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Porous boron nitride fiber/multi-walled carbon nanotube/sulfur composite cathode material for lithium-sulfur batteries

A technology of multi-walled carbon nanotubes and boron nitride fibers, which is applied in battery electrodes, lithium batteries, positive electrodes, etc., can solve the problems of blocked electron conduction channels of carbon materials, hindering the shuttle effect of polysulfides, and complex process, etc. To achieve the effect of inhibiting the shuttle effect, benefiting the integrity and alleviating the volume expansion

Inactive Publication Date: 2021-09-03
HEBEI UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Since fibers and porous materials can adapt to the volume change of the positive electrode and improve the adsorption performance of polysulfides, Zhao et al. (Zhao, D. Qin, S. Wang, G. Chen, Z. Li, Electrochim. Acta 2014,127,123 –131.) and Zhou et al. (G.Zhou, L.Li, C.Ma, S.Wang, Y.Shi, N.Koratkar, W.Ren, F.Li, H.-M.Cheng, Nano Energy 2015,11,356–365.) Carbon fibers and porous carbon materials are used in positive electrode materials, but the process is complicated, the cost of materials is high, the shuttle effect of hindering polysulfides is limited, and carbon materials are prone to agglomeration to make electron conduction channels obstructed

Method used

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  • Porous boron nitride fiber/multi-walled carbon nanotube/sulfur composite cathode material for lithium-sulfur batteries
  • Porous boron nitride fiber/multi-walled carbon nanotube/sulfur composite cathode material for lithium-sulfur batteries
  • Porous boron nitride fiber/multi-walled carbon nanotube/sulfur composite cathode material for lithium-sulfur batteries

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0039] The first step, preparation of porous boron nitride fiber:

[0040] (1) Put 3.78g of melamine (melamine) and 3.71g of boric acid into a large beaker filled with 200ml of deionized water, then put it into a water bath, the temperature of the water bath is 90°C, and keep stirring to obtain a clear and transparent solution;

[0041] (2) Put the clear and transparent solution obtained through the reaction in step (1) into liquid nitrogen for rapid cooling to obtain a white flocculent precipitate;

[0042] (3) The white flocculent precipitate obtained in step (2) is freeze-dried to obtain a white light sample, which is the porous boron nitride fiber precursor;

[0043] (4) heat-treat the sample obtained in step (3) in a nitrogen flow (the nitrogen flow rate is maintained at 60ml / min), and the heat treatment temperature range is 1050° C. to obtain a white light sample, which is a porous boron nitride fiber;

[0044] The average diameter and length of the porous boron nitrid...

Embodiment 2

[0051] In this example, porous boron nitride fibers doped with red phosphorus are used. The mass ratio of red phosphorus to porous boron nitride fibers is 1:9. Red phosphorus and porous boron nitride fibers are evenly mixed together by grinding. Then carry out the above-mentioned mixing and grinding treatment with multi-walled carbon nanotubes, and the parameters of the other steps are the same as those in Example 1.

[0052] Compared with Example 1, the porous boron nitride fiber / multi-walled carbon nanotube / sulfur cathode material doped with red phosphorus can effectively catalyze and improve the conversion process of polysulfides due to the addition of red phosphorus, and can to a certain extent Alleviate the polarization of lithium-sulfur batteries, thereby improving the capacity and cycle stability of the batteries.

Embodiment 3

[0054] The steps of this embodiment are the same as those of Embodiment 1, except that the mass ratio of the porous boron nitride fiber to the multi-walled carbon nanotube is 1 / 1. And the prepared lithium-sulfur battery was charged and discharged at a rate of 0.1C.

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Abstract

The invention is a porous boron nitride fiber / multi-wall carbon nanotube / sulfur composite lithium-sulfur battery cathode material, which includes a structure in which porous boron nitride fibers and multi-wall carbon nanotubes are intertwined, and the intertwined structure Capable of wrapping and wrapping sublimated sulfur. The diameter and length of the porous boron nitride fiber are 50-100 nm and 10-20 μm respectively, and the diameter of the pores on the surface of the porous boron nitride fiber is less than 10 nm. This intertwined porous structure can effectively absorb the electrolyte and help to fix the soluble polysulfides in the cathode region, thereby preventing their diffusion to the anode, reducing the loss of active sulfur and improving the cycle stability. At the same time, it can effectively inhibit the agglomeration of multi-walled carbon nanotubes, and the vacancy defects of porous boron nitride fibers have a great influence on the local electronic structure. The atoms near the vacancies will be very active and can effectively catalyze polysulfides near the vacancies. From Li 2 S 8 to Li 2 S conversion, which can effectively inhibit the shuttle effect of polysulfides.

Description

technical field [0001] The invention relates to a lithium-sulfur battery cathode material, in particular to a porous boron nitride fiber / multi-wall carbon nanotube / sulfur composite type lithium-sulfur battery cathode material. Background technique [0002] Lithium-ion batteries are energy storage devices based on lithium intercalation electrochemistry. Since their successful launch in the 1990s, they have dominated the market for energy sources for portable electronics and electrical appliances. At present, the highest energy density of lithium-ion batteries is close to the limit, but it cannot meet the urgent requirements of emerging electric vehicles, hybrid electric vehicles and next-generation portable electronic devices, which require advanced battery systems with higher energy densities. In line with the development of the times, the research and development of lithium-sulfur batteries have shown mankind the direction of advanced energy in the future, and it is a hot t...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/62H01M4/38H01M10/052
CPCH01M4/38H01M4/625H01M4/628H01M10/052H01M2004/021H01M2004/028Y02E60/10
Inventor 唐成春李梦圆薛彦明
Owner HEBEI UNIV OF TECH