Battery cell pole piece with winding structure and winding battery

Abstract

The invention provides a winding structure battery cell pole piece and a winding battery, the winding structure battery cell pole piece comprises a pole piece body, two side surfaces of the pole piece body are respectively provided with a first active coating and a second active coating, the surface density of the first active coating is smaller than that of the second active coating, and the surface density of the second active coating is smaller than that of the first active coating. And when the pole piece body is wound to form a winding core structure, one side of the first active coating is close to a winding center. The active coatings with different surface densities are adopted on the two sides of the centering pole piece, so that the risk of breakage of the pole piece during folding is reduced, and the energy density of the battery is also improved.

Description

Technical Field

[0001] This invention belongs to the field of batteries, and relates to wound batteries, and more particularly to a wound structure cell electrode and a wound battery. Background Technology

[0002] As the market demands increasingly higher energy density for battery cells, foil materials are becoming thinner, the amount of active material coated on the foil is continuously increasing, and the compaction of electrode materials is constantly being improved. Currently, the amount of active material coated on both sides of the foil in existing wound battery cells is typically the same.

[0003] For example, CN116093248A discloses a lithium-ion battery electrode sheet where the upper and lower sides of the current collector are coated with a first and a second thermistor and pressure-sensitive functional coating slurry prepared by dispersion in a solvent. The outer sides of the first and second thermistor and pressure-sensitive functional coatings are coated with a first active material layer and a second active material layer, respectively. The thickness of both the first and second thermistor and pressure-sensitive functional coatings is 0.5 μm to 20 μm; and the thickness of both the first and second active material layers is 10 μm to 500 μm. CN114141985A discloses a positive electrode sheet comprising a positive current collector and a positive electrode coating. The positive electrode coating comprises a first coating and a second coating. The first coating is coated on the surface of the positive current collector, and the second coating is coated on the surface of the first coating. The thickness of the first coating is 2 to 10 μm; and the thickness of the second coating is 30 to 80 μm.

[0004] However, during the winding process, the innermost layer of the electrode is folded almost 360°, and the foil needs to be stretched during this process. Since the foil has a low elongation at break, this extreme design can easily lead to electrode breakage, rendering it ineffective and causing a decrease in cell capacity, thus affecting user experience. Therefore, preventing electrode breakage during winding is crucial to ensuring battery performance. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a wound structure cell electrode and a wound battery. By designing different coating amounts on both sides of the electrode, the coating amount on the inner side is lower than that on the outer side, thereby achieving a higher compaction density and avoiding the problem of the electrode breaking when folded.

[0006] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a wound structure battery cell electrode sheet, the wound structure battery cell electrode sheet including an electrode sheet body, and a first active coating and a second active coating respectively disposed on two side surfaces of the electrode sheet body, the areal density of the first active coating being less than the areal density of the second active coating, and when the electrode sheet body is wound to form a core structure, one side of the first active coating is close to the winding center.

[0007] As a preferred embodiment of the present invention, the ratio of the areal density of the first active coating to the areal density of the second active coating is 1:(1.2~2), for example, it can be 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9 or 1:2.0, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0008] As a preferred embodiment of the present invention, the areal density of the first active coating is 120 g / m³. 2 ~230g / m 2 For example, it could be 120g / m 2 130g / m 2 140g / m 2 150g / m 2 160g / m 2 170g / m 2 180g / m 2 190g / m 2 200g / m 2 210g / m 2 220g / m 2 Or 230g / m 2 However, this does not apply to all values ​​listed; other unlisted values ​​within the same range also apply.

[0009] As a preferred embodiment of the present invention, the areal density of the second active coating is 150 g / m³. 2 ~360g / m 2 For example, it could be 150g / m 2 160g / m 2 170g / m 2 180g / m 2 200g / m 2 220g / m 2 250g / m 2 260g / m 2 270g / m 2 280g / m 2 300g / m 2 310g / m2 320g / m 2 340g / m 2 350g / m 2 Or 360g / m 2 However, this does not apply to all values ​​listed; other unlisted values ​​within the same range also apply.

[0010] As a preferred embodiment of the present invention, the first active coating and the second active coating each independently include an active material, a conductive agent and a binder.

[0011] The content of conductive agent in the first active coating is less than or equal to the content of conductive agent in the second active coating.

[0012] As a preferred embodiment of the present invention, taking the total mass of the first active coating as 100%, the mass percentage of the conductive agent in the first active coating is 0.5% to 1.0%, for example, it can be 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95% or 1.0%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0013] In one embodiment of the present invention, taking the total mass of the second active coating as 100%, the mass percentage of the conductive agent in the second active coating is 0.8% to 1.5%, for example, it can be 0.8%, 0.85%, 0.9%, 0.95%, 1.0%, 1.1%, 1.2%, 1.25%, 1.3%, 1.35%, 1.4%, 1.45%, or 1.5%, but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0014] This invention increases the proportion of conductive agent in the outer active coating with higher areal density to ensure the overall discharge performance of the wound battery and avoid the adverse effects on battery performance caused by different coating amounts on both sides of the electrode.

[0015] As a preferred embodiment of the present invention, the content of binder in the first active coating is less than or equal to the content of binder in the second active coating.

[0016] As a preferred embodiment of the present invention, taking the total mass of the first active coating as 100%, the mass percentage of the binder in the first active coating is 0.7% to 1.3%, for example, it can be 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 1.0%, 1.1%, 1.15%, 1.2%, 1.25%, or 1.3%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0017] In one embodiment of the present invention, based on the total mass of the second active coating being 100%, the mass percentage of the binder in the second active coating is 0.9% to 1.5%, for example, it can be 0.9%, 0.95%, 1.0%, 1.1%, 1.15%, 1.2%, 1.25%, 1.3%, 1.35%, 1.4%, 1.45%, or 1.5%, but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0018] This invention ensures the overall discharge performance of the wound battery while reducing the risk of electrode powder shedding by increasing the proportion of binder in the outer active coating with higher areal density.

[0019] As a preferred embodiment of the present invention, taking the total mass of the first active coating as 100%, the mass percentage of the active material in the first active coating is 97.7% to 98.8%, for example, it can be 97.7%, 97.8%, 97.9%, 98.0%, 98.1%, 98.2%, 98.3%, 98.4%, 98.5%, 98.6%, 98.7%, or 98.8%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0020] In one embodiment of the present invention, taking the total mass of the second active coating as 100%, the mass percentage of the active material in the second active coating is 97% to 98.3%, for example, it can be 97%, 97.1%, 97.2%, 97.3%, 97.4%, 97.5%, 97.6%, 97.8%, 97.9%, 98.0%, 98.1%, 98.2%, or 98.3%, but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0021] In a second aspect, the present invention provides a wound battery, the wound battery comprising a positive electrode and a negative electrode, wherein the positive electrode adopts the wound structure cell electrode described in the first aspect.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention improves the overall coating amount by designing different amounts of active material coating on both sides of the electrode, resulting in a lower coating amount on the inner side near the winding center and a higher coating amount on the outer side. This leads to a higher compaction density and increases the volumetric energy density of the battery cell, while also preventing the electrode from breaking during winding and folding. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the positive electrode sheet provided in Example 1.

[0024] Figure 2 This is a schematic diagram of the positive electrode sheet provided in Example 1 after it has been folded in half.

[0025] Figure 3 The diagram shows the structure of the positive electrode for Comparative Example 1.

[0026] Figure 4 This is a schematic diagram of the positive electrode sheet after it has been folded in half, as provided for Comparative Example 1.

[0027] Wherein, 1-electrode body; 2-first active coating; 3-second active coating. Detailed Implementation

[0028] It should be understood that in the description of this invention, the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0029] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0030] In one specific embodiment, the present invention provides a wound structure battery cell electrode sheet, which includes an electrode sheet body. A first active coating and a second active coating are respectively disposed on both sides of the electrode sheet body. The areal density of the first active coating is less than that of the second active coating. When the electrode sheet body is wound to form a core structure, one side of the first active coating is closer to the winding center, i.e., located on the inner side of the electrode sheet, while the second active coating is located on the outer side of the electrode sheet.

[0031] In some embodiments, the ratio of the areal density of the first active coating to the areal density of the second active coating is 1:(1.2~2). The unit coating amount on the surface of the electrode with the second active coating is greater than the unit coating amount on the surface with the first active coating. Compared with conventional electrodes with the same density on both sides, the electrode of the present invention is designed with different areal densities. On the one hand, this increases the overall coating amount, reduces the amount of foil, separator, etc. used in the same volume, and increases the proportion of active material, thereby increasing the volumetric and gravimetric energy density of the cell. On the other hand, reducing the coating amount on the side of the electrode closer to the winding center can prevent the electrode from breaking when it is folded during winding.

[0032] Furthermore, the areal density of the first active coating is 120 g / m². 2 ~230g / m 2 The areal density of the second active coating is 150 g / m³. 2 ~360g / m 2 .

[0033] The electrode body described in this invention is an aluminum-based metal foil or a copper-based metal foil.

[0034] The electrode sheet of the battery cell is preferably a positive electrode sheet, and the first active coating and the second active coating are both positive active coatings, which include positive active materials, conductive agents and binders.

[0035] Depending on the type of battery, different materials are selected for the positive electrode active material. For example, the positive electrode active materials for lithium batteries include, but are not limited to, lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium manganese oxide, lithium manganese phosphate, and lithium-rich manganese-based materials. The positive electrode active materials for sodium batteries include, but are not limited to, layered oxides, polyanionic compounds, and Prussian blue compounds.

[0036] The conductive agent includes, but is not limited to, at least one of conductive carbon black, graphene, acetylene black, Ketjen black, conductive graphite, carbon black, carbon nanotubes, and carbon fibers.

[0037] The adhesive includes, but is not limited to, at least one of polyvinylidene fluoride, polytetrafluoroethylene, and polyimide.

[0038] In addition, the first and second active coatings also include solvents and / or dispersants, such as N-methylpyrrolidone, for uniformly dispersing the above components.

[0039] In some embodiments, with the total mass of the first active coating being 100%, the mass percentage of the active material in the first active coating is 97.7% to 98.8%; further, with the total mass of the second active coating being 100%, the mass percentage of the active material in the second active coating is 97% to 98.3%.

[0040] In some embodiments, the content of the conductive agent in the first active coating is less than or equal to the content of the conductive agent in the second active coating. Since increasing the coating amount on the electrode body surface increases the overall thickness of the cell electrode, leading to an increase in resistance, this invention addresses this by increasing the proportion of the conductive agent in the second active coating, which has a high areal density. This reduces the resistivity of the cell electrode, solving the problem of increased resistance and ensuring its discharge performance.

[0041] Specifically, based on the total mass of the first active coating being 100%, the mass percentage of the conductive agent in the first active coating is 0.5% to 1.0%; further, based on the total mass of the second active coating being 100%, the mass percentage of the conductive agent in the second active coating is 0.8% to 1.5%.

[0042] In some embodiments, the binder content in the first active coating is less than or equal to the binder content in the second active coating. By increasing the binder content in the second active coating, which has a high areal density, this invention can improve the adhesion and cohesion between active materials, thereby avoiding problems such as powder shedding or peeling of the active coating, and further ensuring the high discharge performance of the battery cell electrodes.

[0043] Specifically, based on the total mass of the first active coating being 100%, the mass percentage of the binder in the first active coating is 0.7% to 1.3%; further, based on the total mass of the second active coating being 100%, the mass percentage of the binder in the second active coating is 0.9% to 1.5%.

[0044] It should be noted that the total mass of the first active coating refers to the total mass including active materials, conductive agents, and binders; similarly, the total mass of the second active coating refers to the total mass including active materials, conductive agents, and binders.

[0045] In another specific embodiment, the present invention provides a wound battery comprising a positive electrode and a negative electrode, wherein the positive electrode adopts a wound structure cell electrode as described in a specific embodiment.

[0046] The positive electrode body is made of aluminum foil. The first and second active coatings located on both sides of the positive electrode body are both positive electrode active coatings, comprising positive electrode active materials, positive electrode conductive agents, and positive electrode binders. The positive electrode active materials include, but are not limited to, lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium manganese oxide, lithium manganese phosphate, lithium-rich manganese-based materials, layered oxides, polyanionic compounds, and Prussian blue compounds. The positive electrode conductive agents include, but are not limited to, at least one of conductive carbon black, graphene, acetylene black, Ketjen black, conductive graphite, carbon black, carbon nanotubes, and carbon fibers. The positive electrode binders include, but are not limited to, at least one of polyvinylidene fluoride, polytetrafluoroethylene, and polyimide. Furthermore, the first and second active coatings also include solvents and / or dispersants, such as N-methylpyrrolidone, for uniformly dispersing the above components.

[0047] The negative electrode sheet is a conventional negative electrode sheet in the art or other negative electrode sheets disclosed in the prior art.

[0048] Taking a lithium battery as an example, the conventional negative electrode sheet includes a negative electrode sheet body and two negative electrode active coatings located on both sides of the negative electrode sheet body. The negative electrode sheet uses copper-based metal foil. The negative electrode active coatings independently include a negative electrode active material, a negative electrode conductive agent, and a negative electrode binder, with a mass ratio of (93~98.5%):(0~1.5%):(1.5~5.5%). The negative electrode active material includes, but is not limited to, at least one of artificial graphite, natural graphite, silicon carbide materials, and lithium titanate. The negative electrode conductive agent includes, but is not limited to, at least one of conductive carbon black, graphene, acetylene black, Ketjen black, conductive graphite, carbon nanotubes, and carbon fibers. The negative electrode binder includes, but is not limited to, at least one of styrene-butadiene rubber, sodium carboxymethyl cellulose, polyvinylidene fluoride, sodium alginate, and polyimide. Furthermore, the negative electrode active coating also includes a solvent and / or dispersant, such as deionized water, for uniformly dispersing the above components.

[0049] In addition, a separator needs to be inserted when the positive and negative electrode sheets are wound to prevent direct contact between them and a short circuit. Specifically, the negative electrode sheet, the first separator, the positive electrode sheet, and the second separator are stacked in sequence and wound in a predetermined winding direction to form a wound battery. It is ensured that the positive electrode sheet with the lowest areal density is located on the inner side, i.e., closer to the winding center. The separator includes, but is not limited to, PP (Polypropylene) separators, PE (Polyethylene) separators, or PP / PE / PP three-layer composite separators.

[0050] Example 1 The present invention provides a wound battery, which is formed by stacking and winding a positive electrode, a first separator, a negative electrode and a second separator in sequence.

[0051] like Figure 1 and Figure 2 As shown, the positive electrode includes a first electrode body 1. A first active coating 2 and a second active coating 3 are respectively disposed on both sides of the first electrode body 1. When the electrode body 1 is wound to form a core structure, one side of the first active coating 2 is closer to the winding center. The electrode body 1 is made of aluminum foil with a thickness of 8 μm. Both the first active coating 2 and the second active coating 3 include a positive electrode active material, a conductive agent, and a binder. The positive electrode active material is lithium cobalt oxide, the conductive agent is acetylene black, and the binder is polyvinylidene fluoride.

[0052] The surface density of the first active coating 2 is 180 g / m³. 2 With the total mass of the first active coating 2 as 100%, the mass ratio of the positive electrode active material is 98.2%, the mass ratio of the conductive agent is 0.9%, and the mass ratio of the binder is 0.9%.

[0053] The areal density of the second active coating 3 is 220 g / m³. 2 With the total mass of the second active coating 3 as 100%, the mass ratio of the positive electrode active material is 98.2%, the mass ratio of the conductive agent is 0.9%, and the mass ratio of the binder is 0.9%.

[0054] The negative electrode is a conventional electrode, consisting of an 8μm thick copper foil. Two negative electrode active coatings are applied to each of the two surfaces of the copper foil, with the areal density of the negative electrode active coating designed to match the corresponding areal density of the positive electrode. The negative electrode active coating comprises a graphite-silicon-carbon mixed active material in a mass ratio of 96.5:0.5:3, a conductive carbon black and carbon nanotube mixed conductive agent, lithium carboxymethyl cellulose, styrene-butadiene rubber, and a polyacrylic acid mixed binder. Both the first and second separators are PP / PE / PP three-layer composite separators.

[0055] Example 2 This embodiment provides a wound battery, which differs from Embodiment 1 in that the areal density of the second active coating 3 in the positive electrode sheet is 240 g / m². 2 The rest of the structure is the same as in Example 1.

[0056] Example 3 This embodiment provides a wound battery, which differs from Embodiment 1 in that the areal density of the first active coating 2 in the positive electrode sheet is 160 g / m². 2 The areal density of the second active coating 3 is 280 g / m³. 2 The rest of the structure is the same as in Example 1.

[0057] Example 4 This embodiment provides a wound battery, which differs from Embodiment 1 in that the areal density of the first active coating 2 in the positive electrode sheet is 160 g / m². 2 The areal density of the second active coating 3 is 330 g / m³. 2 The rest of the structure is the same as in Example 1.

[0058] Comparative Example 1 This comparative example provides a wound battery, which differs from Example 1 in that: Figure 3 As shown, the areal density of both the first active coating 2 and the second active coating 3 in the positive electrode is 200 g / m². 2 Its wound structure is as follows Figure 4 As shown, the rest of the structure is the same as in Example 1.

[0059] Comparative Example 2 This comparative example provides a wound battery, which differs from Example 1 in that the areal density of both the first active coating 2 and the second active coating 3 is 220 g / m³. 2 The rest of the structure is the same as in Example 1.

[0060] The present invention verifies the breakage of positive electrode sheets in Examples 1-4 and Comparative Examples 1-2 under different compaction density conditions, and tests the energy density of wound batteries. The results are shown in Table 1.

[0061] The method for verifying the breakage of the positive electrode is as follows: Fold the electrode in half 360°, and use a 1kg roller to roll back and forth on the crease three times. Check whether light passes through the crease from the back of the positive electrode with the light source in the opposite direction. Then fold it in the opposite direction and repeat the operation to check whether light passes through the crease. If no light passes through the positive electrode, then no breakage has occurred.

[0062] Table 1 As can be seen from Table 1, compared to a positive electrode sheet with the same density on both sides, the positive electrode sheet in this invention adopts a structure where the areal density of the inner active coating is lower than that of the outer surface. This reduces the thickness of the active coating, thereby reducing the overall thickness of the positive electrode sheet and significantly lowering the risk of breakage during folding. Furthermore, the energy density of the wound battery is also improved. In addition, as the difference in areal density between the two active coatings increases, both its fracture resistance and energy density gradually increase.

[0063] Example 5 This embodiment provides a wound battery, which differs from Embodiment 1 as follows.

[0064] With the total mass of the first active coating 2 as 100%, the mass ratio of the positive electrode active material is 98.5%, the mass ratio of the conductive agent is 0.7%, and the mass ratio of the binder is 0.8%.

[0065] With the total mass of the second active coating 3 as 100%, the mass percentage of the positive electrode active material is 98.0%, the mass percentage of the conductive agent is 1.0%, and the mass percentage of the binder is 1.0%.

[0066] The rest of the structure is the same as in Example 1.

[0067] Example 6 This embodiment provides a wound battery, which differs from Embodiment 2 as follows.

[0068] With the total mass of the first active coating 2 as 100%, the mass ratio of the positive electrode active material is 98.5%, the mass ratio of the conductive agent is 0.7%, and the mass ratio of the binder is 0.8%.

[0069] With the total mass of the second active coating 3 as 100%, the mass percentage of the positive electrode active material is 98.0%, the mass percentage of the conductive agent is 1.0%, and the mass percentage of the binder is 1.0%.

[0070] The rest of the structure is the same as in Example 2.

[0071] Example 7 This embodiment provides a wound battery, which differs from Embodiment 3 as follows.

[0072] With the total mass of the first active coating 2 as 100%, the mass percentage of the positive electrode active material is 97.9%, the mass percentage of the conductive agent is 1.0%, and the mass percentage of the binder is 1.1%.

[0073] With the total mass of the second active coating 3 as 100%, the mass percentage of the positive electrode active material is 97.3%, the mass percentage of the conductive agent is 1.2%, and the mass percentage of the binder is 1.5%.

[0074] The rest of the structure is the same as in Example 3.

[0075] Example 8 This embodiment provides a wound battery, which differs from Embodiment 4 as follows.

[0076] With the total mass of the first active coating 2 as 100%, the mass percentage of the positive electrode active material is 97.9%, the mass percentage of the conductive agent is 1.0%, and the mass percentage of the binder is 1.1%.

[0077] With the total mass of the second active coating 3 as 100%, the mass percentage of the positive electrode active material is 97.3%, the mass percentage of the conductive agent is 1.2%, and the mass percentage of the binder is 1.5%.

[0078] The rest of the structure is the same as in Example 4.

[0079] Example 9 This embodiment provides a wound battery, which differs from Embodiment 1 as follows.

[0080] With the total mass of the first active coating 2 being 100%, the mass percentage of the positive electrode active material is 98%, the mass percentage of the conductive agent is 1.0%, and the mass percentage of the binder is 1.0%.

[0081] With the total mass of the second active coating 3 as 100%, the mass percentage of the positive electrode active material is 98.2%, the mass percentage of the conductive agent is 0.9%, and the mass percentage of the binder is 0.9%.

[0082] The rest of the structure is the same as in Example 1.

[0083] Comparative Example 3 This comparative example provides a wound battery, which differs from Example 5 in that the areal density of both the first active coating 2 and the second active coating 3 in the positive electrode sheet is 200 g / m². 2 The rest of the structure is the same as in Example 5.

[0084] Comparative Example 4 This comparative example provides a wound battery, which differs from Example 5 in that the areal density of both the first active coating 2 and the second active coating 3 is 220 g / m³. 2 The rest of the structure is the same as in Example 5.

[0085] The present invention verifies the breakage of positive electrode sheets in Examples 5-9 and Comparative Examples 3-4 under different compaction density conditions, and tests the energy density of wound batteries. The test methods are as described above, and the results are shown in Table 2.

[0086] Table 2 As can be seen from Tables 1 and 2, compared with the structure where the surface density of the active coatings on both sides of the positive electrode is the same, in Examples 5 to 8, the proportion of conductive agent and binder in the active coating with high surface density in the positive electrode is increased, while still ensuring that it has high fracture resistance and energy density.

[0087] The present invention also tested the resistance of the positive electrode in Examples 1 to 9, and the results are shown in Table 3.

[0088] Table 3 As can be seen from Table 3, in Examples 5-8, increasing the proportion of conductive agent and binder in the high areal density active coating can effectively reduce the electrode resistance and avoid the risk of increased resistance due to increased electrode thickness caused by increased coating amount. In Example 9, maintaining the conductive agent content in the high areal density active coating while increasing the conductive agent in the low areal density active coating can also reduce the electrode resistance.

[0089] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A wound-structured battery cell electrode, characterized in that, The wound structure battery cell electrode includes an electrode body, and a first active coating and a second active coating are respectively provided on both sides of the electrode body. The areal density of the first active coating is less than that of the second active coating. When the electrode body is wound to form a core structure, one side of the first active coating is close to the winding center.

2. The wound structure electrode sheet according to claim 1, characterized in that, The ratio of the areal density of the first active coating to the areal density of the second active coating is 1:(1.2~2).

3. The wound structure electrode sheet according to claim 1 or 2, characterized in that, The areal density of the first active coating is 120 g / m³. 2 ~230g / m 2 .

4. The wound structure electrode sheet according to claim 1 or 2, characterized in that, The areal density of the second active coating is 150 g / m³. 2 ~360g / m 2 .

5. The wound structure electrode sheet according to claim 1, characterized in that, The first active coating and the second active coating each independently include an active material, a conductive agent, and a binder; The content of conductive agent in the first active coating is less than or equal to the content of conductive agent in the second active coating.

6. The wound structure electrode sheet according to claim 5, characterized in that, Based on the total mass of the first active coating being 100%, the mass percentage of the conductive agent in the first active coating is 0.5% to 1.0%. And / or, based on the total mass of the second active coating being 100%, the mass percentage of the conductive agent in the second active coating is 0.8% to 1.5%.

7. The wound structure electrode sheet according to claim 1 or 5, characterized in that, The content of binder in the first active coating is less than or equal to the content of binder in the second active coating.

8. The wound structure electrode sheet according to claim 7, characterized in that, Based on the total mass of the first active coating being 100%, the mass percentage of the binder in the first active coating is 0.7% to 1.3%. And / or, based on the total mass of the second active coating being 100%, the mass percentage of the binder in the second active coating is 0.9% to 1.5%.

9. The wound structure electrode sheet according to any one of claims 5-8, characterized in that, Based on the total mass of the first active coating being 100%, the mass percentage of the active material in the first active coating is 97.7% to 98.8%. And / or, based on the total mass of the second active coating being 100%, the mass percentage of the active material in the second active coating is 97% to 98.3%.

10. A wound battery, characterized in that, The wound battery includes a positive electrode and a negative electrode, wherein the positive electrode adopts the wound structure cell electrode as described in any one of claims 1-9.

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