A novel binder which is a water-soluble gelatin macromolecule modified with L-cysteine is now being used in the sulfur cathode for rechargeable Li/S battery. Cyclic voltammograms, electrochemical impedance spectroscopy, and cycle performance of the prepared cathode were investigated. The results indicated that this novel binder not only served as a strong dispersion and adhesion agent for the cathode materials, but also formed a stable electric network between the active material and the conductive carbon. Less polarization, lower transfer resistance, and enhanced cycle life were achieved due to its improved electrochemical stability during the charge/discharge processes. The prepared cathode exhibited an initial capacity of 1135mAhg(1) and a high reversible capacity of 754mAhg(1) after 50 cycles.