Lithium supplement electrode plate and lithium ion battery thereof

Abstract

The utility model provides a lithium supplement electrode plate and a lithium ion battery, and the lithium supplement electrode plate comprises a current collector which is provided with a first surface and a second surface which are oppositely arranged; the second surface is provided with a coating area and an empty foil area; a first active material layer and a second active material layer; wherein the length L2 of the second active material layer is smaller than the length L1 of the first active material layer, and the length of the empty foil area is L1-L2; the first lithium supplementing film covers the outer surface of the first active material layer; the second lithium supplementing film covers the outer surface of the second active material layer; wherein the second lithium supplementing film comprises a main lithium supplementing film and an auxiliary lithium supplementing film arranged on the inner surface of the main lithium supplementing film, and the auxiliary lithium supplementing film is embedded in the empty foil area. Compared with the prior art, the auxiliary lithium supplementing film is embedded in the empty foil area, so that the thickness difference of a single-face area is effectively compensated, the lithium supplementing film is tightly attached to a pole piece during roller passing, and the effect of uniformly supplementing lithium on the whole face is achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of secondary batteries, in particular to a lithium-supplementing electrode sheet and a lithium-ion battery thereof. Background Art

[0002] Nowadays, lithium-ion batteries are widely used in power, consumption and energy storage due to their advantages such as high energy density, high charging efficiency, excellent cycle performance and high output power. With the continuous advancement of science and technology, the fields of lithium-ion batteries are constantly expanding, and higher requirements are also placed on the structure and performance of lithium-ion batteries. In order to better meet customer needs, the application frequency of silicon-carbon materials is becoming more and more frequent. Currently, silicon is known to be the negative electrode material with the highest specific capacity, with a gram capacity of 4200mAh / g. However, compared with graphite negative electrode materials, the initial efficiency of silicon negative electrode materials is relatively low. Therefore, the negative electrode lithium replenishment requires the lithium source to be coated on the surface of the anode sheet through a physical rolling method. During the first charge and discharge, the lithium in the positive electrode material is replaced to complete the irreversible reaction first, reducing the loss of active lithium in the positive electrode material and improving the energy density. However, at present, the single-sided area of ​​the electrode after lithium strip rolling and compounding cannot be replenished with lithium, which affects the lithium replenishment effect.

[0003] In view of this, it is indeed necessary to provide a technical solution to the above problems. Utility Model Content

[0004] One of the purposes of the present invention is to provide a lithium replenishing electrode sheet to address the deficiencies of the prior art, thereby improving the problem that lithium replenishment cannot be provided to a part of a single side of the electrode sheet due to the thickness difference of the lithium replenishing films on the upper and lower sides of the electrode sheet.

[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] A lithium-supplementing electrode sheet comprises: a current collector having a first surface and a second surface arranged opposite to each other; the second surface having a coating area and a hollow foil area; a first active material layer arranged on the first surface of the current collector; a second active material layer arranged on the coating area of ​​the second surface of the current collector; wherein the length L2 of the second active material layer is less than the length L1 of the first active material layer, and the length of the hollow foil area is L1-L2; a first lithium-supplementing film coated on the outer surface of the first active material layer; a second lithium-supplementing film coated on the outer surface of the second active material layer; wherein the second lithium-supplementing film comprises a main lithium-supplementing film and an auxiliary lithium-supplementing film arranged on the inner surface of the main lithium-supplementing film, and the auxiliary lithium-supplementing film is embedded in the hollow foil area.

[0007] Preferably, the length L3 of the auxiliary lithium film and the length of the empty foil area satisfy the relationship: 0<L3≤L1-L2.

[0008] Preferably, the thickness d of the auxiliary lithium film and the thickness D of the second active material layer satisfy the relationship: 0<d≤D.

[0009] Preferably, the length of the auxiliary lithium film is equal to the length of the empty foil area, and the thickness of the auxiliary lithium film is equal to the thickness of the second active material layer.

[0010] Preferably, the first lithium replenishing film and the second lithium replenishing film both comprise lithium foil; and the substrate of the lithium replenishing film comprises one of a polymer film, ultrathin fiber paper, graphite paper, and nanopaper.

[0011] Preferably, the thickness D of the first active material layer and the second active material layer are both 50 to 150 μm.

[0012] Preferably, the length L1 of the first active material layer is 300-2500 mm; the length L2 of the second active material layer is 300-2500 mm.

[0013] Preferably, the thickness of the main lithium replenishing film is 1 to 5 μm.

[0014] A second object of the present invention is to provide a lithium-ion battery comprising any one of the lithium-supplementing electrode sheets described above.

[0015] Compared to the prior art, the present invention offers the following advantages: The lithium-supplementing electrode sheet provided by the present invention includes a current collector having a first and second opposing surfaces; the second surface having a coating area and a hollow foil area; a first active material layer; a second active material layer; a first lithium-supplementing membrane; and a second lithium-supplementing membrane. The second lithium-supplementing membrane includes a main lithium-supplementing membrane and an auxiliary lithium-supplementing membrane disposed on the inner surface of the main lithium-supplementing membrane, and the auxiliary lithium-supplementing membrane is embedded in the hollow foil area. The auxiliary lithium-supplementing membrane embedded in the hollow foil area effectively compensates for thickness differences between individual surfaces, ensuring close contact between the lithium-supplementing membrane and the electrode sheet during rolling, achieving uniform lithium replenishment across the entire surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic structural diagram of the lithium-replenishing electrode of Example 1 of the present utility model;

[0017] Figure 2 This is a schematic structural diagram of the lithium replenishment front electrode of Example 1 of the present utility model.

[0018] Among them, 1-current collector; 2-active material layer; 21-first active material layer; 22-second active material layer; 3-lithium replenishing membrane; 31-first lithium replenishing membrane; 32-second lithium replenishing membrane; 321-main lithium replenishing membrane; 322-auxiliary lithium replenishing membrane; L1-length of the first active material layer; L2-length of the second active material layer; L1-L2, length of the empty foil area; L3-length of the auxiliary lithium replenishing membrane. DETAILED DESCRIPTION

[0019] In order to make the technical solutions and advantages of the present invention clearer, the present invention and its beneficial effects will be described in further detail below in conjunction with specific implementation methods, but the implementation methods of the present invention are not limited thereto.

[0020] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of this utility model, "plurality" means two or more, unless otherwise specifically defined.

[0021] The first aspect of the present invention is to provide a lithium-replenishing electrode sheet, comprising: a current collector 1 having a first surface and a second surface arranged opposite to each other; the second surface having a coating area and a hollow foil area; a first active material layer 21 arranged on the first surface of the current collector 1; a second active material layer 22 arranged on the coating area of ​​the second surface of the current collector 1; wherein the length L2 of the second active material layer 22 is less than the length L1 of the first active material layer 21, and the length of the hollow foil area is L1-L2; a first lithium-replenishing film 31 coated on the outer surface of the first active material layer 21; a second lithium-replenishing film 32 coated on the outer surface of the second active material layer 22; wherein the second lithium-replenishing film comprises a main lithium-replenishing film 321 and an auxiliary lithium-replenishing film 322 arranged on the inner surface of the main lithium-replenishing film, and the auxiliary lithium-replenishing film 322 is embedded in the hollow foil area.

[0022] In the production process of lithium batteries, the positive electrode sheet, the negative electrode sheet and the separator are wound to form the core part of the battery - the core. In this process, due to differences in the size of the electrode and the separator, the winding tension, the winding speed and other factors, the structure inside the core may not be completely uniform, resulting in the phenomenon that the length of the active material layer coated on both sides of the electrode sheet is different. At the same time, the negative electrode sheet of the lithium battery uses a silicon-carbon material with a high gram capacity. The first efficiency of the silicon-carbon material is relatively low, so lithium replenishment requires the lithium replenishment film to be composited on the negative electrode sheet through a physical rolling method. Due to the phenomenon that the length of the active material layer on both sides of the above-mentioned electrode sheet is different, the conventional lithium replenishment film cannot replenish lithium uniformly, and the energy density cannot be improved; the lithium replenishment electrode sheet in the present invention includes a second lithium replenishment film, and the second lithium replenishment film includes a main lithium replenishment film and an auxiliary lithium replenishment film arranged on the inner surface of the main lithium replenishment film, and the auxiliary lithium replenishment film is embedded in the empty foil area. The auxiliary lithium supplement film is embedded with a hollow foil area, so that when rolling, the thickness difference of the first active material layer is compensated by the special-shaped lithium-carrying film, and it is closely attached to the lithium supplement film, and the entire surface of the electrode is evenly supplemented with lithium.

[0023] In some embodiments, the length L3 of the auxiliary lithium supplement film and the length of the empty foil area satisfy the relationship: 0<L3≤L1-L2. Preferably, when L3 is equal to L1-L2, the fit is tight, the lithium supplement effect is uniform, and the energy density of the electrode is improved.

[0024] In some embodiments, the thickness d of the auxiliary lithium replenishing film and the thickness D of the second active material layer satisfy the relationship: 0<d≤D. Preferably, when d is equal to D, the lithium replenishing effect is maximized.

[0025] In some embodiments, the length of the auxiliary lithium film is equal to the length of the empty foil area, and the thickness of the auxiliary lithium film is equal to the thickness of the second active material layer.

[0026] In some embodiments, the first lithium replenishing membrane and the second lithium replenishing membrane both comprise lithium foil; the substrate of the lithium replenishing membrane comprises one of a polymer film, ultrathin fiber paper, graphite paper, nanopaper, and a polymer and fiber composite film.

[0027] In some embodiments, the thickness D of the first active material layer and the second active material layer is 30 to 150 μm, and can specifically be 30 μm, 33 μm, 36 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, or 150 μm, including but not limited to the values ​​listed above, and is preferably 36 μm.

[0028] In some embodiments, the length L1 of the first active material layer is 400-2500 mm, specifically 400 mm, 500 mm, 600 mm, 700 mm, 800 mm, 900 mm, 1000 mm, 1100 mm, 1200 mm, 1300 mm, 1400 mm, 1500 mm, 1600 mm, 1700 mm, 1800 mm, 1900 mm, 2000 mm, 2100 mm, 2200 mm, 2300 mm, 2400 mm, 2500 mm, including but not limited to the values ​​listed above, preferably 1632 mm. .5mm; the length of the second active material layer L2 is 400-2500mm, specifically 400mm, 500mm, 600mm, 700mm, 800mm, 900mm, 1000mm, 1100mm, 1200mm, 1300mm, 1400mm, 1500mm, 1600mm, 1700mm, 1800mm, 1900mm, 2000mm, 2100mm, 2200mm, 2300mm, 2400mm, 2500mm, and may include but not be limited to the values ​​listed above, and is preferably 1510mm.

[0029] In some embodiments, the thickness of the main lithium replenishing film is 1-5 μm.

[0030] According to the second aspect of the utility model, the utility model also provides a lithium-ion battery, including a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator, wherein the negative electrode sheet is the above-mentioned lithium-supplemented negative electrode sheet; preferably, the lithium salt of the electrolyte used is 1M LiPF6, and the solvent is EC:DEC:DMC 3:4:3; the separator is a PP film; the positive electrode active material used in the positive electrode active material layer is a nickel cobalt manganese oxide ternary material, and the negative electrode current collector is a copper-carbon alloy current collector.

[0031] The preparation method of the lithium-ion battery of the present invention is well known to those skilled in the art. Generally speaking, the preparation method of the battery includes placing a battery cell into a battery case, adding an electrolyte, and then sealing the case to obtain a battery.

[0032] In order to make the technical solutions and advantages of the present invention clearer, the present invention and its beneficial effects will be described in further detail below in conjunction with specific implementation methods and the accompanying drawings, but the implementation methods of the present invention are not limited thereto.

[0033] Unless otherwise specified, the raw materials used in the present invention can be purchased from the market or are commonly used in the field. Unless otherwise specified, the methods in the following embodiments are all conventional methods in the field.

[0034] Example 1

[0035] Preparation of negative electrode sheet:

[0036] A lithium-supplementing negative electrode sheet provided in this embodiment includes a copper foil current collector 1, a silicon-carbon material layer 21, the length L1 of the silicon-carbon material layer 21 is 1632.5 mm; the silicon-carbon material layer 22, the length L2 of the silicon-carbon material layer 22 is 1510 mm, the thickness D of the silicon-carbon material layer 22 is 36 μm, and the length of the empty foil area is 122.5 mm; the length of the first lithium-supplementing film 31 is 1632.5 mm; the length of the main lithium-supplementing film 321 is 1510 mm; the length L3 of the auxiliary lithium-supplementing film 322 is 122.5 mm, and the thickness d of the auxiliary lithium-supplementing film 322 is 36 μm.

[0037] Preparation of lithium-ion batteries:

[0038] The composite negative electrode sheet, positive electrode sheet, separator and electrolyte prepared above are made into a lithium-ion battery according to conventional processes; wherein, the positive electrode active material used in the positive electrode active material layer is a ternary material of lithium nickel cobalt manganese oxide, and the negative electrode current collector is a copper-carbon alloy current collector; the lithium salt of the electrolyte used is 1M LiPF6, and the solvent is EC:DEC:DMC 3:4:3; and the separator is a PP film.

[0039] Example 2

[0040] The difference from Example 1 is that the length of the auxiliary lithium film is 61.25 mm;

[0041] The rest is the same as in Example 1 and will not be described again here.

[0042] Comparative Example 1

[0043] The difference from Example 1 is that the second lithium replenishing film does not include an auxiliary lithium replenishing film.

[0044] The rest is the same as in Example 1 and will not be described again here.

[0045] Comparative Example 2

[0046] The difference from Example 1 is that the thickness of the auxiliary lithium film is 18 μm;

[0047] The rest is the same as in Example 1 and will not be described again here.

[0048] Comparative Example 3

[0049] The difference from Example 1 is that the thickness of the auxiliary lithium film is 12 μm;

[0050] The rest is the same as in Example 1 and will not be described again here.

[0051] The electrochemical performance tests were performed on the batteries prepared in the examples and comparative examples respectively.

[0052] The above test results are shown in Table 1 below.

[0053]

[0054]

[0055] Result analysis: From the above test results, it can be seen that the auxiliary lithium membrane in the embodiment is embedded in the empty foil area of ​​the electrode to replenish lithium on one side of the electrode. When the length of the auxiliary lithium membrane is equal to the empty foil area and the thickness is equal to the silicon-carbon material layer 22, the embedding is the tightest and the lithium replenishment effect is the best. Secondly, both the length and thickness can replenish lithium, but the effect is not as good as Example 1.

[0056] In summary, the present invention provides an auxiliary lithium replenishing film on the lithium replenishing electrode sheet and embeds it in the empty foil area, thereby effectively compensating for the thickness difference of the single-side area, so that the lithium replenishing film and the electrode sheet are closely attached during the roller, achieving the effect of uniform lithium replenishment on the entire surface.

[0057] Based on the disclosure and teachings of the above description, those skilled in the art will be able to make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments described above. Any obvious improvements, substitutions, or modifications made by those skilled in the art based on the present invention fall within the scope of protection of the present invention. In addition, although certain specific terms are used in this description, these terms are for convenience only and do not constitute any limitation on the present invention.

Claims

1. A lithium supplement electrode sheet, characterized in that: include: A current collector having a first surface and a second surface opposite to each other; The second side has a coated area and a blank foil area; a first active material layer, disposed on a first surface of the current collector; A second active material layer is provided in the coating area on the second surface of the current collector; wherein the length L2 of the second active material layer is less than the length L1 of the first active material layer, and the length of the empty foil area is L1-L2; a first lithium replenishing film, covering the outer surface of the first active material layer; a second lithium replenishing film, covering the outer surface of the second active material layer; The second lithium replenishing film includes a main lithium replenishing film and an auxiliary lithium replenishing film arranged on the inner surface of the main lithium replenishing film, and the auxiliary lithium replenishing film is embedded in the empty foil area.

2. The lithium-supplementing electrode sheet according to claim 1, characterized in that: The length L3 of the auxiliary lithium film and the length of the empty foil area satisfy the relationship: 0<L3≤L1-L2.

3. The lithium-supplementing electrode sheet according to claim 1, wherein: The thickness d of the auxiliary lithium film and the thickness D of the second active material layer satisfy the relationship: 0<d≤D.

4. The lithium-supplementing electrode sheet according to claim 1, wherein: The length of the auxiliary lithium film is equal to the length of the empty foil area, and the thickness of the auxiliary lithium film is equal to the thickness of the second active material layer.

5. The lithium-supplementing electrode sheet according to claim 1, wherein: The sum of the thicknesses of the main lithium replenishing film and the second active material layer is h1, and the sum of the thicknesses of the main lithium replenishing film and the auxiliary lithium replenishing film is h2, wherein h1=h2.

6. The lithium-supplementing electrode sheet according to claim 1, characterized in that: The first lithium replenishing film and the second lithium replenishing film both comprise lithium foil; the substrate of the lithium replenishing film comprises one of a polymer film, ultrathin fiber paper, graphite paper, and nanopaper.

7. The lithium-supplementing electrode sheet according to claim 1, characterized in that: The thickness D of the first active material layer and the second active material layer are both 30 to 150 μm.

8. The lithium-supplementing electrode sheet according to claim 1, characterized in that: The length L1 of the first active material layer is 300 to 2500 mm; the length L2 of the second active material layer is 300 to 2500 mm.

9. The lithium-supplementing electrode sheet according to claim 1, wherein: The thickness of the main lithium replenishing film is 1 to 5 μm.

10. A lithium-ion battery, characterized in that: The lithium-supplementing electrode sheet comprises the lithium-supplementing electrode sheet according to any one of claims 1 to 9.

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