A study of novel anode material CoS2 for lithium ion battery

This paper reports the study of cobalt disulfide as a promising anode material for lithium ion batteries. The crystal structure and surface morphology have been characterized by using X-ray diffraction (XRD), SEM and Brunauer-Emmett-Teller (BET) techniques. The results of XRD show that the sample is a cubic phase with a space group Pa3. The grain size of the sample was 30 μm with a special nano-structured characteristic as observed by means of SEM. Charge-discharge experiments show that the sample with 30 wt.% acetylene black at the current density of 50 mA g−1 has the best performance, it shows that the first discharge capacity is up to 1280 mAh g−1. Ex situ XRD experiments were also carried out to determine the structural changes of delithiated/lithiated anode materials and used to analyze the reaction mechanism. Calculated Gibbs free energy change (ΔrG) and electromotive force (emf, E) values for the reaction CoS2 + 4Li+ + 4e− → Co + 2Li2S are −146 kJ mol and 1.898 V, respectively. Based on the results, a possible reaction mechanism of CoS2 anode during intercalation of Li ions was proposed.