KOH Direct Activation for Preparing Activated Carbon Fiber from Polyacrylonitrile-based Pre-oxidized Fiber

The activated carbon fiber（ACF） was prepared from polyacrylonitrile-based pre-oxidized fiber（PANOF） by KOH direct activation. The influence of activation conditions including impregnation ratio（the mass ratio of PANOF to KOH）, activation temperature and activation time on the pore structure and electrochemical properties of ACF was investigated, and the corresponding activation mechanism was proposed. The ACF prepared at an activation temperature of 800℃ and an impregnation ratio（the mass ratio of PANOF to KOH） of 1：2 for an activation time of 1 b in 6 mol/L KOH solution exhibits a specific surface area of 3029 m^2/g, a mesoporosity of 84.2% and a specific capacitance of 288 F/g, and shows a good capacitive performance. The prepared ACF can be used as the electrode material for supercapacitors.

Influence of simulating deep-sea environmental factors on cathodic performance of seawater battery

A metal-dissolved oxygen seawater battery(SWB)uses metal and dissolved oxygen as the reactants,and it is ideal for use as a long-time low-power distributed power supply in deep sea,due to its advantages of open structure in service without electrolyte.However,several simulating deep-sea environmental factors,such as flow rate,dissolved oxygen concentration,and temperature of seawater may af fect the oxygen reduction reaction(ORR)rate and the stability of electrochemically modified polyacrylonitrile-based carbon fiber brush(MPAN-CFB)cathode,which was studied by steady-state polarization and galvanostatic discharge methods.In addition,the scales formed on MPAN-CFB surface were characterized by SEM and XRD.Results show that the ORR rate increased quickly with the increase of the seawater flow rate up to 3 cm/s,and then gradually stabilized.Moreover,the ORR rate was largely af fected by dissolved oxygen concentration,and the concentration of>3 mg/L was favorable.Compared with surface layer temperature of 15℃,the low temperature of deep sea(4℃)has a negligible ef fect on ORR rate.When the working current is too high,it will lead to the formation of CaCO_3 scales(aragonite)of at the cathodic surface,resulting in the decrease of ORR rate,and consequently the damage to the long-time stability of MPAN-CFB.