CN218039282U - A kind of negative pole piece and battery - Google Patents

Abstract

The utility model belongs to the technical field of the battery, a negative pole piece and battery is disclosed. The negative pole piece comprises a current collector and a slurry layer, wherein the slurry layer is coated on the current collector and comprises hard carbon, and the slurry layer containing the hard carbon is coated on the current collector, so that the charge transfer internal resistance and the ohm internal resistance of the negative pole piece can be effectively reduced under the condition of not changing the structure of the current collector, and the performance of a battery is improved.

Description

A kind of negative pole piece and battery

technical field

The utility model relates to the technical field of batteries, in particular to a negative pole piece and a battery.

Background technique

Lithium-ion batteries are widely used in 3C digital products because of their high energy density, long cycle life, no memory effect, and adjustable shape and size. With the development of the new energy industry, lithium-ion batteries are widely used as a new energy used in electric vehicles.

When a lithium-ion battery is being charged, lithium ions come out of the positive electrode into the electrolyte, pass through the separator to the surface of the negative electrode, and then intercalate into the micropores of the negative electrode. In the prior art, the negative pole piece is a monomer with a single material and a single structure. Due to the characteristics of graphite, during the cycle, due to the gas production of the negative electrode and the side reaction with the electrolyte, the structure of the graphite collapses, and the lithium storage sites are destroyed. Lithium precipitation is formed, which intensifies the polarization of the battery, thereby affecting the electrical performance of the battery.

Therefore, there is an urgent need for a negative electrode material and battery to solve the problems in the prior art.

Utility model content

The purpose of the utility model is to provide a negative pole piece and a battery, which can reduce the charge transfer internal resistance and ohmic internal resistance of the negative pole piece, and improve the performance of the battery.

For this purpose, the utility model adopts the following technical solutions:

A negative electrode sheet includes a current collector and a slurry layer, the slurry layer is arranged on the current collector, and the slurry layer is provided with hard carbon.

Optionally, the slurry layer includes a first slurry layer and a second slurry layer, the first slurry layer is disposed on the current collector, and the second slurry layer is disposed on the first slurry layer. On the slurry layer, the hard carbon is disposed on the second slurry layer.

Optionally, the thickness of the second slurry layer is 0.1 μm-10 μm.

Optionally, the solid content of the second slurry layer is 3%-60%.

Optionally, the hard carbon has a spherical structure, and the diameter of the hard carbon is 1 μm-5 μm.

Optionally, the first slurry layer is provided with graphite particles, and the particle diameter of the graphite particles is 15 μm-30 μm.

Optionally, the hard carbon is disposed on the surface layer and the gap of the graphite particles.

Optionally, the thickness of the first slurry layer is 50 μm-100 μm.

Optionally, the solid content of the first slurry layer is 40%-60%.

Another object of the present invention is to provide a battery, which can reduce the polarization of the negative pole piece, increase the lithium analysis window of the negative pole piece, and improve the performance of the battery.

A battery, comprising the above-mentioned negative electrode sheet.

Beneficial effect:

The negative electrode sheet provided by the utility model includes a current collector and a slurry layer. The slurry layer is arranged on the current collector. The slurry layer includes hard carbon. By setting the slurry layer containing hard carbon on the current collector, it can ensure Without changing the current collector structure, it can effectively reduce the charge transfer internal resistance and ohmic internal resistance of the negative electrode sheet, and improve the performance of the battery.

The battery provided by the utility model reduces the internal resistance of the battery and reduces the loss of electric power inside the battery by adopting the above-mentioned negative pole piece, and can obviously improve the performance of the battery.

Description of drawings

FIG. 1 is a schematic structural view of the negative pole piece provided by Embodiment 1 of the present invention.

In the picture:

100, current collector; 200, slurry layer; 210, first slurry layer; 220, second slurry layer.

detailed description

Below in conjunction with accompanying drawing and embodiment the utility model is described in further detail. It can be understood that the specific embodiments described here are only used to explain the utility model, rather than limit the utility model. In addition, it should be noted that, for the convenience of description, only some structures related to the present utility model are shown in the drawings but not all structures.

In the description of the present utility model, unless otherwise clearly stipulated and limited, the terms "connected", "connected" and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or a Integral; it can be mechanically or electrically connected; it can be directly connected or indirectly connected through an intermediary, and it can be the internal communication of two components or the interaction relationship between two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present utility model in specific situations.

In the present invention, unless otherwise clearly specified and limited, a first feature being "on" or "under" a second feature may include direct contact between the first and second features, and may also include the first and second features being in direct contact with each other. The features are not in direct contact but through another feature between them. Moreover, "above", "above" and "above" the first feature on the second feature include that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is horizontally higher than the second feature. "Below", "beneath" and "under" the first feature to the second feature include that the first feature is directly below and obliquely below the second feature, or simply means that the first feature has a lower level than the second feature.

In the description of this embodiment, the terms "up", "down", "left", "right" and other orientations or positional relationships are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of description and simplification of operations. It does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be construed as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in description, and have no special meaning.

Embodiment one

This embodiment provides a negative electrode sheet, as shown in Figure 1, the negative electrode sheet includes a current collector 100 and a slurry layer 200, the slurry layer 200 is arranged on the current collector 100, and hard Carbon, by setting the slurry layer 200 containing hard carbon on the current collector 100, it can ensure that the charge transfer internal resistance and ohmic internal resistance of the negative electrode sheet can be effectively reduced without changing the structure of the current collector 100, and the performance of the battery can be improved. . Moreover, the lithium storage point of the negative pole piece provided by this embodiment is not easy to be damaged, which can ensure that the lithium analysis window has been significantly improved in the high-rate cycle inside the battery and in a low-temperature environment, ensuring that lithium deintercalated from the positive electrode The ions can be embedded in the negative pole piece, which slows down the polarization of the negative pole piece of the battery and improves the life of the battery.

Preferably, as shown in FIG. 1, the slurry layer 200 includes a first slurry layer 210 and a second slurry layer 220, the first slurry layer 210 is coated on the current collector 100, and the second slurry layer 220 is coated On the first slurry layer 210, the hard carbon is arranged in the second slurry layer 220. During the coating process, any coating method such as micro-gravure roll, spray coating or scraping can be selected, and the second slurry The layer 220 is coated on the first slurry layer 210. In this implementation, the second slurry layer 220 is preferably coated on the first slurry layer 210 by a micro-gravure roll, which can ensure that the hard carbon in the second slurry layer The distribution on the 220 is more uniform, further reducing the charge transfer internal resistance and ohmic internal resistance of the negative pole piece.

Optionally, the first slurry layer 210 is provided with graphite particles, and the particle size of the graphite particles is 15 μm-30 μm. Specifically, the diameter of the graphite particles can be 20 μm, 25 μm, etc. In this embodiment, the diameter of the graphite particles is preferably 20 μm. Good electrical conductivity of the first paste layer 210 can be ensured.

Optionally, the hard carbon in this embodiment is arranged on the surface layer and the gap of the graphite particles. It can be understood that at the junction of the second slurry layer 220 and the first slurry layer 210, the second slurry layer 220 Hard carbon can be embedded in the gaps of the graphite particles in the first slurry layer 210 to eliminate the tip effect of the graphite particle surface layer.

Specifically, the first slurry layer 210 is set to graphite, because graphite has excellent comprehensive properties and can improve the conductivity of the current collector. Carbon coating (second slurry layer 220), the hard carbon coating is at the junction with the graphite coating, and the hard carbon can be embedded in the gaps of graphite particles to eliminate the tip effect of graphite and reduce surface polarization. The hard carbon is arranged on the side of the graphite coating away from the current collector 100, because the carbonization temperature of the hard carbon is high and the structure is relatively strong, which can protect the graphite structure on the outside and avoid the collapse of the graphite sheet during the cycle, and this embodiment The hard carbon in the lithium battery has high capacity and low impedance, which can accelerate the lithium ion transmission speed on the surface of the negative electrode, and alleviate the disadvantages of slow electrolyte diffusion caused by overvoltage on the graphite surface.

Preferably, the thickness of the second slurry layer 220 is 0.1 μm-10 μm, specifically, the thickness of the second slurry layer 220 can be 0.2 μm, 0.8 μm, 1 μm, 2 μm, 4 μm, 6 μm, 8 μm, in this embodiment Preferably, the thickness of the second slurry layer 220 is 2.5 μm, which can ensure the best electrical conductivity of the negative electrode sheet.

Preferably, the solid content of the second slurry layer 220 is 3%-60%, specifically, the solid content of the second slurry layer 220 can be 10%, 20%, 30%, 40%, 50%, wherein the solid content The content is the mass percentage of the remaining part of the coating of the second slurry layer 220 after drying under specified conditions. In this embodiment, the solid content of the second slurry layer 220 is preferably 30%, which can ensure that the hard carbon in the second slurry layer 220 is evenly dispersed, further reduces the charge transfer internal resistance and ohmic internal resistance of the negative electrode sheet, and improves the battery life. performance.

Preferably, the hard carbon in this embodiment is spherical particles with a smooth surface and regular shape, and the diameter of the hard carbon is 1 μm-5 μm. Specifically, the diameter of the hard carbon with a spherical structure can be 2 μm, 3 μm, or 4 μm. In this embodiment The diameter of hard carbon particles is preferably 3 μm, which ensures the distribution density of hard carbon on the second slurry layer 220, thereby ensuring that the lithium separation window of the negative electrode sheet can be significantly improved at low temperature.

Optionally, the thickness of the first slurry layer 210 is 50 μm-100 μm, specifically, the thickness of the first slurry layer 210 may be 60 μm, 70 μm, 80 μm, 90 μm and so on.

Optionally, the solid content of the first slurry layer 210 is 40%-60%. Specifically, the solid content of the first slurry layer 210 can be 45%, 50%, 55%, etc. In this embodiment, the solid content of the first slurry layer 210 is preferably 50%, which can ensure that the first slurry layer 210 The graphite particles in the battery are uniformly dispersed, further reducing the charge transfer internal resistance and ohmic internal resistance of the negative electrode sheet, and improving the performance of the battery.

Optionally, the first slurry layer 210 may further include at least one of a conductive agent, a binder and a dispersant, which can improve the conductivity of the current collector 100 .

Specifically, the conductive agent includes one or more of nano-carbon black particles, nano-carbon tubes, nano-carbon short rods, Ketjen black, acetylene black, and graphene.

Specifically, the binder includes carboxymethyl cellulose, sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, polyacrylic acid, sodium polyacrylate, lithium polyacrylate, polyacrylonitrile, styrene-butadiene rubber, polyethylene oxide, One or more of polyvinylidene fluoride, polyvinylpyrrolidone, polyester, polyamide and polymethyl methacrylate.

Specifically, the dispersant is sodium carboxymethylcellulose, polyacrylic acid, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene polymer, polyacrylonitrile, sodium polyphosphate, copolymers of polymer monomers and polymers One or more of the copolymers.

Specifically, in addition to hard carbon particles, the second slurry layer 220 in this embodiment may also include one or more of a conductive agent, an adhesive and a dispersant.

Implementation two

The preparation method of the negative electrode sheet provided by the utility model is to first coat the first slurry layer 210 on the current collector, bake the first slurry layer 210, cold press the first slurry layer 210, and then apply Cloth the second slurry layer 220, the specific coating steps are:

S21. Select the first slurry layer 210 as one of conductive agent, adhesive and dispersant, search for the formula of the first slurry layer 210 correspondingly selected, and prepare the slurry required for the first slurry layer 210 , it should be noted that the formulations of the conductive agent, the adhesive and the dispersant are mature technical means in the field, and will not be repeated here.

S22. Coat the slurry of the first slurry layer 210 on the current collector 100 by spraying or scraping, and then bake to obtain a pole piece. The baking temperature is 60°C-80°C, which is preferred in this embodiment The baking temperature is 70°C.

S23. Perform cold pressing on the pole piece prepared in S22, and the coefficient of cold pressing is less than 1.

S24. Select the second slurry layer 220 as one of the conductive agent, adhesive and dispersant, search for the formula of the second slurry layer 220 for selection, and add hard carbon to prepare the second slurry layer 220 For the required slurry, the solid content of the slurry required for the second slurry layer 220 is 20%.

S25 , coating the slurry of the second slurry layer 220 on the first slurry layer 210 with a micro-gravure roll, and the coating thickness is 2.5 μm.

S26. Baking is performed at a temperature of 70° C. to obtain a negative pole piece.

With the negative pole piece prepared by the method provided in this example, the lithium separation window has been significantly improved, and the performance of the battery has been significantly improved.

Embodiment three

This example provides another way of preparing the negative electrode sheet. The difference from Example 2 is that in this example, in the coating process, after the first slurry layer 210 is coated, the first slurry is baked Material layer 210, continue to coat the second slurry layer 220 on the dried first slurry layer 210, and finally carry out cold pressing, the specific operation steps are:

S31. Select the first slurry layer 210 as one of conductive agent, adhesive and dispersant, search for the formula of the first slurry layer 210 correspondingly selected, and prepare the slurry required for the first slurry layer 210 , it should be noted that the formulations of the conductive agent, the adhesive and the dispersant are mature technical means in the field, and will not be repeated here.

S32 , coating the slurry of the first slurry layer 210 on the current collector 100 by scraping or micro gravure roll, and then baking, the baking temperature is 75°C.

S33. Select the second slurry layer 220 as one of the conductive agent, adhesive and dispersant, search for the formula of the second slurry layer 220 that is selected, and add hard carbon to prepare the second slurry layer 220 For the required slurry, the solid content of the slurry required for the second slurry layer 220 is 25%.

S34 , coating the slurry of the second slurry layer 220 on the dried first slurry layer 210 by doctor blade coating or micro-gravure roll to obtain a pole piece.

S35. Baking the pole piece prepared in S34 at a baking temperature of 75° C., and then cold pressing with a cold pressure coefficient of less than 1 to prepare a negative pole piece.

With the negative pole piece prepared by the method provided in this example, the lithium separation window has been significantly improved, and the performance of the battery has been significantly improved.

Embodiment four

This embodiment provides a battery, including the above-mentioned negative pole piece, which can reduce the internal resistance of the battery, reduce the loss of power inside the battery, and the lithium analysis window has been significantly improved, and the SOC of the battery when lithium analysis occurs (State of charge) is improved, making the battery more resistant to lithium analysis, and significantly improving the performance of the battery.

Apparently, the above-mentioned embodiments of the present utility model are only examples for clearly illustrating the present utility model, rather than limiting the implementation manner of the present utility model. Various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. It is not necessary and impossible to exhaustively list all the implementation manners here. All modifications, equivalent replacements and improvements made within the spirit and principles of the utility model shall be included in the protection scope of the claims of the utility model.

Claims (10)

1. The negative pole piece is characterized by comprising a current collector (100) and a slurry layer (200), wherein the slurry layer (200) is arranged on the current collector (100), and hard carbon is arranged on the slurry layer (200).

2. The negative electrode tab of claim 1, wherein the paste layer (200) comprises a first paste layer (210) and a second paste layer (220), the first paste layer (210) is disposed on the current collector (100), the second paste layer (220) is disposed on the first paste layer (210), and the hard carbon is disposed on the second paste layer (220).

3. Negative electrode sheet according to claim 2, characterized in that the thickness of the second paste layer (220) is 0.1 μm to 10 μm.

4. The negative electrode sheet according to claim 2, wherein the solid content of the second slurry layer (220) is 3-60%.

5. The negative electrode tab of any one of claims 1 to 4, wherein the hard carbon is in a spherical structure and has a diameter of 1 μm to 5 μm.

6. The negative electrode tab of claim 2, characterized in that the first slurry layer (210) is provided with graphite particles having a particle size of 15-30 μm.

7. The negative electrode sheet of claim 6, wherein the hard carbon is disposed on a surface layer and in gaps of the graphite particles.

8. Negative electrode sheet according to claim 2, characterized in that the thickness of the first paste layer (210) is 50 μm-100 μm.

9. The negative electrode sheet according to claim 2, characterized in that the solid content of the first slurry layer (210) is 40-60%.

10. A battery comprising a negative electrode tab according to any one of claims 1 to 9.

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