Pole piece, battery and electronic equipment

Abstract

The invention discloses a pole piece, a battery and electronic equipment, and relates to the technical field of batteries. The pole piece comprises a current collector, a coating and an active substance layer, the coating is arranged on the current collector in the thickness direction of the pole piece, the active substance layer is arranged on the side, away from the current collector, of the coating, the coating comprises at least one first coating and at least one second coating, and the first coating and the second coating are arranged in the direction perpendicular to the thickness of the pole piece. The at least one first coating and the at least one second coating are arranged. The at least one first coating and the at least one second coating are arranged, so that the arrangement form of the coatings is reasonable, the binding power between the current collector and the active material layer is improved, the risk that the active material layer falls off in the subsequent die cutting process and the use process is reduced, the yield is improved, and the use reliability of the pole piece is improved; and the high binding power is beneficial to reducing the resistance of the pole piece and further beneficial to improving the fast charging and power performance of the pole piece.

Description

Technical Field

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

[0002] In the related art, when designing and manufacturing pole pieces, it is necessary to consider the bonding force between the current collector and the active material. Sufficient bonding force can ensure that the active material does not fall off the current collector. The size of the bonding force is an important indicator for evaluating the stability of the pole piece structure. However, the bonding stability between the active material and the current collector is relatively poor, which makes it difficult to ensure the yield rate of the pole piece, seriously affecting the reliability of the pole piece. Moreover, due to the poor bonding force between the current collector and the active material, the pole piece resistance will be large, affecting the fast charging and power performance of the battery. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, one object of the present invention is to provide a pole piece, the bonding force between the current collector and the active material layer of the pole piece is strong, which can reduce the risk of the active material layer falling off during the subsequent die-cutting process and during use.

[0004] The present invention further provides a battery having the pole piece.

[0005] The invention further provides an electronic device having the battery.

[0006] According to an embodiment of the present invention, the pole piece includes: a current collector, a coating and an active material layer. Along the thickness direction of the pole piece, the coating is arranged on the current collector, and the active material layer is arranged on the side of the coating away from the current collector. The coating includes: at least one first coating and at least one second coating, the first coating is one of the conductive layer and the bonding layer, and the second coating is the other of the conductive layer and the bonding layer. Along the direction perpendicular to the thickness of the pole piece, at least one first coating and at least one second coating are arranged; taking the total mass of the coating as 100wt%, the content of the conductive layer is A, satisfying the relationship: 5wt%≤A≤70wt%, and the content of the bonding layer is B, satisfying the relationship: 30wt%≤B≤95wt%.

[0007] According to the pole piece of the embodiment of the present invention, by arranging at least one first coating and at least one second coating, the arrangement form of the coating can be made reasonable, which is beneficial to improving the bonding force between the current collector and the active material layer, reducing the risk of the active material layer falling off during the subsequent die-cutting process and during use, improving the yield rate, and improving the reliability of the pole piece. In addition, the high bonding force is beneficial to reducing the pole piece resistance, which is beneficial to improving the fast charging and power performance of the pole piece.

[0008] In an embodiment of the present invention, the first coating layer and the second coating layer are both multiple, and along a direction perpendicular to the thickness of the pole piece, the multiple first coating layers and the multiple second coating layers are alternately arranged in sequence.

[0009] In an embodiment of the present invention, both the first coating layer and the second coating layer are multiple, the multiple first coating layers are constructed into a grid-like structure, the grid-like structure defines a plurality of grids, and the multiple second coating layers are filled in the plurality of grids.

[0010] In an embodiment of the present invention, the first coating includes a plurality of first sub-coatings and a plurality of second sub-coatings, the first sub-coatings and the second sub-coatings are both one of the conductive layer and the bonding layer, the plurality of first sub-coatings are arranged at intervals along a first direction, and each two adjacent first sub-coatings are connected to a plurality of second sub-coatings arranged at intervals along a second direction, the plurality of first sub-coatings and the plurality of second sub-coatings define a plurality of grids, there are a plurality of second coatings, and the plurality of second coatings are filled in the plurality of grids, wherein the first direction and the second direction are both perpendicular to the thickness direction of the pole piece.

[0011] In an embodiment of the present invention, the single-sided surface density of the coating is C, which satisfies the relationship: 0.1 g / m 2 ≤C≤10g / m 2 ; and / or, the thickness of the coating is D, satisfying the relationship: 0.1μm≤D≤5μm.

[0012] In an embodiment of the present invention, the conductive layer includes: a first conductive agent and a first adhesive, the adhesive layer includes a second adhesive, and the first adhesive and the second adhesive are both high molecular polymers; the first conductive agent includes: at least one of conductive carbon black, KS-6, acetylene black, Ketjen black, conductive fiber, graphene, conductive graphite, graphene oxide, and carbon nanotubes; the first adhesive and the second adhesive both include: at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyethyleneimine, polyaniline, polyacrylic acid, sodium alginate, styrene-butadiene rubber, sodium carboxymethyl cellulose, phenolic resin, and epoxy resin.

[0013] In an embodiment of the present invention, the active material layer includes a first sub-active material layer and a second sub-active material layer, and the first sub-active material layer and the second sub-active material layer are overlapped along the thickness direction of the electrode, and the second sub-active material layer is located on the side of the first sub-active material layer away from the current collector; the first sub-active material layer includes: a first active material, and the second sub-active material layer includes: a second active material, and the first active material and the second active material are different in type and / or particle size and / or powder compaction density and / or specific surface area.

[0014] In an embodiment of the present invention, the particle size of the first active substance satisfies the relationship: 18 μm < D90 ≤ 30 μm and 10 μm < D50 ≤ 20 μm, the particle size of the second active substance satisfies the relationship: 5 μm ≤ D90 ≤ 18 μm and 2 μm ≤ D50 ≤ 10 μm; and / or the powder compaction density of the first active substance is E, which satisfies the relationship: 1.7 g / cm 3 <E≤2g / cm 3 , the powder compaction density of the second active substance is F, which satisfies the relationship: 1.0 g / cm 3 ≤F≤1.7g / cm 3 ; and / or, the specific surface area of ​​the first active substance is G, satisfying the relationship: 0.8g / m 2 ≤G<1.3g / m 2 , the specific surface area of ​​the second active material is H, satisfying the relationship: 1.3 g / m 2 ≤H≤5g / m 2 .

[0015] A battery according to an embodiment of the present invention includes an electrode assembly, which includes: a first pole piece, a second pole piece and a diaphragm, the first pole piece and / or the second pole piece are the above-mentioned pole pieces, and the first pole piece, the diaphragm and the second pole piece are assembled together to form the electrode assembly.

[0016] An electronic device according to an embodiment of the present invention includes the above-mentioned battery.

[0017] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0019] Figure 1 is a schematic diagram of a pole piece according to an embodiment of the present invention;

[0020] Figure 2 Schematic diagram of the distribution of the first coating and the second coating according to an embodiment of the present invention Figure 1 ;

[0021] Figure 3 Schematic diagram of the distribution of the first coating and the second coating according to an embodiment of the present invention Figure 2 ;

[0022] Figure 4 Schematic diagram of the distribution of the first coating and the second coating according to an embodiment of the present invention Figure 3 ;

[0023] Figure 5 Schematic diagram of the distribution of the first coating and the second coating according to an embodiment of the present invention Figure 4 .

[0024] Reference numerals:

[0025] current collector 1;

[0026] Coating 2; first coating 21; first sub-coating 211; second sub-coating 212; second coating 22;

[0027] Active material layer 3; first sub-active material layer 31; second sub-active material layer 32;

[0028] Pole piece 100. DETAILED DESCRIPTION

[0029] Embodiments of the present invention are described in detail below, examples of which 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 only used to explain the present invention, and cannot be understood as limiting the present invention.

[0030] Reference below Figure 1-Figure 5 A pole piece 100, a battery, and an electronic device according to an embodiment of the present invention are described.

[0031] like Figure 1 As shown, the pole piece 100 according to the embodiment of the present invention comprises: a current collector 1, a coating 2 and an active material layer 3, along the thickness direction of the pole piece 100 (ie Figure 1 The coating 2 is disposed on the current collector 1, and the active material layer 3 is disposed on the side of the coating 2 away from the current collector 1. The coating 2 includes: at least one first coating 21 and at least one second coating 22. The first coating 21 is one of the conductive layer and the bonding layer, and the second coating 22 is the other of the conductive layer and the bonding layer. Along a direction perpendicular to the thickness of the pole piece 100, at least one first coating 21 and at least one second coating 22 are arranged.

[0032] Among them, along the thickness direction of the pole piece 100 (ie Figure 1 The current collector 1, the coating 2, and the active material layer 3 are stacked. As some embodiments of the present application, along the thickness direction of the pole piece 100 (i.e. Figure 1 The coating 2 is disposed on both sides of the current collector 1, and the active material layer 3 can be disposed on the side of the coating 2 facing away from the current collector 1.

[0033] The current collector 1 can be copper foil, aluminum foil, composite current collector 1, etc. As some embodiments of the present application, the thickness of the current collector 1 can be any value between 2μm and 50μm. For example, the thickness of the current collector 1 can be but not limited to 2μm, 5μm, 20μm, 50μm, etc. The current collector 1 can be used to collect and conduct current to ensure that the electrons in the battery or electrochemical device can flow smoothly. The coating 2 has the functions of enhancing adhesion, improving conductivity, and protecting the current collector 1. The coating 2 includes at least one first coating 21 and at least one second coating 22. The first coating 21 can be one of the conductive layer and the bonding layer, and the second coating 22 can be the other of the conductive layer and the bonding layer. The conductive layer is used to provide a conductive path, and the bonding layer is used to bond the conductive layer, the current collector 1 and the active material layer 3. At least one first coating 21 and at least one second coating 22 are arranged in a direction perpendicular to the thickness of the electrode 100.

[0034] It should be noted that by arranging at least one first coating 21 and at least one second coating 22 in a direction perpendicular to the thickness of the pole piece 100, during rolling, the temperature can be increased to partially melt the bonding layer to increase the bonding force between the current collector 1 and the active material layer 3, so that the current collector 1 and the active material layer 3 have good and reliable bonding, which can reduce the risk of the active material layer 3 falling off during the subsequent die-cutting process and during use. In addition, by ensuring that the current collector 1 and the active material layer 3 have good and reliable bonding, the resistance of the pole piece 100 can be reduced, which is beneficial to improving the fast charging and power performance of the pole piece 100, and can make the battery using the pole piece 100 have excellent performance.

[0035] In the above embodiment, by arranging at least one first coating 21 and at least one second coating 22, the arrangement form of the coating 2 can be made reasonable, which is beneficial to improving the bonding force between the current collector 1 and the active material layer 3, reducing the risk of the active material layer 3 falling off during the subsequent die-cutting process and during use, improving the yield rate, and improving the reliability of the pole piece 100. In addition, the high bonding force is beneficial to reducing the resistance of the pole piece 100, and further beneficial to improving the fast charging and power performance of the pole piece 100.

[0036] In an embodiment of the present invention, Figure 2 and Figure 3 As shown, there are multiple first coatings 21 and multiple second coatings 22 , and along a direction perpendicular to the thickness of the pole piece 100 , the multiple first coatings 21 and the multiple second coatings 22 are alternately arranged in sequence.

[0037] Among them, both the first coating 21 and the second coating 22 can be multiple, and the multiple first coatings 21 and the multiple second coatings 22 are arranged alternately in sequence, that is, along the direction perpendicular to the thickness of the pole piece 100, except for the first coating 21 and the second coating 22 at the edge, each first coating 21 is adjacent to the second coating 22 on both sides, and each second coating 22 is adjacent to the first coating 21 on both sides, so that the first coating 21 and the second coating 22 can be more evenly distributed in the coating 2, so that the bonding force between the current collector 1 and the active material layer 3 at various locations can be uniform, which can further reduce the risk of the active material layer 3 falling off during the subsequent die-cutting process and during use, and can improve the conductive performance of the pole piece 100.

[0038] It should be noted that if Figure 2 and Figure 3 As shown, the extension direction of the plurality of first coatings 21 and the plurality of second coatings 22 may be aligned with the length direction of the pole piece 100 (i.e. Figure 2 and Figure 3 Alternatively, the extending direction of the plurality of first coatings 21 and the plurality of second coatings 22 may be the same as the length direction of the pole piece 100 (ie, the X direction shown in FIG. 1 ). Figure 2 and Figure 3 There is a certain angle between the pole piece 100 and the pole piece 100, so that the manufacturing of the pole piece 100 can be more flexible to meet different functional requirements.

[0039] In another embodiment of the present invention, Figure 4 As shown, there are multiple first coatings 21 and multiple second coatings 22. The multiple first coatings 21 are constructed into a grid-like structure. The grid-like structure defines multiple grids, and the multiple second coatings 22 are filled in the multiple grids.

[0040] Among them, constructing multiple first coatings 21 into a grid structure can increase the distribution range of the first coating 21, and the arrangement of multiple second coatings 22 filled in multiple grids can increase the distribution range of the second coating 22, so that the distribution of the first coating 21 and the second coating 22 is more uniform, so that the bonding force between the current collector 1 and the active material layer 3 at all locations can be uniform, which can further reduce the risk of the active material layer 3 falling off during the subsequent die-cutting process and during use, and can improve the conductive performance of the pole piece 100.

[0041] In yet another embodiment of the present invention, Figure 5As shown, the first coating 21 includes multiple first sub-coatings 211 and multiple second sub-coatings 212, the first sub-coatings 211 and the second sub-coatings 212 are both one of the conductive layer and the bonding layer, the multiple first sub-coatings 211 are arranged at intervals along the first direction, and each two adjacent first sub-coatings 211 are connected to multiple second sub-coatings 212 arranged at intervals along the second direction, the multiple first sub-coatings 211 and the multiple second sub-coatings 212 define multiple grids, there are multiple second coatings 22, and the multiple second coatings 22 are filled in the multiple grids, wherein the first direction and the second direction are both perpendicular to the thickness direction of the pole piece 100.

[0042] Among them, the first coating 21 includes multiple first sub-coatings 211 and multiple second sub-coatings 212, the first sub-coatings 211 can extend along the first direction, and the multiple first sub-coatings 211 are arranged at intervals along the second direction, the second sub-coatings 212 can extend along the second direction, and each adjacent two first sub-coatings 211 are connected with multiple second sub-coatings 212 arranged at intervals along the first direction. The first direction and the second direction are both perpendicular to the thickness direction of the pole piece 100, and the first direction and the second direction can be perpendicular to each other. The multiple first sub-coatings 211 and the multiple second sub-coatings 212 can define multiple grids, and the multiple second coatings 22 can be filled in the multiple grids. This arrangement can make the distribution of the first coating 21 and the second coating 22 more uniform, so that the bonding force between each part of the current collector 1 and the active material layer 3 can be uniform, which can further reduce the risk of the active material layer 3 falling off during the subsequent die-cutting process and during use, and can improve the conductive performance of the pole piece 100.

[0043] In the embodiment of the present invention, taking the total mass of the coating 2 as 100wt%, the content of the conductive layer is A, satisfying the relationship: 5wt%≤A≤70wt%, and the content of the bonding layer is B, satisfying the relationship: 30wt%≤B≤95wt%.

[0044] The content A of the conductive layer may satisfy the relationship: 5wt%≤A≤70wt%, that is, the content A of the conductive layer may be any value between 5wt% and 70wt%, for example, the content A of the conductive layer may be but not limited to 5wt%, 30wt%, 50wt%, 70wt%, etc. This arrangement may make the content A of the conductive layer reasonable and improve the conductive performance of the electrode 100.

[0045] The content B of the bonding layer can satisfy the relationship: 30wt%≤B≤95wt%, that is, the content B of the bonding layer can be any value between 30wt% and 95wt%, for example, the content B of the bonding layer can be but not limited to 30wt%, 50wt%, 70wt%, 95wt%, etc. Such a setting can make the content of the bonding layer reasonable, can improve the bonding force between the current collector 1 and the active material layer 3, can reduce the risk of the active material layer 3 falling off, and is conducive to improving the stability and safety of the pole piece 100.

[0046] In the embodiment of the present invention, the single-sided surface density of the coating 2 is C, which satisfies the relationship: 0.1 g / m 2 ≤C≤10g / m 2 , and / or, the thickness of the coating 2 is D, satisfying the relationship: 0.1μm≤D≤5μm.

[0047] The single-sided surface density C of the coating 2 can satisfy the relationship: 0.1 g / m 2 ≤C≤10g / m 2 That is, the single-sided surface density C of the coating 2 can be 0.1 g / m 2 Up to 10g / m 2 For example, the single-sided surface density C of the coating 2 may be, but is not limited to, 0.1 g / m 2 , 1g / m 2 , 5g / m 2 , 10g / m 2 Such a configuration can make the single-side surface density of the coating 2 reasonable, can make the pole piece 100 have excellent energy density and power density, can improve the conductive performance of the pole piece 100, and can improve the bonding force between the current collector 1 and the active material layer 3.

[0048] The thickness D of the coating 2 may satisfy the relationship: 0.1 μm ≤ D ≤ 5 μm, that is, the thickness D of the coating 2 may be any value between 0.1 μm and 5 μm, for example, the thickness D of the coating 2 may be, but is not limited to, 0.1 μm, 1 μm, 3 μm, 5 μm, etc. This arrangement may make the thickness of the coating 2 reasonable, may save costs while ensuring the function of the pole piece 100, and may make the thickness of the pole piece 100 smaller, thereby facilitating the improvement of the battery capacity.

[0049] In an embodiment of the present invention, the conductive layer includes: a first conductive agent and a first adhesive, the adhesive layer includes a second adhesive, and both the first adhesive and the second adhesive are high molecular polymers.

[0050] Among them, the conductive layer may include a first conductive agent and a first adhesive. The first conductive agent can collect the microcurrent between the current collector 1 and the active material layer 3 to reduce the contact resistance of the electrode and accelerate the movement rate of electrons, thereby improving the charging and discharging performance. The first adhesive and the second adhesive can be used to bond the first conductive agent to the connected current collector 1 and the active material layer 3. The first adhesive and the second adhesive can both be polymers. The polymer has good adhesion and plasticity, which can enable the first adhesive and the second adhesive to better bond the conductive layer to the connected current collector 1 and the active material layer 3, and can also reduce the risk of the active material layer 3 falling off, which is beneficial to improving the stability and safety of the electrode 100.

[0051] In an embodiment of the present invention, the first conductive agent includes: at least one of conductive carbon black, KS-6, acetylene black, Ketjen black, conductive fiber, graphene, conductive graphite, graphene oxide, and carbon nanotubes, and / or the first binder and the second binder both include: at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyethyleneimine, polyaniline, polyacrylic acid, sodium alginate, styrene-butadiene rubber, sodium carboxymethyl cellulose, phenolic resin, and epoxy resin.

[0052] Among them, the first conductive agent may include at least one of conductive carbon black, KS-6, acetylene black, Ketjen black, conductive fiber, graphene, conductive graphite, graphene oxide, and carbon nanotubes. For example, the first conductive agent may include conductive carbon black, KS-6, and acetylene black. The first conductive agent may also include conductive carbon black, Ketjen black, conductive fiber, and graphene. The first conductive agent may also include acetylene black, conductive graphite, graphene oxide, and carbon nanotubes. In this way, the material included in the first conductive agent can be selected according to product requirements, which is beneficial to improving the selectivity of the first conductive agent. In addition, by making the first conductive agent include multiple materials at the same time, the charging and discharging performance can be improved.

[0053] The first binder and the second binder may both include at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyethylene imine, polyaniline, polyacrylic acid, sodium alginate, styrene-butadiene rubber, sodium carboxymethyl cellulose, phenolic resin, and epoxy resin. For example, the first binder and the second binder may both include polyvinylidene fluoride, polytetrafluoroethylene, and polyethylene imine. The first binder and the second binder may also include polyaniline, polyacrylic acid, and sodium alginate. In this way, the materials included in the first binder and the second binder may be selected according to product requirements, which is beneficial to improving the selectivity of the first binder and the second binder. In addition, by making the first binder and the second binder include multiple materials at the same time, the bonding performance may be improved.

[0054] In an embodiment of the present invention, Figure 1As shown, the active material layer 3 includes a first sub-active material layer 31 and a second sub-active material layer 32. Along the thickness direction of the electrode 100, the first sub-active material layer 31 and the second sub-active material layer 32 are overlapped, and the second sub-active material layer 32 is located on the side of the first sub-active material layer 31 away from the current collector 1. The first sub-active material layer 31 includes: a first active material, and the second sub-active material layer 32 includes: a second active material. The first active material and the second active material are different in type and / or particle size and / or powder compaction density and / or specific surface area.

[0055] Among them, along the thickness direction of the pole piece 100, the current collector 1, the coating 2, the first sub-active material layer 31 and the second sub-active material layer 32 are stacked in sequence, and the second sub-active material layer 32 is located on the side of the first sub-active material layer 31 away from the current collector 1. The first active material and the second active material are different in type and / or particle size and / or powder compaction density and / or specific surface area. For example, the first active material of the first sub-active material layer 31 and the second active material of the second sub-active material layer 32 may be different in type and particle size, or the first active material of the first sub-active material layer 31 and the second active material of the second sub-active material layer 32 may be different in powder compaction density and specific surface area, or the first active material of the first sub-active material layer 31 and the second active material of the second sub-active material layer 32 may be different in type, particle size, powder compaction density and specific surface area. Such a configuration can make the pole piece 100 have the advantages of high energy density, excellent cycle performance and fast charging performance.

[0056] In an embodiment of the present invention, the particle size of the first active substance is greater than the particle size of the second active substance; and / or the powder compaction density of the first active substance is greater than the powder compaction density of the second active substance; and / or the specific surface area of ​​the first active substance is smaller than the specific surface area of ​​the second active substance.

[0057] By making the particle size of the first active material larger than the particle size of the second active material, the performance of the active material layer 3 can be optimized. For example, the energy density, fast charging performance and cycle performance of the active material layer 3 can be improved, and excellent performance matching of the materials can be achieved to improve the efficiency and performance of the electrode 100.

[0058] By making the powder compaction density of the first active material greater than the powder compaction density of the second active material, the first active material can absorb pressure during the rolling process, and can effectively absorb the pressure of the second sub-active material layer 32, reducing the risk of overpressure of the second active material, so that the second sub-active material layer 32 has excellent power performance, and can improve the overall performance and stability of the battery.

[0059] By making the specific surface area of ​​the first active material smaller than the specific surface area of ​​the second active material, the electrochemical performance of the electrode sheet 100 can be improved, the internal resistance can be reduced, the capacity can be increased, and the cycle performance and rate performance can be improved.

[0060] In an embodiment of the present invention, the particle size of the first active material satisfies the relationship: 18 μm<D90≤30 μm and 10 μm<D50≤20 μm, and the particle size of the second active material satisfies the relationship: 5 μm≤D90≤18 μm and 2 μm≤D50≤10 μm.

[0061] Among them, the particle size of the first active substance can satisfy the relationship: 18μm<D90≤30μm and 10μm<D50≤20μm, that is, 90% of the particle size of the first active substance can be any value between 18μm (excluding 18μm) and 30μm, and 50% of the particle size of the first active substance can be any value between 10μm (excluding 10μm) and 20μm. For example, the particle size of the first active substance can be but is not limited to 11μm, 18μm, 20μm, 30μm, etc.

[0062] The particle size of the second active material can satisfy the relationship: 5μm≤D90≤18μm and 2μm≤D50≤10μm, that is, the particle size of 90% of the second active material can be any value between 5μm and 18μm, and the particle size of 50% of the first active material can be any value between 2μm and 10μm, for example, the particle size of the second active material can be but not limited to 2μm, 5μm, 10μm, 18μm, etc. Such a setting can make the particle size of the first active material and the particle size of the second active material reasonable, and can make the particle size of 90% of the first active material larger than the particle size of 90% of the second active material, and can make the particle size of 50% of the first active material larger than the particle size of 50% of the second active material, and can achieve excellent performance matching of materials to improve the efficiency and performance of the pole piece 100.

[0063] In an embodiment of the present invention, the powder compaction density of the first active material is E, which satisfies the relationship: 1.7 g / cm 3 <E≤2g / cm 3 , the powder compaction density of the second active material is F, which satisfies the relationship: 1.0 g / cm 3 ≤F≤1.7g / cm 3 .

[0064] The powder compaction density E of the first active material can satisfy the relationship: 1.7 g / cm 3 <E≤2g / cm 3 That is, the powder compaction density E of the first active material can be 1.7 g / cm 3(excluding 1.7g / cm 3 ) to 2g / cm 3 For example, the powder compaction density E of the first active material may be, but is not limited to, 1.75 g / cm 3 , 1.8g / cm 3 , 1.9g / cm 3 , 2g / cm 3 Such an arrangement can make the powder compaction density of the first active material reasonable, and the first sub-active material layer 31 can absorb pressure during the rolling process, and can effectively absorb the pressure of the second sub-active material layer 32, thereby reducing the risk of overpressure in the second sub-active material layer 32, thereby maintaining the power performance of the second sub-active material layer 32, and improving the overall performance and stability of the battery.

[0065] The powder compaction density F of the second active material can satisfy the relationship: 1.0 g / cm 3 ≤F≤1.7g / cm 3 That is, the powder compaction density E of the second active material can be 1.0 g / cm 3 Up to 1.7g / cm 3 For example, the powder compaction density E of the second active material may be, but is not limited to, 1.0 g / cm 3 , 1.2g / cm 3 , 1.5g / cm 3 , 1.7g / cm 3 Such an arrangement can make the powder compaction density of the second active material reasonable, and can make the powder compaction density of the second active material smaller than the powder compaction density of the first active material, so that the active material layer 3 can have excellent electrochemical reaction efficiency, so that the battery has excellent charge and discharge performance.

[0066] In the embodiment of the present invention, the specific surface area of ​​the first active material is G, which satisfies the relationship: 0.8 g / m 2 ≤G<1.3g / m 2 , the specific surface area of ​​the second active material is H, which satisfies the relationship: 1.3 g / m 2 ≤H≤5g / m 2 .

[0067] The specific surface area G of the first active material can satisfy the relationship: 0.8 g / m 2 ≤G<1.3g / m 2 That is to say, the specific surface area G of the first active material can be 0.8 g / m 2 Up to 1.3g / m 2 (excluding 1.3g / m 2), for example, the specific surface area G of the first active material may be, but is not limited to, 0.8 g / m 2 , 0.9g / m 2 , 1.1g / m 2 , 1.2g / m 2 Such a configuration can make the specific surface area of ​​the first active material reasonable, can improve the electrochemical performance of the electrode 100, can reduce the internal resistance, increase the capacity, and improve the cycle performance and rate performance.

[0068] The specific surface area H of the second active material can satisfy the relationship: 1.3 g / m 2 ≤H≤5g / m 2 That is to say, the specific surface area H of the second active material can be 1.3 g / m 2 Up to 5g / m 2 For example, the specific surface area H of the second active material may be, but is not limited to, 1.3 g / m 2 , 2g / m 2 , 3g / m 2 , 5g / m 2 Such an arrangement can make the specific surface area of ​​the second active material reasonable, and can make the specific surface area of ​​the second active material larger than the specific surface area of ​​the first active material, so that the active material layer 3 can have excellent electrochemical reaction efficiency, and can improve the cycle stability of the battery so that the battery has excellent charge and discharge performance.

[0069] In the embodiment of the present invention, the first sub-active material layer 31 and the second sub-active material layer 32 both further include: a second conductive agent and a third binder, and the third binder is a high molecular polymer.

[0070] Among them, the first sub-active material layer 31 and the second sub-active material layer 32 can also include a second conductive agent and a third binder. The first conductive agent can collect the microcurrent between the current collector 1 and the active material layer 3 to reduce the contact resistance of the electrode and accelerate the movement rate of electrons, thereby improving the charging and discharging performance. The third binder can be used to bond the second conductive agent to the connected structure. The third binder can be a polymer. The polymer has good adhesion and plasticity, which can make the first sub-active material layer 31 and the second sub-active material layer 32 better bonded to each other, and make the first sub-active material layer 31 better bonded to the coating 2, so as to improve the stability and safety of the electrode 100.

[0071] In an embodiment of the present invention, the first active substance and the second active substance both include: at least one of graphite, silicon, hard carbon, soft carbon, silicon carbon, tin, and lithium titanate, and the graphite includes artificial graphite and / or natural graphite; or, the first active substance and the second active substance both include: at least one of lithium cobalt oxide, lithium manganese oxide, lithium titanate, lithium iron phosphate, and nickel cobalt manganese oxide.

[0072] As some embodiments of the present application, the pole piece 100 can be a positive pole piece, and the first active material and the second active material both include: at least one of graphite, silicon, hard carbon, soft carbon, silicon carbon, tin, and lithium titanate. For example: the first active material and the second active material both include graphite, silicon, and hard carbon, or the first active material and the second active material both include soft carbon, silicon carbon, tin, and lithium titanate, or the first active material and the second active material both include graphite, tin, and lithium titanate. The materials included in the first active material and the second active material can be selected according to product requirements to improve the selectivity of the first active material and the second active material, and by making the first active material and the second active material both include multiple materials, it is beneficial to improve the charge and discharge performance of the battery.

[0073] As some embodiments of the present application, the electrode 100 can be a negative electrode electrode, and the first active material and the second active material both include: at least one of lithium cobalt oxide, lithium manganese oxide, lithium titanate, lithium iron phosphate and nickel cobalt manganese oxide. For example, the first active material and the second active material both include lithium cobalt oxide and lithium manganese oxide, or the first active material and the second active material both include lithium titanate and lithium iron phosphate, or the first active material and the second active material both include lithium cobalt oxide and nickel cobalt manganese oxide. The materials included in the first active material and the second active material can be selected according to product requirements to improve the selectivity of the first active material and the second active material, and by making the first active material and the second active material both include multiple materials, it is beneficial to improve the charge and discharge performance of the battery.

[0074] It is understandable that natural graphite can make the first active material and the second active material have good high temperature resistance, electrical conductivity, chemical stability, and environmental protection, and artificial graphite can make the first active material and the second active material have good electrical conductivity, long cycle life, safety, and wide applicability. As some embodiments of the present application, the pole piece 100 proposed in the present application can be made by the following steps:

[0075] In the first step, 1 part of conductive agent, 1 part of adhesive, and 10 parts of deionized water are prepared into a conductive layer slurry.

[0076] In the second step, 1 part of adhesive and 20 parts of deionized water are prepared into a bonding layer slurry.

[0077] In the third step, the conductive layer slurry and the bonding layer slurry are alternately coated on the surface of the current collector 1 by gap extrusion. After drying at 110°C, the first sub-active material layer 31 and the second sub-active material layer 32 are coated. The coating surface density of the first sub-active material layer 31 and the second sub-active material layer 32 are both 50g / m 2 , dried at 110℃.

[0078] The fourth step is to assemble the prepared double-layer coated negative electrode sheet and lithium iron phosphate electrode sheet into a battery, and assemble the battery with the positive electrode sheet, carbonate electrolyte, and separator; the compacted density of the positive electrode sheet powder is 2.45g / cm 3 , single surface density 200g / m 2 The compacted density of the negative electrode powder is 1.6g / cm 3 , single surface density is 90g / cm 3 The diaphragm adopts a single-sided ceramic double-sided adhesive PE diaphragm, the electrolyte is 1M / L LiPF6, and the solution of EC:EMC:DEC=1:1:1, and the battery design capacity is 5Ah soft-pack laminated battery.

[0079] This application prepared six embodiments of the pole piece 100 (embodiment 1 to embodiment 6), and the data are shown in the following table:

[0080]

[0081] According to the above experimental steps, the comparative experiment is carried out as follows, and the specific differences are as follows:

[0082] Comparative Example 1: No carbon coating was performed, plain foil was used as the current collector, and other preparation methods were the same as those in Example 1;

[0083] Comparative Example 2: conventional carbon coating layer 1 μm, single-sided surface density 0.6 g / m 2 , the conductive agent and the binder are not arranged alternately, and the preparation method is the same as that of Example 2;

[0084] Comparative Example 3, only the conductive layer is coated without the adhesive layer coating, and the other preparation methods are the same as those in Example 1;

[0085] Comparative Example 4, only the adhesive layer is coated, and the conductive layer is not coated. The other preparation methods are the same as those in Example 1;

[0086] Comparative Examples 1-4 are the same as the embodiments except for the above differences. Relevant tests were conducted on the above embodiments and comparative examples, and the test results of the above embodiments and comparative examples are shown in the following table:

[0087]

[0088] It can be seen from Examples 1-6 and Comparative Examples 1-4 that the electrode 100 proposed in the present invention having an alternating arrangement of the first coating 21 and the second coating 22 and a double-layer active material layer 3 significantly improves the adhesion of the diaphragm, reduces the internal resistance, and is beneficial to improving low temperature, fast charging performance, cycle performance, and energy density.

[0089] According to an embodiment of the present invention, the battery includes an electrode assembly, and the electrode assembly includes: a first electrode piece, a second electrode piece and a diaphragm. The first electrode piece and / or the second electrode piece is the electrode piece 100 of the above embodiment. The first electrode piece, the diaphragm and the second electrode piece are assembled to form an electrode assembly. By arranging at least one first coating 21 and at least one second coating 22, the arrangement form of the coating 2 can be reasonable, the bonding force between the current collector 1 and the active material layer 3 can be improved, the risk of the active material layer 3 falling off during the subsequent die-cutting process and during use can be reduced, the yield rate can be improved, the reliability of the use of the electrode piece 100 can be improved, and better bonding can reduce the resistance of the electrode piece 100, which is conducive to improving the fast charging and power performance of the electrode piece 100.

[0090] The device according to the embodiment of the present invention includes the above-mentioned battery. By arranging at least one first coating 21 and at least one second coating 22, the arrangement form of the coating 2 can be reasonable, which is conducive to improving the bonding force between the current collector 1 and the active material layer 3, reducing the risk of the active material layer 3 falling off during the subsequent die-cutting process and during use, improving the yield rate, and improving the reliability of the pole piece 100. In addition, the high bonding force is conducive to reducing the resistance of the pole piece 100, which is conducive to improving the fast charging and power performance of the pole piece 100.

[0091] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0092] In the description of the present invention, "first feature" or "second feature" may include one or more of the features.

[0093] In the description of the present invention, "plurality" means two or more.

[0094] In the description of the present invention, a first feature being “on” or “under” a second feature may include that the first and second features are directly in contact with each other, or may include that the first and second features are not in direct contact with each other but are in contact with each other via another feature therebetween.

[0095] In the description of the present invention, “on”, “over” and “above” a first feature from a second feature includes the first feature being directly above and obliquely above the second feature, or simply means that the first feature is horizontally higher than the second feature.

[0096] In the description of this specification, the description with reference to the terms "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 schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0097] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A pole piece (100), characterized in that: include: A current collector (1), a coating (2) and an active material layer (3), wherein along the thickness direction of the pole piece (100), the coating (2) is arranged on the current collector (1), and the active material layer (3) is arranged on a side of the coating (2) away from the current collector (1), the coating (2) comprises: at least one first coating (21) and at least one second coating (22), the first coating (21) being one of a conductive layer and an adhesive layer, and the second coating (22) being the other of the conductive layer and the adhesive layer, and along a direction perpendicular to the thickness of the pole piece (100), at least one first coating (21) and at least one second coating (22) are arranged; Taking the total mass of the coating (2) as 100wt%, the content of the conductive layer is A, satisfying the relationship: 5wt%≤A≤70wt%, and the content of the bonding layer is B, satisfying the relationship: 30wt%≤B≤95wt%.

2. The pole piece (100) according to claim 1, characterized in that: Both the first coating (21) and the second coating (22) are multiple, and along a direction perpendicular to the thickness of the pole piece (100), the multiple first coatings (21) and the multiple second coatings (22) are alternately arranged in sequence.

3. The pole piece (100) according to claim 1, characterized in that: The first coating (21) and the second coating (22) are both multiple, and the multiple first coatings (21) are constructed into a grid-like structure, the grid-like structure defines a plurality of grids, and the multiple second coatings (22) are filled in the plurality of grids.

4. The pole piece (100) according to claim 1, characterized in that: The first coating (21) comprises a plurality of first sub-coatings (211) and a plurality of second sub-coatings (212); the first sub-coatings (211) and the second sub-coatings (212) are each one of the conductive layer and the bonding layer; the plurality of first sub-coatings (211) are arranged at intervals along a first direction; each two adjacent first sub-coatings (211) are connected to a plurality of second sub-coatings (212) arranged at intervals along a second direction; the plurality of first sub-coatings (211) and the plurality of second sub-coatings (212) define a plurality of grids; there are a plurality of second coatings (22); the plurality of second coatings (22) are filled in the plurality of grids; wherein the first direction and the second direction are both perpendicular to the thickness direction of the pole piece (100).

5. The pole piece (100) according to claim 1, characterized in that: The single-sided surface density of the coating (2) is C, which satisfies the relationship: 0.1 g / m 2 ≤C≤10g / m 2 ; And / or, the thickness of the coating (2) is D, satisfying the relationship: 0.1 μm≤D≤5 μm.

6. The pole piece (100) according to claim 1, characterized in that: The conductive layer includes: a first conductive agent and a first adhesive, the adhesive layer includes a second adhesive, and the first adhesive and the second adhesive are both high molecular polymers; The first conductive agent includes: at least one of conductive carbon black, KS-6, acetylene black, Ketjen black, conductive fiber, graphene, conductive graphite, graphene oxide, and carbon nanotubes; the first binder and the second binder both include: at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyethyleneimine, polyaniline, polyacrylic acid, sodium alginate, styrene-butadiene rubber, sodium carboxymethyl cellulose, phenolic resin, and epoxy resin.

7. The pole piece (100) according to any one of claims 1 to 6, characterized in that: The active material layer (3) comprises a first sub-active material layer (31) and a second sub-active material layer (32); along the thickness direction of the pole piece (100), the first sub-active material layer (31) and the second sub-active material layer (32) are stacked, and the second sub-active material layer (32) is located on a side of the first sub-active material layer (31) away from the current collector (1); The first sub-active material layer (31) comprises a first active material, and the second sub-active material layer (32) comprises a second active material, wherein the first active material and the second active material are different in type and / or particle size and / or powder compaction density and / or specific surface area.

8. The pole piece (100) according to claim 7, wherein the particle size of the first active material satisfies the relationship: 18 μm < D90 ≤ 30 μm and 10 μm < D50 ≤ 20 μm, and the particle size of the second active material satisfies the relationship: 5 μm ≤ D90 ≤ 18 μm and 2 μm ≤ D50 ≤ 10 μm; And / or, the powder compaction density of the first active substance is E, which satisfies the relationship: 1.7 g / cm 3 <E≤2g / cm 3 , the powder compaction density of the second active substance is F, which satisfies the relationship: 1.0 g / cm 3 ≤F≤1.7g / cm 3 ; And / or, the specific surface area of ​​the first active material is G, which satisfies the relationship: 0.8 g / m 2 ≤G<1.3g / m 2 , the specific surface area of ​​the second active material is H, satisfying the relationship: 1.3 g / m 2 ≤H≤5g / m 2 .

9. A battery, characterized in that: The invention comprises an electrode assembly, wherein the electrode assembly comprises: a first pole piece, a second pole piece and a diaphragm, wherein the first pole piece and / or the second pole piece is a pole piece (100) according to any one of claims 1 to 8, and the first pole piece, the diaphragm and the second pole piece are assembled together to form the electrode assembly.

10. An electronic device, characterized in that: Comprising a battery according to claim 9.

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