A detection method for the sulfur fixation performance of cathode materials for lithium-sulfur batteries

Abstract

The invention relates to a detection method for the sulfur-fixing performance of a cathode material of a lithium-sulfur battery. The method adopts sulfur content testing equipment and a sulfur electrode shape change testing device to detect the dissolution and loss of elemental sulfur during battery operation. Put the positive electrode materials in different charging and discharging states during the cycle test into the sulfur content detection equipment to obtain the load of elemental sulfur in the positive electrode material in this state; at the same time, the electrode morphology testing device is used to detect the change of the electrode morphology, from the essence The sulfur fixation ability of the positive electrode material was obtained through the above characterization. The detection method can realize the in-situ characterization of the sulfur fixation ability of the cathode material, can accurately reflect the confinement effect of the material on the elemental sulfur, and has a simple, easy-to-control, and good repeatability testing process.

Description

technical field [0001] The invention relates to a detection method for the confinement effect of a positive electrode material on elemental sulfur during the operation of a lithium-sulfur battery, in particular to a detection method for the sulfur-fixing performance of the positive electrode material of a lithium-sulfur battery. Background technique [0002] With the rapid development of communication, mobile electronic equipment, electric vehicles and space technology, there is an urgent need to develop batteries with high energy density. At present, the specific energy of lithium-ion batteries is mostly lower than 200Wh / kg. Due to the limitation of the specific capacity of the existing positive electrode materials, it is difficult to increase the specific energy, and relying on high charging voltage to increase the specific energy will increase the safety of the system. Therefore, it is necessary to develop a new generation of electrochemical energy storage systems to solv...

AI Technical Summary

Problems solved by technology

That is to say, the low utilization rate of sulfur in the positive electrode active material and serious cycle capacity attenuation are the main problems in the current lithium-sulfur battery itself. The main problem is that the lithium sulfide generated by the reaction process usually adheres to the surface of the sulfur, and the conductivity of sulfur and lithium sulfide It is poor, so it hinders the further reaction of sulfur and reduces the utilization rate of elemental sulfur; secondly, the intermediate product Li produced in the process of sulfur reduction or lithium sulfide oxidation 2 S n (3≤n≤6) are all soluble in the electrolyte, and generally diffuse through the separator to the lithium negative electrode to form insoluble Li 2 S or Li 2 S 2 , resulting in the loss of active materials, resulting in poor battery cycle stability; moreover, due to sulfur (2.07g / cm 3 ) and Li 2 S (1.66g / cm 3 ) The difference in density is large, which leads to significant deformation of the positive electrode material before and after the reaction, thereby destroying the electrode structure and ultimately reducing the cycle stability of the battery

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