A comparison of different carbon used as the positive electrode (cathode) in Lithium/Thionyl Chloride (Li/SOCl2) cells

The Li/SOCl2 battery system consists of a Li anode, a carbon cathode, and the LiAlCl4/SOCl2 electrolyte solution. Different varieties of carbon can be used to construct the cathode. Accordingto the literature [1] colloidal Teflon is used as the binding material for fabricating the carbon electrode. The composition of the paste is given as: carbon; 80% by weight; Teflon binder; 20% by weight. The procedure entails rolling the carbon/PTFE mix ontothe syringe. The pretreatment of carbon cathodes with acetone has led to an increase in cell voltage and capacity for Li/SOC12 cells [2]. This treatment is thought to work byremoving impurities from the carbon and increasing the total pore volume and average porediameters. During cell discharge SOC12 reduction takes place at such a cathode, resulting in theprecipitation of reaction products, mainly LiCl, within the pores of the substrate. This leads toeventual passivation of the cathode surface and, hence, cell failure. Most of the Li/SOC12 cell research under taken is to improve the performance of this positive electrode. For this reason, we studied the reduction reaction of SOCl2 on different carbons in a three-electrode cell by cyclicvoltammetry. Carbons that used for this purpose are acetylene black (AB), Vulcan, Multiwalledcarbon nanotube (MWCNT), activated carbon and refined carbon from SAFT Li/SOCl2 battery. The cathode substrate in Li/SOC12 cells provides a conductive surface on which SOC12 isdepolarized. Fig.1 is a comparative cyclic voltammograms (CVs) of the Li/SOCl2 cell with different carbons as cathode in 1 M LiAlCl4/SOCl2. The results of electrochemical techniquesshow that the reduction rate of SOCl2 on surface of Acetylene black, which consists ofsubmicron sized particles and high surface area is better and like as refined carbons from SAFT Li/SOCl2 battery. The reduction rate of SOCl2 on surface of activated carbon and glassy carbon is the worst of all due to the low conductivity.

A comparison of different carbon used as the positive electrode (cathode) in Lithium/Thionyl Chloride (Li/SOCl2) cells Keywords:

Lithium thionyl chloride cell , Glassy carbon , Activated carbon , Acetylene black , Multiwalled carbon nanotube , Vulcan