Preparation method of slitting-free negative electrode current collector based on graphical technology

Abstract

The invention discloses a preparation method of a slitting-free negative electrode current collector based on a graphical technology, and belongs to the technical field of manufacturing of negative electrode current collectors of lithium ion batteries. According to the preparation method, a preset weakening structure is formed in a current collector slitting area through a patterning technology, non-mechanical force separation is achieved, the slitting area is functionalized, the slitting requirement is converted into a preset pattern, and traditional cutter cutting is avoided; according to the method, separation stress is controlled through pattern size / depth, and balance of machining efficiency and mechanical strength is ensured; the device can be integrated with a roll-to-roll (R2R) production line to realize continuous manufacturing; according to the method, the slitting efficiency is improved by 40%, and the material loss is reduced to 1% or below; edge defects can be effectively avoided, and the cycle life of the battery is prolonged by 15-20%; and large-scale R2R production can be compatible, and the single-line cost is reduced by 30%.

Description

Technical Field

[0001] The present invention belongs to the technical field of manufacturing negative electrode current collectors for lithium-ion batteries, and specifically relates to a method for preparing a grid copper or nickel-clad copper negative electrode current collector that is free from mechanical cutting by pre-forming a structured pattern in a cutting area through a graphic technology. Background Art

[0002] Traditional negative electrode current collectors (such as copper foil or nickel-clad copper foil) need to be cut into target sizes through a slitting process, but the slitting process can easily lead to the following problems:

[0003] 1. Mechanical stress causes edge burrs and microcracks, affecting battery cycle performance;

[0004] 2. Additional cleaning is required after slitting, which increases process costs;

[0005] 3. The material utilization rate is low, and the proportion of cutting waste is 5%-10%.

[0006] While existing technologies employ photolithography or etching to fabricate current collector microstructures to improve battery performance, these methods fail to address the inherent drawbacks of the slitting process. Therefore, an integrated manufacturing solution combining slitting requirements with patterning technology is urgently needed. Summary of the Invention

[0007] In order to solve the above problems, the present invention provides a method for pre-graphic processing in the current collector cutting area. By designing specific patterns (such as periodic microgrooves, weakening lines, etc.), the current collector can be separated without mechanical cutting in subsequent processing while maintaining the integrity of the cutting edge.

[0008] The present invention is achieved through the following technical solutions:

[0009] A method for preparing a non-slitting negative electrode current collector based on graphic technology, wherein a preset weakening structure is formed in the current collector cutting area by graphic technology to achieve non-mechanical separation, comprising the following steps:

[0010] Step 1: Substrate pretreatment: Select copper foil or nickel-clad copper foil, clean the surface and dry it;

[0011] Step 2: Graphic design: Design one of the following patterns on both sides of the cutting area, i.e. the target cutting line.

[0012] Microgroove array: width 10-50 μm, depth 30%-70% of substrate thickness;

[0013] Weakened hole array: diameter 20-100μm, spacing 50-200μm;

[0014] Cross-linked fracture line: Laser etching forms continuous or discontinuous stress concentration lines;

[0015] Step 3: Graphic processing: Patterning is formed using photolithography, laser etching, nanoimprinting or laser direct writing technology;

[0016] Step 4: Functional layer processing: Coat conductive glue or deposit active material in the non-cutting area, and keep the patterned area bare.

[0017] Step 5: Cut-free separation: Separate the current collector along the patterned area through slight mechanical force or thermal stress, with smooth edges and no burrs.

[0018] Preferably, the thickness of the substrate in step 1 is 5-20 μm.

[0019] Preferably, the conductive adhesive coated or active material deposited in step 4 is one of graphite and silicon-based materials.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention functionalizes the slitting area, converts the slitting requirements into preset patterns, and avoids traditional tool cutting; the method of the present invention controls the separation stress by pattern size / depth, ensuring a balance between processing efficiency and mechanical strength; the present invention can be integrated with a roll-to-roll (R2R) production line to achieve continuous manufacturing; the method of the present invention improves slitting efficiency by 40%, and reduces material loss to less than 1%; it can effectively avoid edge defects, and the battery cycle life is increased by 15%-20%; it is compatible with large-scale R2R production, and the cost of a single line is reduced by 30%. DETAILED DESCRIPTION

[0022] The present invention will be further described below in conjunction with the embodiments:

[0023] A method for preparing a non-slitting negative electrode current collector based on graphic technology, wherein a preset weakening structure is formed in the current collector cutting area by graphic technology to achieve non-mechanical separation, comprising the following steps:

[0024] Step 1: Substrate pretreatment: Select copper foil or nickel-clad copper foil, clean the surface and dry it;

[0025] Step 2: Graphic design: Design one of the following patterns on both sides of the cutting area, i.e. the target cutting line.

[0026] Microgroove array: width 10-50 μm, depth 30%-70% of substrate thickness;

[0027] Weakened hole array: diameter 20-100μm, spacing 50-200μm;

[0028] Cross-linked fracture line: Laser etching forms continuous or discontinuous stress concentration lines;

[0029] Step 3: Graphic processing: Patterning is formed using photolithography, laser etching, nanoimprinting or laser direct writing technology;

[0030] Step 4: Functional layer processing: Coat conductive glue or deposit active material in the non-cutting area, and keep the patterned area bare.

[0031] Step 5: Cut-free separation: Separate the current collector along the patterned area through slight mechanical force or thermal stress, with smooth edges and no burrs.

[0032] The thickness of the substrate in step 1 is 5-20 μm.

[0033] In step 4, the conductive adhesive coated or the active material deposited is one of graphite and silicon-based materials.

[0034] Example 1 (Photolithography-etching method)

[0035] Step 1. Spin-coat photoresist on the surface of 8μm copper foil, and expose and develop a micro-groove pattern with a width of 30μm and a pitch of 100μm;

[0036] Step 2: Etch to a depth of 5 μm using FeCl3 etching solution;

[0037] Step 3. Coating the graphite negative electrode material, leaving the microgrooves in the cut area exposed;

[0038] Step 4. Apply a pulling force of 5N / m to achieve automatic separation, with an edge roughness of less than 1μm, and separation can be achieved without mechanical cutting.

[0039] Example 2 (Laser processing method)

[0040] Step 1. Use ultraviolet laser to etch a serpentine fracture line with a depth of 3 μm on the surface of nickel-clad copper foil;

[0041] Step 2. The resistance of the fracture line area increases by 20%, and it separates naturally under the winding tension without mechanical slitting.

[0042] The present invention functionalizes the slitting area, converts the slitting requirements into preset patterns, and avoids traditional tool cutting; the method of the present invention controls the separation stress by pattern size / depth, ensuring a balance between processing efficiency and mechanical strength; the present invention can be integrated with a roll-to-roll (R2R) production line to achieve continuous manufacturing; the method of the present invention improves slitting efficiency by 40%, and reduces material loss to less than 1%; it can effectively avoid edge defects, and the battery cycle life is increased by 15%-20%; it is compatible with large-scale R2R production, and the cost of a single line is reduced by 30%.

[0043] In summary, the above is only a preferred embodiment of the present invention and is not intended to limit the scope of implementation of the present invention. All equivalent changes and modifications of the shape, structure, characteristics and spirit described in the scope of the claims of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a non-slicing negative electrode current collector based on graphic technology, characterized in that: The preparation method is to form a preset weakening structure in the current collector cutting area through graphic technology to achieve non-mechanical separation, including the following steps: Step 1: Substrate pretreatment: Select copper foil or nickel-clad copper foil, clean the surface and dry it; Step 2: Graphic design: Design one of the following patterns on both sides of the cutting area, i.e. the target cutting line; Microgroove array: width 10-50 μm, depth 30%-70% of substrate thickness; Weakened hole array: diameter 20-100μm, spacing 50-200μm; Cross-linked fracture line: Laser etching forms continuous or discontinuous stress concentration lines; Step 3: Graphic processing: Patterning is formed using photolithography, laser etching, nanoimprinting or laser direct writing technology; Step 4: Functional layer processing: Coat conductive glue or deposit active material in the non-cutting area, and keep the patterned area bare; Step 5: Cut-free separation: Separate the current collector along the patterned area through slight mechanical force or thermal stress, with smooth edges and no burrs.

2. The method for preparing a non-splitting negative electrode current collector based on graphic technology according to claim 1, characterized in that: The thickness of the substrate in step 1 is 5-20 μm.

3. The method for preparing a non-splitting negative electrode current collector based on graphic technology according to claim 1, characterized in that: In step 4, the conductive adhesive coated or the active material deposited is one of graphite and silicon-based materials.