Detection method of sulfur fixation performance of lithium sulfur battery cathode material

Abstract

The invention relates to a detection method of the sulfur fixation performance of a lithium sulfur battery cathode material. The detection method employs a sulfur content test device and a sulfur electrode appearance change test device to detect dissolving and losing situation of elementary sulfur in an operation process of the battery. The cathode materials in different charging / discharging status during a circulating test process are placed in the sulfur content test device to obtain the loading quantity of the elementary sulfur in the cathode materials under the status. Meanwhile, the sulfur electrode appearance change test device is employed for testing the change of appearance of the electrode to obtain the sulfur fixation capability of the cathode materials in an essentially representation manner. The detection method can achieve in-situ representation of the sulfur fixation performance of the cathode material, can accurately reflect a confinement effect of the material to the elementary sulfur, is simple and easy-to-control in test processes and is good in repeatability.

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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