Yunfei Bu

Enhanced electrochemical properties of a LiNiO2-based cathode material by removing lithium residues with (NH4)2HPO4

Lithium residues on the surface of LiNi0.8Co0.1Mn0.1O2 have been removed by adding (NH4)2HPO4 dissolved in ethanol. Upon precipitating the unmeasurable lithium residue with different amounts of (NH4)2HPO4, the performance of the LiNi0.8Co0.1Mn0.1O2 cathode materials show marked changes. Under the optimized condition, the modified materials exhibit enhanced cycling performance, although X-ray powder diffraction and transmission electron microscopy results demonstrate that the precipitated Li3PO4 is not coated on the surface of LiNi0.8Co0.1Mn0.1O2. The modified material exhibits 66.9% retention after 100 cycles at 2 C, while the pristine material shows only 48.1% retention. The results demonstrate that the removal of lithium residues from the surface of LiNiO2-based materials is effective in decreasing side reactions. This property will be valuable for increasing the available choices of coating methods and materials because the enhancement of the coating will be maximized if the lithium residue can be removed after coating.

Capture of carbon dioxide by amine-loaded as-synthesized TiO2 nanotubes

Titanium-based adsorbents for CO2 capture were prepared through impregnating the as-synthesized TiO2 nanotubes (TiNT) with four kinds of amines, namely monoethanolamine (MEA), ethylenediamine (EDA), triethylenetetramine (TETA) and tetraethylenepentamine (TEPA). The resultant samples were characterized by X-ray diffraction, low-temperature N2 adsorption as well as transmission electron microscopy. The absorption of CO2 was carried out in a dynamic packed column. The sample impregnated with TEPA showed a better adsorption capacity due to its higher amino groups content. In addition, CO2 adsorption capacity increases as the amount of amine loaded increases. Therefore, TiNT-TEPA-69 showed the highest CO2 adsorption capacity among the three samples impregnated with TETA; approximately 4.10 mmol/g at 30°C. In addition, the dynamic adsorption/desorption performance was investigated. The adsorption capacity of TiNT-TEPA-69 dropped slightly (about 2%) during a total of five cycles. The TiNT-TEPA-69 adsorbent exhibited excellent CO2 adsorption/desorption performance.

La0.4Ba 0.6Fe 0.8Zn 0.2O 3−δ as cathode in solid oxide fuel cells for simultaneous NO reduction and electricity generation

A perovskite-type oxide La0.4Ba 0.6Fe 0.8Zn 0.2O 3−δ (LBFZ) was investigated as the cathode material for simultaneous NO reduction and electricity generation in solid oxide fuel cells (SOFCs). The microstructure of LBFZ was demonstrated by X-ray diffraction and scanning electron microscopy. The results showed that a single cubic perovskite LBFZ was formed after calcined at 1100°C. Meanwhile, the solid-state reaction between LBFZ and Ce0.8Sm 0.2O 1.9 (SDC) at 900°C was negligible. To measure the electrochemical properties, SOFC units were constructed with Sm0.9Sr 0.1Cr 0.5Fe 0.5O 3 as the anode, SDC as the electrolyte and LBFZ as the cathode. The maximum power density increased with the increasing NO concentration and temperature. The cell resistance is mainly due to the cathodic polarization resistance.