To improve the performance of Nafion membrane as a separator in vanadium redox battery (VRB) system, a Nafion/TiO 2 hybrid membrane was fabricated by a hydrothermal method. The primary properties of this hybrid membrane were measured and compared with the Nafion membrane. The Nafion/TiO 2 hybrid membrane has a dramatic reduction in crossover of vanadium ions compared with the Nafion membrane. The results of scanning electron microscope, energy dispersive X-ray spectroscopy, and X-ray diffraction of the hybrid membrane revealed that the TiO 2 phase was formed in the bulk of the prepared membrane. Cell tests identified that the VRB with the Nafion/TiO 2 hybrid membrane presented a higher coulombic efficiency (CE) and energy efficiency (EE), and a lower selfdischarge rate compared with that of the Nafion system. The CE and EE of the VRB with the hybrid membrane were 88.8% and 71.5% at 60 mA cm −2 , respectively, while those of the VRB with Nafion membrane were 86.3% and 69.7% at the same current density. Furthermore, cycling tests indicated that the Nafion/TiO 2 hybrid membrane can be applied in VRB system.
Nanostructured Co 3 O 4 in a novel hairy ball-like morphology is successfully synthesized from self-assembled hierarchical Co(CO 3 ) 0.35 Cl 0.2 (OH) 1.10 $1.74H 2 O precursors via a facile hydrothermal method and subsequent annealing in air. The morphological evolution of the Co(CO 3 ) 0.35 Cl 0.2 (OH) 1.10 $1.74H 2 O precursors is investigated by examining the different reaction times during the synthesis. First, fan-shaped microplates are formed, followed by nanowires grown on the surface of the plates. Subsequently, with an extended growth reaction time, the nanowires grow longer to form the hairy ball-like structures. The Co 3 O 4 , obtained from thermal decomposition of the Co(CO 3 ) 0.35 Cl 0.2 (OH) 1.10 $1.74H 2 O precursor in air at 400 C, exhibits highly reversible capacities as an anode material in lithium ion batteries, which retains 860 mA h g À1 at 100 mA g À1 after 50 cycles, with good cycling stabilities and rate capabilities.
To develop a novel and low-cost membrane as a separator of vanadium redox flow battery, sulfonated poly (phthalazinone ether sulfone) (SPPES) was prepared by sulfonating PPES with fuming sulfuric acid. By testing the sulfonation degree, intrinsic viscosity, and solubility of SPPES, the results showed that sulfonated polymers had higher intrinsic viscosities and excellent solubility in most polar solvents. IR analysis revealed that the -SO 3 H group was successfully attached to SPPES backbone. DSC and TG results showed that SPPES exhibited higher T g than that of PPES, and T d at the first weight loss of SPPES was about 300°C. The SPPES membrane (SP-02) showed a dramatic reduction in crossover of vanadium ions across the membrane compared with that of the Nafion membrane. Cell tests identified that VRB with the SPPES membrane exhibited a lower self-discharge rate, higher coulombic efficiency (92.82%), and higher energy efficiency (67.58%) compared with the Nafion system. Furthermore, cycling tests indicated that the single cell with SPPES membrane exhibited a stable performance during 100 cycles.
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