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Preparation and application of manganese dioxide@sulfur@carbon sphere positive electrode composite material with yolk-shell structure

A manganese dioxide and composite material technology, applied in structural parts, battery electrodes, electrical components, etc., can solve problems such as the inability to effectively inhibit the dissolution of lithium polysulfides, the difficulty in efficiently adsorbing lithium polysulfides, and the inability to effectively inhibit the shuttle effect, etc. Achieving the effect of being conducive to full contact, improving low electronic conductivity, and high specific energy density

Active Publication Date: 2020-06-05
DALIAN INST OF CHEM PHYSICS CHINESE ACAD OF SCI
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In addition, sulfur reacts complexly with lithium ions during the discharge process, undergoing a process from long-chain polysulfides (Li 2 S x ,4<x<8) to the process of short-chain lithium sulfide, in which long-chain polysulfide is easily soluble in ether electrolyte, and will shuttle through the separator to the metal lithium negative electrode side to be reduced during the battery cycle, resulting in relatively Low capacity retention, coulombic efficiency, and poor cycle stability, so how to alleviate the shuttle effect of polysulfides is a fundamental scientific problem that still exists in lithium-sulfur batteries
[0004] In the Chinese invention patent with the authorized publication number CN104916828 A, it is mentioned that the carbon-sulfur positive electrode material prepared with hollow carbon spheres as the sulfur carrier solves the problem of cycle performance caused by lithium polysulfide shuttling by confining sulfur in the cavity of the carbon spheres. bad question
However, the physical interaction between non-polar carbon spheres and polar lithium polysulfides in this patent is weak, and it is difficult to efficiently adsorb the dissolved lithium polysulfides, which cannot effectively inhibit the occurrence of the shuttle effect.
At the same time, in the Chinese invention patent with the authorized publication number CN107887605 A, it is proposed to prepare a sulfur positive electrode with nano-sulfur powder, manganese dioxide powder, carbon fiber, and carbon nanotubes as a slurry. Lithium plays an anchoring role, and the battery can achieve good cycle stability in the first 80 cycles, but manganese dioxide with poor conductivity tends to lose electrical contact with the insulating active material sulfur during the cycle, and thus cannot effectively inhibit polysulfide. The dissolution of lithium makes the battery's long-term cycle performance poor

Method used

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  • Preparation and application of manganese dioxide@sulfur@carbon sphere positive electrode composite material with yolk-shell structure
  • Preparation and application of manganese dioxide@sulfur@carbon sphere positive electrode composite material with yolk-shell structure
  • Preparation and application of manganese dioxide@sulfur@carbon sphere positive electrode composite material with yolk-shell structure

Examples

Experimental program
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Effect test

Embodiment 1

[0037] The process of preparing manganese dioxide@carbon material with yolk-shell structure is the same as that of the comparative example. Take 0.1g of manganese dioxide@carbon material, grind it with 0.4g of sublimated sulfur, transfer it to a sealed reactor, heat treat at 155°C for 12h, 300 Heat treatment at ℃ for 2 hours to obtain a manganese dioxide@sulfur@carbon composite material with a yolk-shell structure. The carbon content in the composite material is 24.9%, the manganese dioxide content is 12.6%, and the sulfur content is 62.5%. Among them, the hollow carbon sphere The inner diameter of the cavity is 500nm, the thickness of the carbon layer is 30nm, and the specific surface area is 598m 2 g -1 , the pore volume is 0.584cm 3 g -1 , the coating of the subsequent pole piece and the assembly test of the battery are the same as the comparative example.

[0038] Depend on figure 1 It can be seen that the particle size of manganese carbonate is 600+100nm, from which i...

Embodiment 2

[0044] Manganese carbonate is prepared with comparative example;

[0045] Take 0.1g of manganese carbonate, add 0.1g of CTAB, 5ml of deionized water, 65ml of ethanol, 1ml of concentrated ammonia water, ultrasonically disperse for 30min, add 20ml of ethanol solution containing 0.4ml of tetraethyl orthosilicate within two hours, continue the reaction for 4h, pump Filtration, washing, and drying to obtain manganese carbonate@silicon dioxide with a core-shell structure;

[0046] The manganese dioxide@carbon material with yolk-shell structure is prepared in the same way as the comparative example, and the subsequent sulfur dipping, coating pole piece and battery assembly test are the same as in Example 1. The carbon content in the composite material is 23.5%, and the manganese dioxide content is 13.1% %, the content of sulfur is 63.4%. Among them, the inner diameter of the hollow carbon sphere is 400nm, the thickness of the carbon layer is 30nm, and the specific surface area is 548...

Embodiment 3

[0049] Manganese carbonate is prepared with comparative example;

[0050] Take 0.1g of manganese carbonate, add 0.1g of CTAB, 5ml of deionized water, 65ml of ethanol, 1ml of concentrated ammonia water, ultrasonically disperse for 30min, add 20ml of ethanol solution containing 1.2ml of tetraethyl orthosilicate within two hours, continue the reaction for 4h, pump Filtration, washing, and drying to obtain manganese carbonate@silicon dioxide with a core-shell structure;

[0051] Manganese dioxide@carbon material with yolk-shell structure is the same as the comparative example, and the subsequent sulfur immersion, coating pole pieces and battery assembly tests are the same as in Example 1. The carbon content in the composite material is 24.7%, and the manganese dioxide content is 13.4% %, the content of sulfur is 61.9%. Among them, the inner diameter of the hollow carbon sphere is 600nm, the thickness of the carbon layer is 25nm, and the specific surface area is 462m 2 g -1 , the...

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Abstract

The invention provides a manganese dioxide@sulfur@carbon sphere positive electrode composite material with a yolk-shell structure as well as a preparation method and application thereof. According tothe manganese dioxide@sulfur@carbon sphere composite material, manganese dioxide of a flaky structure serves as a core and is distributed in a cavity with a carbon sphere serving as a shell, sulfur isdistributed between the manganese dioxide core and the carbon shell, and the composite material comprises 10%-30% of carbon, 10%-30% of manganese dioxide and 40%-80% of sulfur. The hollow carbon spheres provide sufficient sulfur loading space; moreover, the rich point-to-point contact among the carbon spheres ensures the rapid transmission of electrons, the flaky manganese dioxide core layer in the carbon sphere cavity has a strong chemical adsorption conversion effect on polysulfide, the shuttle effect can be effectively inhibited by combining the physical limitation effect of the carbon layer, and the capacity retention ratio, the cycling stability and the rate capability of the battery are improved.

Description

technical field [0001] The invention belongs to the technical field of new energy, and specifically relates to the preparation and application of a manganese dioxide@sulfur@carbon sphere cathode composite material with a yolk-shell structure. Background technique [0002] With the consumption of non-renewable resources such as fossils, people have accelerated the development and utilization of new energy sources. Among them, secondary batteries are playing an increasingly important role as an important energy carrier. At present, lithium-ion batteries have been widely used in energy storage fields such as small mobile power supplies and power batteries due to their good safety, cycle stability, and low cost. However, due to its low theoretical specific capacity (<300mAh g -1 ) has been unable to meet people's demand for high specific energy batteries, therefore, it is of great significance to develop a new type of secondary battery with high specific energy, long cycle l...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/38H01M4/505H01M4/62
CPCH01M4/38H01M4/505H01M4/625Y02E60/10
Inventor 陈剑邵钦君
Owner DALIAN INST OF CHEM PHYSICS CHINESE ACAD OF SCI
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