Electrostatic Spray Deposition Technique Research Articles

Enhanced lithium storage performance in three-dimensional porous SnO2-Fe2O3 composite anode films

As one of the most promising anode materials in lithium-ion batteries (LIBs), SnO2 attracts wide research attention. The practical application of SnO2 anodes, however, is mainly hampered by huge volume variation during cycling and large initial irreversible capacity. In this paper, three-dimensional porous SnO2-Fe2O3 composite films have been fabricated using the electrostatic spray deposition technique. As an anode for LIBs, the hierarchical porous SnO2-Fe2O3 film possesses a high reversible capacity (1034.1 mAh g-1) and a high initial Coulombic efficiency of 82.9% at a current density of 0.2 A g-1. At the same time, it shows good capacity retention with a capacity of 1025.6 mAh g-1 after 240 cycles and excellent rate performance. The enhanced lithium storage performance should be attributed to the synergistic effect between SnO2 and Fe2O3, as well as the three-dimensional hierarchical porous structure. The results demonstrate that such a three-dimensional porous composite anode shows great potential for application in high-energy lithium-ion batteries.

Preparation of polypyrrole-coated CuFe2O4 and their improved electrochemical performance as lithium-ion anodes

CuFe2O4 network, prepared via the electrostatic spray deposition technique, with high reversible capacity and long cycle lifetime for lithium ion battery anode material has been reported. The reversible capacity can be further enhanced by coating high electronic conductive polypyrrole (PPy). At the current density of 100 mA·g−1, Li/CuFe2O4 electrode delivers a reversible capacity of 842.9 mAh·g−1 while the reversible capacity of Li/PPy-coated CuFe2O4 electrode increases up to 1106.7 mAh·g−1. A high capacity of 640.7 mAh·g−1 for the Li/PPy-coated CuFe2O4 electrode is maintained in contrast of 398.9 mAh·g−1 for Li/CuFe2O4 electrode after 60 cycles, which demonstrates good electrochemical performance of the composite due to the increase of electronic conductivity. The electrochemical impedance spectroscopy (EIS) further reveals that the Li/PPy-coated CuFe2O4 electrode has a lower charge transfer resistance than the Li/CuFe2O4 electrode.

Continuous Fabrication of SOFC Assembly by ESD Technique – Dense Thin Film YSZ Electrolyte

Electrostatic spray deposition (ESD) was used to prepare a completely dense 0.7µm thin film of YSZ. The method of fabricating a SOFC cell assembly by a continuous ESD process with only one sintering step is discussed and illustrated.

Continuously gradient anode functional layer for BCZY based proton-conducting fuel cells

This study examined the effects of a continuously gradient anode functional layer (AFL) on the performance of the BaCe0.5Zr0.35Y0.15O3−δ (BCZY) based proton conducting fuel cell. The gradient AFL composed of NiO and BCZY was fabricated by the electrostatic slurry spray deposition (ESSD) technique with a rotation stage. For the comparison, the single cells without AFL and with homogeneous AFL were also prepared and the electrochemical properties were evaluated by full cell test and electrochemical impedance spectroscopy (EIS). Power density of the single cell with the gradient AFL exhibited 521 mW/cm2 at 700 °C which was higher by 48% and 16% compared to single cells without the AFL and with the homogeneous AFL. In addition, impedance spectra showed that both ohmic and polarization resistances under open circuit voltage (OCV) at 700 °C decreased from 0.3218 and 0.3462 to 0.2168 and 0.2203 Ωcm2. This performance enhancement is primarily attributed to modified microstructure of the AFL which has a continuously gradient interface to effectively reduce a mismatch between electrolyte and anode.

Nanostructured Electrodes Via Electrostatic Spray Deposition for Energy Storage System

Energy storage system (such as Li-ion battery and supercapacitor) is an important technology in today’s society, and has been widely used as the power source for portable electronics, electrical vehicles and hybrid electrical vehicles. Lots of research has focused on improving its performance, however, many crucial challenges need to be addressed to obtain high performance for further applications. Recently, an electrostatic spray deposition (ESD) technique has attracted great interests to satisfy the goals. Due to its many advantages, such as simplicity, cost-effective setup, non-vacuum, low temperature deposition conditions, good control for tailoring film composition and morphology, and high deposition efficiency, the ESD technique shows very promising prospects compared to other conventional deposition techniques. It provides a simple but versatile strategy for generating single or multi-component materials with varied morphologies, such as sponge-like, dense, porous and fractal, etc. It is belived that controling structures is an effective way to optmize electrochemical performance in reagrding volume change buffering, short ion diffusion passway, etc.. In this talk, our recent research outcomes related to the ESD derived anodes for Li-ion batteries and supercapacitors, such as graphene, Li4Ti5O12, Sn, SnO2, NiO, Fe2O3, Co3O4, CoO, and Cu2O, etc. Will be summarized and discussed.

Fabrication of Y-doped barium cerium zirconate thin films by electrostatic spray deposition technique for protonic ceramic fuel cell application

This study aims to fabricate BaCe0.4Zr0.4Y0.2O3−δ (BCZY) thin film by electrostatic spray deposition (ESD) technique. Effects of ESD parameters, i.e. type of precursor, substrate temperature, applied voltage, nozzle-to-substrate distance and flow rate, were systematically studied and optimized for acquiring dense and crack-free as-deposited thin films. The half-cells of protonic ceramic fuel cell (PCFC) were subsequently fabricated by electro-depositing and co-sintering BCZY thin film electrolytes on the 60wt% NiO–40wt% BCZY anode substrates. Since dense BCZY films could not be attained on bare NiO–BCZY anode substrates, the anode functional layers (AFLs) with lower mass fractions of NiO:BCZY at 10:90, 30:70 and 50:50 was co-pressed on top of NiO–BCZY anode substrates. After co-sintering at 1500°C for 10h in air, the increasing BCZY film density was observed in the following order: AFL50:50<AFL30:70<AFL10:90. The PCFC half-cell with dense BCZY film on AFL10:90 anode was then achieved, thus confirming the potential application of the ESD technique for the thin-film PCFC application.

Freestanding Micro‐SOFCs with Electrodes Prepared by Electrostatic Spray Deposition

AbstractWe report a freestanding micro solid oxide fuel cell with both the anode and cathode deposited using electrostatic spray deposition (ESD) technique. The cell is consisted of dense yittria‐stabilized zirconia (YSZ) electrolyte (100 nm thick), porous lanthanum strontium manganite (LSM)–YSZ cathode (∼3 μm thick), and porous NiO‐YSZ anode (∼3 μm thick). LSM‐YSZ and NiO‐YSZ composite powders were initially prepared by glycine nitrate process and super‐critical fluid processes, respectively, and both cathode and anode layers were deposited by the ESD. The resulting freestanding micro cell exhibited an open circuit voltage close to the theoretical value of 1.09 V, and a maximum power density of 41.3 mWcm–2 at 640 °C.

Synthesis of three-dimensionally porous MnO thin films for lithium-ion batteries by improved Electrostatic Spray Deposition technique

The three-dimensionally porous MnO thin-film electrodes supported on nickel foam and stainless steel substrates were prepared by the improved electrostatic spray deposition (ESD) technique. X-ray diffraction, scanning electron microscopy, and galvanostatic cell cycing are employed to characterize the structures and electrochemical performance of the MnO thin-film electrodes. The results show that these as-prepared MnO thin-film electrodes have a special three dimensional porous network structure and also have stable cycling performance with a reversible capacity of over 850 mAh g−1 after 50 cycles at a current density of 80mAg−1. The MnO thin-film deposited on the nickel foam shows the highest initial columbic efficiency (83.9%), the lowest initial capacity loss (14.2%), and the best rate performance with a high capacity of 498.4 mAh g−1 at a current density of 1200mAg−1. The experimental results suggest that such the MnO thin-film with a special structure is a promising anode material for lithium-ion batteries.

Fabrication and Characterization of SnO₂/Graphene Composites as High Capacity Anodes for Li-Ion Batteries.

Tin-oxide and graphene (TG) composites were fabricated using the Electrostatic Spray Deposition (ESD) technique, and tested as anode materials for Li-ion batteries. The electrochemical performance of the as-deposited TG composites were compared to heat-treated TG composites along with pure tin-oxide films. The heat-treated composites exhibited superior specific capacity and energy density than both the as-deposited TG composites and tin oxide samples. At the 70th cycle, the specific capacities of the as-deposited and post heat-treated samples were 534 and 737 mA·h/g, respectively, and the corresponding energy densities of the as-deposited and heat-treated composites were 1240 and 1760 W·h/kg, respectively. This improvement in the electrochemical performance of the TG composite anodes as compared to the pure tin oxide samples is attributed to the synergy between tin oxide and graphene, which increases the electrical conductivity of tin oxide and helps alleviate volumetric changes in tin-oxide during cycling.

Enhanced photocatalytic performance of graphene–ZnO nanoplatelet composite thin films prepared by electrostatic spray deposition

Graphene–ZnO (G–ZnO) composite thin films were produced using the electrostatic spray deposition technique (ESD). The effects of the concentration of graphene and annealing temperature on the structural and photocatalytic properties of the G–ZnO films were studied by X-ray diffraction, scanning electron microscopy, atomic force microscopy, Raman spectroscopy, and UV–visible spectroscopy. We demonstrated that the G–ZnO films exhibit enhanced activities towards the photodegradation of methylene blue dye. A G–ZnO film with 0.1wt% graphene that was annealed at 300°C showed the highest photo-degradation activity. We found that the incorporation of graphene reduced electron–hole recombination in the ZnO film.

Controllable deposition of gadolinium doped ceria electrolyte films by magnetic-field-assisted electrostatic spray deposition

This paper describes a simple and low-temperature approach to fabrication of dense and crack-free gadolinium doped ceria (GDC) thin films with controllable deposition by a magnetic-field-assisted electrostatic spray deposition technique. The influences of external permanent magnets on the deposition of GDC films were investigated. The coating area deposited using two magnets with the same pole arrangement decreased in comparison with the case of no magnets, whereas the largest deposition area was obtained in the system of the opposite poles. Analysis of as-deposited films at 450°C indicated the formation of uniform, smooth and dense thin films with a single-phase fluorite structure. The films produced in the system using same poles were thicker, smaller in crystallite size and smoother than those fabricated under other conditions. Additionally, the GDC film deposited using the same pole arrangement showed the maximum in electrical conductivity of about 2.5×10−2S/cm at a low operating temperature of 500°C.

Engineering nanostructured anodes via electrostatic spray deposition for high performance lithium ion battery application

Lithium ion batteries (LIBs) have been widely employed as the most popular energy source in today's portable electronics and are considered as one of the most promising energy strategies for electrical vehicle and plug-in hybrid electrical vehicle application, which has recently been under intense research and development. However, many crucial challenges need to be addressed to obtain high performance LIBs for further application. Recently, electrostatic spray deposition (ESD) technique has attracted much attention as a promising tool for electrode formation. The ESD is based on applying a high DC voltage to generate a high electrostatic force and accelerate atomized liquid droplets at the tip of a nozzle; the aerosol formed by charged droplets is sequentially deposited on a heated substrate to create an electrode for LIBs. This technique provides a simple but versatile strategy for generating single or multi-component materials with various type of morphologies, such as sponge-like, dense, porous and fractal, etc. In this review, an overview of the latest development and understanding of various anodes synthesized by the ESD technique in LIBs is briefly reviewed and discussed. Our attention is mainly focused on three different anode categories: (1) intercalation–de-intercalation anodes, such as graphite, Li4Ti5O12 and TiO2, etc.; (2) alloying–de-alloying anodes, such as Sn and SnO2, etc.; (3) conversion reaction anodes, such as NiO, Fe2O3, Co3O4, CoO, and Cu2O, etc. Moreover, our recent research outcome related to the ESD derived anodes for LIBs is highlighted.

A Humidity Sensor Based on Silver Nanoparticles Thin Film Prepared by Electrostatic Spray Deposition Process

In this work, thin film of silver nanoparticles for humidity sensor application was deposited by electrostatic spray deposition technique. The influence of the deposition times on properties of films was studied. The crystal structures of sample films, their surface morphology, and optical properties have been investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and UV-VIS spectrophotometer, respectively. The crystalline structure of silver nanoparticles thin film was found in the orientation of (100) and (200) planes of cubic structure at diffraction angles 2θ = 38.2° and 44.3°, respectively. Moreover, the silver nanoparticles thin films humidity sensor was fabricated onto the interdigitated electrodes. The sensor exhibited the humidity adsorption and desorption properties. The sensing mechanisms of the device were also elucidated by complex impedance analysis.

Fabrication of Samarium Doped Ceria Electrolyte on Rough Glass Substrate with High Electrical Conductivity by Electrostatic Spray Deposition for Intermediate Temperature Solid Oxide Fuel Cells

Samarium-doped ceria (SDC) thin films have been fabricated on unetched and etched glass substrates by an electrostatic spray deposition (ESD) technique for intermediate-temperature solid oxide fuel cells (SOFCs). The influence of substrate surface was studied to prepare a dense and crack-free SDC thin film with high electrical conductivity. With a heat treatment temperature of 400°C, dense and crack-free SDC thin films were obtained on both unetched and etched glass substrates. The SDC films were nanocrystalline with cubic fluorite structure at the heat treatment temperature of 400°C. The results revealed that the SDC film deposited on the etched glass substrate was smaller in thickness and higher in electrical conductivity than that on the unetched glass substrate. The maximum in electrical conductivity of the SDC film deposited on the etched substrate was approximately 1.34×10-1 S/cm at a low operating temperature of 600°C.

Structural, optical and electrical properties of tin oxide thin films by electrostatic spray deposition

Abstract Tin oxide (SnO2) thin films were deposited by electrostatic spray deposition (ESD). The structural, optical and electrical properties of the films for different solvents were studied. The morphology of the deposited thin films was investigated by scanning electron microscopy. The optical transmission spectra of the films showed 66–75% transmittance in the visible region of spectrum. The electrical resistivity of thin films deposited using the different solvents ranged 1.08 × 10−3–1.34 × 10−3 Ω-cm. Overall, EG and PG were good solvents for depositing SnO2 thin films by the ESD technique with stable cone jet.

Electrostatic Spray Deposition of Porous SnO2/Graphene Anode Films and Their Enhanced Lithium-Storage Properties

Porous SnO₂/graphene composite thin films are prepared as anodes for lithium ion batteries by the electrostatic spray deposition technique. Reticular-structured SnO₂ is formed on both the nickel foam substrate and the surface of graphene sheets according to the scanning electron microscopy (SEM) results. Such an assembly mode of graphene and SnO₂ is highly beneficial to the electrochemical performance improvement by increasing the electrical conductivity and releasing the volume change of the anode. The novel engineered anode possesses 2134.3 mA h g⁻¹ of initial discharge capacity and good capacity retention of 551.0 mA h g⁻¹ up to the 100th cycle at a current density of 200 mA g⁻¹. This anode also exhibits excellent rate capability, with a reversible capacity of 507.7 mA h g⁻¹ after 100 cycles at a current density of 800 mA g⁻¹. The results demonstrate that such a film-type hybrid anode shows great potential for application in high-energy lithium-ion batteries.

Electrostatic spray-deposited CuInGaSe2 nanoparticles: Effects of precursors' Ohnesorge number, substrate temperature, and flowrate on thin film characteristics

The effect of precursor viscosity, substrate temperature, and flow rate on CuInGaSe2 nanoparticle-based thin films deposited by an electrostatic spray deposition (ESD) technique are studied. ESD is superior to pneumatic spraying because it produces nano-scale, self-dispersive (non-agglomerating), highly wettable (electrowetting) and adhesive droplets, which collectively yield a uniform coating on the substrate. The synthesized CuInGaSe2 nanoparticles were added to 4 different solvents: ethanol (E), butyl carbitol (BC), ethylene glycol (EG), and diethylene glycol (DEG). Subsequently, the solvents were electrostatically sprayed onto a molybdenum-coated soda-lime glass substrate. The solvent that yielded the most uniform surface morphology for the coated materials was identified. The surface roughness of the coated CIGS thin film, which depends on viscosity and the substrate temperature, was studied by AFM characterization.

Electrostatic spray deposition of graphene nanoplatelets for high-power thin-film supercapacitor electrodes

Thin-film electrodes of graphene nanoplatelets (GNPs) were fabricated through the electrostatic spray deposition (ESD) technique. The combination of a binder-free deposition technique and an open pore structure of graphene films results in an excellent power handling ability of the electrodes. Cyclic voltammetry measurements of 1-μm-thick electrodes yield near rectangular curves even at a very high scan rate of 20 V s−1. Thin-film electrodes (1 μm thickness) show specific power and energy of about 75.46 kW kg−1 and 2.93 W h kg−1, respectively, at a 5 V s−1 scan rate. For the thin-film electrode, about 53 % of the initial specific capacitance of electrodes at low scan rates was retained at a high scan rate of 20 V s−1. Although the thickness of the thin-film electrodes has influence on their rate capability, an electrode with an increased thickness of 6 μm retained about 30 % if its initial capacitance at a very high scan rate of 20 V s−1. The results show that the ESD-fabricated GNP electrodes are promising candidates for thin-film energy storage for applications that require moderate energy density and very high power and rate handling ability.

Electrostatic spray deposition of porous Fe2V4O13 films as electrodes for Li-ion batteries

Porous thin films composed of complex Fe/V oxides (crystalline Fe2V4O13 and amorphous Fe2V4O12.29) are prepared by electrostatic spray deposition technique. The crystalline Fe2V4O13 thin film shows a high initial capacity of 409mAhg−1. The cyclic voltammetry analysis of a Fe2V4O13/Li cell reveals that the crystalline Fe2V4O13 undergoes an irreversible phase transition when the lower cut-off voltage is below 2.5V. Compared with the crystalline Fe2V4O13, the amorphous Fe2V4O12.29 thin film delivers a lower initial capacity of 349.9mAhg−1 but exhibits better cycling performance in the voltage range of 1.0–4.0V. After 50 cycles, its capacity can still reach around 200mAhg−1. X-ray photoelectron spectroscopy (XPS) reveals that the Fe2V4O12.29 thin film contains ions of mixed valence states V5+/V4+ and Fe3+/Fe2+, resulting in better rate capability for Fe2V4O12.29 than for Fe2V4O13. These results indicate that the amorphous Fe/V-oxide film is a promising electrode material for high energy applications.

Three-dimensional porous Fe0.1V2O5.15 thin film as a cathode material for lithium ion batteries

Three-dimensional (3D) porous V2O5 and Fe0.1V2O5.15 thin films have been prepared by electrostatic spray deposition technique. X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy are employed to investigate the structures and valence states of the films. Galvanostatic cell cycling, cyclic voltammetry and impedance spectroscopy are used to characterize their electrochemical properties. The Fe0.1V2O5.15 thin film shows much better cycling performance than the non-doped V2O5 thin film. Fe3+ can act as a stabilizing agent in the layered V2O5 and increase the reversibility of the charge and discharge processes towards deeper depth of lithium insertion/extraction. The dissolution of the active material in the electrolyte can also be significantly suppressed in the Fe-doped sample. Nevertheless, the Fe-doping causes a slight decrease in lithium ion diffusion coefficient.