowest interfacial resistance of the positive electrodes is given by the amorphous state, followed in order by the tetragonal and the rhombohedral symmetry, and that the diffusion coefficients of lithium-ions in the electrodes increase in the same order. SIMS demonstrates that the fastest lithium-ion self-diffusibility into the LWOs is found in the amorphous state, followed in order by tetragonal and rhombohedral symmetry. Furthermore, the amorphous state LWO modification shows smooth lithium-ion diffusion between the LWO and LCO layers after the electrochemical test. Conversely, the rhombohedral LWO modification demonstrates congested lithium-ion diffusion between the LWO and LCO layers after the test. Thus, fast lithium-ion self-diffusibility into the LWO-modified LCO contributes to enhancing the diffusion of lithium-ions, resulting in the reduction of interfacial resistance.

Influence of surface disorder, oxygen defects and bandgap in TiO2 nanostructures on the photovoltaic properties of dye sensitized solar cells

We present a detailed study on the microstructural, structural and optical properties of hydrogen treated (HT) diverse TiO2 nanostructures (TNS) in comparison to the as-prepared (AP) samples. The effect of oxygen vacancies (VO), introduced in the anatase TiO2 by hydrogenation, on the photovoltaic (PV) characteristics is discussed. Raman spectroscopy shows A1g second order scattering modes due to VO-influenced surface structural changes. EELS confirm the presence of Ti4+/Ti3+ mixed states and oxygen deficiency in all TNS-HT. Bandgap (Eg) of TNS can be tuned by controlling the temperature and/or duration of annealing. The indirect bandgap is found to be larger (~3.2–3.4eV) for TNS derived from Ti-foil, whereas TNS prepared using wet-chemical methods exhibit Eg in the range of 3.1–3.3eV. The introduction of VO red-shifts the band-edge by ~0.25eV. Hydrogenation decreases the PV efficiency (η) by 2–4 times compared to η=6–7% observed in DSSCs of diverse nanostructures. Despite the reduction in interfacial resistance enhancing electron generation and transport in TNS-HT samples, EIS studies indicate that the drop in η (%) is mainly due to the recapture of conduction band electrons via defect states shortening the electron lifetime.

Electrical characterization of a mixed potential propylene sensor

In this article, electrical characterization of a ‘La0.8Sr0.2CrO3/YSZ/Pt’ non-Nernstian propylene gas sensor is reported. The effect of the concentration of the test gas (25–200ppm) on the sensor response was studied using impedance spectroscopy and current–voltage curves. For a fixed operating temperature of 510°C, the interfacial resistance was seen to decrease with increase in the analyte concentration. A 48% reduction in interfacial resistance has been observed when switched from air to 200ppm of propylene. I–V studies show a non-linear relationship. The slope of the curves around zero current matches the resistances measured by ac impedance. The controlled interface sensor design facilitated impedancemetric and potentiometric sensing schemes.

Reduction of Interfacial Resistance between LiMn2O4 and Thio-LISICON

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Nanoengineered BSCF Cathode Materials for Intermediate-Temperature Solid-Oxide Fuel Cells

A recently reported promising cathode material for solid-oxide fuel cells (SOFCs), namely, (BSCF) is fabricated in nanocrystalline form by a chemical alloying approach. The approach is comprised of solution chemical synthesis of a precursor and its thermochemical processing toward the desired phase. All the constituent elements, Ba, Sr, Co, and Fe, were coprecipitated from an aqueous solution of their salts to produce a precursor with a well-defined composition, fine particle size, high homogeneity, and high reactivity. After calcining and sintering at , the individual oxides were alloyed into nanostructured perovskite (with and ) of high purity. Spark plasma sintering was used for compaction to preserve the material’s nanostructure, and sintered compacts demonstrated a significant increase in electrical conductivity values at temperatures up to , compared to the earlier reports. The measured conductivity values are sufficiently high for cathode applications with a maximum of about at in air and at in , respectively. These values are about twice as high as conventional BSCF mainly due to the reduction in interfacial resistance, implying a high promise for nanoengineered BSCF as cathode material at low or intermediate-temperature SOFCs.

Electrochemical characteristics of copper silicide-coated graphite as an anode material of lithium secondary batteries

Copper silicide-coated graphite as an anode material was prepared by the sequential employments of plasma enhanced chemical vapor deposition (PECVD) and radio frequency magnetron sputtering (RFMS) method at 300 °C. The silicon-coated graphite exhibited an initial discharge capacity of 540 mAh/g with 76% coulomb efficiency, and the discharge capacity was sharply decreased down to 50% of initial capacity after 30 cycles, probably due to large volume changes during the charge–discharge cycling. Copper silicide-coated graphite, however, exhibited an initial discharge capacity of 480 mAh/g with higher retention capacity of 87% even after 30 cycles, probably due to the enhanced interfacial conductivity. The copper silicide film on the graphite surface played as the active anode material of lithium secondary batteries via the reduction of interfacial resistance and mitigation of volume changes during repeated cycles.

Low Temperature Composite Cathodes for SOFC Applications

Improved cathode materials are critical to reducing the operating temperature of SOFCs. State-of-the-art cathode materials require operating temperatures above 800°C to provide low interfacial resistance, and sintering temperatures >1000°C to achieve sufficient adherence to the electrolyte layer. Composite materials have been identified as a promising approach to improving electrode behavior through the increase of the three-phase-boundary (tpb) area. Electrocatalytic effects have also been proposed as a mechanism that may explain the reduction in interfacial resistance. To investigate the relationship between component composition, surface area, and processing routes, a series of low temperature anode and cathode materials have developed using a nanocomposite approach. It has been demonstrated nanocomposite materials allow significantly lower processing temperatures and better performance than conventional composite materials, but require careful processing to take full advantage of the synergistic effects.