Battery, battery module and electric equipment

Abstract

The invention belongs to the technical field of lithium ion battery preparation, and particularly relates to a battery which comprises electrolyte and a pole piece, the pole piece is in contact with the electrolyte, a contact angle is formed between the pole piece and the electrolyte, the contact angle is 10-60 degrees, the surface of the pole piece is coated with a graphite layer, and the surface of the pole piece is coated with a graphite layer. The friction coefficient e between the graphite layer and the electrolyte satisfies the relational expression: 0.15 (N.m.s2) < = e < = 0.25 (N.m.s2), and the lithium ion infiltration degree of the main body area and the edge area of the pole piece can be increased by limiting the formula: 0.8 < =-(e / A2-A1 / B1) < = 1.3 between the contact angle and the friction coefficient e. The reaction resistance of separation and embedding of lithium ions in the pole piece main body area and the edge area is reduced, the diffusion rate difference of the pole piece main body lithium ions is reduced, the diffusion rate difference of the lithium ion pole piece main body area and the edge area is solved, and the overall consistency of the battery is improved.

Description

Technical Field

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

[0002] Ion batteries are widely used in electronic equipment, power vehicles and other fields due to their advantages such as high weight, high specific power, high voltage platform, low self-discharge, long cycle life, no memory effect and good safety.

[0003] However, 3C portable products such as smart phones, watches, and tablets on the market now have higher requirements for lithium batteries, such as higher energy density, faster charging speed, excellent rate discharge capability, and charging and discharging temperature rise.

[0004] However, during high-rate charging, the thinning of the side edges causes the head of the battery cell to be thin, resulting in poor overall flatness of the battery cell and easy lithium deposition at the head.

[0005] The essence of the lithium plating problem at the head and tail is that the thinning process at the head and tail leads to poor electrode bonding, resulting in the migration path and diffusion rate of lithium ions at the head and tail being inconsistent with the main body. Therefore, the lithium ions in the main body have completed the embedding reaction, but the lithium ions at the head and tail have not yet entered the graphite layers and cannot undergo embedding reaction, resulting in inconsistent potential at the head and tail of the battery, causing poor consistency of the battery. Summary of the invention

[0006] The purpose of the present invention is to provide a battery to solve the technical problem of inconsistency between the head and tail of the existing battery in view of the shortcomings of the prior art.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] One of the purposes of the present application is to provide a battery pole piece including an electrolyte and a pole piece, wherein the pole piece is in contact with the electrolyte, a contact angle is formed between the pole piece and the electrolyte, and the angle of the contact angle is 10°-60°, and a graphite layer is coated on the surface of the pole piece, and the friction coefficient e between the graphite layer and the electrolyte is 0.15 (N·m·s 2 )≤e≤0.25(N·m·s 2 ).

[0009] Furthermore, the surface of the electrolyte has a tangent, the edge of the electrolyte in contact with the electrode has a contact point, the contact point is located on the electrode, the tangent passes through the contact point and is tangent to the surface of the electrolyte, and the side of the tangent facing the electrolyte forms the contact angle with the surface of the electrode.

[0010] Furthermore, the electrode sheet includes a main body region and an edge region, the edge region is located on at least one side of the main body region, and when the electrolyte is located in the main body region, the contact angle is 20°-60°;

[0011] When the electrolyte is located in the edge region, the contact angle is 10°-20°.

[0012] Further, the pole piece includes an anode and a cathode, the contact angle of the electrolyte in the main area of ​​the anode is A1, the contact angle of the electrolyte in the edge area of ​​the anode is A2, the contact angle of the electrolyte in the main area of ​​the cathode is B1, and the contact angle of the electrolyte in the edge area of ​​the cathode is B2, satisfying the relationship:

[0013] and / or,

[0014] and / or,

[0015] and / or,

[0016] Furthermore, the contact angle A1 between the surface of the graphite layer and the anode main region, the contact angle A2 between the anode edge region and the cathode main region satisfy the relationship: 0.8<-(e1 / A2-A1 / B1)<1.3.

[0017] Furthermore, the time for lithium ions in the main area of ​​the cathode to migrate to the main area of ​​the anode is t1, and the time for lithium ions in the edge area of ​​the cathode to migrate to the edge area of ​​the anode is t2, and t1 and t2 satisfy the relationship: 0≤t1-t2≤0.5 seconds.

[0018] Furthermore, the width of the main area of ​​the anode is H1, the width of the edge area of ​​the anode is H2, the width of the main area of ​​the cathode is J1, and the width of the edge area of ​​the cathode is J2, satisfying the relationship: 0<H2

[0019] Furthermore, the width H2 of the edge region of the anode is greater than or equal to the width J2 of the edge region of the cathode, the width H2 of the edge region of the anode is ≤7 mm, and the width J2 of the edge region of the cathode is ≤6 mm.

[0020] On the other hand, the present application discloses a battery module, including a box, in which a plurality of batteries are placed.

[0021] On the other hand, the present application discloses an electrical device, comprising the battery module described above.​

[0022] The beneficial effects of the present invention are as follows: by limiting the contact angle of the pole piece / electrolyte and the friction coefficient e to satisfy the formula: 0.8≤-(e / A2-A1 / B1)≤1.3, the degree of lithium ion infiltration in the main area and edge area of ​​the pole piece can be increased, the reaction resistance of lithium ion removal and embedding in the main area and edge area of ​​the pole piece can be reduced, the diffusion rate difference of lithium ions in the main body of the pole piece can be reduced, the difference in the diffusion rate of lithium ions in the main area and edge area of ​​the pole piece can be solved, and the overall consistency of the battery can be improved. When the diaphragm with poor adhesion is used, the battery cell is easy to soften, resulting in inconsistent potentials at various locations on the surface of the battery cell, and the battery cell softens and deforms during the cycle. Controlling the contact angle and friction coefficient here can effectively improve the degree of infiltration of the electrolyte and the pole piece, thereby effectively improving the problems of softening and deformation of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The following will refer to the attached Figure 1 and Figure 2 To describe the features, advantages and technical effects of exemplary embodiments of the present invention.

[0024] Figure 1 Schematic diagram of the contact angle in the present invention;

[0025] Figure 2 It is a schematic diagram of the structure of the anode and cathode in the present invention.

[0026] In the figure: 1. Pole piece; 2. Electrolyte; 3. Contact angle;

[0027] 11. Marginal area; 12. Main area. DETAILED DESCRIPTION

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0029] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0030] The following is combined with Figure 1 and Figure 2The present invention is further described in detail, but is not intended to limit the present invention.

[0031] Implementation

[0032] The present embodiment discloses a battery, including an electrolyte 2 and a pole piece 1, wherein the pole piece 1 contacts the electrolyte 2, and a contact angle is formed between the pole piece 1 and the electrolyte 2, and the contact angle is 10°-60°. The surface of the pole piece 1 is coated with a graphite layer, and the friction coefficient between the graphite layer and the electrolyte 2 is e, which satisfies the relationship: 0.15 (N·m·s 2 )≤e≤0.25(N·m·s2), the contact angle and the friction coefficient e satisfy the formula: 0.8≤-(e / A2-A1 / B1)≤1.3. Specifically, by limiting the parameters of the contact angle, this embodiment can increase the degree of lithium ion infiltration in the main area 12 and the edge area 11 of the pole piece 1, reduce the reaction resistance of lithium ion removal and embedding in the main area 12 and the edge area 11 of the pole piece 1, narrow the difference in the diffusion rate of lithium ions in the main body of the pole piece 1, solve the difference in the diffusion rate of lithium ions in the main area 12 and the edge area 11 of the pole piece 1, and improve the overall consistency of the battery.

[0033] It should be noted that only when the above-mentioned contact angle, friction coefficient e and -(e / A2-A1 / B1) all satisfy the relationship, can the technical effect to be achieved in this application be achieved.

[0034] In this embodiment, the surface of the electrolyte 2 has a tangent, and the edge of the electrolyte 2 in contact with the electrode 1 has a contact point, the contact point is located on the electrode 1, the tangent passes through the contact point and is tangent to the surface of the electrolyte 2, and the side of the tangent facing the electrolyte 2 forms a contact angle with the surface of the electrode 1.

[0035] Specifically, the contact angle refers to the tangent of the gas-liquid interface at the intersection of gas, liquid and solid. The angle θ between this tangent on the liquid side and the solid-liquid boundary line is a measure of the degree of wettability. The larger the contact angle, the better the wetting effect of the electrolyte 2 on the electrode 1. If the contact angle is too small, it reflects that the stock of the electrolyte 2 in the battery is insufficient. If the contact angle is too small and the stock of the electrolyte 2 in the battery is insufficient, it can be seen that the electrolyte 2 cannot efficiently infiltrate the electrode 1, thereby affecting the performance of the battery.

[0036] It should be noted that the maximum contact angle will not exceed 90 degrees, but can be infinitely close to 90 degrees.

[0037] In this embodiment, the electrode 1 includes a main region 12 and an edge region 11 , and the edge region 11 is located on at least one side of the main region 12 . When the electrolyte 2 is located in the main region 12 , the contact angle is 20°-60°.

[0038] Specifically, the main area 12 is located at the center of the electrode 1, and the edge area 11 is located at the center of the electrode 1. In the present embodiment, each electrode 1 has two edge areas 11, and the two edge areas 11 cover the main area 12. When the electrode 1 is manufactured, due to the coating process and the position, the parameters of the active material between the main area 12 and the edge area 11 will have slight changes. Therefore, the electrode 1 is divided into the main area 12 and the edge area 11. In the present embodiment, when the electrolyte 2 is located in the main area 12, the contact angle thereof is 20 degrees, 25 degrees, 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees, 55 degrees, and 60 degrees. The minimum contact angle at this location cannot be less than 20 degrees, and the maximum cannot be greater than 60 degrees.

[0039] In this embodiment, when the electrolyte 2 is located in the edge region 11 , the contact angle is 10°-20°.

[0040] Specifically, when the electrolyte 2 is located in the edge area 11, the contact angle is 10 degrees, 12 degrees, 14 degrees, 16 degrees, 18 degrees, and 20 degrees. The minimum contact angle at this location cannot be less than 10 degrees. A contact angle less than 10 degrees represents that the electrode 1 completely absorbs the electrolyte 2, so that the electrolyte 2 in the edge area 11 is insufficiently wetted, and the performance of the edge area 11 of the electrode 1 cannot be brought into play. The contact angle in the edge area 11 cannot be greater than 20 degrees. A contact angle greater than 20 degrees will cause excessive wetting of the edge area 11 of the electrode 1, and too much electrolyte 2 will remain on the surface of the electrode 1, thereby affecting the performance of the battery.

[0041] In this embodiment, the electrode 1 includes an anode and a cathode, the contact angle of the electrolyte 2 in the main area 12 of the anode is A1, the contact angle of the electrolyte 2 in the edge area 11 of the anode is A2, the contact angle of the electrolyte 2 in the main area 12 of the cathode is B1, and the contact angle of the electrolyte 2 in the edge area 11 of the cathode is B2, satisfying the relationship:

[0042] and / or,

[0043] and / or,

[0044] and / or,

[0045] Specifically, the minimum contact angle of the main area 12 on the anode is twice the contact angle of the main area 12 on the cathode. By limiting the contact angle of the main area 12 on the anode, the wettability of the main area 12 on the anode is improved. After the lithium ions are separated from the cathode, the wettability of the main area 12 on the anode is better, so that the lithium ions can be embedded in the main area 12 of the anode more quickly, thereby improving the overall output power of the battery.

[0046] Alternatively, the minimum contact angle of the anode upper edge region 11 is twice the contact angle of the cathode upper edge region 11. By limiting the contact angle of the anode upper edge region 11, the wettability of the anode upper edge region 11 is improved. After the lithium ions are separated from the cathode, the lithium ions can be more quickly embedded in the anode edge region 11 due to the better wettability of the anode upper edge region 11, thereby improving the overall output power of the battery.

[0047] Alternatively, the minimum contact angle of the main area 12 on the anode is twice the contact angle of the edge area 11 on the anode. By limiting the contact angle of the main area 12 on the anode, the wettability of the main area 12 on the anode is improved. After the lithium ions are separated from the cathode, the lithium ions are more inclined to be embedded in the main area 12 of the anode due to the better wettability of the main area 12 on the anode, so that the energy density of the main area 12 of the anode is higher, the energy is concentrated and stored, and the lithium ions are prevented from being separated from the edge area 11 of the anode, thereby preventing the loss of internal energy of the battery.

[0048] Alternatively, the minimum contact angle of the main area 12 on the cathode is twice the contact angle of the edge area 11 on the cathode. By limiting the contact angle of the main area 12 on the cathode, the wettability of the main area 12 on the cathode is improved. After the lithium ions are separated from the anode, the lithium ions are more inclined to be embedded in the main area 12 of the cathode due to the better wettability of the main area 12 on the cathode, so that the energy density of the main area 12 of the cathode is higher, the energy is concentrated and stored, and the lithium ions are prevented from being separated from the edge area 11 of the cathode, thereby preventing the loss of internal energy of the battery.

[0049] In this embodiment, the time for lithium ions in the cathode main area 12 to migrate to the anode main area 12 is t1, and the time for lithium ions in the cathode edge area 11 to migrate to the anode edge area 11 is t2, and t1 and t2 satisfy the relationship: 0≤t1-t2≤0.5 seconds.

[0050] Specifically, the time difference between t1 and t2 is 0.1 second, 0.2 second, 0.3 second, 0.4 second and cannot exceed 0.5 second. If the time difference between t1 and t2 is too large or too small, it will cause inconsistent lithium ion migration rates in the main area 12 and the edge area 11 of the electrode 1, affecting the overall battery efficiency of the final battery.

[0051] In this embodiment, the width of the main area 12 of the anode is H1, the width of the edge area 11 of the anode is H2, the width of the main area 12 of the cathode is J1, and the width of the edge area 11 of the cathode is J2, satisfying the relationship: 0<H2

[0052] ​Specifically, the width of the main area 12 on the anode is greater than the width of the edge area 11 on the anode. After the lithium ions are embedded in the main area 12, the lithium ions embedded in the main area 12 are not easily separated from the electrode 1 due to the buffering of the edge areas 11 on both sides of the main area 12, thereby ensuring that the energy in the battery will not be lost. At the same time, the main area 12 can accommodate more lithium ions and prevent the lithium ions from escaping from the edge area 11.

[0053] In this embodiment, the width H2 of the edge region 11 of the anode is greater than or equal to the width J2 of the edge region 11 of the cathode.

[0054] Specifically, the width of the edge region 11 on the anode is greater than the width of the edge region 11 on the cathode, so that the edge region 11 of the anode can embed more lithium ions.

[0055] In this embodiment, the width of the anode upper edge region 11 is H2, satisfying the relationship: H2≤7mm,

[0056] Specifically, the edge area 11 of the anode is located on both sides of the main area 12 of the anode, and the edge area 11 of the anode is also the area closest to the outside. Therefore, the width of the edge area 11 of the anode cannot be too small, and a width of at least 7 mm is required to accommodate lithium ions that cannot be embedded in the main area 12 of the anode. At the same time, the lithium ions are buffered by the edge area 11 of the anode to prevent the lithium ions from escaping from the electrode 1 at the edge area 11 of the anode.

[0057] In this embodiment, the width of the cathode upper edge region 11 is J2, which satisfies the relationship: J2≤6 mm.

[0058] Specifically, the edge area 11 of the cathode is located on both sides of the main area 12 of the cathode, and the edge area 11 of the cathode is also the area closest to the outside. Therefore, the width of the edge area 11 of the cathode cannot be too small, and a width of at least 6 mm is required to accommodate lithium ions that cannot be embedded in the main area 12 of the cathode. At the same time, the lithium ions are buffered by the edge area 11 of the cathode to prevent the lithium ions from escaping from the electrode 1 at the edge area 11 of the cathode.

[0059] The specific embodiments are as follows:

[0060] Embodiment 1

[0061] In this embodiment, the contact angle A1 of the main body region 12 on the anode is: 40 degrees;

[0062] The contact angle A2 of the anode upper edge region 11 is: 16 degrees;

[0063] The contact angle B1 of the main area 12 on the cathode is: 40 degrees;

[0064] The contact angle B2 of the cathode upper edge region 11 is: 15 degrees;

[0065] A1 / B1 is 1.0; A2 / B2 is 1.1; A1 / A2 is 2.5; B1 / B2 is 2.7;

[0066] The friction coefficient e is: 0.20; -(e / A2-A1 / B1) is: 0.988.

[0067] Embodiment 2

[0068] In this embodiment, different from the first embodiment, the contact angle A1 of the main body region 12 on the anode is: 30 degrees;

[0069] The contact angle A2 of the anode upper edge region 11 is: 18 degrees;

[0070] The contact angle B1 of the main area 12 on the cathode is: 25 degrees;

[0071] The contact angle B2 of the cathode upper edge region 11 is: 15 degrees;

[0072] A1 / B1 is 1.2; A2 / B2 is 1.2; A1 / A2 is 1.7; B1 / B2 is 1.7;

[0073] The friction coefficient e is: 0.20; -(e / A2-A1 / B1) is: 1.189.

[0074] Although some parameters of this embodiment are modified compared with the first embodiment, they do not exceed the range defined in the first embodiment.

[0075] Embodiment 3

[0076] In this embodiment, different from the first embodiment, the contact angle A1 of the main body region 12 on the anode is: 20 degrees;

[0077] The contact angle A2 of the anode upper edge region 11 is: 10 degrees;

[0078] The contact angle B1 of the main area 12 on the cathode is: 20 degrees;

[0079] The contact angle B2 of the cathode upper edge region 11 is: 10 degrees;

[0080] A1 / B1 is 1.0; A2 / B2 is 1.0; A1 / A2 is 2.0; B1 / B2 is 2.0;

[0081] The friction coefficient e is: 0.20; -(e / A2-A1 / B1) is: 0.980.

[0082] Although some parameters of this embodiment are modified compared with the first embodiment, they do not exceed the range defined in the first embodiment.

[0083] Embodiment 4

[0084] In this embodiment, different from the first embodiment, the contact angle A1 of the main body region 12 on the anode is: 60 degrees;

[0085] The contact angle A2 of the anode upper edge region 11 is: 20 degrees;

[0086] The contact angle B1 of the main area 12 on the cathode is: 60 degrees;

[0087] The contact angle B2 of the cathode upper edge region 11 is: 20 degrees;

[0088] A1 / B1 is 1.0; A2 / B2 is 1.0; A1 / A2 is 3.0; B1 / B2 is 3.0;

[0089] The friction coefficient e is: 0.20; -(e / A2-A1 / B1) is: 0.990.

[0090] Although some parameters of this embodiment are modified compared with the first embodiment, they do not exceed the range defined in the first embodiment.

[0091] Embodiment 5

[0092] In this embodiment, different from the first embodiment, the contact angle A1 of the main body region 12 on the anode is: 40 degrees;

[0093] The contact angle A2 of the anode upper edge region 11 is: 16 degrees;

[0094] The contact angle B1 of the main area 12 on the cathode is: 40 degrees;

[0095] The contact angle B2 of the cathode upper edge region 11 is: 15 degrees;

[0096] A1 / B1 is 1.0; A2 / B2 is 1.1; A1 / A2 is 2.5; B1 / B2 is 2.7;

[0097] The friction coefficient e is 0.15; -(e / A2-A1 / B1) is: 0.990.

[0098] Although some parameters of this embodiment are modified compared with the first embodiment, they do not exceed the range defined in the first embodiment.

[0099] Embodiment 6

[0100] In this embodiment, different from the first embodiment, the contact angle A1 of the main body region 12 on the anode is: 40 degrees;

[0101] The contact angle A2 of the anode upper edge region 11 is: 16 degrees;

[0102] The contact angle B1 of the main area 12 on the cathode is: 40 degrees;

[0103] The contact angle B2 of the cathode upper edge region 11 is: 15 degrees;

[0104] A1 / B1 is 1.0; A2 / B2 is 1.1; A1 / A2 is 2.5; B1 / B2 is 2.7;

[0105] The friction coefficient e is 0.25; -(e / A2-A1 / B1) is: 0.984.

[0106] Although some parameters of this embodiment are modified compared with the first embodiment, they do not exceed the range defined in the first embodiment.

[0107] Comparative Example 1

[0108] In this comparative example, the difference from the first embodiment is that the contact angle A1 of the main body region 12 on the anode is: 70 degrees;

[0109] The contact angle A2 of the anode upper edge region 11 is: 5 degrees;

[0110] The contact angle B1 of the main area 12 on the cathode is: 70 degrees;

[0111] The contact angle B2 of the cathode upper edge region 11 is: 5 degrees;

[0112] A1 / B1 is 1.0; A2 / B2 is 1.0; A1 / A2 is 14.0; B1 / B2 is 14.0;

[0113] The friction coefficient e is: 0.20; -(e / A2-A1 / B1) is: 0.960.

[0114] In this comparative example, the contact angle exceeds or does not meet the range in the first embodiment, while the friction coefficient e and the relationship -(e / A2-A1 / B1) both meet the limited range in the first embodiment.

[0115] Comparative Example 2

[0116] In this comparative example, the difference from the first embodiment is that the contact angle A1 of the main body region 12 on the anode is: 40 degrees;

[0117] The contact angle A2 of the anode upper edge region 11 is: 16 degrees;

[0118] The contact angle B1 of the main area 12 on the cathode is: 40 degrees;

[0119] The contact angle B2 of the cathode upper edge region 11 is: 15 degrees;

[0120] A1 / B1 is 1.0; A2 / B2 is 1.1; A1 / A2 is 2.5; B1 / B2 is 2.7;

[0121] The friction coefficient e is: 0.50; -(e / A2-A1 / B1) is: 0.968.

[0122] In this comparative example, the friction coefficient e exceeds the range defined in the first embodiment, while the contact angle and the relationship -(e / A2-A1 / B1) both satisfy the range defined in the first embodiment.

[0123] Comparative Example 3

[0124] In this comparative example, the difference from the first embodiment is that the contact angle A1 of the main body region 12 on the anode is: 40 degrees;

[0125] The contact angle A2 of the anode upper edge region 11 is: 16 degrees;

[0126] The contact angle B1 of the main area 12 on the cathode is: 40 degrees;

[0127] The contact angle B2 of the cathode upper edge region 11 is: 15 degrees;

[0128] A1 / B1 is 1.0; A2 / B2 is 1.1; A1 / A2 is 2.5; B1 / B2 is 2.7;

[0129] The friction coefficient e is: 0.10; -(e / A2-A1 / B1) is: 0.993.

[0130] In this comparative example, the friction coefficient e is lower than the range defined in the first embodiment, while the contact angle and the relationship -(e / A2-A1 / B1) both satisfy the range defined in the first embodiment.

[0131] Comparative Example 4

[0132] In this comparative example, the contact angle A1 of the main body region 12 on the anode is: 40 degrees;

[0133] The contact angle A2 of the anode upper edge region 11 is: 10 degrees;

[0134] The contact angle B1 of the main area 12 on the cathode is: 20 degrees;

[0135] The contact angle B2 of the cathode upper edge region 11 is: 10 degrees;

[0136] A1 / B1 is 2.0; A2 / B2 is 1.0; A1 / A2 is 4.0; B1 / B2 is 2.0;

[0137] The friction coefficient e is: 0.20; -(e / A2-A1 / B1) is: 1.980.

[0138] In this comparative example, -(e / A2-A1 / B1) is: 1.980, which exceeds or does not meet the range defined in the embodiment, while the contact angle and the friction coefficient e both meet the range defined in the first embodiment.

[0139] Comparative Example 5

[0140] In this comparative example, the contact angle A1 of the main body region 12 on the anode is: 20 degrees;

[0141] The contact angle A2 of the anode upper edge region 11 is: 1 degree;

[0142] The contact angle B1 of the main area 12 on the cathode is: 20 degrees;

[0143] The contact angle B2 of the cathode upper edge region 11 is: 1 degree;

[0144] A1 / B1 is 1.0; A2 / B2 is 1.0; A1 / A2 is 20.0; B1 / B2 is 20.0;

[0145] The friction coefficient e is: 0.25; -(e / A2-A1 / B1) is: 0.750.

[0146] In this comparative example, the contact angles A2 and B2 are far lower than the range defined in Example 1. In this case, the final -(e / A2-A1 / B1) of 0.75 is also far lower than the range defined in Example 1.

[0147] Comparative Example 6

[0148] In this comparative example, the contact angle A1 of the main body region 12 on the anode is: 15 degrees;

[0149] The contact angle A2 of the anode upper edge region 11 is: 15 degrees;

[0150] The contact angle B1 of the main area 12 on the cathode is: 15 degrees;

[0151] The contact angle B2 of the cathode upper edge region 11 is: 5 degrees;

[0152] A1 / B1 is 1.0; A2 / B2 is 3.0; A1 / A2 is 1.0; B1 / B2 is 3.0;

[0153] The friction coefficient e is: 0.10; -(e / A2-A1 / B1) is: 0.993.

[0154] In this comparative example, the value of the friction coefficient e is lower than the range defined in the first embodiment, while the contact angle and the relationship -(e / A2-A1 / B1) both satisfy the range defined in the first embodiment.

[0155] The following figure is a specific data table of Example 1 to Comparative Example 6:

[0156]

[0157] Table 1

[0158] It should be noted that if the contact angle is less than 90 degrees, it means that the surface of the electrode 1 is hydrophilic, and the liquid can easily wet the electrode 1; if the contact angle is greater than 90 degrees, it means that the surface of the electrode 1 is hydrophobic, that is, the liquid is not easy to wet and fix, and the liquid can easily move on the surface of the electrode 1, thereby affecting the stability of the battery.

[0159] Then, Table 2 was obtained by testing different embodiments and comparative examples in Table 1. The following example was made into batteries by making the pole pieces 1 in the embodiments and comparative examples in Table 1. The initial capacity of the batteries was 5000 mAh. The batteries of different embodiments and comparative examples were tested, and finally the following Table 2 was obtained:

[0160]

[0161] Table 2

[0162] It can be seen from the data in Table 2 that the swelling percentages of the edge area 11 and the main area 12 of the electrode 1 in Example 1 are the lowest. Subsequently, the electrode 1 of different embodiments and comparative examples are assembled into batteries with a capacity of 5000 mAh for testing.

[0163] It can be seen from Table 2 that the battery in Example 1 is tested again after 1000 cycles, and the battery capacity is 4350mAh, while the battery capacities in Example 2 to Comparative Example 6 are 4250mAh, 4175mAh, 4200mAh, 4300mAh, 4322mAh, 4000mAh, 4050mAh, 4100mAh, 4100mAh, 3900mAh, and 3900mAh, respectively. From this, it can be seen that after 1000 cycles, the battery capacity of the battery in Example 1 is best maintained and the battery capacity loss is minimal.

[0164] And it can be seen from Table 2 that the battery made of the pole piece 1 in Examples 1 to 6 is measured, and its battery capacity retention rate is much higher than that of the battery made of the pole piece 1 in Comparative Examples 1 to 6. By comparing Examples 1 to 6 with Comparative Example 1, it can be seen that when the contact angle between the electrolyte and the pole piece body is too large, the friction coefficient is large. At this time, the window of the position of the battery cell pole piece body is satisfied, but the influence of the edge effect is still not eliminated at this time, so the battery cell still shows a thicker head. By comparing Examples 1 to 6 with Comparative Example 6, it can be seen that when the contact angle between the electrolyte and the pole piece body is too small, the friction coefficient is small, the dynamic performance of the entire battery is the worst, and the window of the electrochemical system is insufficient. At this time, the lithium precipitation of the pole piece of the battery cell body is the most serious, and the corresponding battery cell Swelling is the worst. At this time, there is still the influence of the edge effect, so there is still a difference between the battery cell head and the body Swelling. Therefore, only by controlling the relationship between the electrolyte, the pole piece body, the edge and the friction coefficient, can the dynamic performance of the entire battery system be optimized and the edge effect can be controlled within the optimal range.

[0165] In the present invention, the method of changing the contact angle and the friction coefficient is:

[0166] 1. Regulate the contact angle by changing environmental factors such as temperature and pressure;

[0167] 2. By controlling the injection efficiency, that is, by controlling the rate at which the electrolyte 2 flows out, the rate at which the electrolyte 2 flows out can be reduced or increased according to the large or small contact angle;

[0168] 3. Extend the vacuum standing time before injection from the original 24 hours to 48 hours;

[0169] 4. Extend the standing time after injection. Currently, the general method is "24 hours of standing at room temperature plus 24 hours of standing at high temperature". This can be changed to "24 hours of standing at room temperature plus 36 hours of standing at high temperature".

[0170] 5. The electrolyte 2 is injected in batches at different positions to facilitate the electrolyte 2 to fully infiltrate the electrode 1, thereby increasing the contact angle.

[0171] The greater the graphitization degree of graphite, the easier it is for the carbon material to be graphitized, and the higher the degree of order of its crystal structure. In the present invention, the graphitization degree is between 2.0 and 3.0. The higher the graphitization degree, the fewer the corresponding lattice defects, and the easier it is for lithium ions to enter the graphite and undergo an intercalation reaction in the graphite. It also provides space for subsequent lithium ions, especially when the kinetics are insufficient in the late cycle. By limiting this parameter at the source, the resistance to the intercalation reaction of lithium ions will be much smaller.

[0172] The specific methods to improve graphitization are: 1. Select high-quality raw materials. Different raw materials have different graphitization degrees. Selecting high-quality raw materials can improve the graphitization degree of the electrode;

[0173] 2. Improve the degree of graphitization. The degree of graphitization of graphite electrodes can be improved through multiple calcinations during the manufacturing process;

[0174] 3. Control the manufacturing process. Controlling the temperature and time during the manufacturing process can better control the graphitization degree of the graphite electrode.

[0175] Here, by limiting the relationship between the graphitization degree and contact angle of the negative electrode graphite, the head-tail reaction resistance is reduced, and the lithium ion migration rate gap between the head-tail and the main body is shortened to a deeper extent. At the same time, the migration resistance of electrons will also be smaller, and the polarization of the battery will be significantly improved. The overall dynamic performance of the battery is greatly improved.

[0176] In this application, by limiting parameters such as the contact angle, other additional effects are also achieved: improving battery cycle life; reducing battery polarization; the battery can cover a higher charging rate; reducing the injection time, improving production efficiency, saving production costs, saving energy, and contributing to carbon neutrality.

[0177] At the same time, the present invention also has other technical effects:

[0178] 1. The current K value of lithium-ion batteries is poor. By controlling the contact angles at different positions of the pole piece 1, the wettability of the electrolyte 2 at the edge of the pole piece 1 can be improved, thereby improving the K value;

[0179] 2. Inhibit polarization at the edge of pole piece 1, thereby improving interface resistance and extending service life;

[0180] 3. Control the contact angles at different positions to ensure the consistency of the cell thickness;

[0181] 4. The open circuit voltage of the battery is relatively stable when it is at rest, and the platform voltage is higher when it is discharged.

[0182] In some embodiments, a battery cell is also included, and the battery cell can be a rolled core or a laminated battery cell. It should be noted that other structures and operations of the battery cell are known to those skilled in the art and will not be described in detail here.

[0183] In the present invention, the cathode is the positive electrode, and the anode is the negative electrode.

[0184] The battery in the present invention may refer to a battery cell or a battery module, wherein a battery module includes a plurality of battery cells. A "battery" may also refer to a battery pack, which includes a plurality of grouped battery packs.

[0185] Specifically, the battery includes the above-mentioned battery cell, which includes a negative electrode sheet 1, a positive electrode sheet 1, a separator and an electrolyte 2. Since the battery cell is made using the above-mentioned structure, the battery of the embodiment of the present invention solves the problem of lithium deposition easily occurring at the head and tail of a multi-pole lithium-ion battery, thereby improving the electrical performance, safety performance and cycle life of the lithium-ion battery, and therefore has a higher weight energy density and good comprehensive performance.

[0186] In some embodiments, the positive electrode includes a positive current collector and a positive active material coated on the positive current collector, and the positive active material layer includes a binder, which improves the bonding between the positive active material particles and also improves the bonding between the positive active material and the current collector. Non-limiting examples of binders include polyvinyl alcohol, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene 1,1-difluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc.

[0187] In some embodiments, the positive electrode active material layer includes a conductive material to impart conductivity to the electrode. The conductive material may include any conductive material as long as it does not cause chemical changes. Non-limiting examples of conductive materials include carbon-based materials (e.g., natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, etc.), metal-based materials (e.g., metal powder, metal fiber, etc., including, for example, copper, nickel, aluminum, silver, etc.), conductive polymers (e.g., polyphenylene derivatives) and mixtures thereof.

[0188] In some embodiments, the negative electrode includes a negative electrode current collector and a negative electrode active material coated on the negative electrode current collector, and the negative electrode active material is selected from one or more of natural graphite, artificial graphite, mesophase microcarbon beads (referred to as MCMB), hard carbon, soft carbon, silicon, silicon-carbon composites, Li-Sn alloys, Li-Sn-O alloys, Sn, SnO, SnO2, spinel-structured lithiated TiO2-Li4Ti5O12, and Li-Al alloys.

[0189] In some embodiments, the negative electrode active material may include a binder that improves the bonding between the negative electrode active material particles and the bonding between the negative electrode active material and the current collector. Non-limiting examples of binders include polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyacrylic acid, polyacrylonitrile, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc.

[0190] In some embodiments, the negative electrode active material also includes a conductive material to impart conductivity to the electrode. The conductive material may include any conductive material as long as it does not cause chemical changes. Non-limiting examples of conductive materials include carbon-based materials (e.g., natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, etc.), metal-based materials (e.g., metal powder, metal fiber, etc., such as copper, nickel, aluminum, silver, etc.), conductive polymers (e.g., polyaniline, polythiophene, phenylene derivatives) and mixtures thereof.

[0191] In some embodiments, an isolation membrane is also included between the positive electrode and the negative electrode. There is no particular limitation on the isolation membrane, and any known porous structure isolation membrane with electrochemical stability and chemical stability can be selected. For example, it can be a single-layer or multi-layer film of one or more of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.

[0192] In some embodiments, the electrolyte 2 includes an organic solvent and an electrolyte salt. The organic solvent is used as a medium for transmitting ions in the electrochemical reaction, and an organic solvent known in the art for the electrochemical device electrolyte 22 can be used. The electrolyte salt is used as a source of ions, and an electrolyte salt known in the art for the electrochemical device electrolyte 22 can be used.

[0193] For example, the organic solvent used for lithium ion secondary batteries can be one or more of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), cyclopentane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS), and diethyl sulfone (ESE), preferably two or more.

[0194] For example, the electrolyte salt used in lithium-ion secondary batteries can be one or more of LiPF6 (lithium hexafluorophosphate), LiBF4 (lithium tetrafluoroborate), LiClO4 (lithium perchlorate), LiAsF6 (lithium hexafluoroarsenate), LiFSI (lithium bis(fluorosulfonyl)imide), LiTFSI (lithium bis(trifluoromethanesulfonyl)imide), LiTFS (lithium trifluoromethanesulfonate), LiDFOB (lithium difluorooxalatoborate), LiBOB (lithium dioxalatoborate), LiPO2F2 (lithium difluorophosphate), LiDFOP (lithium difluorobis(oxalatophosphate)) and LiTFOP (lithium tetrafluorooxalatophosphate).

[0195] The positive electrode, the separator and the negative electrode are stacked in order, and the separator is placed between the positive electrode sheet 1 and the negative electrode sheet 1 to play an isolating role, so as to obtain a battery cell, or the battery cell can be obtained by winding; the battery cell is placed in a shell, and the electrolyte 2 is injected and sealed to prepare a battery.

[0196] In addition, the embodiment of the present application also provides a battery module, including a box and a plurality of the above-mentioned batteries disposed in the box. The batteries are arranged in an orderly and tight manner in the box, and the battery module adopts the above-mentioned battery composition, so that the service life of the battery module is longer, and the battery efficiency of the battery module will not cause a large loss during long-term use.

[0197] In addition, an embodiment of the present application also provides an electrical device, including the above-mentioned battery module. The electrical device with such a battery module can have a longer service life.

[0198] Electrical equipment may be vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, electric tools, and the like. Vehicles may be fuel vehicles, gas vehicles, or new energy vehicles, and new energy vehicles may be pure electric vehicles, hybrid vehicles, or extended-range vehicles, and the like; spacecraft include airplanes, rockets, space shuttles, and spacecraft, and the like; electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, and the like; electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, and the like. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical equipment.

[0199] For the convenience of explanation, the following description takes the electric device as a vehicle as an example.

[0200] Exemplarily, the electrical device is a vehicle, and the battery pack is disposed inside the vehicle, and the battery pack can be disposed at the bottom, head, or tail of the vehicle. The battery pack can be used to power the vehicle, for example, the battery pack can be used as an operating power source for the vehicle.

[0201] The vehicle may also include a controller and a motor, wherein the controller is used to control the battery pack to provide power to the motor, for example, for starting, navigating, and operating power requirements of the vehicle during driving.

[0202] In some embodiments, the battery pack can not only be used as the operating power source of the vehicle, but also as the driving energy source of the vehicle, completely or partially replacing fuel or natural gas to provide driving force for the vehicle to meet the needs of vehicle driving.

[0203] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode includes only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

[0204] According to the disclosure and teaching of the above description, those skilled in the art to which the present invention belongs can also change and modify the above embodiment. Therefore, the present invention is not limited to the above specific embodiment, and any obvious improvement, replacement or modification made by those skilled in the art on the basis of the present invention belongs to the protection scope of the present invention. In addition, although some specific terms are used in this specification, these terms are only for the convenience of description and do not constitute any limitation to the present invention.

Claims

1. A battery, characterized in that: The invention comprises an electrolyte and an electrode, wherein the electrode contacts the electrolyte, a contact angle is formed between the electrode and the electrolyte, and the contact angle is 10°-60°. The surface of the electrode is coated with a graphite layer, and the friction coefficient e between the graphite layer and the electrolyte is 0.15 (N·m·s 2 )≤e≤0.25(N·m·s 2 ).

2. The battery according to claim 1, characterized in that: The surface of the electrolyte has a tangent, the edge of the electrolyte in contact with the electrode has a contact point, the contact point is located on the electrode, the tangent passes through the contact point and is tangent to the surface of the electrolyte, and the side of the tangent facing the electrolyte forms the contact angle with the surface of the electrode.

3. The battery according to claim 2, characterized in that: The electrode sheet comprises a main body region and an edge region, wherein the edge region is located on at least one side of the main body region, and when the electrolyte is located in the main body region, the contact angle is 20°-60°; When the electrolyte is located in the edge region, the contact angle is 10°-20°.

4. The battery according to claim 3, characterized in that: The pole piece includes an anode and a cathode, the contact angle of the electrolyte in the main area of ​​the anode is A1, the contact angle of the electrolyte in the edge area of ​​the anode is A2, the contact angle of the electrolyte in the main area of ​​the cathode is B1, and the contact angle of the electrolyte in the edge area of ​​the cathode is B2, satisfying the relationship: and / or, and / or, and / or, 5. The battery according to claim 4, characterized in that: The contact angle A1 of the graphite layer surface with the anode main region, the contact angle A2 of the anode edge region and the contact angle B1 of the cathode main region satisfy the relationship: 0.8<-(e1 / A2-A1 / B1)<1.

3.

6. The battery according to claim 5, characterized in that: The time for lithium ions in the main area of ​​the cathode to migrate to the main area of ​​the anode is t1, and the time for lithium ions in the edge area of ​​the cathode to migrate to the edge area of ​​the anode is t2. t1 and t2 satisfy the relationship: 0≤t1-t2≤0.5 seconds.

7. The battery according to claim 6, characterized in that: The width of the main area of ​​the anode is H1, the width of the edge area of ​​the anode is H2, the width of the main area of ​​the cathode is J1, and the width of the edge area of ​​the cathode is J2, satisfying the relationship: 0<H2<H1; and / or, 0<J2<J1.

8. The battery according to claim 7, characterized in that: The width H2 of the edge region of the anode is greater than or equal to the width J2 of the edge region of the cathode, the width H2 of the edge region of the anode is ≤7 mm, and the width J2 of the edge region of the cathode is ≤6 mm.

9. A battery module, characterized in that: It comprises a casing, in which the batteries according to multiple claims 1 to 8 are placed.

10. An electrical equipment, characterized in that: The battery module according to claim 9.

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