Synthesis of bimetallic sulfide CuCo2S4 and its application in lithium-sulfur batteries

Lithium-sulfur batteries have received extensive attention in recent years due to the high specific energy. However, their development needs to overcome many problems such as the shuttle effect of intermediate products, the insulation of sulfur, and the volume expansion of the cathode. To effectively suppress the shuttle effect, this paper uses a method derived from Prussian blue analogs to synthesize a spinel bimetallic sulfide CuCo2S4 and use it for the cathode of lithium-sulfur batteries. XRD, SEM, TEM, BET, XPS and other characterizations were used to analyze the crystal structure and morphology of the synthesized materials, and the electrochemical performance of the CuCo2S4-S composite cathode was tested by cyclic voltammetry and galvanostatic charge and discharge process. Studies show that the CuCo2S4-S cathode exhibits excellent electrochemical performance. The first initial capacity is 959 mA•h•g-1 at the rate of 0.2C, and 591 mA•h•g-1 remains after 100 cycles. The high discharge specific capacity and good cycling stability are attributed to the hollow structure inside the CuCo2S4 material that can accommodate the active material sulfur and play a role in physical confinement; at the same time, the polar CuCo2S4 can effectively chemically adsorb polysulfides and suppress capacity loss caused by the shuttle effect of polysulfides. © 2020, Chemical Industry Press Co., Ltd. All right reserved.