The electrochemical behavior of aqueous processing lithium cobalt oxide (LiCoO2) cathodes used hydrogen peroxide (H2O2)-treated vapor-grown carbon fibers (VGCFs) as a conductive agent for lithium-ion batteries has been investigated and improved. The sedimentation experiments show that the dispersibility in water of H2O2-treated VGCFs is better than that of KS-6 (flaky graphite) or as-received VGCFs. This improvement is due to the surface chemistry of H2O2-treated VGCFs has become more hydrophilic that was evidenced by its significant shift of iso-electric point (I.E.P) from pH 6.7 to 5.0. As a result, the H2O2-treated VGCFs can be well-dispersed in the LiCoO2 electrode which was observed by scanning electron microscope. Furthermore, the rate capability results of electrodes show that addition with H2O2-treated VGCFs has better performance than that with KS-6 or as-received VGCFs.