A kind of lithium-sulfur battery positive electrode material and its preparation method and lithium-sulfur battery

A lithium-sulfur battery and cathode material technology, which is applied to battery electrodes, lithium storage batteries, non-aqueous electrolyte storage batteries, etc., can solve the problem of reducing ionic conductivity, poor sulfur conductivity, and the improvement effect of lithium-sulfur battery cycle performance and rate performance is not obvious. and other problems, to achieve the effect of alleviating changes in sulfur pressure and volume, improving cycle stability, and inhibiting shuttle effect

Active Publication Date: 2019-09-17
宁波智正伟盈信息科技有限公司
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Problems solved by technology

However, lithium-sulfur batteries have three serious problems: (1) The conductivity of sulfur is very poor, and the final product of its reaction, Li 2 S 2 and Li 2 S is an insulator, which is not conducive to the high rate performance of the battery; (2) polysulfide compounds, the intermediate discharge products of lithium-sulfur batteries, will dissolve into the electrolyte, reducing the ion conductivity, and their migration between the positive and negative electrodes will lead to active material (3) During the charging and discharging process, the volume of sulfur changes greatly, which is easy to damage the battery
However, the positive electrode material in the above technical solution has a limited inhibitory effect on the dissolution of polysulfides and the shuttle effect, and the improvement effect on the cycle performance and rate performance of lithium-sulfur batteries is not obvious.

Method used

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  • A kind of lithium-sulfur battery positive electrode material and its preparation method and lithium-sulfur battery
  • A kind of lithium-sulfur battery positive electrode material and its preparation method and lithium-sulfur battery
  • A kind of lithium-sulfur battery positive electrode material and its preparation method and lithium-sulfur battery

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preparation example Construction

[0033] The present invention also provides a preparation method for the lithium-sulfur battery cathode material described in the above technical solution, comprising the following steps:

[0034] (1) mixing the nano silicon dioxide suspension with the nano titanium dioxide to obtain a mixed suspension;

[0035] (2) adding surfactant, phenols, formaldehyde and catalyst successively to the mixed suspension obtained in said step (1), and polycondensation reaction to obtain the first precursor;

[0036](3) Mix the first precursor obtained in the step (2) with a mixed solvent, add tetraethyl orthosilicate, and perform a hydrolysis reaction to obtain a second precursor;

[0037] (4) Etching the second precursor obtained in step (3) after calcining to obtain a titanium dioxide-carbon hollow sphere composite; the titanium dioxide-carbon hollow sphere composite includes carbon hollow spheres and carbon hollow spheres attached to the Nano-titanium dioxide on the inner and outer surface...

Embodiment 1

[0072] Prepare a mixed solution (75mL ethanol + 3.2mL ammonia water (26wt%) + 10mL deionized water), under the condition of continuous stirring, quickly add 6ml tetraethyl orthosilicate to the above solution within 3s, and react at 20°C for 1h , separating the solid product and drying to obtain silica with a particle size of 250nm;

[0073] Disperse the prepared silicon dioxide and 2.5g of titanium dioxide in a mixed solvent of 130mL deionized water and 50mL ethanol, and stir at 20°C for 20min; then add 0.8g cetyltrimethylammonium bromide, 0.35g Resorcinol, 0.5mL of formaldehyde and 2mL of ammonia water (26wt%) were reacted at 30°C for 15h, and the solid product was separated and dried to obtain a precursor 1;

[0074] Disperse the precursor into a mixed solution of 75mL ethanol, 10mL deionized water and 3.2mL ammonia water (26wt%). Under stirring conditions, 3mL tetraethyl orthosilicate was quickly added to the above solution within 3s to separate the solid product and dry t...

Embodiment 2

[0081] The lithium-sulfur battery cathode material prepared in Example 1 was assembled into a lithium-sulfur battery: the titanium dioxide-carbon hollow sphere / sulfur prepared in Example 1 was used as the cathode material, carbon black (SuperP) was used as the conductive material, polyylidene difluoride Ethylene is the binder, the current collector is an aluminum sheet, the negative electrode is a lithium sheet, the diaphragm is a Celgard2400 film, the supporting sheet is a spring sheet, and the electrolyte is 1M lithium bistrifluoromethanesulfonylimide (LiTFSI) dissolved in 1,3 - dioxolane (DOL) / ethylene glycol dimethyl ether (DME) = 1:1 V%, and 1% lithium nitrate was added.

[0082] The charge-discharge curve of the lithium-sulfur battery prepared in this example is as follows Figure 4 shown. from Figure 4 It can be seen that at 1C, the discharge capacity of the battery remains 691mAh g after 200 cycles -1 .

[0083] The rate performance of the lithium-sulfur battery p...

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Abstract

The invention provides a positive electrode material for a lithium sulfur battery and a preparation method therefor and a lithium sulfur battery. The positive electrode material for the lithium sulfur battery provided by the invention comprises a hollow carbon sphere, nano titanium dioxide attaching to internal and external surfaces of the hollow carbon sphere, and elemental sulfur filling the hollow carbon sphere, wherein the mass content of the elemental sulfur is 60-80%. Experimental results have shown that the lithium sulfur battery prepared by the positive electrode material for the lithium sulfur battery provided by the invention maintains a discharge capacity of 691 mAh.g<-1> after 200 times of cycling, and maintains a discharge capacity of 671 mAh.g<-1> after 300 times of cycling while maintaining a coulombic efficiency of about 97%, at a discharge rate of 1 C; and in cycling at a high discharge rate of 4 C, the lithium sulfur battery can maintain a discharge capacity of 527 mAh.g<-1>, and can still maintain a discharge capacity of 1042 mAh.g<-1> after the discharge rate returns to 1C.

Description

technical field [0001] The invention relates to the technical field of functional materials, in particular to a lithium-sulfur battery cathode material, a preparation method thereof, and a lithium-sulfur battery. Background technique [0002] With the increase of automobile production day and night, the gradual depletion of petroleum resources, and the increasingly serious environmental pollution, it is urgent to develop renewable energy to replace the previous energy supply system, especially the electrochemical energy storage system. Lithium-ion battery is the secondary battery system with the best comprehensive performance at present. After nearly 20 to 30 years of hard work, the capacity of the positive and negative electrode materials of lithium-ion battery is close to its theoretical limit, but it is still difficult to meet the requirements of the energy storage system day and night. growing demand. Therefore, it is necessary to develop new electrode materials with en...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/36H01M4/485H01M4/38H01M10/052H01M4/583H01M4/62
CPCH01M4/362H01M4/38H01M4/485H01M4/583H01M4/625H01M10/052Y02E60/10
Inventor 王贤保姚佳梅涛
Owner 宁波智正伟盈信息科技有限公司
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