Xiangguo Teng

Nafion-sulfonated organosilica composite membrane for all vanadium redox flow battery

A novel Nafion-sulfonated diphenyldimethoxysilane (N-sDDS) composite membrane is prepared and employed in vanadium redox flow battery (VRB). Ion exchange capacity, proton conductivity, water transport behavior, and the cell performances are characterized. Fourier transform-infrared and X-ray diffraction analysis indicate that the sulfonated diphenyldimethoxysilane (sDDS) particles are successfully introduced into the Nafion matrix. In VRB single cell test, the VRB with N-sDDS membrane exhibits nearly the same coulombic efficiency as the unmodified Nafion membrane, but higher voltage efficiency than that of the VRB with unmodified Nafion membrane. The VRB with N-sDDS composite membrane keeps a stable performance after 60 times charge–discharge test. In the self-discharge test, the VRB with the N-sDDS membrane presented a lower self-discharge rate than that of the VRB with Nafion membrane. All results show that the addition of s-DDS is a simple and efficient way to improve the conductivity of Nafion, and the composite membrane shows good potential use for VRB.

Preparation of a novel carbon nanofiber as a high capacity air electrode for nonaqueous Li-O2 batteries

A new carbon nanofiber codoped with nitrogen and phosphorus (NPCNF) that has a high specific surface area and good electrocatalytic properties for the oxygen reduction reaction (ORR) was synthesized using a template‐free method. The fabrication process involves the pyrolysis of phytic acid doped polyaniline aerogel. A nonaqueous Li‐O2 battery with a specific capacity as high as 12 607 mA h g−1 was constructed by using an oxygen electrode based on NPCNFs supported by Ni foam. The NPCNF electrode showed a lower overpotential than pure carbon. The observed excellent electrochemical performance could be because of the unique foamlike N‐ and P‐codoped carbon microstructure, which had a high ORR catalytic activity. These results indicate that the use of NPCNF as a cathode material could be a feasible approach to obtain a high‐capacity Li–O2 battery.

Establishment and practical application of the electron transfer model in lithium-air batteries

The electron transfer failure model is proposed to analyze the effects of discharge products on the air electrode performance in lithium-air batteries. In order to understand how the air electrode products are obtained during the discharge cycle, three kinds of carbon-based air electrode are constructed, and discharged products are analyzed by powder XRD and SEM techniques. It can be concluded that the air electrode is covered with the products, indicating that the discharge products closely depended on the surface states of carbon materials. EIS studies show that the value of Rct value changes due to the deposition of discharge products on carbon materials. Finally, all present studies show that the air electrode failure is mainly caused by the difficulty of charge transfer.