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Preparation method of lithium-sulfur battery positive electrode

A lithium-sulfur battery and cathode technology, which is applied in the field of preparation of lithium-sulfur battery cathodes, can solve the problems of surface tension and volume shrinkage electrode cracks, dilute the theoretical energy density of lithium-sulfur batteries, and reduce the volumetric energy density of lithium-sulfur batteries. Avoid local agglomeration of materials, good electrode structure and compositional homogeneity, and promote the effect of dissolution and reaction

Inactive Publication Date: 2020-02-04
TONGJI UNIV
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Problems solved by technology

[0005] 2) Excessive electrolyte addition seriously dilutes the theoretical energy density of lithium-sulfur batteries
The addition of too many conductive additives causes huge surface tension and volume shrinkage inside the electrode sheet during the solvent volatilization process, resulting in electrode cracking, which limits the preparation of high-capacity lithium-sulfur battery cathodes
Although the current three-dimensional current collector can increase the surface loading capacity of the lithium-sulfur battery electrode, the three-dimensional electrode will reduce the volumetric energy density of the lithium-sulfur battery due to its developed pore structure, and on the other hand, it will require more electrolysis. liquid to fill the pores to reduce the mass energy density of the battery

Method used

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  • Preparation method of lithium-sulfur battery positive electrode

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preparation example Construction

[0034] The preparation method of lithium-sulfur battery cathode provided by the invention comprises the following steps:

[0035] Step 1, uniformly mixing the active material sulfur, conductive agent, and binder to obtain a mixture, then adding a dispersing solvent to the mixture and mixing uniformly to obtain an electrode slurry;

[0036] Step 2, uniformly coating the electrode slurry on the positive electrode current collector to obtain a wet electrode coated with the slurry;

[0037] Step 3, placing the wet electrode coated with the slurry in a low temperature environment of -80°C to -5°C and freezing it for 1h to 5h until the wet electrode is frozen and formed, so that the dispersion solvent in the wet electrode is solidified and crystallized to obtain a solidified electrode;

[0038] Step 4, placing the coagulation electrode in a vacuum environment with a vacuum degree of 0.1 Pa to 100 Pa for 1 h to 5 h to sublimate the ice crystals in the solid phase of the coagulation ele...

Embodiment 1

[0055] Mix 2g commercial sublimated sulfur powder, 0.53g Ketjen black (ECP 200JD), 2.66g styrene-butadiene rubber and carboxymethyl cellulose mixed binder aqueous solution (the mass ratio of SBR and CMC is 1:1, the binder aqueous solution is solid Phase content is 5%), and successively add 50ml ball mill tank (sulfur, Ketjen black, binder mass ratio is 75:20:5), then add appropriate amount of ball mill beads and 8g water therein, then at 350 rpm The ball milled at a high speed for 2 hours, and then the evenly milled electrode slurry was evenly coated on the aluminum foil of the current collector with an automatic coating machine, and the coating thickness was controlled at 200 microns to obtain a wet electrode, and then the prepared wet electrode was quickly The electrode is placed in a freezing environment of minus 40 degrees to solidify the water solvent into ice crystals. The freezing time is 2 hours. Finally, the frozen solidified electrode is taken out and placed in a vacu...

Embodiment 2

[0065] Add 2g commercial sublimated sulfur powder, 0.875g Ketjen black (ECP 600JD), 1.66g LA133 binder aqueous solution (the solid phase content of the binder aqueous solution is 15%) into a 50ml ball mill jar (sulfur, Ketjen black, binder The agent mass ratio is 64:28:8), and then add appropriate amount of ball milling beads and 8g of water, and then ball mill at a speed of 350 rpm for 2 hours, and then use an automatic coating machine to obtain the uniform electrode slurry obtained by ball milling Evenly and evenly coated on the aluminum foil of the current collector, the coating thickness is controlled at 300 microns to obtain a wet electrode, and then the prepared wet electrode is quickly placed in a freezing environment of minus 30 degrees to solidify the water solvent into ice crystals, and the freezing time is 2 hours, and finally take out the frozen solidified electrode and place it in a vacuum environment with a vacuum degree of 0.1 Pa for 2 hours to sublimate the prev...

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Abstract

The invention provides a preparation method of a lithium-sulfur battery positive electrode. The preparation method comprises the following steps: uniformly mixing an active substance sulfur, a conductive agent and a binder to obtain a mixture, then adding a dispersing solvent into the mixture, and uniformly mixing to obtain electrode slurry; uniformly coating a positive electrode current collectorwith the electrode slurry to obtain a wet electrode coated with the slurry; freezing the wet electrode coated with the slurry in a low-temperature environment of -80 to -5 DEG C for 1-5 hours until the wet electrode is frozen and formed, so that the dispersing solvent in the wet electrode is solidified and crystallized to obtain a solidified electrode; placing the solidified electrode in a vacuumenvironment with the vacuum degree of 0.1-100Pa for 1-5 hours, so that solid-phase sublimation of ice crystals in the solidified electrode is carried out to obtain a solid-phase sublimated electrode;and carrying out rolling treatment on the solid-phase sublimated electrode, and controlling the porosity of the electrode to be 50-70% to obtain the lithium-sulfur battery positive electrode. The preparation method is simple, and the problem of electrode cracking in the preparation of a high-sulfur-carrying positive electrode by adopting a traditional hot drying method is effectively solved.

Description

technical field [0001] The invention belongs to the field of lithium batteries, and in particular relates to a method for preparing a positive electrode of a lithium-sulfur battery. Background technique [0002] With the development of portable electronic products, energy storage technology and new energy vehicles, modern society has put forward higher requirements for battery energy density. Lithium-ion batteries are limited by the intercalation / extraction reaction mechanism of electrode materials, and there is little room for improvement in their energy density. Moreover, the current lithium-ion battery cathode material is mainly composed of transition metal oxides, and its raw material cost has been high. It is imminent to develop a new generation of new battery systems with high energy density and low cost. Lithium-sulfur batteries have a high specific capacity (1672mAhg -1 ) and energy density (2600Wh kg -1 ), and the positive electrode material is rich in elemental...

Claims

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Application Information

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IPC IPC(8): H01M4/139H01M4/04H01M10/052
CPCH01M4/139H01M4/04H01M10/052Y02E60/10
Inventor 谢勇李洒伽龙黄云辉潘国宇
Owner TONGJI UNIV
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