Preparation method for nitrogen doped graphene/manganese dioxide/hollow sulfur composite material

Abstract

The invention provides a preparation method for a nitrogen doped graphene / manganese dioxide / hollow sulfur composite material, wherein the preparation method comprises the following multiple steps: step (1), adding a sulfur powder to carbon disulfide, and stirring and dissolving to form a homogeneous solution; step (2), carrying out ball milling of a high-purity nickel powder by a high energy ball mill, after ball milling, adding into the solution, stirring to form a homogeneous suspension, mechanically stirring, and spray-drying to form sulfur-coated spherical particles; step (3) adding the spherical particles to a ferric chloride solution, carrying out stirring reaction, washing with water, and filtering; and step (4), adding the precipitate after filtration to a solution containing manganese chloride and potassium permanganate, stirring into a homogeneous suspension, carrying out heating and stirring reaction, centrifuging, and washing with water to obtain sulfur particles coated with manganese dioxide. The design of a hollow structure of the composite material can reserve a space for volume expansion of the sulfur material in charging and discharging processes, and the electrochemical performance can be effectively improved.

Description

Technical field [0001] The invention relates to the synthesis of nano materials, in particular to a preparation method of a lithium-sulfur battery cathode material. Background technique [0002] Lithium-sulfur battery is a battery system with metallic lithium as the negative electrode and elemental sulfur as the positive electrode. Lithium-sulfur batteries have two discharge platforms (approximately 2.4 V and 2.1 V), but their electrochemical reaction mechanism is more complicated. Lithium-sulfur batteries have the advantages of high specific energy (2600 Wh / kg), high specific capacity (1675 mAh / g), and low cost. They are considered to be a new generation of batteries with great development prospects. However, it currently has problems such as low active material utilization, low cycle life and poor safety, which severely 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 in...

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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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