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Developing a rational design for oxide‐based solid electrolytes to promote ionic conductivity, decrease the sintering temperature, and improve stability with metallic Li is challenging. Herein, core–shell‐structured Li1.3Al0.3Ti1.7(PO4)3@Li2O–2B2O3 (LATP–LBO) microspheres are prepared using one‐pot spray pyrolysis. Phase separation between crystalline LATP and amorphous LBO leads to the formation of a core–shell‐structured LATP–LBO composite. On the surface of LATP–LBO composite, the LBO shell forms a liquid phase during low‐temperature sintering, thereby enhancing the densification. The LBO shell also decreases the grain boundary resistance by forming a thin layer between the LATP grains, thus increasing the total ionic conductivity. Because Li‐ion conductive LBO occupies the grain boundary, a total ionic conductivity of 1.519 × 10−4 S cm−1 is achieved at a low sintering temperature of 700 °C. Additionally, the LBO shell provides good electrochemical stability for LATP with metallic Li. The improved ionic conductivity and chemical stability can be attributed to the synergistic advantages of the spherical morphology, core–shell structure, and uniformity of LBO. [ABSTRACT FROM AUTHOR]

A simple one-pot synthesis of metal selenide/reduced graphene oxide (rGO) composite powders for application as anode materials in sodium-ion batteries was developed. The detailed mechanism of formation of the CoSe x-rGO composite powders that were selected as the first target material in the spray pyrolysis process was studied. The crumple-structured CoSe x-rGO composite powders prepared by spray pyrolysis at 800 °C had a crystal structure consisting mainly of Co0.85Se with a minor phase of CoSe2. The bare CoSe x powders prepared for comparison had a spherical shape and hollow structure. The discharge capacities of the CoSe x-rGO composite and bare CoSe x powders in the 50th cycle at a constant current density of 0.3 A g−1 were 420 and 215 mA h g−1, respectively, and their capacity retentions measured from the second cycle were 80 and 46 %, respectively. The high structural stability of the CoSe x-rGO composite powders for repeated sodium-ion charge and discharge processes resulted in superior sodium-ion storage properties compared to those of the bare CoSe x powders. [ABSTRACT FROM AUTHOR]

Composite powders of the configuration Si@carbon@void@graphene were prepared by a one-step spray pyrolysis process, by adding polyvinylpyrrolidone (PVP) to a precursor solution containing graphene oxide (GO) sheets and silicon nanoparticles (NPs). Morphological analysis indicates that the individual Si NPs are coated with amorphous carbon and encapsulated in a micrometer-sized graphene ball structure that offers a large amount of buffer space. The addition of PVP improves the stability of the colloidal spray solution containing the GO sheets and the Si NPs. Consequently, the prepared Si@C@void@graphene composite powders have a relatively more uniform morphology than the Si@void@graphene composite powders prepared from the spray solution without PVP. The first charge and discharge capacities of the Si@C@void@graphene electrode measured at 0.1 A g−1 are as high as 3102 and 2215 mA h g−1, respectively. With an increase in the current rate from 0.5 to 11 A g−1, 46 % of the original capacity (i.e., 2134 mA h g−1) is maintained. After 500 cycles at a high rate of 7 A g−1, the Si@C@void@graphene electrode shows 84 % capacity retention and 99.8 % of the average Coulombic efficiency. The superior cycling and rate capabilities of the prepared Si@C@void@graphene electrode could be attributed to the uniform carbon coating of the Si NPs and the graphene ball structure, which facilitates efficient diffusion of Li ions and prevents the penetration of electrolyte into graphene ball during cycling. [ABSTRACT FROM AUTHOR]

Fe 3 O 4 -decorated graphene balls were prepared by a spray pyrolysis process. Analysis by Raman spectroscopy and X-ray photoelectron spectroscopy indicated that the spray pyrolysis at 800 °C resulted in the complete reduction of graphene oxide sheets containing oxygen functional groups into graphene sheets, leading to the formation of Fe 3 O 4 -decorated graphene balls. The graphene content in the composite ball was 27 wt%. The Brunauer–Emmett–Teller surface area of the Fe 3 O 4 -decorated graphene balls was as high as 130 m 2 g −1 . The initial discharge and charge capacities of the Fe 3 O 4 -decorated graphene balls at a high current density of 7 A g −1 were 1210 and 843 mAh g −1 , respectively, and the discharge capacity was as high as 690 mAh g −1 even after 1000 cycles. The stable reversible discharge capacities of the Fe 3 O 4 -decorated graphene balls decreased from 1040 to 540 mAh g −1 with the increase in current density from 1 to 30 A g −1 . The Fe 3 O 4 -decorated graphene balls with a uniform distribution of ultrafine Fe 3 O 4 nanocrystals below 15 nm showed superior electrochemical properties as anode materials for lithium ion batteries. The overall structure of the Fe 3 O 4 -decorated graphene balls was maintained even after long-term cycling. [ABSTRACT FROM AUTHOR]

Layered-layered yolk-shell powders with composition 0.6Li(Li 1/3 Mn 2/3 )O 2 · 0.4Li(Ni 1/3 Co 1/3 Mn 1/3 )O 2 are prepared by spray pyrolysis. Metal oxides-carbon composite powders are first formed as an intermediate product near the reactor entrance by drying and decomposition of droplets. Combustion, contraction, and recombustion processes of intermediate product produce yolk-shell-structured powders. The yolk-shell structure of the powders prepared directly by spray pyrolysis is maintained even after post-treatment at 800 °C; this treatment temperature yields the best electrochemical performance. The composition of the powders post-treated at 800 °C is Li 1.12 Ni 0.14 Co 0.14 Mn 0.59 O 2 . Mean grain sizes of the yolk-shell 0.6Li(Li 1/3 Mn 2/3 )O 2 ·0.4Li(Ni 1/3 Co 1/3 Mn 1/3 )O 2 powders, post-treated at 700, 750, and 800 °C, measured from high resolution TEM images, are 47, 54, and 79 nm, respectively, and their BET surface areas are 14, 9, and 7 m 2 g −1 . The initial discharge capacities of the powders, post-treated at the above temperatures, are 188, 280, and 239 mA h g −1 , respectively, and their initial Coulombic efficiencies are 87, 80, and 78%. Discharge capacities after 50 cycles of the post-treated powders are 81, 194, and 183 mA h g −1 , respectively, and the corresponding capacity retentions are 43, 70, and 77%. [ABSTRACT FROM AUTHOR]

High-temperature flame spray pyrolysis is employed for finding highly efficient nanomaterials for use in lithium-ion batteries. CoO x-FeO x nanopowders with various compositions are prepared by one-pot high-temperature flame spray pyrolysis. The Co and Fe components are uniformly distributed over the CoO x-FeO x composite powders, irrespective of the Co/Fe mole ratio. The Co-rich CoO x-FeO x composite powders with Co/Fe mole ratios of 3:1 and 2:1 have mixed crystal structures with CoFe2O4 and Co3O4 phases. However, Co-substituted magnetite composite powders prepared from spray solutions with Co and Fe components in mole ratios of 1:3, 1:2, and 1:1 have a single phase. Multicomponent CoO x-FeO x powders with a Co/Fe mole ratio of 2:1 and a mixed crystal structure with Co3O4 and CoFe2O4 phases show high initial capacities and good cycling performance. The stable reversible discharge capacities of the composite powders with a Co/Fe mole ratio of 2:1 decrease from 1165 to 820 mA h g−1 as the current density is increased from 500 to 5000 mA g−1; however, the discharge capacity again increases to 1310 mA h g−1 as the current density is restored to 500 mA g−1. [ABSTRACT FROM AUTHOR]

A facile, one-pot method for synthesizing spherical- like metal sulfide-reduced graphene oxide (RGO) composite powders by spray pyrolysis is reported. The direct sulfidation of ZnO nanocrystals decorated on spherical-like RGO powders resulted in ZnS-RGO composite powders. ZnS nanocrystals with a size below 20 nm were uniformly dispersed on spherical-like RGO balls. The discharge capacities of the ZnS-RGO, ZnO-RGO, bare ZnS, and bare ZnO powders at a current density of 1000 mAg-1 after 300 cycles were 628, 476, 230, and 168 mAhg-1, respectively, and the corresponding capacity retentions measured after the first cycles were 93, 70, 40, and 21 %, respectively. The discharge capacity of the ZnS-RGO composite powders at a high current density of 4000 mAg-1 after 700 cycles was 437 mAhg-1. The structural stability of the highly conductive ZnS-RGO composite powders with ultrafine crystals during cycling resulted in excellent electrochemical properties. [ABSTRACT FROM AUTHOR]

VO2-decorated reduced graphene balls were prepared by a one-pot spray-pyrolysis process from a colloidal spray solution of well-dispersed graphene oxide and ammonium vanadate. The graphene-VO2 composite powders prepared directly by spray pyrolysis had poor electrochemical properties. Therefore, the graphene-VO2 composite powders were transformed into a reduced graphene ball (RGB)-V2O5 (RGB) composite by post-treatment at 300 °C in an air atmosphere. The TEM and dot-mapping images showed a uniform distribution of V and C components, originating from V2O5 and graphene, consisting the composite. The graphene content of the RGB-V2O5 composite, measured by thermogravimetric analysis, was approximately 5 wt %. The initial discharge and charge capacities of RGB-V2O5 composite were 282 and 280 mA h g−1, respectively, and the corresponding Coulombic efficiency was approximately 100 %. On the other hand, the initial discharge and charge capacities of macroporous V2O5 powders were 205 and 221 mA h g−1, respectively, and the corresponding Coulombic efficiency was approximately 93 %. The RGB-V2O5 composite showed a better rate performance than the macroporous V2O5 powders. [ABSTRACT FROM AUTHOR]

A spray-pyrolysis process is introduced as an effective tool for the preparation of yolk-shell-structured materials with electrochemical properties suitable for anode materials in Li-ion batteries (LIBs). Yolk-shell-structured ZnO-Mn3O4 systems with various molar ratios of the Zn and Mn components are prepared. The yolk-shell-structured ZnO-Mn3O4 powders with a molar ratio of 1:1 of the Zn and Mn components are shown to have high capacities and good cycling performances. [ABSTRACT FROM AUTHOR]

Crumpled graphene-MoO2 composite powders are directly prepared by means of spray pyrolysis and from a stable graphene oxide colloidal solution in the presence of Mo ions. The crumpled graphene-MoO2 composite powders are transformed into MoO3-based composite powders after post-treatment at 300 °C. The transmission electron microscopy and dot-mapping images of the post-treatment composite powders show uniform distribution of MoO3 nanocrystals in the crumpled graphene powders. The two typical D and G bands of graphene are observed at 1350 and 1590 cm−1, respectively, in the Raman spectrum of the graphene-MoO3 composite. In addition, the crumpled graphene-MoO3 powders exhibit superior electrochemical behavior compared to that of pure MoO3 as an anode material for lithium-ion batteries. The initial discharge capacities of the graphene-MoO3 composite and bare MoO3 powders at a current density of 2 A g−1 are 1490 and 1225 mA h g−1, respectively. The capacity retention of the graphene-MoO3 composite is 87 % after the first cycle, whereas that of bare MoO3 is 47 %, as measured after 100 cycles. The reversible discharge capacity of the graphene-MoO3 composite decreases slightly from 1228 to 845 mA h g−1 as the current density increases from 0.5 to 3 A g−1. [ABSTRACT FROM AUTHOR]

We have reported for the first time the preparation of yolk-shell-structured Li4Ti5O12 powders for use as anode materials in lithium-ion batteries. One Li4Ti5O12 yolk-shell-particle powder is directly formed from each droplet containing lithium, titanium, and carbon components inside the hot wall reactor maintained at 900 °C. The precursor Li4Ti5O12 yolk-shell-particle powders, which are directly prepared by spray pyrolysis, have initial discharge and charge capacities of 155 and 122 mA h g−1, respectively, at a current density of 175 mA g−1. Post-treatment of the yolk-shell-particle powders at temperatures of 700 and 800 °C improves the initial discharge and charge capacities. The initial discharge capacities of the Li4Ti5O12 powders with a yolk-shell structure and a dense structure post-treated at 800 °C are 189 and 168 mA h g−1, respectively. After 100 cycles, the corresponding capacities are 172 and 152 mA h g−1, respectively (retentions of 91 and 90 %). [ABSTRACT FROM AUTHOR]

In this study, we report the first preparation of phase-pure Co9S8 yolk-shell microspheres in a facile two-step process and their improved electrochemical properties. Yolk-shell Co3O4 precursor microspheres are initially obtained by spray pyrolysis and are subsequently transformed into Co9S8 yolk-shell microspheres by simple sulfidation in the presence of thiourea as a sulfur source at 350 °C under a reducing atmosphere. For comparison, filled Co9S8 microspheres were also prepared using the same procedure but in the absence of sucrose during the spray pyrolysis. The prepared yolk-shell Co9S8 microspheres exhibited a Brunauer-Emmett-Teller (BET) specific surface area of 18 m2 g−1 with a mean pore size of 16 nm. The yolk-shell Co9S8 microspheres have initial discharge and charge capacities of 1008 and 767 mA h g−1 at a current density of 1000 mA g−1, respectively, while the filled Co9S8 microspheres have initial discharge and charge capacities of 838 and 638 mA h g−1, respectively. After 100 cycles, the discharge capacities of the yolk-shell and filled microspheres are 634 and 434 mA h g−1, respectively, and the corresponding capacity retentions after the first cycle are 82 % and 66 %. [ABSTRACT FROM AUTHOR]

Spherical, hollow MnSC composite powders were prepared from a solution of manganese salt, thiourea, and sucrose by one-pot spray pyrolysis. The MnSC composite powders were generated by direct sulfidation of MnO with hydrogen sulfide gas generated in situ by decomposition of thiourea during spray pyrolysis. Sucrose, which is used as a carbon source material, plays a key role in the formation of the MnSC composite powders by improving the reducing atmosphere around the powders. Dot-mapping images of the composite powders demonstrated uniform distribution of the manganese, sulfur, and carbon components within the MnSC composite powder. Fine crystals of MnS were uniformly mixed with carbon derived from polymerization and carbonization of sucrose. The carbon content of the MnSC composite powders was 26 wt %. The discharge capacities of the MnSC composite powders in the 2nd and 200th cycles were 863 and 967 mA h g−1, respectively, at a current density of 1000 mA g−1. The spherical and hollow morphology of the MnSC composite powders was completely retained, even after 200 cycles. The enhanced cycling and rate performance of the MnSC composite powders is ascribed to the structural stability of the composite powders. [ABSTRACT FROM AUTHOR]

Charging up the batteries: The preparation and electrochemical properties of the yolk–shell LiV3O8 powders (see scheme) have been described for the first time. These powders have superior rate and cycling performances as a direct result of their unique particle structure and stability during cycling. [ABSTRACT FROM AUTHOR]

Several yolk-shell-structured CuO-Fe2O3 powders with various Cu/Fe molar ratios have been successfully prepared under equivalent reaction conditions using a one-pot spray pyrolysis process. The Cu and Fe components are uniformly distributed throughout the powders, irrespective of composition. The Brunauer-Emmett-Teller surface areas of the yolk-shell CuO-Fe2O3 systems increased from 5 to 16 m2 g−1 if the Cu/Fe molar ratios are decreased from 3:1 to 1:3. The initial discharge and charge capacities of the yolk-shell CuO-Fe2O3 system (Cu/Fe=1:2), showing maximum values at a constant current density of 1000 mA g−1, are 1436 and 1012 mA h g−1, respectively. After 130 cycles, the discharge capacities of the yolk-shell CuO-Fe2O3 powders with Cu/Fe molar ratios of 1:3, 1:2, 1:1, 2:1, and 3:1 are 1159, 1151, 755, 655, and 651 mA h g−1, respectively. The discharge capacities of the yolk-shell and dense powder samples after 50 cycles, when subjected to a series of current density increases from 500 to 5000 mA g−1, are 735 and 495 mA h g−1, respectively. [ABSTRACT FROM AUTHOR]

Treading on eggshells: WO3 powders are prepared by using a one‐step spray pyrolysis process. Different spray solutions are used (with or without sucrose), and particles with various morphologies (yolk‐shell, hollow, and dense‐structured) are achieved. The yolk‐shell composite demonstrates electrochemical properties that are superior to the particles with dense and hollow structures at a high current density. [ABSTRACT FROM AUTHOR]

Abstract: WO3 hollow spheres were prepared by ultrasonic spray pyrolysis of a citric-acid-containing precursor solution, and their trimethylamine-sensing characteristics were investigated. The WO3 hollow spheres showed a high response to 5ppm of trimethylamine (R a/R g =56.9, R a: resistance in air, R g: resistance in gas) with low cross-responses to 5ppm C2H5OH, CO, CH4, C3H8, H2, NH3, and NO2. The high gas response observed was explained by the effective electron depletion of small primary particles and the enhanced gas accessibility of hollow structures with thin and porous shells. The enhanced trimethylamine selectivity was discussed in terms of the interaction between basic analyte gas and acidic sensing materials. [Copyright &y& Elsevier]

Abstract: Pure and Ag-doped BaTiO3 nanopowders were prepared by spray pyrolysis. Precursor powders, prepared from a spray solution with citric acid and ethylenediaminetetraacetic acid (EDTA) as chelating agents, had large, hollow particles irrespective of Ag doping. Both pure and Ag-doped powders had partially aggregated particles after post-treatment at 900°C that could be easily milled to nanoparticles. The mean sizes of the pure and Ag-doped BaTiO3 particles were 75 and 91nm, respectively. The Ag-doped particles were mainly of cubic BaTiO3 crystal structure, with small Ag phases observed. High-density BaTiO3 pellets were formed by sintering the powders at the low temperature of 1000°C. The silver was uniformly distributed in a tetragonal BaTiO3 phase without phase separation in the doped pellet. The dielectric constants of the pellets formed from the pure and Ag-doped BaTiO3 powders were 1826 and 2400, respectively. [Copyright &y& Elsevier]

Abstract: The various types of drying control chemical additives are applied to control the morphological and electrochemical characteristics of the Li4Ti5O12 powders prepared by spray pyrolysis. The Li4Ti5O12 powders obtained from the spray solutions with formamide, N,N-dimethylformamide, N-methylacetamide and 1,4-dioxane have dense structures and fine sizes. On the other hand, the Li4Ti5O12 powders obtained from the spray solution with glycerol have hollow structure and large size. The Li4Ti5O12 powders obtained from the spray solutions with formamide, N,N-dimethylformamide and 1,4-dioxane have high initial discharge capacities of 167, 166 and 163mAh/g at a constant current density of 0.1C. The discharge capacity of the Li4Ti5O12 powders obtained from the spray solution with formamide is 95% of the initial discharge capacity after 60 cycles. [Copyright &y& Elsevier]

Abstract: High-density Li4Ti5O12 powders comprising spherical particles are prepared by spray pyrolysis from a solution containing dimethylacetamide (drying control chemical additive) and citric acid and ethylene glycol (organic additives). The prepared powders have high discharge capacities and good cycle properties. The optimum concentration of dimethylacetamide is 0.5M. The addition of dimethylacetamide to the polymeric spray solutions containing citric acid and ethylene glycol helps in the effective control of the morphology of the Li4Ti5O12 powders. At a constant current density of 0.17mAg−1, the initial discharge capacities of the powders obtained from the spray solution with and without the organic additives are 171 and 167mAhg−1, respectively. [Copyright &y& Elsevier]

Abstract: Spherical shape borate-based bioactive glass powders with fine size were directly prepared by high temperature spray pyrolysis. The powders prepared at temperatures between 1200 and 1400°C had mixed phase with small amounts of fine crystal and an amorphous rich phase. Glass powders with amorphous phase were prepared at a temperature of 1500°C. The mean size of the glass powders prepared by spray pyrolysis was 0.76μm. The glass powders prepared at a temperature of 1200°C had two distinct exothermic peaks (T c1 and T c2) at temperatures of 588 and 695°C indicating crystallization. The glass transition temperature (T g ) of the powders prepared at a temperature of 1200°C was 480°C. Phase-separated crystalline phases with spherical shape were observed from the surface of the pellet sintered at a temperature of 550°C. Crystallization of the pellet was completely occurred at temperatures of 750 and 800°C. The pellets sintered at temperatures below 700°C had single crystalline phase of CaNa3B5O10. The pellet sintered at a temperature of 800°C had two crystalline phases of CaNa3B5O10 and CaB2O4. [Copyright &y& Elsevier]

Abstract: Fine-sized La2O3–B2O3–TiO2 glass powders with spherical shape were directly prepared by spray pyrolysis at a temperature of 1500°C. The optimum flow rate of the carrier gas to prepare the glass powders with dense inner structure and fine size by complete melting was 10L/min. The ratio of La/Ti was identified to be 2.06:1, which was close to the original starting ratio of La/Ti in mixture of the spray solution. The T g and T c of the powders were 614 and 718°C. The crystal structures within the powders were observed from the sintered disc at 630°C. The mean sizes of the powders changed from 0.24 to 0.71μm when the concentrations of the spray solution were changed from 0.025 to 0.5M. The BET surface areas of the powders changed from 4.4 to 1.6m2/g. The grain sizes of the sintered discs increased with increasing the sintering temperatures. The main crystal structure of the sintered discs was LaBO3. [Copyright &y& Elsevier]

Abstract: Fine-sized LiNi0.8Co0.15Mn0.05O2 cathode particles with high discharge capacities and good cycle properties were prepared by spray pyrolysis from the polymeric precursor solutions. The cathode particles obtained from the spray solution without polymeric precursors had irregular morphology and hardly aggregated morphology. On the other hand, the cathode particles obtained from the spray solution with citric acid and ethylene glycol had fine size and regular morphologies. The cathode particles obtained from the spray solution containing adequate amounts of citric acid and ethylene glycol had several hundreds nanometer and narrow size distribution. The maximum discharge capacity of the cathode particles was 218mAh/g when the excess of lithium component added to the spray solution was 6mol% of the stoichiometric amount to obtain the LiNi0.8Co0.15Mn0.05O2 particles. The discharge capacities of the fine-sized LiNi0.8Co0.15Mn0.05O2 particles dropped from 218 to 213mAh/g by the 50th cycle at a current density of 0.1C. [Copyright &y& Elsevier]

Abstract: Li4Ti5O12 anode powders were prepared by post-treatment of the precursor powders obtained by spray pyrolysis at various preparation conditions. The precursor powders had fine size, narrow size distribution, dense inner structure and homogeneous composition when the flow rate of the carrier gas and the preparation temperature were 10lmin−1 and 800°C. The spherical shapes of the precursor powders obtained at the optimum preparation conditions maintained after post-treatment at a temperature of 800°C. The mean sizes of the Li4Ti5O12 powders were controlled by changing the concentrations of the spray solution. The initial discharge capacities and cycle properties of the Li4Ti5O12 powders were strongly affected by the preparation temperatures of the precursor powders. The optimum preparation temperature of the precursor powders was 800°C when the flow rate of the carrier gas was 10lmin−1. The discharge capacities and cycle properties of the Li4Ti5O12 powders were not affected by flow rates of the carrier gas. The Li4Ti5O12 powders had good cycle properties irrespective of the concentrations of the spray solution. However, the Li4Ti5O12 powders obtained from the spray solutions with high concentration above 0.5M had high discharge capacities than those obtained from the spray solutions with low concentration below 0.1M. [Copyright &y& Elsevier]

Abstract: The effects of the precursor types of Ni and Fe components on the morphology, mean size, and magnetic property of NiFe2O4 powders prepared by spray pyrolysis from the spray solution, with citric acid were studied. The precursor powders with hollow and thin wall structure turned to the nano-sized NiFe2O4 powders after post-treatment at a temperature of 800°C. The nickel ferrite powders obtained from the spray solution with ferric chloride had nanometer sizes and narrow size distributions irrespective of the types of nickel precursor. The nickel ferrite powders obtained from the spray solution with ferric nitrate and nickel chloride also had nanometer size and narrow size distribution. The saturation magnetizations of the NiFe2O4 powders changed from 37 to 42emu/g according to the types of the Fe and Ni precursors. The saturation magnetizations of the NiFe2O4 powders increased with increasing the Brunauer-Emmett-Teller (BET) surface areas of the powders. [Copyright &y& Elsevier]

Abstract: The effects of the ratio of manganese and nickel components on the characteristics of Li x (Mn y Ni1−y )O z cathode powders prepared by spray pyrolysis are investigated. The LiMn2O4, LiMn1.5Ni0.5O4 and LiNi0.5Mn0.5O2 cathode powders have spherical shape and non-agglomeration characteristics even after post-treatment. However, the spherical shape of the cathode powders disappeared with increasing the content of nickel component into the Li x (Mn y Ni1−y )O z cathode powders. The mean crystallite sizes of the LiMn2O4 and LiMn1.5Ni0.5O4 cathode powders with spinel crystal structure are each 50 and 42nm. The mean crystallite sizes of the LiNiO2, LiNi0.75Mn0.25O2 and LiNi0.5Mn0.5O2 cathode powders with layered crystal structures are 40, 30 and 17nm, respectively. The initial discharge capacity of the spherical shape LiMn2O4 powders is 121mAh/g. The initial discharge capacities of the powders increased with increasing the nickel content into the Li x (Mn y Ni1−y )O z cathode powders up to 206mAh/g. [Copyright &y& Elsevier]

Abstract: Spherical-shaped Li4Ti5O12 anode powders with a mean size of 1.5μm were prepared by spray pyrolysis. The precursor powders obtained by spray pyrolysis had no peaks of crystal structure of Li4Ti5O12. The powders post-treated at temperatures of 800 and 900°C had the single phase of spinel Li4Ti5O12. The powders post-treated at a temperature of 1000°C had main peaks of the Li4Ti5O12 phase and small impurity peaks of Li2Ti3O7. The spherical shape of the precursor powders was maintained after post-treatment at temperatures below 800°C. The Brunauer–Emmett–Teller (BET) surface areas of the Li4Ti5O12 anode powders post-treated at temperatures of 700, 800 and 900°C were 4.9, 1.6 and 1.5m2/g, respectively. The initial discharge capacities of Li4Ti5O12 powders were changed from 108 to 175mAh/g when the post-treatment temperatures were changed from 700 to 1000°C. The maximum initial discharge capacity of the Li4Ti5O12 powders was obtained at a post-treatment temperature of 800°C, which had good cycle properties below current densities of 0.7C. [Copyright &y& Elsevier]

Abstract: Nano-sized hydroxyapatite (HAp) powders with high crystallinity and appropriate stoichiometry were prepared by high-temperature flame spray pyrolysis process from the spray solutions with polyethylene glycol (PEG). The mean sizes of the HAp powders obtained from the spray solutions with PEG were changed from several tens to several hundreds nanometers according to the concentrations of PEG added to the spray solutions at a post-treatment temperature of 800°C. In the TEM-EDX spectrum, the composition ratio of calcium and phosphorous components was 1.69. The HAp powders post-treated at a low temperature of 400°C had fiber-like morphology. On the other hand, the post-treated HAp powders at temperatures of 600 and 1000°C had each rod-like morphology with low aspect ratio and spherical-like morphology. The mean sizes of the HAp powders post-treated at temperatures of 600 and 1000°C were each 32 and 213nm. [Copyright &y& Elsevier]

Abstract: Nano-sized manganese oxide particles were prepared by low-pressure spray pyrolysis using the new type of liquid aerosol generator called as FEAG process. The particles prepared from polymeric precursors spray solution with organic additives had large size, hollow and fractured morphologies due to the gas evolution from the decomposition of the organic additives. The precursor particles with micron size, hollow and thin wall structures turned to nano-sized manganese oxide particles after post-treatment at temperatures of 700 and 800°C. The optimum concentrations of citric acid (CA) and ethylene glycol (EG) to prepare the nano-sized manganese oxide particles by spray pyrolysis using the FEAG process were 0.3M each. The manganese oxide particles prepared from the polymeric precursors spray solutions with high concentrations of CA and EG had spherical shape and porous morphologies. [Copyright &y& Elsevier]

Phosphor materials have been used for applications in fluorescence lamps and display devices. Such phosphors have been mostly produced by the conventional solid-state reaction technique. In solid-state reactions, high reaction temperature and long heating time are required to obtain a pure phase of the multi-component particles, and agglomerated particles of irregular shape is unavoidable. Therefore, milling process is necessary in the solid-state technique. These process characteristics decrease the brightness of phosphor particles. Recently, extensive efforts were given in production of phosphors particles by spray pyrolysis in order to have fine size and spherical morphology. In this manuscript, phosphor particles produced by spray pyrolysis for photoluminescence applications were reviewed. Phosphorescence phenomenon is briefly explained with the energy transfer mechanism including the intersystem crossing. In the main context, phosphor materials are categorized into three parts following the color (red, green, and blue) characteristics. As expected, phosphor particles generated by spray pyrolysis have a big advantage in obtaining spherical morphology, compared with the particles from the conventional solid-state processes. Therefore, high packing density and uniformity of films for final display devices are predicted, and it could further help achieving high photoluminescent intensity in final products. [ABSTRACT FROM AUTHOR]

Abstract: Eu-doped barium strontium silicate phosphor particles with high photoluminescence intensity under long wavelength ultraviolet were prepared from the spray solution containing NH4Cl flux by spray pyrolysis. It was found that the addition of NH4Cl to the spray solution makes it possible to greatly improve the photoluminescence intensity of Ba1.488Sr0.5SiO4:Eu0.012 phosphor particles under long wavelength ultraviolet of 410nm. The highest photoluminescence intensity, which was achieved when the NH4Cl content was 5wt.%, was about 150% of Ba1.488Sr0.5SiO4:Eu0.012 particles prepared from the spray solution without flux material at the post-treatment temperature of 1050°C. The particle size of Ba1.488Sr0.5SiO4:Eu0.012 phosphor particles were enlarged by using the NH4Cl flux in the spray solution because of the large grain growth which was identified from the sharpening of the XRD peaks. Adding the NH4Cl flux into the spray solution was found to lower the optimal post-treatment temperature at which the Ba1.488Sr0.5SiO4:Eu0.012 phosphor particles are fully crystallized and have the maximum photoluminescence intensity. The phosphor particles prepared from spray solution containing 5wt.% NH4Cl flux had the maximum photoluminescence intensity at post-treatment temperature of 1100°C. [Copyright &y& Elsevier]

Flame-assisted spray pyrolysis was applied to prepare BaMgAl10O17:Eu (BAM) blue phosphor particles with spherical shape, which exhibited improved photoluminescence characteristics under vacuum ultraviolet (147 nm) excitation. It was found that simply controlling the property of the precursor solution to be sprayed was helpful to suppress the formation of hollow structure and made it possible to produce dense and spherical-shaped BAM particles by using the flame-assisted spray pyrolysis process. The film of prepared BAM powder was built up on slide glass. Then, the prepared spherical particles produced not only better uniform surface, but also higher particle density in comparison with the commercial BAM particles which have irregular shape. The photoluminescence intensity of the spherical-shaped BAM particles prepared by the flame-assisted spray pyrolysis was lower than that of the commercial powder. The phosphor film made from BAM particles with fine size and spherical shape, however, showed higher photoluminescence intensity than that prepared with the irregular-shaped commercial particles due to higher particle density and uniformity of the film. [Copyright &y& Elsevier]

Green-emitting LaPO4:Ce,Tb phosphor particles were synthesized by a large-scale spray pyrolysis. The prepared phosphor particles had a completely spherical shape, fine size, and high brightness under ultraviolet. The phosphor particles had the maximum photoluminescence intensity after posttreatment at 1300 °C even without flux material. The phosphor particles had a spherical shape and non-aggregation characteristics. The types of phosporous source affected the morphological characteristics and photoluminescence of the prepared particles. Particles prepared from a solution with ammonium hydrogen phosphate had a higher brightness than those prepared from solutions with ammonium dihydrogen phosphate, ammonium phosphate, or phosphoric acid. The maximum brightness of particles prepared by spray pyrolysis was 109% that of the commercial product with non-spherical shape and large size. [Copyright &y& Elsevier]

Highly crystalline Co3O4 yolk–shell powders with a filled core and various shell numbers are prepared by a simple one-pot spray pyrolysis process. Co3O4 yolk–shell powders exhibited a high initial discharge capacity of 548 mA h g−1 and retained their capacities very well, even at a high discharge rate of 10 000 mA g−1. [ABSTRACT FROM AUTHOR]

Scalable continuous ultrasonic spray pyrolysis is used to develop a facile one-pot method of synthesizing sandwich structured core–shell particles consisting of a Pd core, a V2O5 inner layer, and a porous SiO2 outer layer. Pd@SiO2 yolk–shell particles are easily formed by removing the V2O5 inner layer. [ABSTRACT FROM AUTHOR]

We report three-dimensional (3D) porous microspheres comprising interconnected carbon nanotubes (CNT) decorated with hollow NiCo 2 O 4 polyhedrons (H-NCO/CNT) for high-performance lithium-ion batteries (LIBs). The rationally designed composites are successfully fabricated via the combination of spray-pyrolysis and solution-based methods. The macroporous CNT microsphere obtained by spray pyrolysis acts as a substrate for the growth of the zeolitic imidazolate framework-67 (ZIF-67) in ethanol solution. During ion exchange and subsequent oxidation processes, the ZIF-67 polyhedrons were converted into hollow NiCo 2 O 4 polyhedrons consisting of small crystal domains. Rational design of such composite microspheres offers a highly conductive 3D porous network that simultaneously enables fast ion and electron diffusion deep inside the electrodes during cycling. In addition, the hollow polyhedron interiors can accommodate large volume changes and shorten the transport pathway for the ions and electrons. Owing to these structural advantages, high capacity, long cycle life, and excellent rate capability are achieved from H-NCO/CNT microspheres when applied as LIB anodes; the discharge capacity of H-NCO/CNT microspheres remained at 1673 mA h g −1 after 200 cycles at a current density of 1.0 A g −1 . Even when cycled at a high current density of 20.0 A g −1 , a high capacity of 639 mA h g −1 could be achieved. [ABSTRACT FROM AUTHOR]

CoP-carbon nanotube (CNT) composite microspheres with high porosity for hydrogen evolution reaction (HER) are synthesized by facile spray pyrolysis and subsequent low-temperature phosphidation. Highly active CoP nanocrystals are successfully decorated on conductive CNT backbone microspheres. Decomposition of polystyrene nanobeads during spray pyrolysis forms macropores over the CoP-CNT composite microspheres, which facilitate electrolyte permeation and maximize the active site exposure. In addition, such morphology not only enhances the electron transfer along the microsphere, but also minimizes the polarization of H 2 gas during HER. Due to the synergistic effect between CoP nanocrystals and CNT backbone, along with the unique morphology, the CoP-CNT composite microspheres demonstrate outstanding HER performance in an acidic electrolyte with a low overpotential of 119 mV at 10 mA cm −2 and a small Tafel slope of 64 mV dec −1 . Moreover, the catalyst maintains its excellent catalytic activity over 2000 cycles. This study marks the versatility of the spray pyrolysis process for the synthesis of conductive substrate-supported electrocatalysts with a wide variety of materials and structures. [ABSTRACT FROM AUTHOR]

Three-dimensional macroporous carbon nanotubes microspheres highly loaded with phase-pure NiCo 2 O 4 hollow nanospheres are synthesized by the spray pyrolysis process and are characterized for potential use in lithium-ion batteries. Polystyrene nanobead template and the nanoscale Kirkendall diffusion process are first combined and are applied to the spray pyrolysis process to form macroporous NiCo 2 O 4 /carbon nanotubes composite microspheres with extremely high rate performance as anode materials for lithium-ion batteries. Metallic NiCo 2 /carbon nanotubes composite microspheres—formed as intermediate products—are transformed into composite microspheres of phase-pure NiCo 2 O 4 hollow nanospheres and carbon nanotubes by the nanoscale Kirkendall diffusion process. The mean size of the hollow NiCo 2 O 4 nanospheres decorated on the carbon nanotubes backbone is 28 nm. The macroporous NiCo 2 O 4 /carbon nanotubes composite microspheres have discharge capacities of 840, 748, 677, 591, 514, 451, 391, 337, and 289 mA h g −1 at current densities of 0.5, 1, 2, 5, 10, 15, 20, 25, and 30 A g −1 , respectively. The discharge capacity of the macroporous NiCo 2 O 4 /carbon nanotubes microspheres for the 500th cycle at a current density of 3 A g −1 is 572 mA h g −1 . The uniquely structured hollow NiCo 2 O 4 nanosphere/carbon nanotubes composite microspheres have superior cycling and rate performances for lithium-ion storage. [ABSTRACT FROM AUTHOR]

Unique-structured (Mn 1/3 Co 2/3 )O-carbon nanotubes (MnCoO-CNT) composite microspheres synthesized by one-pot spray pyrolysis were studied as air electrode for lithium–oxygen (Li-O 2 ) batteries. The (Mn 1/3 Co 2/3 )O nanocrystals were first introduced as efficient electrocatalysts for oxygen reduction reactions (ORRs) and oxygen evolution reactions (OERs). In addition, the optimum structure of CNT microspheres was designed as efficient support material for (Mn 1/3 Co 2/3 )O nanocatalysts with high electrical conductivity and high accommodation ability for Li 2 O 2 products. The macroporous MnCoO-CNT composite microspheres exhibited excellent bifunctional oxygen catalytic activities in terms of a positive half-wave potential (0.67 V) for ORRs and high limiting diffusion current (35 mA cm −2 at 1.0 V) for OERs. When applied as a cathode material for Li–O 2 batteries, the MnCoO–CNT microspheres delivered a high discharge capacity (37142 mA h g −1 at 200 mA g −1 ), excellent rate capability (4458 mA h g −1 at 2000 mA g −1 ), and long-term cycle stability (245 cycles at a capacity of 500 mA h g −1 at 200 mA g −1 ). The synergetic effect of macroporous CNT microspheres with high electrical conductivity and high electrocatalytic activities of the (Mn 1/3 Co 2/3 )O nanocatalyst were responsible for the superior performance of MnCoO–CNT composite microspheres as cathode material for Li–O 2 batteries. [ABSTRACT FROM AUTHOR]

P2-type Na 2/3 Ni 1/3 Mn 2/3 O 2 plates with homogeneous composition and regular morphology are prepared by spray pyrolysis. The rhombohedral P3-Na 2/3 Ni 1/3 Mn 2/3 O 2 microspheres formed by one-pot spray pyrolysis transform into hexagonal P2-Na 2/3 Ni 1/3 Mn 2/3 O 2 plates after post-treatment at temperatures between 800 and 1000 °C. The mean size and thickness of P2-Na 2/3 Ni 1/3 Mn 2/3 O 2 plates obtained after post-treatment at 900 °C are 2.2 μm and 550 nm, respectively. The initial discharge capacities of P2-Na 2/3 Ni 1/3 Mn 2/3 O 2 plates formed at 800, 900, and 1000 °C at a current rate of 0.1C are 69, 86, and 80 mA h g −1 , respectively, while the discharge capacities after 200 cycles are 68, 80, and 76 mA h g −1 , respectively. However, the discharge capacities of P3-Na 2/3 Ni 1/3 Mn 2/3 O 2 powders decrease from 62 to 50 mA h g −1 after 200 cycles. P2-Na 2/3 Ni 1/3 Mn 2/3 O 2 plates show low charge-transfer resistance and also exhibit better rate performance than P3-Na 2/3 Ni 1/3 Mn 2/3 O 2 powders. [ABSTRACT FROM AUTHOR]

Phase-pure β-NiMoO 4 yolk-shell spheres for lithium-ion battery anodes were prepared for the first time by one-pot spray pyrolysis, and their electrochemical properties were investigated. The yolk-shell-structured β-NiMoO 4 powders exhibited high initial discharge/charge capacities (1634/1253 mA h g −1 ) at a current density of 1000 mA g −1 . After 200 cycles, these powders exhibited a high discharge capacity of 1292 mA h g −1 , whereas the initial discharge capacity (1341 mA h g −1 ) of the filled structured NiMoO 4 powders was dramatically decreased to 479 mA h g −1 . The significant enhancement of the cycling performance of the β-NiMoO 4 powders with ultrafine crystallite size was attributed to the structural stability of the yolk-shell structure. [ABSTRACT FROM AUTHOR]

Co 2 (OH) 3 Cl/reduced graphene oxide (RGO) composite powders for use as anodes in lithium ion batteries were prepared directly by spray pyrolysis from a colloidal solution of graphene oxide sheets and cobalt chloride. Co 2 (OH) 3 Cl nanocrystals less than 10 nm in size were uniformly distributed throughout the spherical Co 2 (OH) 3 Cl/RGO composite powder. CoCl 2 ·6H 2 O/RGO, CoCl 2 ·6H 2 O/Co 3 O 4 /RGO, and Co 3 O 4 powders were also prepared by post-treatment of the Co 2 (OH) 3 Cl/RGO powders at 200, 300, and 400 °C, respectively, in air. The initial discharge capacities of the Co 2 (OH) 3 Cl/RGO, CoCl 2 ·6H 2 O/RGO, CoCl 2 ·6H 2 O/Co 3 O 4 /RGO, and Co 3 O 4 powder electrodes at a current density of 1000 mA g −1 were 1685, 1518, 1655, and 1046 mA h g −1 , respectively, and their discharge capacities after 200 cycles were 1186, 1030, 884, and 805 mA h g −1 , respectively. The discharge capacities of the Co 2 (OH) 3 Cl/RGO composite powder electrode for the 2nd and 600th cycles at a current density of 5000 mA g −1 were 1063 and 833 mA h g −1 , respectively. The Co 2 (OH) 3 Cl/RGO powders had smaller charge transfer resistance and faster lithium-ion diffusion rate than the other materials. [ABSTRACT FROM AUTHOR]

Abstract: An ultraselective and ultrasensitive trimethylamine (TMA) sensor was achieved using MoO3 nanoplates-prepared by ultrasonic spray pyrolysis followed by a heat treatment at 450°C. The small and thin MoO3 nanoplates with gas-accessible structures showed an unusually high response to 5ppm TMA (ratio of resistance to air and gas=373.74) at 300°C with detection limit as low as 45ppb. Moreover, the ratios of the cross-responses to interfering gases (i.e., 5ppm C2H5OH, CO, CH4, C3H8, H2, and NO2) to the response to 5ppm TMA were extremely low (0.008–0.016). The source of the ultraselective and highly sensitive detection of TMA with negligible interference from other gases is discussed with respect to the acid/base properties, size, and morphology of the MoO3 sensing materials. [Copyright &y& Elsevier]

Abstract: The CuO-loaded SnO2 hollow spheres were prepared by ultrasonic spray pyrolysis and their H2S sensing characteristics in dry and humid atmospheres for the diagnosis of halitosis were investigated. The loading of CuO to SnO2 hollow spheres decreased the humidity dependence of H2S sensing characteristics down to negligible level, increased the gas response (ratio of resistance to air and gas) in highly humid atmosphere (relative humidity 80%) to 1ppm H2S from 3.13 to 22.4, and enhanced the selectivity to H2S over CO, NH3, CH3COCH3, C6H6, CH3C6H5, (CH3)2C6H4, and NO at 300°C. Ultraselective and ultrasensitive detection of H2S under highly humid atmosphere with negligible interferences from other biomarker gases provides a promising and reliable analysis tool for real-time diagnosis of halitosis from exhaled breath. [Copyright &y& Elsevier]

Abstract: Spherical bare nickel sulfide and nickel sulfide–carbon composite powders are prepared by a one-step spray pyrolysis. Submicron bare nickel sulfide particles with a dense structure have mixed crystal phases of NiS, Ni7S6, and Ni x S6. The nickel sulfide–carbon composite powders prepared from a spray solution containing 0.1 M sucrose have a main crystal structure of Ni7S6 phase with small impurity peaks of NixS6 phase. A nickel oxide–carbon composite powder is first formed as an intermediate product in the front part of the reactor at 800 °C. Fast decomposition of thiourea at this high temperature results in the evolution of hydrogen sulfide gas, which then forms the nickel sulfide–carbon composite powders by direct sulfidation of nickel oxide under the reducing atmosphere. Nickel sulfide nanocrystals with a size of a few nanometers are uniformly distributed inside the spherical carbon matrix. The nickel sulfide–carbon composite powders prepared with 0.1 M sucrose have an excellent discharge capacity of 472 mA h g−1 at a high current density of 1000 mA g−1, even after 500 cycles, with the corresponding capacity retention measured after the first cycle being 86%. [Copyright &y& Elsevier]

Highlights: [•] Review on electrochemical performance of electrode particles designed by spray pyrolysis. [•] Formation mechanism of various structure and composite via spray pyrolysis. [•] Relationship between specific particle structures and battery performance. [ABSTRACT FROM AUTHOR]

Li2TiO3–LiCrO2 cathode powders of various compositions are prepared by spray pyrolysis. Pure Li2TiO3 powder and Li2TiO3–LiCrO2 composite cathode powder have a spherical shape, nonaggregated structure, and fine sizes even after post-treatment at 700 °C under nitrogen atmosphere. The optimum post-treatment temperature to obtain composite powders with high initial discharge capacity, high coulombic efficiency, and good cycle properties is 700 °C. The initial charge capacities increase when the LiCrO2 content of the composite increase. However, the 0.55Li2TiO3–0.45LiCrO2 composite cathode powders have the highest initial discharge capacity of 203 mAh g−1, in which the capacity retention after 30 cycles is 96%. The dQ/dV curve of the first charge curve has a distinct oxidation peak at approximately 3.9 V, which corresponds to Cr oxidation. The oxidation peak shifts to a lower voltage range at approximately 3.6 V after the first cycling because an irreversible reaction takes place in the initial charge process. The composite cathode powders with low LiCrO2 content have low initial charge/discharge capacities and good cycle properties because of the stabilizing effect of high amounts of an inactive Li2TiO3 component. [ABSTRACT FROM AUTHOR]

Abstract: The preparation of precursors of BaTiO3 nanopowders with various amounts of Ag by spray pyrolysis is reported. The precursor powders obtained with hollow and thin-wall particles are composed of uniformly dispersed Ba, Ti, and Ag components. After post-treatment and a simple milling process, the precursor powders, irrespective of the amount of Ag, are transformed into Ag–BaTiO3 composite nanoparticles. The mean particle size of the Ag (10mol%)–BaTiO3 powders is 142nm. BaTiO3 pellets containing Ag exhibit dense structures even at a low sintering temperature of 1000°C. BaTiO3 pellets with 10mol% Ag show the highest dielectric constant of 2950, as opposed to the pure BaTiO3 pellets (without Ag), whose dielectric constant is 1827. [Copyright &y& Elsevier]