The Study On The Anode Performance Of Direct Carbon Fuel Cell

The direct carbon fuel cell(DCFC) is a special type of high temperature fuel cell that directly uses solid carbon as anode and fuel,in which chemical energy stored in solid carbon is directly converted into electrical power without carbon combustion or gasification and with no need for thermal engine.DCFCs have the advantages of high energy per unit volume,rich carbon fuels,higher achievable efficiency and less emissions.In this paper the electrochemical oxidation of activated carbon in molten carbonates were studied.DCFCs were assembled and tested.The influences of pre-wetting,acid-base treatments,carbon loading,carbon particle size,reaction temperature and reaction atmosphere on the performance of the electrochemical oxidation of the activated carbon were investigated by linear sweeping voltammetry and electrochemical impedance spectroscopy.The results showed that the electrochemical oxidation activity of carbon was significantly improved by pre-wetting,acid-base treatments,increase in reaction temperature, and decrease in carbon particle size.The content of the activated carbon in carbonates and aeration with N₂ also enhance carbon oxidation performance.The open-circuit potential(OCP) and the current density at -0.2 V of the HCl treated activated carbon with 15 g carbon content and＜0.1 mm carbon particles size reached -1.40 V and 240 mA/cm² at 850℃respectively.Lithium aluminate powder was synthesized using the solid reaction process, and the size of powder was in the range 1～3μm.Lithium aluminate membrane was fabricated using these powders by tape-casting method.The cathode-lithium aluminate membrane assembly containing the lithium aluminate matrix and nickel foam cathode were prepared by pressing.Three DCFCs were assembled:carbon powder-membrane-cathode sandwich type,carbon mud-membrane-sandwich type and mud-membrane-cathode tubule type.Their discharge performances were evaluated.The mud-membrane-cathode tubule type DCFC displayed an open circuit voltage of 1.18 V and a maximum power density of 82 mW/cm² at 850℃, The cell current density reached 107 mA/cm² at 0.1 V.