A lithium-sulfur battery

Abstract

The invention belongs to the technical field of lithium-sulfur batteries, and in particular relates to a new system of lithium-sulfur batteries, including an electrolyte solution and a diaphragm matched therewith. Including an electrolyte and a diaphragm, it is characterized in that: the electrolyte is a lithium salt solution with a concentration of 0.1-3mol / L, and the lithium salt solute in the lithium salt solution is lithium fluoride, lithium chloride, lithium bromide or lithium iodide One or more mixtures; solvents are N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, tetramethylsulfone, tetrahydrofuran, N-methylpyrrolidone, acetonitrile One or a mixture of two or more of them; the diaphragm is a microporous membrane with a pore size of 0.5-10 nanometers or a dense membrane containing anions. adopted. After surface modification and hot pressing, the microporous separator can be fully infiltrated in the small-molecule lithium salt electrolyte, and at the same time has a suitable size to allow the electrolyte ions to pass freely and inhibit or prevent the migration of polysulfides. Lithium salts are cheap, giving batteries a cost advantage.

Description

technical field [0001] The invention belongs to the technical field of lithium-sulfur batteries, and in particular relates to a new system of lithium-sulfur batteries, including an electrolyte solution and a diaphragm matched therewith. Background technique [0002] With the continuous development of economy and society, energy and environmental problems are becoming more and more serious. Energy conservation and emission reduction, development and utilization of new energy and renewable energy, and development of efficient and clean energy conversion and storage technologies are important issues and challenges for today's society, science and technology, and industry. In recent years, lithium batteries with metallic lithium as the negative electrode, including lithium-air batteries and lithium-sulfur batteries, have received great attention because metallic lithium has the lowest density, the most negative electrode potential, the best electronic conductivity and The highe...

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Problems solved by technology

[0004] Despite the above advantages, lithium-sulfur batteries are still far from being practical. The current main problems include: (1) The lithium metal in the negative electrode reacts with the sulfur dissolved in the electrolyte, and the elemental sulfur gradually shrinks in the positive electrode area and forms Polysulfide, polysulfide strips from the positive electrode and enters the electrolyte, and then reacts with metal lithium, the positive electrode active material is lost and eroded, and finally causes the positive electrode area to collapse; (2) During the discharge process of the lithium-sulfur battery, the formed polysulfide After the sulfides enter the electrolyte, the highly enriched polysulfides cause the viscosity of the electrolyte to increase, resulting in a decrease in the conductivity of the electrolyte and a significant drop in battery performance; (3) The operating temperature of the lithium-sulfur battery system is as high as 300-400 °C, which Requires more expensive high-temperature-resistant materials and complex preparation processes to prevent battery burnout

[0006] The above-mentioned various technologies have a certain inhibitory effect on the dissolution loss and shuttling of polysulfides, but they cannot fundamentally solve the problem, because the pore size of the used diaphragm is much larger than the size of polysulfide ions, and polysulfides pass through the diaphragm. The resistance to migration to the negative electrode is small, and a good sulfur blocking effect cannot be achieved

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