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Composite anode of multi-layer structure for lithium-sulfur rechargeable battery and preparation method

A lithium-sulfur secondary battery and composite positive electrode technology, which is applied in electrode manufacturing, battery electrodes, structural parts, etc., can solve the problems of reducing the conductivity of lithium negative electrodes, irreversible electrochemical reactions, and poor reversibility of charge and discharge, and achieve improved cycle performance , Improve the first capacity retention rate and cycle stability, and the effect of controllable thickness

Inactive Publication Date: 2013-04-17
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

On the other hand, the polysulfide intermediates formed during charge and discharge are dissolved in an anionic organic solvent and permeate through the separator to reach the anode, where an electrically insulating precipitate (Li 2 S 2 and Li 2 S), reducing the conductivity of the lithium negative electrode, resulting in poor reversibility of charge and discharge, and a decrease in capacity
During the discharge process, the expansion and accumulation of solid precipitates on the surface of the cathode can also lead to irreversible electrochemical reactions, which in turn leads to mass loss of active materials and further causes capacity fading.

Method used

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  • Composite anode of multi-layer structure for lithium-sulfur rechargeable battery and preparation method
  • Composite anode of multi-layer structure for lithium-sulfur rechargeable battery and preparation method
  • Composite anode of multi-layer structure for lithium-sulfur rechargeable battery and preparation method

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] Using polyvinyl alcohol as binder, conductive carbon black as conductive agent, and carbon nanotube-sulfur composite materials with sulfur content of 10%, 25%, 50%, and 75% as active material, according to active material: conductive Agent: The binder is mixed in a mass ratio of 8:1:1, ground evenly, scraped on the aluminum foil current collector, dried in a vacuum oven at 60°C for 24 hours, and then placed in a magnetron sputtering machine. A layer of conductive carbon is sputtered on its surface (the sputtering time is 10min, and the target used is a conductive carbon target), and a multi-layer structure composite sulfur positive electrode can be obtained. The thickness of the carbon film is 10nm. The electrochemical cycle performance was tested in the voltage range of V. See Table 1 under the current density of 160mA / g(S).

[0022] Experimental conditions and results of table 1 example 1

[0023]

Embodiment 2

[0025] Use PVDF as the binder (NMP as the solvent), acetylene black as the conductive agent, and sublimed sulfur powder as the active substance, mix according to the mass ratio of active substance: conductive agent: binder: 6:3:1, and grind evenly , scrape-coated on the carbon mesh current collector, dried in a vacuum oven at 60°C for 24 hours, used it as the cathode, and used the silver plate as the anode, and silver-plated the surface in a silver nitrate solution to obtain a composite sulfur cathode with a multi-layered structure , the thickness of the coating is 2, 100, 750, 2000nm respectively, and the electrochemical cycle performance of the assembled button battery is tested in the voltage range of 3.0-1.5V and the current density of 160mA / g(S). its 1 st ,2 nd and 50 th The discharge specific capacity is shown in Table 2.

[0026] Experimental condition and result of table 2 example 2

[0027]

Embodiment 3

[0029] Sodium carboxymethyl cellulose is used as binder, conductive carbon black is used as conductive agent, molybdenum disulfide is used as active material, mixed according to the mass ratio of active material: conductive agent: binder is 5:3:2, and ground Evenly, scrape it on the aluminum mesh collector, dry it in a vacuum drying oven at 60°C for 24 hours, insert it into the solution containing aniline monomer after treatment, and add potassium persulfate solution drop by drop to make the polyaniline sticky. Attached to the surface of the pole piece and dried to obtain a multi-layer structure composite sulfur positive electrode, the thickness of the coating is 1000nm, and it is assembled into a button battery. Electrochemical cycle performance The electrochemical cycle performance was tested. its 1 st ,2 nd and 50 th The discharge specific capacities are 1051, 903, and 843mAh / g, respectively.

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Abstract

The invention provides a composite anode of a multi-layer structure for a lithium-sulfur rechargeable battery and a preparation method, which is characterized in that: an anode active substance, a conductive agent, and a binder are uniformly mixed, and then are coated on a current collector, and after coat is dried, a layer of conductive film is sprayed on the surface. The anode surface film is used for conducting and cutting off the sulfur in a cyclic process, thereby effectively raising a first capacity conservation rate of the battery and the cyclic stability.

Description

technical field [0001] The invention belongs to the field of preparation of positive electrodes of sulfur secondary batteries, and relates to a method for preparing composite sulfur positive electrodes with a multi-level structure. Background technique [0002] With the gradual depletion of natural resources such as coal and oil, the energy crisis has become one of the major issues that human beings must solve in the future. And rechargeable batteries that are safe, cheap, high energy density and long life have attracted more and more attention. [0003] Lithium-sulfur rechargeable batteries have very broad application prospects and are one of the most promising candidates for future lithium batteries. The theoretical specific capacity of elemental sulfur is 1675mAh / g, and when assembled with lithium to form a battery, its theoretical specific energy reaches 2600Wh / kg, which meets the requirements of electric vehicles for batteries, and also meets the requirements of "light...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/1397H01M4/04H01M4/136
CPCY02E60/10
Inventor 张凯李劼方静李强赖延清张治安邓兆丰刘芳洋
Owner CENT SOUTH UNIV
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