Battery and electric equipment

Abstract

The invention discloses a battery and electric equipment, the battery comprises a battery cell, the battery cell comprises a positive plate and a negative plate, the battery cell is formed by winding after the positive plate and the negative plate are laminated, the positive plate comprises a first section and a second section which are connected with each other, one end of the first section far away from the second section is a winding starting point of the positive plate, and the other end of the first section far away from the second section is a winding starting point of the negative plate; one end, far away from the first section, of the second section is a winding end point of the positive plate, the content of the adhesive in the first section is W1, the content of the adhesive in the second section is W2, and W1 is greater than W2. The battery provided by the invention can have relatively high safety.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a battery and an electrical device. Background Art

[0002] In related technologies, a battery consists of a housing and a cell. The cell comprises a positive electrode sheet and a negative electrode sheet, which are stacked and wound to form a cylindrical cell. The positive electrode sheet comprises aluminum foil and a positive electrode active material, which is coated on the aluminum foil. The negative electrode sheet comprises copper foil and a negative electrode active material, which is coated on the copper foil.

[0003] Furthermore, when the existing positive electrode sheet is wound, the inner circle of the positive electrode sheet is prone to breakage or creases and material dropout, which will lead to lower battery safety. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a battery with high safety.

[0005] The present invention also provides an electrical device.

[0006] A battery according to an embodiment of the first aspect of the present invention includes:

[0007] A battery cell includes a positive electrode sheet and a negative electrode sheet. The battery cell is formed by stacking the positive electrode sheet and the negative electrode sheet and then winding them. The positive electrode sheet includes a first section and a second section connected to each other. The end of the first section away from the second section is the starting point of the winding of the positive electrode sheet, and the end of the second section away from the first section is the end point of the winding of the positive electrode sheet. The content of the adhesive in the first section is W1, and the content of the adhesive in the second section is W2, and W1>W2.

[0008] The battery according to the embodiment of the present invention has at least the following beneficial effects: the positive electrode sheet includes a first section and a second section connected to each other, the end of the first section away from the second section is the starting point of the winding of the positive electrode sheet, and the end of the second section away from the first section is the end point of the winding of the positive electrode sheet. In the prior art, when the positive electrode sheet is wound to form a battery cell, the winding head of the positive electrode sheet is prone to breakage or creases and falling off. In the present application, by making the content of the adhesive in the first section greater than the content of the adhesive in the second section, the flexibility of the first section is adjusted to make the first section softer. In this way, when the positive electrode sheet is wound, the risk of breakage or creases and falling off of the first section can be effectively reduced, thereby improving the safety of the battery. Specifically, the battery can have higher safety.

[0009] For batteries according to some embodiments of the present invention, 1%≤W1≤5%.

[0010] According to batteries of some embodiments of the present invention, 0.5%≤W2≤3%.

[0011] According to some embodiments of the present invention, in the battery, along the winding direction of the battery cell, the length of the first segment is L1, the length of the second segment is L2, and 5%≤L1 / (L1+L2)≤20%.

[0012] In batteries according to some embodiments of the present invention, the content of the positive electrode active material in the first segment is C1, and 92%≤C1≤97.8%.

[0013] In batteries according to some embodiments of the present invention, the content of the positive electrode active material in the second segment is C2, and 94%≤C2≤98.5%.

[0014] In batteries according to some embodiments of the present invention, the compaction density of the first segment is P1, the compaction density of the second segment is P2, and P2 ≥ P1.

[0015] According to some embodiments of the present invention, the battery has a 3.3 g / cm 3 ≤P1≤3.5g / cm 3 .

[0016] According to some embodiments of the present invention, the battery has a 3.45 g / cm 3 ≤P2≤3.7g / cm 3 .

[0017] An electrical device according to an embodiment of the second aspect of the present invention comprises the battery described in any one of the embodiments of the first aspect.

[0018] The electrical equipment according to the embodiment of the present invention has at least the following beneficial effects: the positive electrode sheet includes a first section and a second section connected to each other, the end of the first section away from the second section is the starting point of the winding of the positive electrode sheet, and the end of the second section away from the first section is the end point of the winding of the positive electrode sheet. In the prior art, when the positive electrode sheet is wound to form a battery cell, the winding head of the positive electrode sheet is prone to breakage or creases and falling off. In the present application, by making the content of the adhesive in the first section greater than the content of the adhesive in the second section, the flexibility of the first section is adjusted to make the first section softer. In this way, when the positive electrode sheet is wound, the risk of breakage or creases and falling off in the first section can be effectively reduced, thereby improving the safety of the battery. Specifically, the battery can have higher safety. Furthermore, the safety of the electrical equipment having the battery is also higher.

[0019] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0021] Figure 1 Schematic diagram of the expanded positive electrode sheet in a battery according to some embodiments of the present invention.

[0022] Reference numerals:

[0023] Positive electrode sheet 100 , first section 200 , second section 300 . DETAILED DESCRIPTION

[0024] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0025] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0026] In the description of the present invention, "several" means more than one, "plurality" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0027] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0028] In the description of the present invention, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the exemplary expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0029] In some embodiments, the battery includes: a shell and a battery cell. The shell can be made of metal or other materials, such as aluminum-plastic film. The shape of the shell can be cylindrical or rectangular. The battery cell includes a positive electrode sheet 100 and a negative electrode sheet. A separator is provided between the positive electrode sheet 100 and the negative electrode sheet. The battery cell is formed by stacking the positive electrode sheet 100 and the negative electrode sheet and then winding them. The shape of the battery cell can be approximately cylindrical or rectangular. When the battery cell is cylindrical, it can be formed by winding the positive electrode sheet 100 and the negative electrode sheet. When the battery cell is a rectangular parallelepiped, after the positive electrode sheet 100 and the negative electrode sheet are wound, they need to be extruded to form a rectangular parallelepiped. When winding the positive electrode sheet 100, the starting section of the winding of the positive electrode sheet 100 is too curvature, which may cause the positive electrode sheet 100 to easily break or fall off.

[0030] Furthermore, the positive electrode sheet 100 includes an aluminum foil and a positive electrode active material layer, and the positive electrode active material layer includes a positive electrode active material, a conductive agent, and an adhesive. The positive electrode sheet 100 includes a first section 200 and a second section 300 connected to each other. The end of the first section 200 away from the second section 300 is the starting point of the winding of the positive electrode sheet 100, and the end of the second section 300 away from the first section 200 is the end point of the winding of the positive electrode sheet 100. That is, after the positive electrode sheet 100 is wound to form a battery cell, the first section 200 is located in the inner layer of the battery cell, and the second section 300 is located in the outer layer of the battery cell. Among them, the content of the adhesive in the first section 200 is W1, and the content of the adhesive in the second section 300 is W2, and W1>W2. Specifically, the positive electrode sheet 100 includes a first section 200 and a second section 300 connected to each other. The end of the first section 200 away from the second section 300 is the starting point of the winding of the positive electrode sheet 100, and the end of the second section 300 away from the first section 200 is the end point of the winding of the positive electrode sheet 100. In the prior art, when the positive electrode sheet 100 is wound to form a battery cell, the winding head of the positive electrode sheet 100 is prone to breakage or creases and falloff. In the present application, by making the content of the adhesive in the first section 200 greater than the content of the adhesive in the second section 300, the flexibility of the first section 200 is adjusted, making the first section 200 more flexible. In this way, when the positive electrode sheet 100 is wound, the first section 200 can effectively reduce the risk of breakage or creases and falloff, thereby improving the safety of the battery. Specifically, the battery can have higher safety.

[0031] The following is an explanation through experiments.

[0032] Comparative Example 1:

[0033] (1) Preparation of negative electrode sheet: The negative electrode active materials artificial graphite, conductive carbon black, sodium carboxymethyl cellulose (CMC), and styrene-butadiene rubber (SBR) were mixed in a weight ratio of 96.5:0.5:1.2:1.8, deionized water was added as a solvent, and a slurry with a weight percentage of 50 wt% was prepared. The mixture was stirred evenly and the slurry was evenly coated on one surface of a copper foil with a thickness of 8 μm. The single-sided coating density was 1.27 g / dm 2 , compacted density 1.66g / cm 3 ;

[0034] (2) Preparation of positive electrode sheet: The positive electrode active material high nickel ternary (NCM), conductive carbon black, and polyvinylidene fluoride (PVDF) are mixed in a weight ratio of 97.8:1.0:1.2, and N-methylpyrrolidone (NMP) is added as a solvent to prepare a slurry with a solid content of 75wt%, which is used as the active material slurry of the first section 200 (slurry A). The positive electrode active material high nickel ternary (NCM), conductive carbon black, and polyvinylidene fluoride (PVDF) are mixed in a weight ratio of 97.8:1.0:1.2, and N-methylpyrrolidone (NMP) is added as a solvent to prepare a slurry with a solid content of 75wt%, which is used as the active material slurry of the second section 300 (slurry B). Slurry A and slurry B are respectively evenly coated on the 12um aluminum foil of the first section 200 and the second section 300; the single-sided coating surface density is 2.5g / dm 2 , compacted density 3.6g / cm 3 ;

[0035] (3) Preparation of diaphragm: A 14 μm thick polyethylene porous polymer film was used as the separator.

[0036] (4) Preparation of electrode assembly: The negative electrode sheet, separator and positive electrode sheet are wound into a battery cell with a winding needle diameter of 3.5 mm.

[0037] (5) Compare the cathode fragments or electrode folds and dropouts during the winding process.

[0038] Comparative Example 2:

[0039] Preparation of the positive electrode sheet: The positive electrode active material, high nickel ternary metal (NCM), conductive carbon black, and polyvinylidene fluoride (PVDF), were mixed in a weight ratio of 97.6:1.0:1.4. N-methylpyrrolidone (NMP) was added as a solvent to prepare a slurry with a solid content of 75 wt%. This slurry was used as the active material slurry (Slurry A) for the first stage 200. All other parameters were the same as those in Comparative Example 1.

[0040] Comparative Example 3:

[0041] Preparation of the positive electrode sheet: The positive electrode active material, high nickel ternary metal (NCM), conductive carbon black, and polyvinylidene fluoride (PVDF), were mixed in a weight ratio of 97.4:1.0:1.6. N-methylpyrrolidone (NMP) was added as a solvent to prepare a slurry with a solid content of 75 wt%. This slurry was used as the active material slurry (Slurry A) for the first stage 200. All other parameters were the same as those in Comparative Example 1.

[0042] Comparative Example 4:

[0043] Preparation of the positive electrode sheet: The positive electrode active material, high nickel ternary metal (NCM), conductive carbon black, and polyvinylidene fluoride (PVDF), were mixed in a weight ratio of 97.3:1.0:1.7. N-methylpyrrolidone (NMP) was added as a solvent to prepare a slurry with a solid content of 75 wt%. This slurry was used as the active material slurry (Slurry A) for the first stage 200. All other parameters were the same as those in Comparative Example 1.

[0044] Comparative Example 5:

[0045] Preparation of the positive electrode sheet: The positive electrode active material, high nickel ternary metal (NCM), conductive carbon black, and polyvinylidene fluoride (PVDF), were mixed in a weight ratio of 97.2:1.0:1.8. N-methylpyrrolidone (NMP) was added as a solvent to prepare a slurry with a solid content of 75 wt%. This slurry was used as the active material slurry (Slurry A) for the first stage 200. All other parameters were the same as those in Comparative Example 1.

[0046] Example 1:

[0047] Preparation of the positive electrode sheet: The positive electrode active materials, high nickel ternary metal (NCM), conductive carbon black (Super P), and polyvinylidene fluoride (PVDF), were mixed in a weight ratio of 97.1:1.0:1.9. N-methylpyrrolidone (NMP) was added as a solvent to prepare a slurry with a solid content of 75 wt%. This slurry was used as the active material slurry (Slurry A) for the first stage 200. All other parameters were the same as those in Comparative Example 1.

[0048] Example 2:

[0049] Preparation of the positive electrode sheet: The positive electrode active material, high nickel ternary metal (NCM), conductive carbon black, and polyvinylidene fluoride (PVDF), were mixed in a weight ratio of 97.0:1.0:2.0. N-methylpyrrolidone (NMP) was added as a solvent to prepare a slurry with a solid content of 75 wt%. This slurry was used as the active material slurry (Slurry A) for the first stage 200. All other parameters were the same as those in Comparative Example 1.

[0050] Table 1

[0051]

[0052] It can be seen from Table 1 above that when the content of the adhesive in the first section 200 is relatively low, the first section 200 is prone to breakage or creases and fall-off during winding.

[0053] Furthermore, in some embodiments, 1%≤W1≤5%. The content of the binder in the first segment 200 as W1 specifically refers to the weight percentage of the binder in the first segment 200 in the positive electrode active material layer. W1 can specifically be 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3.0%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4.0%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9% or 5.0%. Specifically, when the content of W1 is less than 1%, due to the small content of adhesive in the first section 200, the first section 200 is prone to breakage or creases and falling off during the winding process. When the content of W1 is greater than 5%, the first section 200 can effectively avoid the problem of breakage or creases and falling off, but due to the excessive content of adhesive, this will result in less positive electrode active material in the first section 200, thereby lowering the energy density of the battery.

[0054] Furthermore, in some embodiments, 0.5% ≤ W2 ≤ 3%. The binder content W2 in the second segment 300 specifically refers to the weight percentage of the binder in the second segment 300 to the positive electrode active material layer. W2 can specifically be 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, or 3.0%. Specifically, when the content of W2 is less than 0.5%, the binder content in the second segment 300 is relatively low, which may cause the positive electrode active material layer to fall off the aluminum foil. When the content of W2 is greater than 3%, the content of the binder is too high, which results in less positive electrode active material in the second section 300 , thereby lowering the energy density of the battery and poor conductivity of the positive electrode sheet 100 .

[0055] Furthermore, in some embodiments, along the winding direction of the battery cell, the length of the first section 200 is L1, the length of the second section 300 is L2, and 5% ≤ L1 / (L1+L2) ≤ 20%. Specifically, along the winding direction of the battery cell, the length of the first section 200 is L1, which means that after the positive electrode sheet 100 is unfolded, the length of the first section 200 is L1. The sum of the lengths of L1+L2 is the total length of the positive electrode sheet 100. Specifically, L1 / (L1+L2) can be equal to 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%. Specifically, when L1 / (L1+L2) is less than 5%, the length of the first segment 200 is relatively short, so when the positive electrode sheet 100 is wound, the second segment 300 may break or crease near the first segment 200, causing the material to fall off. When L1 / (L1+L2) is greater than 20%, the length of the first segment 200 is too long, which may result in a low content of positive electrode active material and a low energy density of the battery.

[0056] Furthermore, in some embodiments, the content of the positive electrode active material in the first segment 200 is C1, 92% ≤ C1 ≤ 97.8%. Specifically, C1 can be 92%, 93%, 94%, 95%, 96%, 97%, 97.1%, 97.2%, 97.3%, 97.4%, 97.5%, 97.6%, 97.7%, or 97.8%. The positive electrode active material primarily participates in the electrochemical reaction, thereby enabling the battery to output current. When C1 is greater than 97.8%, the proportion of the positive electrode active material is high, which can lead to a decrease in the content of the conductive agent and binder. For example, the binder content can be reduced while the conductive agent content remains unchanged. When the binder content in the first segment 200 is low, the first segment 200 has poor flexibility, which may cause the first segment 200 to break or crease during the winding process. When C1 is less than 92%, this may result in a low energy density of the battery. Specifically, when C1 satisfies 92%≤C1≤97.8%, the battery has higher safety and higher energy density.

[0057] Furthermore, in some embodiments, the content of the positive electrode active material in the second section 300 is C2, 94% ≤ C2 ≤ 98.5%. C2 can specifically be equal to 94%, 95%, 96%, 97%, 98%, 98.1%, 98.2%, 98.3%, 98.4% or 98.5%. The positive electrode active material mainly plays the role of participating in the electrochemical reaction, thereby allowing the battery to output current. Among them, when C2 is greater than 98.5%, the proportion of the positive electrode active material is high, which will lead to a reduction in the content of the conductive agent and the adhesive, which will result in a larger internal resistance of the positive electrode sheet 100 and hindered ion diffusion. When C2 is less than 94%, this may result in a lower energy density of the battery.

[0058] Furthermore, in some embodiments, the compaction density of the first segment 200 is P1, and the compaction density of the second segment 300 is P2, and P2 ≥ P1. Specifically, P2 can be equal to P1, or P2 can be greater than P1. When P2 is greater than P1, the compaction density of the first segment 200 is lower, which can improve the flexibility of the first segment 200, thereby effectively avoiding the first segment 200 from breaking or creases. When P2 is equal to P1, the compaction density of the first segment 200 and the second segment 300 is the same, which can maintain consistent uniformity at various positions of the positive electrode sheet 100, effectively avoiding problems such as poor contact or obstructed ion transmission in local areas of the positive electrode sheet 100.

[0059] Further, in some embodiments, 3.3 g / cm 3 ≤P1≤3.5g / cm 3 Specifically, P1 can be equal to 3.3 g / cm 3 、3.31g / cm 3 、3.32g / cm 3 、3.33g / cm 3 、3.34g / cm 3 、3.35g / cm 3 、3.36g / cm 3 、3.37g / cm 3 、3.38g / cm 3 、3.39g / cm 3 、3.40g / cm 3 、3.41g / cm 3 、3.42g / cm 3 、3.43g / cm 3 、3.44g / cm 3 、3.45g / cm 3 、3.46g / cm 3 、3.47g / cm 3 、3.48g / cm 3 、3.49g / cm3 or 3.5g / cm 3 When P1 is less than 3.3g / cm 3 When P1 is greater than 3.5 g / cm3, the compaction density of the first section 200 is low, which may cause poor contact or low energy density in the first section 200. 3 When the first section 200 is wound, the compaction density of the first section 200 is high, which may make the first section 200 brittle, thereby causing the first section 200 to break or fall off at creases during the winding process.

[0060] Further, in some embodiments, 3.45 g / cm 3 ≤P2≤3.7g / cm 3 Specifically, P2 can be equal to 3.45 g / cm 3 、3.46g / cm 3 、3.47g / cm 3 、3.48g / cm 3 、3.49g / cm 3 、3.50g / cm 3 、3.51g / cm 3 、3.52g / cm 3 、3.53g / cm 3 、3.54g / cm 3 、3.55g / cm 3 、3.56g / cm 3 、3.57g / cm 3 、3.58g / cm 3 、3.59g / cm 3 、3.60g / cm 3 、3.61g / cm 3 、3.62g / cm 3 、3.63g / cm 3 、3.64g / cm 3 、3.65g / cm 3 、3.66g / cm 3 、3.67g / cm 3 、3.68g / cm 3 、3.69g / cm 3 or 3.7g / cm 3 When P2 is less than 3.45g / cm 3 When P2 is greater than 3.7 g / cm3, the compaction density of the second section 300 is low, which may cause poor contact or low energy density in the first section 200. 3 When the second section 300 is used, the problem of particle breakage and obstruction of ion transmission may occur.

[0061] Furthermore, in some embodiments, the weight percentage of the conductive agent in the first segment 200 and the second segment 300 is F, and 1% ≤ F ≤ 3%. Specifically, F can be 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, or 3%. When F is greater than 3%, the conductive agent content in the first segment 200 is high, which results in a low binder content in the first segment 200, making it more likely to break, crease, or fall off during winding. When F is less than 1%, the conductive agent content in the first segment 200 is low, which results in a high internal resistance in the first segment 200 and reduces the cycle life of the positive electrode sheet 100.

[0062] Furthermore, in some embodiments, the single-sided areal density of the second section 300 is D1, and the single-sided areal density of the first section 200 is D2, 1.0 g / dm 2 ≤D1≤2.6g / dm 2 , 1.0g / dm 2 ≤D2≤2.6g / dm 2 Specifically, D1=D2, and D1 can be 1.0 g / dm 2 , 1.1g / dm 2 , 1.2g / dm 2 , 1.3g / dm 2 , 1.4g / dm 2 , 1.5g / dm 2 , 1.6g / dm 2 , 1.7g / dm 2 , 1.8g / dm 2 , 1.9g / dm 2 , 2.0g / dm 2 , 2.1g / dm 2 , 2.2g / dm 2 , 2.3g / dm 2 , 2.4g / dm 2 , 2.5g / dm 2 or 2.6g / dm 2 When D1 is less than 1.0g / dm 2 When D2 is greater than 2.6 g / dm 2This may result in a larger thickness of the first section 200 and the second section 300, which may easily cause cracking problems. In addition, it may also make it difficult for the electrolyte to penetrate. Among them, D2 can be 1.0g / dm 2 , 1.1g / dm 2 , 1.2g / dm 2 , 1.3g / dm 2 , 1.4g / dm 2 , 1.5g / dm 2 , 1.6g / dm 2 , 1.7g / dm 2 , 1.8g / dm 2 , 1.9g / dm 2 , 2.0g / dm 2 , 2.1g / dm 2 , 2.2g / dm 2 , 2.3g / dm 2 , 2.4g / dm 2 , 2.5g / dm 2 or 2.6g / dm 2 .

[0063] Furthermore, in some embodiments, the binder in the positive electrode active material layer includes at least one of polyvinylidene fluoride, polyacrylic acid, polyacrylonitrile and sodium alginate.

[0064] In some embodiments, the electrical device includes a battery according to any of the above embodiments. Specifically, the positive electrode sheet 100 includes a first segment 200 and a second segment 300 connected to each other. The end of the first segment 200 away from the second segment 300 is the starting point of the winding of the positive electrode sheet 100, and the end of the second segment 300 away from the first segment 200 is the end point of the winding of the positive electrode sheet 100. In the prior art, when the positive electrode sheet 100 is wound to form a battery cell, the winding head of the positive electrode sheet 100 is prone to breakage or creases and falloff. In the present application, by making the content of the adhesive in the first segment 200 greater than the content of the adhesive in the second segment 300, the flexibility of the first segment 200 is adjusted, making the first segment 200 more flexible. In this way, when the positive electrode sheet 100 is wound, the first segment 200 can effectively reduce the risk of breakage or creases and falloff, thereby improving the safety of the battery. Specifically, the battery can have higher safety. Furthermore, the safety of the electrical device having the battery is also higher.

[0065] While the embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to the embodiments described above. Various modifications may be made within the scope of knowledge possessed by a person skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof may be combined with one another unless there is a conflict.

Claims

1. A battery, characterized in that include: A battery cell includes a positive electrode sheet and a negative electrode sheet. The battery cell is formed by stacking the positive electrode sheet and the negative electrode sheet and then winding them. The positive electrode sheet includes a first section and a second section connected to each other. The end of the first section away from the second section is the starting point of the winding of the positive electrode sheet, and the end of the second section away from the first section is the end point of the winding of the positive electrode sheet. The content of the adhesive in the first section is W1, and the content of the adhesive in the second section is W2, and W1>W2.

2. The battery according to claim 1, characterized in that 1％≤W1≤5％。 3. The battery according to claim 1, characterized in that 0.5％≤W2≤3％。 4. The battery according to claim 1, characterized in that Along the winding direction of the battery core, the length of the first section is L1, the length of the second section is L2, and 5%≤L1 / (L1+L2)≤20%.

5. The battery according to claim 1, characterized in that The content of the positive electrode active material in the first section is C1, 92%≤C1≤97.8%.

6. The battery according to claim 1, characterized in that The content of the positive electrode active material in the second section is C2, 94%≤C2≤98.5%.

7. The battery according to claim 1, characterized in that The compaction density of the first section is P1, the compaction density of the second section is P2, and P2≥P1.

8. The battery according to claim 7, characterized in that 3.3g / cm 3 ≤P1≤3.5g / cm 3 。 9. The battery according to claim 7, characterized in that 3.45g / cm 3 ≤P2≤3.7g / cm 3 。 10. Electrical equipment, characterized in that: Comprising the battery according to any one of claims 1 to 9.

Images