CN-122000299-A - High-load sulfur positive electrode for high-performance lithium sulfur battery and preparation method thereof

Abstract

The invention discloses a high-load sulfur positive plate for a high-performance lithium sulfur battery, and a preparation and modification method thereof. The active material of the positive plate is vulcanized polyacrylonitrile (SPAN), and the surface of the positive plate is subjected to laser etching treatment with specific power to form a porous structure. The preparation method comprises the steps of preparing SPAN, a binder and a conductive agent into slurry according to a specific proportion, coating and drying, and etching the electrode surface by adopting 1.5W-6W laser. According to the invention, the regular micron-sized grooves are created on the surface of the positive plate by laser etching, the patterned structure effectively enhances electrolyte infiltration, improves charge transmission dynamics, and relieves stress accumulation in the charge-discharge process, so that the structural stability and the cycle performance of the electrode under high sulfur loading are obviously improved. The method has simple process and low cost, and provides an effective scheme for preparing the high-performance and high-load lithium sulfur battery.

Inventors

• MA FENG
• DING HAODONG

Assignees

• 武汉科技大学

Dates

Publication Date

20260508

Application Date

20260306

Claims (8)

1. 1. The positive plate for the high-load lithium sulfur battery is characterized by comprising a current collector and a positive electrode material layer coated on the current collector, wherein the positive electrode material layer comprises an active material, a binder and a conductive agent, the active material is vulcanized polyacrylonitrile, and the surface of the positive electrode material layer is subjected to laser etching treatment to form a porous structure.
2. 2. The positive electrode sheet according to claim 1, wherein in the positive electrode material layer, the mass ratio of the active material, the binder and the conductive agent is (7-9): (1.8-2.2): 2, wherein the binder is polyvinylidene fluoride, and the conductive agent is ketjen black.
3. 3. The positive plate according to claim 2, wherein the ketjen black has a bulk density of 17.0-50.0 g/L and a DBP oil absorption value of 440-510 mL/100g.
4. 4. The positive electrode sheet according to claim 1, wherein the laser power of the laser etching process is 1.5W to 6W.
5. 5. A high capacity lithium sulfur battery comprising the positive electrode sheet, lithium negative electrode sheet, separator and electrolyte of any one of claims 1-4.
6. 6. The high-load lithium sulfur battery of claim 5 wherein the electrolyte comprises a lithium salt and an organic solvent, the lithium salt being at least one of LiPF 6 , liTFSI, liFSI, and the organic solvent being an ether solvent or an ester solvent.
7. 7. The high capacity lithium sulfur battery of claim 5 wherein the lithium negative electrode sheet is a metallic lithium foil.
8. 8. A method for producing the positive electrode sheet according to any one of claims 1 to 4, comprising the steps of: (1) Preparing slurry, namely mixing a vulcanized polyacrylonitrile active material, a polyvinylidene fluoride binder and a Keqin black conductive agent in proportion, grinding and dispersing the mixture in an organic solvent to form uniform slurry; (2) Coating and drying, namely coating the slurry on a current collector, and drying to obtain a positive plate substrate; (3) And (3) performing laser etching, namely performing etching treatment on the surface of the positive plate substrate by using laser with the power of 1.5W-6W to obtain the positive plate with the porous structure on the surface.

Description

High-load sulfur positive electrode for high-performance lithium sulfur battery and preparation method thereof Technical Field The invention belongs to the technical field of electrochemistry, and particularly relates to a high-load lithium-sulfur battery positive electrode and a preparation method thereof. Background Energy is an important foundation for the survival and development of human society, and with the increase of global population and the continuous development of countries, the consumption of non-renewable energy is increasing, and the demand of novel consumer electronics industry for energy storage systems is also increasing. The positive electrode material uses sulfur as the positive electrode, the theoretical specific capacity of the positive electrode material reaches 1675 mAh g-1, the theoretical specific capacity is far higher than that of the traditional lithium ion battery .（Yan J, Li W, Wang R, et al. An in Situ Prepared Covalent Sulfur–Carbon Composite Electrode for High-Performance Room-Temperature Sodium–Sulfur Batteries [J]. ACS Energy Letters, 2020, 5(4): 1307~1315）., the sulfur used in the sulfur positive electrode has rich reserves in the crust, the price is low, and the cost can be saved to a great extent. Considering the influence of other inactive components such as current collector, electrolyte, conductive agent, etc., the actual energy density of the lithium-sulfur battery can reach 600 Wh kg-1, which is far higher than the existing lithium ion battery in the market. At present, the lithium sulfur battery still has a plurality of problems to limit the practical application of 1) and the shuttle effect, namely, the elemental sulfur on the positive electrode carbon material is reduced and combined with lithium ions in electrolyte during the discharging process of the battery, so that the elemental sulfur is converted into lithium polysulfide (LiPS). The portion LiPS is separated from the positive electrode material and dissolved in the electrolyte, and then migrates to the negative electrode through the separator and reacts short with lithium to cause loss of active material. 2) the conductivity of S and Li2S2 and Li2S was poor. The conductivities of elemental sulfur and Li2S at room temperature are 5x 10-30S cm-1 and 3.6x10-7S cm-1, respectively, 3) the volume effect. The densities of elemental sulfur and the discharge end product Li2S were 2.03 g cm-3 and 1.66 g cm-3, respectively. As the battery is charged and discharged, the volume of the electrode system is changed continuously with the progress of the reaction, so that the contact between the active material and the conductive material is reduced, and even the active material is peeled off, so that the electrode structure is damaged. The existing anode has a certain effect by modifying a carbon material (such as porous carbon and the like) or introducing a catalyst, but has the defects of complex process, high cost, poor compatibility and the like. Thus, there is a need for a simple and efficient method that enables stable cycling during battery operation (especially at high load conditions) without creating safety hazards. Disclosure of Invention The invention aims to solve the technical problems of unstable electrode structure, slow charge transmission dynamics and the like of a high-load lithium sulfur battery positive electrode in a circulating process, provides a high-load lithium sulfur battery with excellent circulating stability, and aims to provide a positive plate subjected to laser surface modification. In order to achieve the above purpose, the technical scheme adopted by the invention is as follows: A high-load lithium-sulfur battery comprises a positive plate, a lithium negative plate, a diaphragm and electrolyte. The active material of the positive plate is vulcanized polyacrylonitrile (SPAN), and the surface of the active material layer of the positive plate is subjected to laser etching treatment to form a patterned microstructure. The positive plate is prepared by mixing a vulcanized polyacrylonitrile active material, a binder and a conductive agent according to a preset proportion, dispersing the mixture in an organic solvent to prepare uniform slurry, coating the slurry on a current collector, drying to form a positive plate substrate, and finally, carrying out etching treatment on the surface of the positive plate substrate by adopting laser. Preferably, the power of the laser etching may be selected and optimized within a certain range. Preferably, the electrolyte comprises a lithium salt and an organic solvent, which may be selected from an ester or ether solvent. Preferably, the lithium negative electrode sheet is a metal lithium foil. The invention also provides a preparation method of the high-load lithium sulfur battery, which mainly comprises the steps of laser etching treatment of a positive plate, stacking of battery elements and liquid injection packaging under inert atmosphere. Compared