Electrodeposition of Carbon-Metal Powders in Alkali Carbonate Melts

In the frame of the preparation of carbonaceous materials that could serve for instance as anodic components in lithium batteries, an original way has been proposed based on the electroreduction of carbonate ions in ternary molten Li-Na-K carbonates. The TEM and XRD analyses show that the powders produced at the cathode are made of carbon nanoparticles composed of both amorphous and graphitized domains. The characteristic properties of the product depend on the operating conditions: voltage, melt temperature and annealing temperature. BET investigations show that the active surface area of the powders obtained at high voltage (6 V) and low melt temperature (450 degrees C) grows to a value of up to 1300 m(2) g(-1). An improvement of the anodic material in lithium batteries can be obtained by introducing in the carbon powder suitable metals such as tin. The production of such mixtures can be realized directly, in one single operation, by electroreduction of metal ions dissolved in the alkali carbonate melt. The mechanism of metal deposition is briefly studied by cyclic voltammetry. Composite powders are electrodeposited at constant potential. TEM and EDX investigations show that they are made of an intimate mixture of carbon and metal grains at the nanometric scale, the metallic grains size ranging from 5 to 20 nm. (C) 2014 The Electrochemical Society. All rights reserved.