Compound diaphragm for lithium-sulfur battery

Abstract

The invention provides a compound diaphragm for a lithium-sulfur battery. The diaphragm is prepared by the following steps of: (1) adding MoS2 powder into a hexane solution of n-butyllithium, performing a stirring reaction, performing filtration, and washing the solution with cyclohexane and water to obtain laminar MoS2; and (2) adding graphite oxide and the laminar MoS2 into water for ultrasonic dispersion to form a suspended liquid, then adding the suspended liquid into a suction flask padded with a Celgard diaphragm and filter paper, and drying the suction flask, and tearing off the filter paper to obtain the compound diaphragm for the lithium-sulfur battery. The laminar MoS2 in a laminar MoS2 / graphene oxide layer can form severe chemical absorption on polysulfide formed in the charging and discharging processes, and can effectively prevent the polysulfide from penetrating through the diaphragm to reach a cathode to reduce a shuttle flying effect, so that the service life of the lithium-sulfur battery is prolonged.

Description

technical field [0001] The invention relates to the field of lithium-sulfur batteries, in particular to a lithium-sulfur battery diaphragm. Background technique [0002] A lithium-sulfur battery is a battery system in which metallic lithium is used as the negative electrode and elemental sulfur is used as the positive electrode. Lithium-sulfur batteries have two discharge platforms (about 2.4 V and 2.1 V), but their electrochemical reaction mechanism is relatively complicated. Lithium-sulfur batteries have the advantages of high specific energy (2600 Wh / kg), high specific capacity (1675 mAh / g), and low cost, and are considered to be a promising new generation of batteries. However, at present, there are problems such as low utilization of active materials, low cycle life and poor safety, which seriously restrict the development of lithium-sulfur batteries. The main reasons for the above problems are as follows: (1) elemental sulfur is an electronic and ion insulator, and i...

AI Technical Summary

Problems solved by technology

This phenomenon, known as the shuttle effect, reduces the availability of sulfur active species

At the same time insoluble Li 2 S and Li 2 S 2 Deposited on the surface of the lithium negative electrode, which further deteriorates the performance of the lithium-sulfur battery; (3) the final product of the reaction, Li 2 S is also an electronic insulator and will be deposited on the sulfur electrode, while lithium ions migrate slowly in solid lithium sulfide, slowing down the electrochemical reaction kinetics; (4) sulfur and the final product Li 2 The density of S is different. When sulfur is lithiated, the volume expands by about 79%, which easily leads to Li 2 Pulverization of S, causing safety problems in lithium-sulfur batteries

The above deficiencies restrict the development of lithium-sulfur batteries, which is also a key issue that needs to be solved in current research on lithium-sulfur batteries.

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