Method for improving wettability of lithium-ion batteries

Abstract

This invention belongs to the field of lithium-ion battery technology and relates to a method for improving the wettability of lithium-ion batteries. After rolling and flattening a lithium iron phosphate positive electrode sheet, it is positioned and then aligned with the front and back surfaces using a laser while undergoing longitudinal etching. This creates microchannels for electrolyte transport on the electrode surface. Then, activated carbon material is implanted into these microchannels using electrostatic flocking technology. The electrolyte is transported to the microchannels via the activated carbon, providing sufficient electrolyte to the electrode. The activated carbon has a large specific surface area and strong liquid absorption and retention capabilities, significantly improving the wettability of the electrode.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology and relates to a method for improving the wettability of lithium-ion batteries. Background Technology

[0002] Currently, energy storage and power batteries are mainly divided into two major categories: lithium iron phosphate batteries and ternary lithium batteries. Energy density, cycle life, and safety performance are the three key indicators of lithium-ion batteries. Among them, the high safety and long cycle life of lithium iron phosphate batteries are gradually becoming the target of the new energy field.

[0003] Nevertheless, the low energy density of lithium iron phosphate (LFP) batteries has also constrained their development in the new energy field. LFP has a low theoretical specific capacity, and the actual specific capacity is currently only slightly different from the theoretical capacity, limiting the potential for further improvement. The main approach to increasing the energy density of LFP batteries is towards high-compact electrode technology. However, high-compact LFP materials and electrodes significantly reduce the liquid absorption and retention capabilities, leading to a decline in electrical performance, especially in cycle life. This hinders the development of LFP batteries in areas requiring high energy density and long lifespan. Improving the liquid absorption and retention capabilities of high-compact LFP batteries could significantly expand their application scope. Summary of the Invention

[0004] The purpose of this invention is to provide a method for improving the wettability of lithium-ion batteries, solving the problems of liquid absorption and retention in high-energy lithium iron phosphate batteries, thereby improving the cycle performance of high-energy lithium iron phosphate batteries.

[0005] The present invention provides a method for improving the wettability of lithium-ion batteries, comprising the following steps:

[0006] 1) Flatten and position the rolled lithium iron phosphate positive electrode sheet;

[0007] 2) Use laser to perform longitudinal etching on both sides of the electrode to construct microchannels for electrolyte transport on the surface of the lithium iron phosphate electrode;

[0008] 3) Vacuum cleaning is performed on the etched areas of the electrode during laser etching;

[0009] 4) Activated carbon materials are implanted into microchannels using electrostatic flocking technology.

[0010] According to the method for improving the wettability of lithium-ion batteries, the etching controls the microchannel width to be 5μm~10μm and the microchannel depth to be 10μm-20μm.

[0011] According to the method for improving the wettability of lithium-ion batteries, microchannels are etched vertically through the electrode surface, with a spacing of 5cm-10cm between the microchannels on the electrode surface.

[0012] According to the method for improving the wettability of lithium-ion batteries, the activated carbon implantation thickness is 5μm-10μm, and the specific surface area of ​​the activated carbon is 1500m². 2 / g-2500 m 2 / g, pore volume 0.7 ml / g -1.0 ml / g.

[0013] According to the method for improving the wettability of lithium-ion batteries, the front and back of the electrode are aligned during laser etching, and the etching positions are the same.

[0014] According to the method for improving the wettability of a lithium-ion battery, the lithium-ion battery is a cylindrical lithium battery, the foil thickness of the lithium iron phosphate positive electrode is 12μm±1μm, and the single-sided thickness of the lithium iron phosphate material is μm±2μm.

[0015] According to the method for improving the wettability of lithium-ion batteries, the microchannel width is controlled at 8μm±1μm, the microchannel depth at 15μm±1μm, the etched microchannels vertically penetrate the electrode sheet, and the microchannel spacing on the electrode sheet surface is 6cm±0.2cm.

[0016] According to the method for improving the wettability of lithium-ion batteries, the activated carbon implantation thickness is 8μm±1μm, and the specific surface area of ​​the activated carbon is 1800m². 2 / g±200 m 2 / g, pore volume 0.7ml / g -1.0ml / g.

[0017] The advantages and effects of this invention are:

[0018] 1. This invention flattens and positions the rolled lithium iron phosphate positive electrode sheet, and uses a laser to align the front and back of the electrode sheet and simultaneously etch it longitudinally. This method achieves high etching efficiency and ensures that the etching positions on the front and back of the electrode sheet are the same, thus avoiding wrinkling of the electrode sheet caused by uneven tension on the front and back sides.

[0019] 2. Activated carbon material is implanted into microchannels using electrostatic flocking technology. The electrolyte is transported to the microchannels using activated carbon as a carrier to supply sufficient electrolyte to the electrode. Activated carbon has a large specific surface area and strong liquid absorption and retention capacity, which greatly improves the wettability of the electrode. Attached Figure Description

[0020] Figure 1 The battery 1C charge-discharge cycle performance curves were prepared for the positive electrode sheet without laser etching and activated carbon implantation, as well as the positive electrode sheet with laser etching and activated carbon implantation, in the examples.

[0021] Figure 1 In the diagram, #1 and #2 are batteries made from positive electrode sheets that have undergone laser etching and activated carbon implantation, while #3 and #4 are batteries made from positive electrode sheets that have not undergone laser etching and activated carbon implantation. Detailed Implementation

[0022] The specific details of this invention will be further explained below:

[0023] The present invention provides a method for improving the wettability of lithium-ion batteries, comprising the following steps: First, after rolling and flattening the lithium iron phosphate positive electrode sheet, it is positioned and then aligned with the front and back of the electrode sheet by laser etching, thereby constructing a lithium iron phosphate electrode sheet electrolyte transport microchannel on the electrode sheet surface. The width of the microchannel is controlled to be 5μm~10μm, the depth of the microchannel is 10μm-20μm, and the etched microchannel penetrates the electrode sheet vertically in the longitudinal direction. The spacing between the microchannels on the electrode sheet surface is 5cm-10cm.

[0024] The laser etching process requires aligning the front and back of the electrode and then etching it longitudinally at the same time. This process is highly efficient and ensures that the etching positions on both sides of the electrode are the same, thus avoiding wrinkling of the electrode caused by uneven tension on both sides.

[0025] During the laser etching process, vacuum dust removal is performed on the etched areas of the electrode to ensure that the dust on the electrode surface is within acceptable limits.

[0026] Then, activated carbon material is implanted into the microchannel using electrostatic flocking technology. The thickness of the activated carbon implantation is 5μm-10μm, the specific surface area of ​​the activated carbon is 1500m2 / g-2500 m2 / g, and the pore volume is 0.7 ml / g-1.0 ml / g. The electrolyte is transported to the microchannel using activated carbon as a carrier to supply sufficient electrolyte to the electrode. The large specific surface area of ​​activated carbon and its strong liquid absorption and retention capacity greatly improve the wettability of the electrode.

[0027] The present invention will be illustrated through specific real-time parameters;

[0028] 1) First, flatten and position the rolled 18650-2000mAh-3.2V lithium iron phosphate positive electrode sheet. The thickness of the positive electrode sheet foil is 12μm±1μm, and the thickness of the lithium iron phosphate material on one side is 140μm±2μm.

[0029] 2) Use a laser to align the front and back of the electrode and simultaneously etch longitudinally to construct a lithium iron phosphate electrode electrolyte transport microchannel on the electrode surface;

[0030] 3) Control the microchannel width to 8μm±1μm, the microchannel depth to 15μm±1μm, etch the microchannel vertically through the electrode, and the microchannel spacing on the electrode surface to 6cm±0.2cm.

[0031] 4) Vacuum cleaning is performed on the etched area of ​​the electrode during the laser etching process.

[0032] 5) Then, activated carbon material was implanted into the microchannels using electrostatic flocking technology. The implanted activated carbon thickness was 8μm±1μm, and the specific surface area of ​​the activated carbon was 1800m². 2 / g±200 m2 / g, pore volume 0.7ml / g -1.0ml / g.

[0033] The electrolyte is transported to the microchannels using activated carbon as a carrier to supply sufficient electrolyte to the electrode. Activated carbon has a large specific surface area and strong liquid absorption and retention capacity, which greatly improves the wettability of the electrode.

[0034] A cathode sheet prepared by laser etching and activated carbon implantation exhibits a 18650-2000mAh-3.2V capacity, with a 1C charge-discharge cycle life increased by over 30%. The 1C charge-discharge cycle life curves of batteries made from cathode sheets without laser etching and activated carbon implantation, and those made from cathode sheets with laser etching and activated carbon implantation, are shown below. Figure 1 As shown.

[0035] Figure 1 In the diagram, #1 and #2 are batteries made from positive electrode sheets that have undergone laser etching and activated carbon implantation, while #3 and #4 are batteries made from positive electrode sheets that have not undergone laser etching and activated carbon implantation.

[0036] This invention utilizes laser to align the front and back surfaces of the electrode and simultaneously perform longitudinal etching. This method achieves high etching efficiency and ensures that the etching positions on both sides of the electrode are the same, thus avoiding wrinkling of the electrode caused by uneven tension on both sides.

[0037] This invention utilizes electrostatic flocking technology to implant activated carbon material into microchannels. The electrolyte is transported to the microchannels using activated carbon as a carrier to supply sufficient electrolyte to the electrode. Activated carbon has a large specific surface area and strong liquid absorption and retention capabilities, which greatly improves the wettability of the electrode.

Claims

1. A method for improving the wettability of lithium-ion batteries, characterized in that, Includes the following steps, The rolled lithium iron phosphate positive electrode sheet is flattened and positioned. Laser etching was used to longitudinally etch the front and back sides of the electrode to construct microchannels for electrolyte transport in lithium iron phosphate electrodes on the electrode surface. During laser etching, the etched area of ​​the electrode is vacuumed to remove dust. Activated carbon materials are implanted into microchannels using electrostatic flocking technology.

2. The method for improving the wettability of lithium-ion batteries according to claim 1, characterized in that, The etching controls the microchannel width to be 5μm~10μm and the microchannel depth to be 10μm-20μm.

3. The method for improving the wettability of lithium-ion batteries according to claim 1, characterized in that, The etched microchannels penetrate vertically through the electrode surface, with a spacing of 5cm-10cm between the microchannels on the electrode surface.

4. The method for improving the wettability of lithium-ion batteries according to claim 1, characterized in that, The activated carbon implant thickness is 5μm-10μm, and the specific surface area of ​​the activated carbon is 1500m². 2 / g-2500m 2 / g, with a micropore volume of 0.7ml / g-1.0ml / g.

5. The method for improving the wettability of lithium-ion batteries according to claim 1, characterized in that, During laser etching, the front and back of the electrode are aligned and the etching positions are the same.

6. The method for improving the wettability of a lithium-ion battery according to claim 1, characterized in that, The lithium-ion battery is a cylindrical lithium battery, with a foil thickness of 12μm±1μm for the lithium iron phosphate positive electrode and a single-sided thickness of 140μm±2μm for the lithium iron phosphate material.

7. The method for improving the wettability of a lithium-ion battery according to claim 6, characterized in that, The microchannel width is controlled at 8μm±1μm, the microchannel depth at 15μm±1μm, and the etched microchannels vertically penetrate the electrode sheet. The spacing between the microchannels on the electrode sheet surface is 6cm±0.2cm.

8. The method for improving the wettability of lithium-ion batteries according to claim 4, characterized in that, The activated carbon implant thickness is 8μm±1μm, and the specific surface area of ​​the activated carbon is 1800m². 2 / g±200m 2 / g, with a micropore volume of 0.7ml / g-1.0ml / g.

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