Electrode Thickness Research Articles

Morphological Evolution of Sn-Metal-Based Anodes for Lithium-Ion Batteries Using Operando X-Ray Imaging.

Sn-based electrodes are promising candidates for next-generation lithium-ion batteries. However, it suffers from deleterious micro-structural deformation as it undergoes drastic volume changes upon lithium insertion and extraction. Progress in designing these materials is limited to complex structures. There is a significant need to develop an alloy-based anode that can be industrially manufactured and offers high reversible capacity. This necessitates a profound understanding of the interplay between structural changes and electrochemical performance. Here, operando X-ray imaging is used to correlate the morphological evolution to electrochemical performance in foil and foam systems. The 3D Sn-foam-like structure electrode is fabricated in-house as a practical approach to accommodate the volume expansion and alleviate the mechanical stress experienced upon alloying/dealloying. Results show that generating pores in Sn electrodes can help manage the volume expansion and mitigate the severe mechanical stress in thick electrodes during alloying/dealloying processes. The foam electrode demonstrates superior electrochemical performance compared to non-porous Sn foil with an equivalent absolute capacity. This work advances the understanding of the real-time morphological evolution of Sn bulky electrodes.

Stabilizing Schottky-to-Ohmic Switching in HfO2-Based Ferroelectric Films via Electrode Design.

The discovery of ferroelectric phases in HfO2-based films has reignited interest in ferroelectrics and their application in resistive switching (RS) devices. This study investigates the pivotal role of electrodes in facilitating the Schottky-to-Ohmic transition (SOT) observed in devices consisting of ultrathin epitaxial ferroelectric Hf0.93Y0.07O2 (YHO) films deposited on La0.67Sr0.33MnO3-buffered Nb-doped SrTiO3 (NbSTO|LSMO) with Ti|Au top electrodes. These findings indicate combined filamentary RS and ferroelectric switching occurs in devices with designed electrodes, having an ON/OFF ratio of over 100 during about 105 cycles. Transport measurements of modified device stacks show no change in SOT when the ferroelectric YHO layer is replaced with an equivalent hafnia-based layer, Hf0.5Zr0.5O2 (HZO). However, incomplete SOT is observed for variations in the top electrode thickness or material, as well as LSMO electrode thickness. This underscores the importance of employing oxygen-reactive electrodes and a bottom electrode with reduced conductivity to stabilize SOT. These findings provide valuable insights for enhancing the performance of ferroelectric RS devices through integration with filamentary RSmechanism.

Enhancing Mechanical Resilience in Li-Ion Battery Cathodes with Nanoscale Elastic Framework Coatings.

Lattice volume changes in Li-ion batteries active materials are unavoidable during electrochemical cycling, posing significant engineering challenges from the particle to the electrode level. In this study, we present an elastic framework coating designed to absorb and reversibly release strain energy associated with particle volume changes, thereby enhancing mechanical resilience at both the particle and electrode levels. This framework, composed of multiwalled carbon nanotubes (MWCNTs), is applied to nickel-rich LiNi0.9Co0.05Mn0.05O2 (NCM9055) cathodes at a low loading of 0.5 wt %, effectively mitigating critical issues such as particle cracking, volume changes, and electrode thickness variations during cycling. Leveraging these advantages, an energy-dense electrode is achieved with a high active material loading of 20 mg cm-2, without the need for additional carbon additives. Demonstrated in a pouch cell format, this electrode achieves an exceptional capacity retention of 77.7% after 1000 cycles. This approach provides a comprehensive solution for designing Li-ion batteries capable of withstanding lattice volume variations, offering valuable insights for next-generation batteries technologies.

Transport characterization of solid-state Li2FeS2 cathodes from a porous electrode theory perspective

This work investigates the cathode active material Li2FeS2 in all-solid-state batteries. Promising areal capacities can be achieved upon increasing the active material fraction and electrode thickness, but coming at the cost of rate capability.

Rate capability and electrolyte concentration: Tuning MnO2 supercapacitor electrodes through electrodeposition parameters.

Manganese dioxide (MnO2) is a well-known pseudocapacitive material that has been extensively studied and highly regarded, especially in supercapacitors, due to its remarkable surface redox behavior, leading to a high specific capacitance. However, its full potential is impeded by inherent characteristics such as its low electrical conductivity, dense morphology, and hindered ionic diffusion, resulting in limited rate capability in supercapacitors. Addressing this issue often requires complicated strategies and procedures, such as designing sophisticated composite architectures. This study introduces a straightforward and cost-effective approach to tune and enhance the rate capability of MnO2 pseudocapacitor electrodes fabricated via the electrodeposition method. Among the electrodeposition parameters, the deposition time and electrolyte concentration, which influence the mass loading, electrode thickness, microstructure, and electrochemical properties, were the primary focus. Various electrodes were prepared potentiostatically in a two-electrode cathodic electrodeposition setup on a Ni foam substrate in a KMnO4 aqueous electrolyte, with bath concentrations (in terms of Mn ion) of 0.01 and 0.1M, and electrodeposition times ranging from 1 to 15min. Optimal rate capabilities were achieved at low bath concentrations and deposition times, primarily due to the structural properties of electrodes prepared under such circumstances. While electrodeposition at a 0.1M electrolyte concentration resulted in the formation of electrolytic MnO2 with high supercapacitive rate sensitivity, reducing the bath concentration to 0.01M primarily led to the formation of birnessite δ-MnO2, capable of maintaining a reasonable specific capacitance in the range of approximately 90-100 Fg-1 with almost no sensitivity to the charging/discharging rate, as confirmed by galvanostatic charge-discharge (1-10 Ag-1) and cyclic voltammetry (10-100mVs-1) examinations. Along with the positive structural impacts of the layered birnessite with large interlayer spacing, the porous morphology (vertically aligned two-dimensional interconnected columns) and low thickness (≈2μm) of the electrode prepared at the lowest bath concentration and electrodeposition time (0.01M in 1min electrode) contributed to its fast ionic diffusion kinetics for pseudocapacitive charge storage and the consequent high rate capability.

Dry-processed thick electrode design with a porous conductive agent enabling 20 mA h cm−2 for high-energy-density lithium-ion batteries

Dry-processed thick cathodes designed with a porous spherical conductive agent exhibit superior electrochemical performances, even with high areal capacities of up to 20 mA h cm−2 and a high composite density of 3.65 g cm−3.

Freeze-thaw synergistic salt template prepared self-supporting MXene/wood-derived porous carbon electrode for supercapacitors

Supercapacitors are anticipated to be utilized in the upcoming generation of emerging energy storage devices. The electrode stands out as the most crucial component of the supercapacitor, and a bulk electrode containing sufficient electrochemically active substances is beneficial for enhancing the energy density of the energy storage device. Furthermore, the pore structure and wettability regulation of the electrode are pivotal factors that determine its electrochemical performance. In this study, we propose a monolithic electrode which was created by impregnating different concentrations of MXene dispersions into wood-based carbon materials co-treated with freeze-thaw/LiCl salt template, assisted by freezing treatment. The integration of MXene and freeze-thaw/LiCl salt template wood results in a layered porous structure that enhances both wettability and conductivity of the electrode. Freeze-thaw/LiCl salt template carbonized wood@MXene-4 (FCW@MXene-4) demonstrates an impressive electrochemical performance reaching 7.7 F cm−2 (184.5 F g−1) at a current density of 1 mA cm−2. Additionally, when assembled into a symmetric supercapacitor (SSC), it exhibits high specific capacitance at 3.4 F cm−2 (34.1 F g−1/17 F cm−3) and high energy density at 0.478 mWh cm−2 (6 Wh kg−1/2.39 mWh cm−3) at 1 mA cm−2, with a capacity retention rate of 88 % after 10,000 cycles. This research introduces an innovative self-supporting thick electrode design strategy for high-performance energy storage devices.

Hyper-Thick Electrodes for Lithium-Ion Batteries Enabled by Micro-Electric-Field Process.

Increasing electrode thickness is a key strategy to boost energy density in lithium-ion batteries (LIBs), which is essential for electric vehicles and energy storage applications. However, thick electrodes face significant challenges, including poor ion transport, long diffusion paths, and mechanical instability, all of which degrade battery performance. To overcome these barriers, a novel micro-electric-field (μ-EF) process is introduced that enhances particle alignment during fabrication with reduced distance between anode and cathode. This process produces hyper-thick (≈700µm) electrodes with low tortuosity and improved ion diffusion. The μ-EF electrodes achieve high areal capacities (≈8mAhcm-2), while maintaining power density and long cycle life. The electrodes show stable performance under high C-rate cycling and retain structural integrity after 1000 cycles at 2 C. By offering a scalable solution to the challenges of thick electrode fabrication, the μ-EF process represents a significant advancement for high-capacity LIBs in electric vehicles and energy storage systems.

Optimizing the Power Performance of Lithium‐Ion Batteries: The Role of Separator Porosity and Electrode Mass Loading

This study investigates the concealed effect of separator porosity on the electrochemical performance of lithium‐ion batteries (LIBs) in thin and thick electrode configuration. The effect of the separator is expected to be more pronounced in cells with thin electrodes due to its high volumetric/resistance ratio within the cell. However, the electrochemical analyses show similar power performance regardless of the separator porosity in the thin electrode configuration. In contrast, for cells with thick electrodes, separator porosity significantly impacts the direct current‐internal resistance (DC‐IR) and the capacity retention at a high rate. This behavior is attributed to ion concentration gradients in the upper regions of thick electrodes, while Li+ transfer to lower regions is hampered as the electrode thickness increases. These findings suggest that the intrinsic properties of individual cell components, such as separator porosity, are highly dependent on the overall cell design. Moreover, while high‐porosity separators enhance power performance, particularly in thick electrode configurations, they exhibit lower thermal stability and tensile strength. In conclusion, this study highlights the need for an integrated approach to optimizing separator characteristics, considering both electrochemical performance and safety trade‐offs in LIBs.

A Polymer-Binder-Free Approach to Creating Functional LiFePO4 Cathodes by Organic Ionic Plastic Crystal-Derived Ion-Conductive Binders

Lithium-ion batteries are a promising technology to promote the phase-out of fossil fuel vehicles. Increasing efforts are focused on improving their energy density and safety by replacing current materials with more efficient and safer alternatives. In this context, binary composites of organic ionic plastic crystals (OIPCs) and lithium salts show promise due to their impressive mechanical properties and ionic conductivity. Taking advantage of this, the present paper substitutes the commercial non-electrochemically active binder with an OIPC component, N-ethyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide ([C2mpyr][FSI]), in combination with LiFSI. Slurry-formulation experiments revealed that varying the new binder’s composition allows the production of diverse LiFePO4 (LFP) cathodes via the conventional fabrication process. Large amounts of OIPC−lithium salt mixtures in the composition yielded thick electrodes with expected nominal areal capacities of up to 3.74 mAh/cm2, where the balanced composition with a reduced Li+ concentration can demonstrate >1.5 mAh/cm2 at 0.1C. Lowering the amount of these ion-conductive binders enabled LFP cathodes to perform effectively under fast cycling conditions at a C-rate as high as 2C. Preliminary battery tests with a limited Li+ source demonstrated the feasibility of full-cell operation without using the lithium-metal anode. This work paves the way for developing advanced rechargeable batteries using OIPC-based ion-conductive binders for a wide range of applications.

Large-Bandwidth Lithium Niobate Electro-Optic Modulator for Frequency-Division Multiplexing RFID Systems

In the face of increasingly complex application scenarios, there is an urgent need for (Radio Frequency Identification) RFID systems that are capable of accurately identifying microwave signals of different frequency bands. Based on the acumen detection characteristics of microwave signals by lithium niobate electro-optic modulators, applying large-bandwidth thin-film lithium niobate electro-optic modulation to RFID systems can achieve efficient operation across multiple frequency bands. This study discusses, in detail, the design, simulation, fabrication, and testing process of the electro-optic modulator to obtain a high-performance, large-bandwidth lithium niobate electro-optic modulator. By using multilayer lithography techniques to prepare thick traveling-wave electrodes, the problem of irregular cross-sections during the fabrication of thick electrodes has been successfully reduced, improving the stability and controllability of the device. Test results show that the insertion loss of the electro-optic modulator is about 6 dB, the extinction ratio is 36.5 dB, the optical waveguide mode field is 1 μm, the full-band characteristic impedance is 50 Ω, the test bandwidth is 50 GHz, and the half-wave voltage is 1.8 V. Compared with existing optimization schemes, this design not only achieves a large bandwidth and a small half-wave voltage, but also proposes a new fabrication process scheme, optimizing the process and resulting in samples with stable performance.

Dry‐Pressed Fabrication of Lithium‐Ion Electrodes Over 500 μm Thick

AbstractIn stationary storage, thick electrodes can minimize inactive material components to increase energy density and decrease cost, but they face challenges in performance and manufacturability. This work discusses a method to fabricate thick‐format lithium‐ion electrodes and a model to explore transport constraints for functional thick electrodes. Thick lithium iron phosphate (LFP) electrodes were fabricated using a solvent‐free pressing process that adopts methods from alkaline electrode manufacturing for low‐cost scale‐up. LFP electrodes with thicknesses up to 1 mm and capacities up to ~15 mAh/cm2 exhibited good rate performance (~98 % utilization at C/10, ~95 % at C/5, ~76 % at C/2). A physics‐based LFP half‐cell model was developed to aid in characterizing transport within these thick electrodes, revealing opportunities to further improve performance by decreasing tortuosity.

Vertical channels enable excellent lithium storage kinetics and cycling stability in silicon/carbon thick electrode

Vertical channels enable excellent lithium storage kinetics and cycling stability in silicon/carbon thick electrode

Unique Characteristics of Pulse-Echo Sensing Systems for Ultrasonic Immersion Testing in Harsh Environments.

Ultrasound is an excellent way to acquire data that reveal useful information about systems operating in harsh environments, which may include elevated temperature, ionizing radiation, and aggressive chemicals. The effects of harsh environments on piezoelectric materials have been studied in much more depth than the other aspects of ultrasonic transducers used in pulse-echo mode. Therefore, finite element simulations and laboratory experiments are used to demonstrate the unique characteristics of pulse-echo immersion testing. Using an aluminum nitride piezoelectric element mounted on a vessel wall, characteristics associated with electrode thickness, couplant, backing material, and an acoustic matching layer are investigated. Considering a wave path through a vessel wall and into a fluid containing a target, when the travel distance in the fluid is relatively short, it can be difficult to discern the target echo from the reverberations in the vessel wall. When an acoustic matching layer between the vessel wall and the fluid does not suffice, a simple subtractive signal-processing method can minimize the reverberations, leaving just the target echoes of interest. Simulations and experiments demonstrate that sufficient target echoes are detected to determine the time of flight. Furthermore, a simple disc-like surface anomaly on the target is detectable.

Research on Structural Parameter Design of High Voltage Plane Switch

Abstract In order to determine the structural parameters of the three electrodes of the high-voltage plane switch, the effects of the main electrode gap distance, trigger electrode width, main electrode radius, electrode thickness and other structural parameters on the static breakdown voltage (SBV) of the high-voltage plane switch were obtained by simulation calculation. The optimized structure parameters of the planar switch are obtained, including primary electrode gap 2.0mm, trigger electrode width 1.2mm, trigger electrode in the center of the two main electrodes, and electrode thickness 4 μ m. The performance of the designed high-voltage planar switch is basically consistent with that of the spark gap switch.

Correlation and application of thermal expansion coefficient/elastic modulus for co-sintered composite cermet/ceramic materials

Deformation and stress concentration appearing during high-temperature sintering process significantly affect production quality of solid oxide cell (SOC), due to mismatched mechanical and thermophysical properties of the sintered electrode and electrolyte. In this study, a coarse-grained molecular dynamics (CG-MD) method is developed to evaluate and correlate coefficient of thermal expansion (CTE) and elastic modulus during the entire co-sintering process (including temperature-increasing, −insulation, and -decreasing stages). It is revealed that, in the sintered porous cermet electrode, CTE primarily exhibits an increasing trend until temperature-decreasing stage. Compared to the constant values commonly applied in the literature, the elastic modulus experiences a decay trend with a reduction of 32.14 % in the porous electrode and 9.68 % reduction in the dense electrolyte. The obtained CTE and elastic modulus are correlated with the sintering parameters and further applied to a macroscopical model for predicting overall sintering warpage and stress in a co-sintered SOC half-cell composed of a thick porous electrode and a thin dense layer. The varied CTE is identified as the main factor influencing warpage deformation, while the elastic modulus as a more significant impact on the von Mises stress during the co-sintering of the half-cell. Analysis is further conducted by orthogonal testing method for sintering temperature, sintering time, material content and diameter ratio of the porous cermet nanoparticles, aiming to optimize the varied CTE and elastic modulus, particularly during the temperature-insulation process. Subsequently, the optimized properties are implemented, and it is found that, after sintering insulation for 120 min, the maximum warpage displacement is about 7.34 mm, which represents a decrease of approximately 14.11 %; while the von Mises stress is observed to be 379.24 MPa, which indicates a reduction of around 37.33 % compared with the predictions by the constant properties.

The role of lithium metal electrode thickness on cell safety

The role of lithium metal electrode thickness on cell safety

Additive Fabrication of Polyaniline and Carbon-Based Composites for Energy Storage.

The growing demand for efficient energy storage systems, particularly in portable electronics and electric vehicles, has led to increased interest in supercapacitors, which offer high power density, rapid charge/discharge rates, and long cycle life. However, improving their energy density without compromising performance remains a challenge. In this study, we developed novel 3D-printed reduced graphene oxide (rGO) electrodes coated with polyaniline (PANI) to enhance their electrochemical properties. The rGO 3D-printed electrodes were fabricated using direct ink writing (DIW), which allowed precise control over thickness, ranging from 4 to 24 layers. A unique ink formulation was optimized for the printing process, consisting of rGO, cellulose acetate (CA) as a binder, and acetone as a solvent. The PANI coating was applied via chemical oxidative polymerization (COP) with up to five deposition cycles. Electrochemical testing, including cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS), revealed that 12-layer electrodes with three PANI deposition cycles achieved the highest areal capacitance of 84.32 mF/cm2. While thicker electrodes (16 layers and beyond) experienced diminished performance due to ion diffusion limitations, the composite electrodes demonstrated excellent cycling stability, retaining over 80% of their initial capacitance after 1500 cycles. This work demonstrates the potential of 3D-printed PANI/rGO electrodes for scalable, high-performance supercapacitors with customizable architectures.

Magnetically-Controlled Graphite Alignment for Fast and Stable Anion Intercalation.

Dual-ion batteries (DIBs) are emerging as promising candidates for fast-charging electric vehicles owing to their ability to intercalate both cations and anions. However, increasing the energy density of DIBs, especially with thick graphite cathodes, remains a challenge due to structural instability during anion intercalation. In this study, a magnetically controlled method is introduced to vertically align graphite particles in thick electrodes, significantly improving the performance of DIBs. This novel architecture creates dense, low-tortuosity paths for fast anion transport and structural stability, allowing for high mass loadings exceeding 20mgcm-2. The vertically aligned graphite cathodes demonstrate a discharge capacity of 1.02mAhcm-2 at 5C, retaining 85.6% capacity after 1000 cycles at 1C, outperforming randomly and horizontally aligned graphite electrodes. Optimized electrodes also exhibit superior structural integrity and reduced formation of cathode electrolyte interphase compared to conventional designs. This study highlights the effectiveness of electrode architectural optimization in enhancing both energy density and fast-charging capabilities, providing a straightforward approach to developing next-generation DIBs with high performance and stability for practical applications in electric vehicles.

Printed for Performance: Harnessing the Electrochemical Potential of Prussian White Thick Electrodes v ia 3D Printing

The development of Prussian White (PW, Na1.92Fe[Fe(CN)6]) for water-based inks for thick, structured electrodes will be presented. PW is a derivative of Prussian blue analogues (PBA) and has the structural formula of AxM2[M1(CN)6]1-y, where A an alkaline metal such as Na or K, and M is usually a transitional metal such as Fe or Mn. Here, our PW is a strong Na-ion contender to replace Li-ion usage due to their low cost, efficient synthesis methods and comparable capacity to that Lithium iron phosphate of around 160 mAh/g. However, to match the performance of LFP, thick PW electrodes will need to be fabricated and here the mass transport of the electrode can be limiting. Thus, it is imperative to develop a Na-ion battery (NIB), that can exhibit both high energy and high power density, whilst maintaining cost and sustainability. To overcome this limitation of PW, the manufacturing of electrodes through careful battery design can be studied further to achieve a high performing cell.Thicker electrodes (>100 µm) have the potential to have both high power and higher energy, however there is a trade-off between both. When increasing the thickness of a standard two-dimensional (2D) electrode this lengthens the ionic pathways, limiting ionic transport across these thick electrodes. To overcome these restraints, we can introduce a 3D architecture within the electrode microstructure to maintain favourable, short ionic pathways hence, reducing the tortuosity within the electrode microstructure. This overcomes the mass transport limiting effects and now only the electron kinetic mechanism will be restrictive. One electrode deposition method that is used to create structured electrodes is by using a 3D printer (i.e., direct ink writing). Where electrode ink is loaded into a syringe and pressure is applied to extrude the ink through a nozzle.Prussian White is investigated here to see whether it has potential to be 3D printed via extrusion to create our desired thick and structured electrodes. 3D structured electrodes are achieved through tuning the ink rheology, these are compared against our standard 2D electrodes and with hopes to overcome the ionic and mass transport limits of 2D thick electrodes.Here, the overpotentials, impedance measurements and operando XRD from a synchrotron source will be evaluated, to understand how PW will transform under various electrochemical techniques. Further, there will be a direct electrochemical performance comparison between our 3D printed and 2D electrodes, through rate testing and Galvanostatic Intermittent Titration Technique (GITT). Here, we have seen the mass transport improve in our thick 2.8 mAh/cm2 3D printed electrodes, compared against our standard 2D electrode due to differences in the overpotentials. Thus, demonstrating our 3D printed electrodes can surpass the constraints linked to mass transport in thick electrodes, as we have now changed the kinetics at the electrode surface. Overall, we have achieved a multi-disciplinary project as we are discovering new electrode manufacturing processes, whilst using a Na-ion material to create the next-generation of batteries. Figure 1