One-pot Spray Pyrolysis Process Research Articles

분무열분해 단일공정을 통한 리튬이온전지 음극소재용 MoO3 나노분말

MoO₃ nanopowders having an average size of 150 nm as anode materials for lithium ion batteries were synthesized by one-pot spray pyrolysis process. During the spray pyrolysis process, concentration difference in a droplet occurred due to the high flow rate of the carrier gas, which induced hollow intermediate powders. The intermediate hollow powders are composed of MoO_x and C, and subsequently they are decomposed into MoO₃ nanopowders without C under oxidation atmosphere. When MoO₃ nanopowders were used as anode materials, the cell showed reversible discharge capacity of 390 mA h g-¹ at a current density of 1.0 A g^-1 even after 1,000 cycles. The overwhelming cycle stability of the cell is attributed to the MoO₃ nanopowders with 150 nm that act as an effective anode material by shortening the diffusion length of Li ions to the electrode and increasing the contact surface with the electrolyte during cycles.

One-pot spray pyrolysis for core–shell structured Sn@SiOC anode nanocomposites that yield stable cycling in lithium-ion batteries

A novel strategy is reported for the synthesis of high-capacity anode materials with good cycling stability for use in lithium-ion batteries. A facile one-pot spray pyrolysis process is conducted using an ethanol solution of Sn acetate and diphenylsilanediol (DPSD). Phase separation between Sn and DPSD leads to the formation of core@shell-structured Sn@DPSD nanoparticles, and subsequent heat-treatment in an inert atmosphere carbonizes the DPSD to form Sn@SiOC nanoparticles (∼50 nm). When applied as an anode material in lithium-ion batteries (LIBs), the Sn core retains its high energy density, while the SiOC shell limits volume expansion of the core and protects it from pulverization and agglomeration. The Sn@SiOC nanoparticles exhibit a reversible capacity of 917 mA h g −1 at 0.1C and stable cycling performance for 200 cycles at 1C. The nanoparticle formation mechanism is investigated by optimizing the Sn acetate/DPSD ratio in the precursor solution, and the origin of the enhanced properties is investigated by comparing the results of Sn@SiOC nanoparticles with those of SiOC nanoparticles and Sn microspheres. SiOC shows considerable promise as a coating material for Sn nanoparticles, which may serve as a milestone in the synthesis of nanosized electrode materials with coatings that can prolong the cycle lives of rechargeable batteries.

Highly porous structured Sr-doped La2NiO4/NiO composite cathode with interconnected pores for lithium-oxygen batteries

• Highly porous OP-SLNO was prepared by one-pot spray pyrolysis. • OP-SLNO showed improved catalytic abilities for both OER and ORR. • OP-SLNO with interconnected pores was suitably applied to Li-O 2 batteries. • Interconnected pores provided space to accommodate abundant discharge products. One-pot spray pyrolysis process is a promising continuous process for mass production of nanostructured powder. The highly porous microspheres containing pores interconnected from the inner to the outer side of particle are prepared by one-pot spray pyrolysis process. In this study, Sr-doped layered perovskite oxide is selected as the first target material. A colloid comprising mono-sized spherical templates were used as a precursor to synthesize the porous Sr-doped La 2 NiO 4 /NiO composite powder. The fine and spherical templates construct a highly open and porous structure throughout the resulting particle’s inner bulk and surfaces. The fabricated powder shows improved catalytic abilities for both OER and ORR, based on the results of the RDE measurements. Owing to the open-pore structure, the overpotentials for both discharge and charge processes are lowered attributing to extremely improved cycle life of over 180 cycles when applied to Li-O 2 cell, while the filled-structured powder gives less than 50 cycles. Furthermore, the Li-O 2 cell reveals definitely improved discharge capacity of 13,130 mA h g −1 under 200 mA g −1 owing to the interconnected pore structure, when compared to discharge capacities of closed-pores-containing powder (9,547 mA h g −1 ) and filled-structured powder (7,541 mA h g −1 ).

Se-decorated SnO2/rGO composite spheres and their sodium storage performances

SnO2 is considered a promising anode material for sodium-ion batteries due to its high theoretical capacity and low cost. However, the poor electrical conductivity and dramatic volume variation during charge/discharge cycling is a major limitation in its practical applicability. Here we propose a simple one-pot spray pyrolysis process to construct unique pomegranate-like SnO2/rGO/Se spheres. The ideal structural configuration of these architectures was effective in alleviating the large volume variation of SnO2, besides facilitating rapid electron transfer, allowing the devised anode to exhibit superior sodium storage performances in terms of capacity (506.7 mAh/g at 30 mA/g), cycle performance (397 mAh/g after 100 cycles at 50 mA/g) and rate capability (188.9 mAh/g at an ultrahigh current density of 10 A/g). The experimental evidence confirms the practical workability of p-SnO2/rGO/Se spheres in SIBs.

Hierarchical yolk-shell CNT-(NiCo)O/C microspheres prepared by one-pot spray pyrolysis as anodes in lithium-ion batteries

This paper presents a hierarchical yolk–shell-structured microsphere comprising a hierarchical carbon nanotube (CNT)-(NiCo)O/C yolk and an embossed hollow thin shell (hereafter denoted as CNT-(NiCo)O/C microsphere) prepared by a one-pot spray pyrolysis process for potential use as an anode in lithium-ion batteries. During spray pyrolysis, the hierarchical CNT-(NiCo)O/C yolk, whose frame is linked with CNTs, is formed by mutual binding of the CNTs and size-controlled polystyrene (PS) nanobeads and subsequent selective decomposition of these nanobeads. Further, phase separation of melted poly(vinylpyrrolidone) facilitates the formation of the hollow shell. The discharge capacity of the CNT-(NiCo)O/C microspheres after 1000 cycles at an extremely high current density of 5.0 A g−1 is 598 mA h g−1. The CNT-(NiCo)O/C microspheres show reversible discharge capacities of 886, 709, 509, and 294 mA h g−1 at current densities of 0.5, 5, 20, and 50 A g−1, respectively. The unique nanostructure of the CNT-(NiCo)O/C microspheres with high electrical conductivity promotes the transfer kinetics of electrons and Li+ ions, which consequently leads to their improved electrochemical performances.

Electrochemical properties of amorphous GeOx-C composite microspheres prepared by a one-pot spray pyrolysis process

Amorphous GeO2-GeO-C (GeOx-C) composite powders, containing a small amount of the GeC phase, are prepared by a one-pot spray pyrolysis process. The GeOx-C composite powders have a completely spherical shape and are non-aggregated. The Ge 3d components in the XPS spectrum of the composite occupy 53.3%, 40.1%, and 6.6% of the total for GeO2, GeO, and GeC, respectively. The amount of amorphous carbon in the GeOx-C composite powder is estimated at 18.3%, based on the TG and XPS analysis. The initial discharge and charge capacities of the GeOx-C composite powders at a current density of 1Ag−1 are 1873 and 908mAhg−1, respectively. The discharge capacities of the GeOx-C composite and commercial GeO2 powders for the 1200th cycle are 723 and 169mAhg−1, respectively, and their corresponding capacity retentions from the 2nd cycle are 70.1% and 19.0%, respectively. The high structural stability of the composite during repeated lithium insertion and desertion processes results in excellent long-term cycling performance.

Electrochemical properties of WO3-reduced graphene oxide composite powders prepared by one-pot spray pyrolysis process

In this work, we report the preparation of WO3-reduced graphene oxide (rGO) composite powders by spray pyrolysis process using a stable graphene oxide colloidal solution with ammonium tungstate. The ultrafine WO3 nanocrystals below 10 nm in size are dispersed within the rGO matrix. The bare WO3 powders prepared from the aqueous spray solution of ammonium tungstate are spherical and do not aggregate. The bare WO3 and WO3-rGO composite powders show monoclinic and cubic crystal structures, respectively. The initial discharge capacities of the bare WO3 and WO3-rGO composite powders at a current density of 100 mA g−1 are 771 and 941 mA h g−1, respectively, and their initial Coulombic efficiencies are 67 and 65%, respectively. The discharge capacities of the bare WO3 and WO3-rGO composite powders at the 300th cycle are 282 and 546 mA h g−1, respectively.

Design and synthesis of multiroom-structured metal compounds–carbon hybrid microspheres as anode materials for rechargeable batteries

A novel structure denoted as a “multiroom carbon hybrid”, which comprises empty voids dispersed in metal oxide-, sulfide-, and selenide-carbon composites is introduced. Multiroom-structured carbon hybrid microspheres of single component Co3O4 and NiO and multicomponent (Ni0.5Co0.5)Ox were successfully prepared using a one-pot spray pyrolysis process. Liquid-liquid phase segregation during the spray pyrolysis process is a key requirement for generating multiroom-structured metal oxide-carbon hybrid microspheres. Multiroom-structured CoSe2-graphitic carbon (GC) and CoS2-CoS-GC hybrid microspheres were also prepared using a simple post-treatment process. Multiroom-structured CoSe2-GC hybrid microspheres have superior sodium-ion storage properties to bare CoSe2 microspheres. The reversible discharge capacities of the CoSe2-GC and CoS2-CoS-GC hybrid microspheres for the 100th cycles at a current density of 0.2Ag−1 are 393 and 334mAhg−1, respectively. The discharge capacity of the multiroom-structured Co3O4-C hybrid microspheres for lithium-ion storage at a high current density of 3Ag−1 for the 150th cycle is 1243mAhg−1.

Robust synthesis of hierarchical mesoporous hybrid NiO–MnCo2O4 microspheres and their application in Lithium-ion batteries

Hierarchical mesoporous hybrid NiO–MnCo2O4 microspheres are synthesized by a robust one-pot spray pyrolysis process. The mesoporous hybrid NiO–MnCo2O4 microspheres are comprised of homogeneously dispersed nanoscaled NiO and MnCo2O4 subunits. Specific surface area of the mesoporous hybrid NiO–MnCo2O4 microspheres is determined to be 10.2m2g−1 with dominant pore size of 25.8nm. The as-obtained material is evaluated as anode material for LIBs. The as-prepared hybrid NiO–MnCo2O4 sample demonstrate better electrochemical performances, including higher reversible capacity and superior rate capability, compared with the single-phase NiO and MnCo2O4 samples. These superior electrochemical performances should be mainly attributed to its porous microstructure characteristics and the synergistic effects between the well-dispersed NiO and MnCo2O4 nanophases. The strategy is simple and flexible, so it could be readily generalized to construct other hybrid metal oxides materials.

An aerosol synthesized CeO2:Eu3+/Na+ red nanophosphor with enhanced photoluminescence

In this work, CeO2:Eu3+/Na+ nanoparticles were synthesized via a one-pot spray pyrolysis process using ethylene glycol as an organic additive. The luminescence intensity of CeO2:Eu3+ was improved about 16.5 times via Na+ codoping.

A new strategy of spray pyrolysis to prepare porous carbon nanosheets with enhanced ionic sorption capacity

We developed a new synthetic strategy to control the microstructure of carbon particles via ultrasonic spray pyrolysis. Porous carbon nanosheets with high ion-sorption capacitance were prepared by the one-pot spray pyrolysis process.

One-pot Aerosol Synthesis of Carbon Nanotube-Zn2GeO4 Composite Microspheres for Enhanced Lithium-ion Storage Properties

Three-dimensional (3D) carbon nanotube (CNT)-multicomponent metal oxide composite microspheres with non-aggregation characteristics are prepared using a simple one-pot spray pyrolysis process, applying water-soluble metal salt and oxidized CNT fibers. The hierarchical porous 3D structure of the CNT is formed by networking the flexible CNTs with a high aspect ratio during the drying stage of a droplet. Subsequently, the Zn and Ge salts are deposited over the CNTs to form the ZnO-CNT and GeO2-CNT composite microsphere. Decomposition of Zn and Ge salts into their respective oxides and the conversion reaction to form Zn2GeO4 at 700°C, produce the Zn2GeO4-CNT composite microsphere. The initial discharge capacities of the Zn2GeO4, Zn2GeO4-CNT, ZnO-CNT, and GeO2-CNT microspheres, at a current density of 1.5Ag−1, are 1351, 1211, 1387, and 1631mAhg−1, respectively, and their discharge capacities at the 300th cycle are 415, 762, 261, and 480mAhg−1, respectively. The CNT-Zn2GeO4 composite microspheres, selected as the first target material, show electrochemical properties superior to those of the bare Zn2GeO4, CNT-ZnO, and CNT-GeO2 composite microspheres. The synergetic effect of the multicomponent composition of Zn2GeO4 and the CNT support result in excellent Li-ion storage properties of the Zn2GeO4-CNT composite microspheres.

Synergetic Effect of Yolk-Shell Structure and Uniform Mixing of SnS-MoS₂ Nanocrystals for Improved Na-Ion Storage Capabilities.

Mixed metal sulfide composite microspheres with a yolk-shell structure for sodium-ion batteries are studied. Tin-molybdenum oxide yolk-shell microspheres prepared by a one-pot spray pyrolysis process transform into yolk-shell SnS-MoS2 composite microspheres. The discharge capacities of the yolk-shell and dense-structured SnS-MoS2 composite microspheres for the 100th cycle are 396 and 207 mA h g(-1), and their capacity retentions measured from the second cycle are 89 and 47%, respectively. The yolk-shell SnS-MoS2 composite microspheres with high structural stability during repeated sodium insertion and desertion processes have low charge-transfer resistance even after long-term cycling. The synergetic effect of the yolk-shell structure and uniform mixing of the SnS and MoS2 nanocrystals result in the excellent sodium-ion storage properties of the yolk-shell SnS-MoS2 composite microspheres by improving their structural stability during cycling.

Co9S8–carbon composite as anode materials with improved Na-storage performance

The synthesis and electrochemical performance of a composite of Co9S8 nanoparticles and amorphous carbon is studied as an anode material for sodium-ion batteries. The Co9S8–carbon composite powder was fabricated through a one-pot spray pyrolysis process using thiourea and polyvinylpyrrolidone as sulfur and carbon sources, respectively. The Co9S8 nanoparticles are entirely covered by an amorphous carbon layer. The initial discharge and charge capacities of the Co9S8–carbon composite powder were 689 and 475mAhg−1, respectively, at a current density of 0.5Ag−1. The Co9S8–carbon composite powders exhibited a stable cyclability with a reversible capacity of 404mAhg−1 for the 50th cycle and a superior rate capability compared with bare Co1−xS powder. The improvement of Na-storage performance could be attributed to the small size and entanglement of the Co9S8 nanoparticles within the carbon matrix.

Capacitive properties of reduced graphene oxide microspheres with uniformly dispersed nickel sulfide nanocrystals prepared by spray pyrolysis

Nickel sulfide-reduced graphene oxide (RGO) composite powders with spherical shapes are prepared by a one-pot spray pyrolysis process. The optimum mole ratio of nickel nitrate and thiourea to obtain nickel sulfide–RGO composite powders with high initial capacities and good cycling performance is 1:8. The bare nickel sulfide and nickel sulfide–RGO composite powders prepared directly by spray pyrolysis have mixed crystal structures of hexagonal α-NiS and cubic Ni3S4 phases. The bare nickel sulfide powders are prepared from the spray solution without graphene oxide sheets. The nickel sulfide–RGO composite powders have sharp mesopores approximately 3.5nm in size. The discharge capacities of the nickel sulfide–RGO composite powders for the 1st and 200th cycles at a current density of 1000mAg−1 are 1046 and 614mAhg−1, respectively, and the corresponding capacity retention measured from the second cycle is 89%. However, the discharge capacities of the bare nickel sulfide powders for the 1st and 200th cycles at a current density of 1000mAg−1 are 832 and 16mAhg−1, respectively. The electrochemical impedance spectroscopy (EIS) measurements reveal the high structural stability of the nickel sulfide–RGO composite powders during cycling.

Superior electrochemical properties of rutile VO2-carbon composite microspheres as a promising anode material for lithium ion batteries

We report a new process to prepare VO2(R)-carbon composite microspheres, which can be used as an anode material in lithium ion batteries. Crystalline V2O3-carbon composite microspheres prepared by a one-pot spray pyrolysis process are transformed into VO2(R)-carbon composite microspheres by heat treatment at 300°C under air atmosphere. Polyvinylpyrrolidone (PVP), which is used as the carbon source, affects the morphologies, crystal structures, and electrochemical properties of the vanadium oxide materials. The carbon content of the VO2(R)-carbon composite powders is about 12.5 wt%. The bare vanadium oxide powders prepared from the spray solution without PVP show rod-like or spherical morphologies. The initial discharge and charge capacities of the VO2(R)-carbon composite powders are 1091 and 659mAhg−1, respectively. The discharge capacity of the VO2(R)-carbon composite powders after 100 cycles is 637mAhg−1 and their capacity retention after 100 cycles measured from the second cycle is 96.0%. The high structural stability encountered during lithium insertion and extraction improves the electrochemical properties of the VO2(R)-carbon composite powders.

General formation of tin nanoparticles encapsulated in hollow carbon spheres for enhanced lithium storage capability.

A new simple process for synthesis of heterogeneous yolk-shell microspheres is introduced. The core/shell-structured microspheres are prepared by a one-pot spray pyrolysis process. The removal of one kind of metal oxide by a dry process produces heterogeneous yolk-shell microspheres. The yolk-shell Sn@C microspheres show superior electrochemical properties as anode materials for lithium-ion batteries.

Design and synthesis of micron-sized spherical aggregates composed of hollow Fe2O3 nanospheres for use in lithium-ion batteries.

A novel structure denoted a "hollow nanosphere aggregate" is synthesized by introducing nanoscale Kirkendall diffusion to the spray pyrolysis process. The hollow Fe2O3 nanosphere aggregates with spherical shape and micron size are synthesized as the first target material. A solid iron oxide-carbon composite powder that is prepared by a one-pot spray pyrolysis process is transformed into the hollow Fe2O3 nanosphere aggregates by sequential post-pyrolysis treatments under reducing and oxidizing atmospheres. The nanoscale Kirkendall diffusion plays a key role in the formation of the hollow Fe2O3 nanosphere aggregates with spherical shape and micron size. The unique structure of the hollow Fe2O3 nanosphere aggregates results in their superior electrochemical properties as an anode material for lithium ion batteries by improving the structural stability during cycling. The hollow metal oxide nanosphere aggregates with various compositions for wide applications including energy storage can be prepared by the simple fabrication method introduced in this study.

Superior electrochemical performances of double-shelled CuO yolk–shell powders formed from spherical copper nitrate–polyvinylpyrrolidone composite powders

Spherical copper nitrate–polyvinylpyrrolidone (PVP) composite powders coated with a copper nitrate hydroxide [Cu2(OH)3NO3]–carbon composite are prepared by a one-pot spray pyrolysis process. In this, Cu2(OH)3NO3 and carbon are formed by dehydration of copper nitrate and carbonization of PVP, respectively. Thermal decomposition of the composite powders is then performed at 300 °C under an air atmosphere, producing the final yolk–shell-structured CuO powders. The electrochemical properties of these powders are then compared with those of commercial CuO nanopowders. The discharge capacities of the CuO yolk–shell powders and the commercial CuO nanopowders after 240 cycles at a current density of 500 mA g−1 are 590 and 302 mA h g−1, respectively. Furthermore, the discharge capacity of the CuO yolk–shell powders is as high as 615 mA h g−1, even after 1000 cycles at a current density of 1000 mA g−1. Electrochemical impedance spectroscopy reveals that the structural stability of the CuO yolk–shell powders during cycling lowers the charge transfer resistance, and thereby improves the lithium ion diffusion rate.

Electrochemical properties of tin oxide flake/reduced graphene oxide/carbon composite powders as anode materials for lithium-ion batteries.

Hierarchically structured tin oxide/reduced graphene oxide (RGO)/carbon composite powders are prepared through a one-pot spray pyrolysis process. SnO nanoflakes of several hundred nanometers in diameter and a few nanometers in thickness are uniformly distributed over the micrometer-sized spherical powder particles. The initial discharge and charge capacities of the tin oxide/RGO/carbon composite powders at a current density of 1000 mA g(-1) are 1543 and 1060 mA h g(-1), respectively. The discharge capacity of the tin oxide/RGO/carbon composite powders after 175 cycles is 844 mA h g(-1), and the capacity retention measured from the second cycle is 80%. The transformation during cycling of SnO nanoflakes, uniformly dispersed in the tin oxide/RGO/carbon composite powder, into ultrafine nanocrystals results in hollow nanovoids that act as buffers for the large volume changes that occur during cycling, thereby improving the cycling and rate performances of the tin oxide/RGO/carbon composite powders.