Electrochemical characterization of a polypyrrole/Co0.2CrOx composite as a cathode material for lithium ion batteries

Polypyrrole/Co0.2CrOx, (PPy/Co0.2CrOx) composites were synthesized by polymerizing pyrrole onto the surface of cobalt chromium oxide (CrOx) in acidic media. The PPy/Co0.2CrOx composites increase the reversible capacity of the electrochemically active material up to 20%. At C/10 rate, a reversible capacity of 215 mAh/g was obtained for PPy/Co0.2CrOx composite, compared to 178 mAh/g for the virgin material, an increase of over 21%. Conductivity experiments corroborated the galvanostatic cycling tests, with the composite cathode material showing high electronic conductivity than bare material. Fitting the impedance results to an equivalent circuit reveals that addition of polypyrrole reduces the ohmic resistance due to the better conductivity and the inclusion of electrochemically active polypyrrole in the composite. Finally, the composite electrodes also showed very good rate capability and better cycling behavior compared to that of the bare material. © 2003 Elsevier B.V. All rights reserved.