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A kind of graphene/metal lithium composite electrode and preparation method thereof

A composite electrode and graphene technology, applied in battery electrodes, circuits, electrical components, etc., can solve the problems of reducing the size of metal lithium, high internal impedance of the electrode, weakening the role of the matrix skeleton, etc., to inhibit the growth of surface dendrites, The method is simple and easy to operate, and the effect of increasing the composite area

Active Publication Date: 2020-10-09
NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI
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  • Abstract
  • Description
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  • Application Information

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Problems solved by technology

In recent years, metal lithium is loaded inside the three-dimensional porous material matrix by electrochemical deposition or heating and melting, and local micronanoization of metal lithium is carried out to prepare composite metal lithium electrodes. The study uses stable metal lithium powder as the electrode, but because of the inert layer on the surface, it will cause problems such as high internal impedance of the electrode and increase in the polarization voltage of the battery, so it can only be used by rolling activation.
[0003] In the research of metal lithium electrodes in the prior art, it is difficult to accurately control the loading capacity of metal lithium, and the metal lithium is combined with a three-dimensional porous matrix. Although the composite electrode can effectively suppress the problems existing in the metal lithium electrode, it is often the metal Lithium loading is excessive and poorly controllable
In addition, in the existing composite metal lithium electrode materials, the local size of metal lithium is still on the scale of hundreds of microns or even centimeters, which cannot reduce the size of dispersed / composited metal lithium to the micron level. There is not much difference between the lieutenant and the bulk lithium metal, and it also weakens the role of the matrix framework in guiding the deposition
Although some people directly use micron-sized metal lithium powder to prepare metal lithium electrodes by cold pressing, but due to the inert layer on the surface of metal lithium powder, the negative electrode material has a large impedance and high voltage polarization after being assembled into a battery. The cycle stability is not greatly improved, and the practicability is poor

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  • A kind of graphene/metal lithium composite electrode and preparation method thereof
  • A kind of graphene/metal lithium composite electrode and preparation method thereof
  • A kind of graphene/metal lithium composite electrode and preparation method thereof

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preparation example Construction

[0025] The invention provides a preparation method of a graphene / metal lithium composite electrode, comprising:

[0026] A) mixing graphene powder, binder solution and metal lithium powder to obtain graphene-metal lithium powder mixed slurry;

[0027] B) coating the graphene-metal lithium powder mixed slurry to obtain pole pieces;

[0028] C) heating and activating the pole piece to obtain a graphene / metal lithium composite electrode.

[0029] In the present invention, firstly, the graphene powder, the binder solution and the lithium metal powder are mixed to obtain a graphene-lithium metal powder mixed slurry; preferably, the graphene powder and the binder solution are firstly mixed to obtain the mixed slurry.

[0030] Wherein, the binder solution is obtained by dissolving the binder in a solvent, and the binder preferably includes polyvinylidene fluoride; the solvent preferably includes N-methylpyrrolidone.

[0031] The mass fraction of the polyvinylidene fluoride in the b...

Embodiment 1

[0055] Take 2.0 g of PVDF powder, add it into 38 g of NMP solution, and stir the above solution until PVDF is completely dissolved to obtain a PVDF / NMP solution with a mass fraction of 5%. Weigh 0.05 g of graphene powder below 20 microns into a reagent bottle, add 2.0 g of the above solution, then transfer the reagent bottle to a glove box, and stir for 12 hours in an argon protective atmosphere. Then weigh 0.35g of metal lithium powder with a thickness of less than 50 microns, slowly add it into the above solution, and continue stirring at the same time to obtain a uniform graphene / metal lithium powder slurry.

[0056] The above slurry was coated in a glove box, copper foil was used as a current collector, and a 250 μm thick scraper was used to scrape the sample, and then the sample was placed in an argon protective atmosphere and dried naturally to obtain a 200 μm thick pole piece. The shape of the pole piece was measured, and the results were as follows: figure 1 as shown,...

Embodiment 2

[0060] Take 2.0 g of PVDF powder, add it into 38 g of NMP solution, and stir the above solution until PVDF is completely dissolved to obtain a PVDF / NMP solution with a mass fraction of 5%. Weigh 0.035g of graphene powder below 15 microns into a reagent bottle, add 2g of the above solution, and then add 1.5g of NMP solution, then transfer the reagent bottle to a glove box, and stir for 12h in an argon atmosphere. Then weigh 0.815g of metal lithium powder below 40 microns, slowly add it into the above solution, and continue stirring at the same time to obtain a uniform graphene / metal lithium powder slurry.

[0061] The above slurry was coated in a glove box, copper foil was used as a current collector, and a 200 μm thick scraper was used to scrape the sample, and then the sample was placed in an argon protective atmosphere and dried naturally to obtain a 150 μm thick pole piece.

[0062] After the drying is complete, the pole piece is cut out with a puncher, and then the pole pi...

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Abstract

The invention provides a preparation method of a graphene / metal lithium composite electrode. The preparation method comprises the following steps: mixing graphene powder, a binder solution and metal lithium powder to obtain graphene-metal lithium powder mixed slurry; coating the graphene-metal lithium powder mixed slurry to obtain a pole piece; and heating and activating the pole piece to obtain the graphene / metal lithium composite electrode. In the preparation method provided by the invention, the micron-sized metal lithium powder is adopted as a lithium source for being compounded with the micron-sized graphene material, and the metal lithium powder is heated, melted and activated, so that metal lithium fully spreads among sheets of graphene, the compounding size of the metal lithium andthe graphene is reduced, and the compounding area is enlarged. In the preparation method provided by the invention, the loading amount of the metal lithium in the composite electrode can be accurately controlled, and the dispersion size of the metal lithium can be reduced. By utilizing the graphene as a three-dimensional conductive framework, the current density can be dispersed to provide activesites for the deposition of the metal lithium, and inhibit the growth of surface dendrites to obtain a highly reversible lithium metal electrode. The composite metal lithium anode is prepared by adopting a 'cathode coating' way, so that the method is simple.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a graphene / metal lithium composite electrode and a preparation method thereof. Background technique [0002] The wide application of lithium-ion batteries in mobile devices and electric vehicles has put forward higher requirements for the energy density and power density of lithium-ion batteries. The development and research of positive electrode materials are becoming more and more perfect. To improve the overall performance of lithium-ion batteries, research on high-performance negative electrode materials has great prospects. Metal lithium, with its advantages of high specific capacity, light weight and low potential, is often considered as the ultimate lithium-ion battery anode material. However, due to its high activity, lithium metal will form dendrites and "dead lithium" during charging and discharging, which hinders its further development. At present, mos...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/1395H01M4/134H01M4/36H01M4/38H01M4/62H01M10/0525
CPCH01M4/134H01M4/1395H01M4/364H01M4/382H01M4/625H01M4/628H01M10/0525Y02E60/10
Inventor 朱文华邓伟周旭峰刘兆平
Owner NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI
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