Modified micro-modeling copper foil structure

Abstract

The utility model relates to a modified micro-textured copper foil structure, which is characterized in that notches and salient points are rolled on the surface of a copper foil and are uniformly and alternately arranged in an array along the length and width direction of the copper foil, the thickness of the copper foil is t, the section structures of the notches and the salient points are vertically symmetrical and identical, the maximum outer diameter of the notches and the salient points is (3-4) t, and the height of the notches and the salient points is (0.5-0.7) t, and the distances between the adjacent notches and salient points in the length direction and the width direction are the same and are (6-8) t. The copper foil is simple in structure, the surface roughness of the copper foil can be effectively improved, the structural strength of the copper foil and the performance of the adhesion active material layer are both considered, and the rate performance of a battery is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to lithium battery technical field, specifically speaking, a modified micro -molding copper foil structure for negative pole piece. BACKGROUND

[0002] The performance of lithium battery is not only related to the performance of main material, but also related to the adhesion strength of pole piece active material and current collector, that is, pole piece peeling force. If the pole piece peeling force is too small, on the one hand, it is easy to fall off, and it is easy to fall off or break at the bending place of pole piece, so as to pierce the diaphragm and appear internal short circuit or lithium precipitation; on the other hand, the graphite material will swell and shrink after multiple charge and discharge of pole piece, and if the peeling force is too small, it can lead to the separation of current collector, affect the rate and cycle performance of battery, and make the battery decay faster. Therefore, the adhesion strength of the adhesion active material layer on the copper foil of the negative pole piece is extremely high, the existing main research and development direction needs to pay attention to the adhesion of the coating during the adjustment of the active material layer, so the adhesion performance improvement of the copper foil structure is ignored. SUMMARY

[0003] The utility model provides a simple structure, can effectively improve the roughness of copper foil, and the adhesion performance of copper foil structure strength and active material layer is considered.

[0004] The technical scheme adopted by the utility model is: a modified micro -molding copper foil structure, characterized by: recess and convex point are uniformly and alternately arranged in the form of array along the length and width direction of copper foil on the surface of copper foil, the thickness of copper foil is t, the cross section structure of recess and convex point is symmetrical and same up and down, the maximum outer diameter of recess and convex point is (3-4) t, the height of recess and convex point is (0.5-0.7) t, the length and width direction distance between adjacent recess and convex point is same and (6-8) t.

[0005] The cross section structure of the convex point and the recess is an isosceles conical platform structure or a ball head structure.

[0006] The outermost point of the convex point is integrally rolled with the inner recess, and the innermost point of the recess is integrally rolled with the inner convex point.

[0007] The outermost point of the convex point is integrally rolled with the inner recess, and the innermost point of the recess is integrally rolled with the inner convex point.

[0008] The cross section structure of the convex point and the recess is an isosceles conical platform structure or a ball head structure.

[0009] The maximum outer diameter of the inner recess and the outer convex point is (0.6-0.8) times the maximum outer diameter of the recess and the convex point, and the height of the inner recess and the outer convex point is (0.6-0.8) times the height of the recess and the convex point.

[0010] The present utility model rolls the notches and the convex points of the uniform alternate array on the copper foil, thereby modifying the copper foil structure, increasing the copper foil roughness, improving the adhesion strength between the copper foil and the active material coating, reducing the contact resistance between the two, thereby reducing the total battery internal resistance, and helping to improve the rate performance of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 It is a structural schematic diagram of the present utility model embodiment one.

[0012] Figure 2 It is a rate test performance diagram of the battery made of the modified copper foil and the ordinary copper foil of the present utility model.

[0013] Figure 3 It is a structural schematic diagram of the present utility model embodiment two.

[0014] In the figure: copper foil 1, notch 2, convex point 3, outer convex point 4, inner notch 5. DETAILED DESCRIPTION

[0015] The following is further illustrated in combination with the drawings and embodiments.

[0016] Figure 1 The present utility model embodiment one is a modified micro-molded copper foil structure, wherein the notches 2 and the convex points 3 are uniformly and alternately arranged along the length and width directions of the copper foil 1 on the surface of the copper foil 1, the thickness of the copper foil is 8±1um, the cross-sectional structure of the notches and the convex points is symmetrical and the same, the cross-sectional structure of the convex points and the notches is an isosceles conical table structure, the maximum outer diameter of the notches and the convex points is 30±1.5um, the height of the notches and the convex points is 5±1um, and the length and width direction spacing between adjacent notches and convex points is the same and is 60±3um.

[0017] The above-mentioned modified micro-molded copper foil is prepared into an experimental group cylindrical battery according to the processes of homogenization, coating, rolling, striping, sheet making, winding, grooving, liquid injection, pre-charging, formation and capacity distribution on the production line of the company, and the theoretical capacity is 2500mAh. The positive active material is a ternary material, the negative active material is a silicon / graphite mixture, and the electrolyte is a LiFP6 liquid electrolyte. The ordinary copper foil is prepared into a comparative group base cylindrical battery in the same way. 4, the two batteries are subjected to rate test, the discharge current is 10A until 2.5V, the charging current is 4.5A until 4.2V, and the cutoff is 0.1A, and the test results are shown in the table. Figure 2 The discharge capacity of the comparative group base cylindrical battery is 2459mAh, and the discharge capacity of the experimental group cylindrical battery is 2511mAh. The modified micro-molded copper foil structure of the present application improves the rate performance of the battery.

[0018] Figure 3In the second embodiment, a modified micro-structured copper foil structure is shown. The copper foil 1 has recesses 2 and protrusions 3 alternately arranged in an array along the length and width of the copper foil. The thickness of the copper foil is 8±1um. The cross-sectional structure of the recesses and protrusions is symmetrical and identical. The cross-sectional structure of the protrusions and recesses is an isosceles conical platform structure. The maximum outer diameter of the recesses and protrusions is 30±1.5um. The height of the recesses and protrusions is 5±1um. The length and width of the space between adjacent recesses and protrusions is 60±3um. An inner recess 5 is formed in the outer conical platform of the protrusions 3. An inner protrusion 4 is formed in the inner conical bottom of the recesses 2. The maximum outer diameter of the inner recesses and protrusions is 20±1um. The height of the inner recesses and protrusions is 3.5±0.5um.

[0019] The modified micro-structured copper foil described above is used to prepare experimental group cylindrical batteries on the production line of the company according to the processes of homogenization, coating, rolling, slitting, sheeting, winding, grooving, liquid injection, pre-charging, formation, and containerization. The theoretical capacity is 2500mAh. The positive active material is a ternary material, the negative active material is a silicon / graphite mixture, and the electrolyte is a LiFP6 liquid electrolyte. A base group cylindrical battery is prepared using a common copper foil in the same way. 4. The two batteries are subjected to rate testing. The discharge current is 10A until 2.5V, the charge current is 4.5A until 4.2V, and the cutoff is 0.1A. The test results are as follows: the discharge capacity of the base group cylindrical battery is 2459mAh, and the discharge capacity of the experimental group cylindrical battery is 2523mAh.

Claims

1. A modified microstructured copper foil structure, characterized by: The concave and convex points are alternately and uniformly arranged in an array along the length and width directions of the copper foil, the thickness of the copper foil is t, the cross-section structure of the concave and convex points is symmetrical and same, the maximum outer diameter of the concave and convex points is (3-4)t, the height of the concave and convex points is (0.5-0.7)t, and the length and width direction spacing between adjacent concave and convex points is same and (6-8)t.

2. The modified microstructured copper foil structure of claim 1, wherein: The cross-section structure of the concave and convex points is isosceles conical table structure or ball head structure.

3. The modified microstructured copper foil structure of claim 1, wherein: The outermost point of the convex point is integrally rolled with the concave point, and the innermost point of the concave point is integrally rolled with the convex point.

4. The modified microstructured copper foil structure of claim 2, wherein: The outermost point of the convex point is integrally rolled with the concave point, and the innermost point of the concave point is integrally rolled with the convex point.

5. The modified microstructured copper foil structure according to claim 3 or 4, characterized by: The outermost point of the convex point is integrally rolled with the concave point, and the innermost point of the concave point is integrally rolled with the convex point.

6. The modified microstructured copper foil structure according to claim 3 or 4, characterized by: The cross-section structure of the concave and convex points is isosceles conical table structure or ball head structure.

7. The modified microstructured copper foil structure of claim 5, wherein: The maximum outer diameter of the concave and convex points is (0.6-0.8)t, and the height of the concave and convex points is (0.6-0.8)t. The maximum outer diameter of the concave and convex points is (0.6-0.8)t, and the height of the concave and convex points is (0.6-0.8)t.

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