Electrochemical behaviors of naphtho [1,8-cd][1,2]dithiol, dibenzo[c,e][1,2]dithiin, and naphtho[1,8-cd:4,5-c′d′]bis[1,2]dithiol their application to lithium polymer batteries

It is known that the organic disulfides reductively cleave to corresponding two thiols and oxidatively recombine to parent disulfides by appropriate conditions. Therefore, we examined the applications of organic disulfides as electrode active materials for the lithium batteries. Dibenzo[c,e][1,2]dithiin (2), naphtho[1,8-cd][1,2]dithiol (3), and naphtho[1,8-cd: 4,5-c' d']bis[1,2] dithiol (4) were prepared, and their applicability to the lithium polymer batteries was investigated. It has been found that these organic disulfides favored the intramolecular redox reaction of the S-S bond, such as 3 or 4, rather than the intermolecular same type reaction, such as diphenyldisulfide (1). On the result of cyclic voltammetry measurement and the electrochemical charge/discharge measurement, 2, 3, and 4 showed good properties as active cathode materials. Especially, 4 is good for an active material of a high capacity cell; a four-electron redox system is operative in one molecule. (C) 2002 The Electrochemical Society.