Zongping Shao

A novel efficient oxide electrode for electrocatalytic oxygen reduction at 400–600 °C

A novel SrNb(0.1)Co(0.9)O(3-delta) electrode material, which possesses not only high electrical conductivity but also large oxygen vacancy concentration at 400-600 degrees C, shows an excellent performance in the application of reduced temperature solid-oxide fuel cells.

La-doped BaFeO3−δ perovskite as a cobalt-free oxygen reduction electrode for solid oxide fuel cells with oxygen-ion conducting electrolyte

Cobalt-free small La3+-doped BaFeO3−δ is synthesized and systematically characterized towards application as an oxygen reduction electrode material for intermediate temperature solid oxide fuel cells (IT-SOFCs) with oxygen-ion conducting electrolyte. The formation of an oxygen vacancy-disordered perovskite oxide with cubic lattice symmetry is demonstrated by XRD, after the doping of only 5 mol% La3+ into BaFeO3−δ parent oxide with the formation of Ba0.95La0.05FeO3−δ (BLF). The structural, thermal, electrical and electrochemical properties of BLF have been evaluated. High structural stability, high thermal expansion coefficient, high oxygen vacancy concentration, and relatively low electrical conductivity, are demonstrated. BLF shows a superior electrocatalytic activity, which is comparable to those state-of-the-art cobalt-based mixed conducting cathodes, in addition, it demonstrates a favorable long-term operational stability. It thus promises as a new cathode candidate for IT-SOFCs with oxygen-ion conducting electrolyte.

High performance cobalt-free perovskite cathode for intermediate temperature solid oxide fuel cells

Bi doping of SrFeO3−δ results in the formation of a structure with high symmetry and extraordinary electrochemical performance for Bi0.5Sr0.5FeO3-δ, which is capable of competing effectively with the current Co-based cathode benchmark with additional advantages of lower thermal expansion and cost.

Binder-free α-MoO3 nanobelt electrode for lithium-ion batteries utilizing van der Waals forces for film formation and connection with current collector

We demonstrate a facile and effective way for the fabrication of a flexible, homogeneous and neat α-MoO3 thin-film electrode for lithium-ion batteries with high performance without using any binder and conductive additives. Single-crystalline α-MoO3 nanobelts with uniform width of around 200 nm and length at the micrometer level are first synthesized by a simple water-based hydrothermal route. The as-obtained α-MoO3 slurry is then directly deposited onto a copper foil current collector by the doctor blade method. The formation of the α-MoO3 film and its good adhesion to the current collector is realized via van der Waals attraction forces through a drying process. The structure and morphology of the α-MoO3 nanobelt particles and thin-film electrode are systematically characterized by XRD, Raman spectra, TEM, SEM and XPS techniques, and the electrochemical properties are investigated by CV and constant current discharge–charge test techniques. The α-MoO3 film electrode exhibits a reversible specific capacity of ∼1000 mA h g−1 at 50 mA g−1 and a stable capacity retention of 387–443 mA h g−1 at 2000 mA g−1, indicating its high Li storage capacity, superior rate performance and good cycling stability. The electrode material, as well as the fabrication technique, is highly promising for practical use in high energy and power density lithium-ion batteries.

Nitrogen- and TiN-modified Li4Ti5O12: one-step synthesis and electrochemical performance optimization

It is believed that a TiN coating can increase the electrical conductivity, and consequently the performance, of an electrode. In this work, a simple one-step synthesis of nitrogen- and TiN-modified Li4Ti5O12, i.e. solid-state reaction of Li2CO3 and TiO2 anatase in an ammonia-containing atmosphere, is introduced. The reducing ammonia atmosphere could cause the partial reduction of Ti4+ to Ti3+ and the doping of nitrogen into the Li4Ti5O12 lattice, in addition to the formation of the TiN phase. By controlling the ammonia concentration of the atmosphere and using a slight Ti excess in the reactants, Li4Ti5O12, nitrogen-doped Li4Ti5O12, or TiN-coated nitrogen-doped Li4Ti5O12 were obtained. Both the electrical conductivity and the TiN thickness were closely related to the ammonia concentration in the atmosphere. Synthesis under reducing atmosphere also resulted in powders with a different plate shape particulate morphology from that synthesized in air, and such plate-shape powders had an ultrahigh tap density of ∼1.9 g cm−3. Interestingly, the formation of TiN was not beneficial for capacity improvement due to its insulation towards lithium ions, unlike the nitrogen doping. The sample prepared under 3% NH3–N2, which was free of TiN coating, showed the best electrode performance with a capacity of 103 mA h g−1 even at 20 C with only 3% capacity decay after cycling 100 times.

Facile Mechanochemical Synthesis of Nano SnO2/Graphene Composite from Coarse Metallic Sn and Graphite Oxide: An Outstanding Anode Material for Lithium‐Ion Batteries

A facile method for the large-scale synthesis of SnO2 nanocrystal/graphene composites by using coarse metallic Sn particles and cheap graphite oxide (GO) as raw materials is demonstrated. This method uses simple ball milling to realize a mechanochemical reaction between Sn particles and GO. After the reaction, the initial coarse Sn particles with sizes of 3-30 μm are converted to SnO2 nanocrystals (approximately 4 nm) while GO is reduced to graphene. Composite with different grinding times (1 h 20 min, 2 h 20 min or 8 h 20 min, abbreviated to 1, 2 or 8 h below) and raw material ratios (Sn:GO, 1:2, 1:1, 2:1, w/w) are investigated by X-ray diffraction, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy and transmission electron microscopy. The as-prepared SnO2 /graphene composite with a grinding time of 8 h and raw material ratio of 1:1 forms micrometer-sized architected chips composed of composite sheets, and demonstrates a high tap density of 1.53 g cm(-3). By using such composites as anode material for LIBs, a high specific capacity of 891 mA h g(-1) is achieved even after 50 cycles at 100 mA g(-1).

Electric Power and Synthesis Gas Co‐generation From Methane with Zero Waste Gas Emission

A harmonic generator: Co-generation of electric power and synthesis gas from methane is achieved using a single-chamber solid oxide fuel cell (see picture; SDC=samarium-doped ceria, YSZ=yttrium-stabilized zirconia). The process utilizes methane completely with zero greenhouse gas emissions.

A Comparative Study of Oxygen Reduction Reaction on Bi- and La-Doped SrFeO3 − δ Perovskite Cathodes

In this work the oxygen reduction reaction on Bi0.5Sr0.5FeO3-delta (BSF) and La0.5Sr0.5FeO3-delta (LSF) as cathodes for intermediate temperature solid oxide fuel cells (600-750 degrees C) is compared in detail. Partial substitution of Sr in SrFeO3-delta with 50 mole % of Bi or La results in the distinct structural features which strongly impact its electrochemical characteristics due to the presence of a lone electron pair in Bi3+, which is not available in La3+. Cubic structure for BSF favours higher ionic conductivity and enhanced formation of oxygen vacancies relative to rhombohedral structure for LSF. Large oxygen nonstoichiometry for BSF, nevertheless, leads to the dominance of Fe3+ and subsequent low electronic conductivity relative to LSF. It was found that upon cathodic polarization, the oxygen vacancies are created on LSF which helps reducing its interfacial resistance afterward, which is not the case for BSF. Overall, BSF demonstrates good electrochemical performance which can be further optimized by enhancing its electronic conductivity

A novel method to enhance rate performance of an Al-doped Li4Ti5O12 electrode by post-synthesis treatment in liquid formaldehyde at room temperature

An amenable method for improving rate performance of Li4Ti4.85Al0.15O12 electrode by post-synthesis treatment in formaldehyde aqueous solution at room temperature is introduced. The as-prepared samples are characterized by XRD, BET, SEM, HR-TEM, XPS and electronic conductivity measurement. The treatment causes no noticeable change on the phase structure and has only little effect on the specific surface area and particulate morphologies. It also only slightly decreases the lithium ion diffusion coefficient. However, it substantially increases the electronic conductivity due to the creation of Ti3+ in the oxide lattice. The post-synthesis treatment for a period of 4 h effectively increases the capacity at 10 C rate for Li4Ti4.85Al0.15O12 from 125 mA h g−1 for the untreated sample to 160 mA h g−1, and the electrode performance is also fairly stable. This method is highly attractive for synthesis of high-performance Li4Ti5O12 electrodes owing to its simplicity, energy saving and efficiency. As a general method, post-synthesis treatment using formaldehyde may be applicable to other electrodes.

Synthesis of well-crystallized Li4Ti5O12 nanoplates for lithium-ion batteries with outstanding rate capability and cycling stability

As a lithium-intercalation material, high crystallinity is important for Li4Ti5O12 to achieve good capacity and cycling stability, while a large surface area and a short lithium diffusion distance are critical to increase rate capacity. In this study, well-crystallized Li4Ti5O12 nanoplates with outstanding electrochemical performance were facially prepared through a two-step hydrothermal preparation with benzyl alcohol–NH3·H2O (BN) as the solvent and a subsequent intermediate-temperature calcination at 500 °C for 2 h in air. To support the superiority of benzyl alcohol–NH3·H2O (BN) for hydrothermal synthesis, ethanol–NH3·H2O (EN) was also comparatively studied as solvent. In addition, different hydrothermal reaction times were tried to locate the optimal reaction time. The nature of as-prepared Li4Ti5O12–BN (LTO–BN) and Li4Ti5O12–EN (LTO–EN) was characterized by XRD, N2 adsorption/desorption tests, SEM, TEM and TGA-DSC. Compared with EN, the BN hydrothermal solvent facilitated the formation of nanosheet-Li4Ti5O12 with wall thicknesses of 8–15 nm and better crystallization. After a 6 h hydrothermal reaction at 180 °C and subsequent calcination, well-crystallized Li4Ti5O12–BN nanoplates were produced, which demonstrate a superior discharge capacity of 160 mA h g−1, even at 40 C, maintaining a capacity of 88.8% compared with that at 1 C. The nanoplates also exhibited excellent cycling stability, retaining a discharge capacity of 153 mA h g−1 after 1000 charge–discharge cycles at 10 C.