Zhenfa Liu

Carbon aerogel-based supercapacitors modified by hummers oxidation method

Carbon aerogels of an inter-connected three-dimensional (3D) structure are a potential carbon material for supercapacitors. We report a new oxidation modification method to prepare a series of modified carbon aerogels (OM-CA) by Hummers oxidation method. Oxidation-modified carbon aerogels (OM-CA) are obtained from carbon aerogel powders oxidized by Hummers method. Sulfuric acid stoichiometry is studied in order to investigate the effect of the surface oxygen group on surface area and electrochemical performance. Additionally, heteroatoms are doped into carbon aerogels in the oxidation process. The effect of heteroatom doping on electrochemical performance as a supercapacitor electrode material is investigated. When the amount of sulfuric acid is 40 wt%, the dopping manganese content is 0.9 mol%, the specific surface area of OM-CA is 450 m2/g, and its specific capacitance is 151 F g-1 at 0.5 A g-1, which is achieved by heteroatom doping and texture properties. In addition, OM-CA composite supercapacitors exhibit a stable cycle life at a current density of 0.5 A g-1 and retain 98.0% of initial capacitance over 500 cycles, and OM-CA-40% still presents a higher capacity, up to 148 F g-1 at 0.5 A g-1. The high specific surface area and specific capacitance suggest the porous carbon material has potential applications in supercapacitors.

Effect of the scale inhibitor on ion content in reverse osmosis system for seawater desalination

A scale inhibitor was synthesized from polysuccinimide with 2-aminoethanesulfonic acid and aspartic acid. The effect of scale inhibitor on ion content in reverse osmosis system for seawater desalination was studied. The results showed that the ion content of permeate water is lower with the scale inhibitor added in RO system for seawater desalination than without scale inhibitor. On the contrary, the ion content of concentrate water is higher when with scale inhibitor in RO system.

Nitrogen doped CNT/Li4Ti5O12 composite for the improved high-rate electrochemical performance of lithium-ion batteries

A novel Li4Ti5O12 (LTO) composite with nitrogen doped multi-walled carbon nanotubes (CNTs), denoted N-C-LTO, was successfully prepared via simple thermal annealing of CNTs in the presence of melamine. For comparison, LTO, C-LTO (Li4Ti5O12/CNT) were also synthesized. N-C-LTO demonstrated the best electrochemical performance among the samples. Even at a high charge/discharge rate of 20 C, the reversible capacity was maintained at the high level of 100 mAhg-1. Moreover, after 150 cycles at 3.0 C, 90.7 % of the capacity was retained with negligible capacity fading. The excellent electrochemical performance was possibly due to the nitrogen in the doped CNTs, which maintained the benefits of the nitrogen as good electron donating.