Pole piece, battery cell and electric device

Abstract

An electrode tab, an electrode and an electric device, the electrode tab comprising a current collector, two active material layers and two transition layers. The current collector comprises a support layer, and a first conductive layer and a second conductive layer arranged on both sides of the support layer in a first direction. One of the active material layers is arranged on a side of the first conductive layer away from the support layer, and the other active material layer is arranged on a side of the second conductive layer away from the support layer. One of the transition layers is arranged between at least part of the first conductive layer and the corresponding active material layer and protrudes out of the active material layer in a second direction, and the other transition layer is arranged between at least part of the second conductive layer and the corresponding active material layer and protrudes out of the active material layer in the second direction. The active material layer comprises active material particles, and the average particle size of the active material particles is 5-20 mu m; the transition layer comprises solid particles, and the average particle size of the solid particles is 500-1500 nm. The electrode tab can improve the structural strength.

Description

Technical Field

[0001] This application relates to the field of energy storage technology, and in particular to an electrode, a battery cell, and an electrical device. Background Technology

[0002] Existing composite current collectors have a three-layer sandwich structure, with a polymer layer in the middle and a metal layer on the outside. The metal layer is used to coat the active material layer and is then compacted by cold pressing to form the electrode. The relatively large average particle size of the active material particles in the active material layer can easily cause extrusion damage to the metal layer, affecting the structural strength of the electrode. Summary of the Invention

[0003] In view of the above, this application provides an electrode sheet that can improve structural strength.

[0004] Embodiments of this application provide an electrode, which includes a current collector, two active material layers, and two transition layers. The current collector includes a support layer, and a first conductive layer and a second conductive layer disposed on both sides of the support layer in a first direction, the first direction being the thickness direction of the current collector. One active material layer is disposed on the side of the first conductive layer opposite to the support layer, and the other active material layer is disposed on the side of the second conductive layer opposite to the support layer. One transition layer is disposed between at least a portion of the first conductive layer and the corresponding active material layer, and the other transition layer is disposed between at least a portion of the second conductive layer and the corresponding active material layer. The active material layers include active material particles with an average particle size of 5 μm to 20 μm. The transition layers include solid particles, which include at least one of alumina, silicon oxide, silicon carbide, tin oxide, indium oxide, titanium dioxide, cobalt oxide, chromium trioxide, boehmite, amorphous carbon, lithium phosphorus oxynitride, and titanium diboride. The average particle size of the solid particles is 500 nm to 1500 nm.

[0005] In the aforementioned electrode, the solid particles are less prone to expansion when in contact with the electrolyte compared to the active material particles, thus allowing the transition layer to buffer the deformation caused by the expansion of the corresponding active material layer. By limiting the average particle size of the active material particles to 5 μm to 20 μm, the cycle performance, energy density, and lithium plating performance of the electrode are improved. By limiting the average particle size of the solid particles to 500 nm to 1500 nm, production costs are controlled and interfacial resistance is reduced. Furthermore, the average particle size of the solid particles is smaller than that of the active material particles, which helps the solid particles act as a buffer between the active material particles and the current collector, reducing the risk of crush damage to the first or second conductive layer caused by the larger active material particles directly contacting the current collector, thereby improving the structural strength of the electrode.

[0006] In some embodiments of this application, the transition layer protrudes from the edge of the peripheral side of the corresponding active material layer along a second direction, and the second direction is perpendicular to the first direction.

[0007] In the above scheme, one transition layer is disposed between at least a portion of the first conductive layer and the corresponding active material layer and protrudes from the peripheral edge of the corresponding active material layer along the second direction, and the other transition layer is disposed between at least a portion of the second conductive layer and the corresponding active material layer and protrudes from the peripheral edge of the corresponding active material layer along the second direction. This allows the portion of the transition layer corresponding to the edge of the active material layer to alleviate the shear force on the position corresponding to the current collector during the cold pressing process, thereby reducing the risk of damage to the current collector due to excessive shear force and improving the structural strength of the electrode.

[0008] In some embodiments of this application, the average particle size of the active material particles is 5 to 15 μm, and the average particle size of the solid particles is 500 nm to 1500 nm. This further improves the cycle performance, energy density, and lithium plating performance of the electrode, further controls production costs, reduces interfacial resistance, and further facilitates the solid particles to act as a buffer between the active material particles and the current collector, reducing the risk of large-sized active material particles directly contacting the current collector and causing crush damage to the first or second conductive layer, thus improving the structural strength of the electrode.

[0009] In some embodiments of this application, the average particle size of the active material particles is 10 μm to 15 μm to further improve the cycle performance, energy density, and lithium plating performance of the electrode. The average particle size of the solid particles is 800 nm to 1000 nm to further control production costs and reduce interfacial resistance. Furthermore, it is beneficial for the solid particles to act as a buffer between the active material particles and the current collector, reducing the risk of large-sized active material particles directly contacting the current collector and causing crush damage to the first or second conductive layer, thereby improving the structural strength of the electrode.

[0010] In some embodiments of this application, the compaction density of the active material layer is 3 g / cm³. 3 Up to 4.5 g / cm 3 The compaction density of the transition layer is 1.6 g / cm³. 3 Up to 3g / cm 3The active material layer and the corresponding transition layer are simultaneously subjected to cold pressing. The material differences between the active material layer and the transition layer result in different compaction densities. During cold pressing, the compaction density of the active material layer is the primary consideration. If the compaction density of the active material layer is too low (less than 3 g / cm³), the energy density of the electrode may be too low. If the compaction density is too high (greater than 4.5 g / cm³), the current collector may be subjected to excessive shear force, leading to damage and affecting the structural strength of the electrode. Furthermore, it may reduce the ion transport channels, impacting the electrode's cycle performance. By limiting the compaction density of the active material layer to between 3 g / cm³ and 4.5 g / cm³, the energy density and cycle performance of the electrode are improved, while reducing the risk of damage from excessive shear force on the current collector.

[0011] In some embodiments of this application, the compaction density of the active material layer is 4.1 g / cm³. 3 Up to 4.3 g / cm 3 The compaction density of the transition layer is 2.2 g / cm³. 3 Up to 2.4 g / cm 3 This is to further improve the energy density and cycle performance of the electrode, and reduce the risk of damage caused by excessive shear force on the current collector.

[0012] In some embodiments of this application, the transition layer includes interconnected connecting portions and extension portions. Along the first direction, the projection of the connecting portion coincides with the projection of the corresponding active material layer, which helps reduce the risk of extrusion damage to the first or second conductive layer caused by direct contact between active material particles and the current collector, thereby improving the structural strength of the electrode. The projection of the extension portion surrounds the projection of the corresponding active material layer, and the projection of the extension portion is also located within the projection of the current collector. This allows the edge of the transition layer corresponding to the active material layer to alleviate the shear force on the corresponding position of the current collector during cold pressing, thereby reducing the risk of damage to the current collector due to excessive shear force and improving the structural strength and conductivity of the electrode.

[0013] In some embodiments of this application, the connecting portion is provided with a through hole extending through the connecting portion in a first direction. The active material layer passes through the through hole and connects to the corresponding first conductive layer or second conductive layer. Along the first direction, the projection of the through hole is located within the projection range of the corresponding active material layer. The shear force applied to the current collector at the edge of the active material layer during cold pressing is greater than that at other parts of the current collector. By providing the through hole, the transition layer is adapted to the part of the current collector that experiences greater shear force, thereby reducing the risk of active material particles at the edge of the active material layer directly contacting the current collector and causing extrusion damage to the first conductive layer or second conductive layer. Furthermore, the through hole alleviates the shear force at the corresponding position of the current collector during cold pressing, thereby reducing the risk of damage to the current collector due to excessive shear force.

[0014] In some embodiments of this application, along the first direction, the overlapping area of ​​the projection of the connecting part and the corresponding active material layer includes an inner periphery and an outer periphery. The outer periphery is disposed around the periphery of the inner periphery, and the distance L5 between the inner periphery and the outer periphery satisfies: 0 < L5 ≤ 1 mm. Since the edge stress of the active material layer is large, setting a transition layer at the edge position is beneficial to play a buffering role between the edge of the active material layer and the current collector, and is also beneficial to increase the volume of the part of the active material layer passing through the through hole, thereby increasing the volume of the part with a larger thickness in the active material layer and improving the energy density of the electrode.

[0015] In some embodiments of this application, 0 < L5 ≤ 0.5 mm, which further facilitates increasing the volume of the active material layer passing through the through hole, thereby facilitating the increase of the volume of the thicker portion of the active material layer and improving the energy density of the electrode.

[0016] In some embodiments of this application, the current collector includes two first end faces disposed opposite each other along a second direction, the active material layer includes two second end faces disposed opposite each other along a second direction, and the transition layer includes two third end faces disposed opposite each other along a second direction. Along the second direction, among the first, second, and third end faces located on one side of the active material layer, the current collector between the first and third end faces forms an empty foil area for connecting the electrode terminals, and the transition layer between the second and third end faces is a partial extension. The distance L1 between the first and third end faces satisfies: 0.2mm ≤ L1 ≤ 1.8mm, to limit the area of ​​the empty foil area. When L1 is too small (less than 0.2mm), the area connecting the empty foil area to the electrode terminals is easily small, resulting in a risk of weak connection strength; when L1 is too large (greater than 1.8mm), the empty foil area occupies a large space in the second direction X, resulting in wasted space and affecting the energy density of the electrode. By limiting L1 to 1.8 mm (0.2 mm ≤ L1 ≤ 1.8 mm), the connection strength between the empty foil area and the electrode terminal is improved, and the space waste generated by the empty foil area in the second direction is reduced, which is beneficial to improving the energy density of the electrode. The distance L2 between the second end face and the third end face satisfies: 0 < L2 ≤ 1.5 mm, so as to facilitate visual detection of whether the transition layer protrudes from the peripheral edge of the corresponding active material layer along the second direction, and to reduce the space waste caused by the large space occupied by the extension in the second direction.

[0017] In some embodiments of this application, 0.4mm≤L1≤0.6mm is used to further improve the connection strength between the empty foil area and the electrode terminal, and to reduce the space waste generated by the empty foil area in the second direction, which is beneficial to improving the energy density of the electrode. 0.2mm≤L2≤0.5mm is used to further facilitate visual detection of whether the transition layer protrudes from the peripheral edge of the corresponding active material layer along the second direction, and to reduce the space waste caused by the large space occupied by the extension in the second direction.

[0018] In some embodiments of this application, the current collector includes two fourth end faces disposed opposite each other along a third direction, the active material layer includes two fifth end faces disposed opposite each other along a third direction, and the transition layer includes two sixth end faces disposed opposite each other along a third direction, wherein the first direction, the second direction, and the third direction are perpendicular to each other. Along the third direction, among the fourth, fifth, and sixth end faces located on the other side of the active material layer, the current collector between the fourth and sixth end faces forms an empty foil area for connecting the electrode terminals, and the transition layer between the fifth and sixth end faces is a partial extension. The distance L3 between the fourth and sixth end faces satisfies: 0.2mm ≤ L3 ≤ 1.8mm, to limit the area of ​​the empty foil area. When L3 is too small (less than 0.2mm), the area connecting the empty foil area to the electrode terminals is relatively small, resulting in a risk of weak connection strength; when L3 is too large (greater than 1.8mm), the empty foil area occupies a large space in the second direction X, resulting in wasted space and affecting the energy density of the electrode. By limiting L3 to 1.8mm (0.2mm ≤ L3 ≤ 1.8mm), the connection strength between the empty foil area and the electrode terminal is improved, and the space waste generated by the empty foil area in the third direction is reduced, which is beneficial to improving the energy density of the electrode. The distance L4 between the fifth and sixth end faces satisfies: 0 < L4 ≤ 1.5mm, so as to facilitate visual inspection of whether the transition layer protrudes from the peripheral edge of the corresponding active material layer in the third direction, and to reduce the space waste caused by the large space occupied by the extension in the third direction.

[0019] In some embodiments of this application, 0.4mm≤L3≤0.6mm is used to further improve the connection strength between the empty foil area and the electrode terminal, and to reduce the space waste generated by the empty foil area in the third direction, which is beneficial to improving the energy density of the electrode. 0.2mm≤L4≤0.5mm is used to further facilitate visual inspection of whether the transition layer protrudes from the periphery of the corresponding active material layer in the third direction, and to reduce the space waste caused by the large space occupied by the extension in the third direction.

[0020] In some embodiments of this application, along the first direction, the thickness H1 of the current collector satisfies: 4μm≤H1≤16μm, to meet the structural strength requirements of the current collector and reduce space waste generated by the current collector, which is beneficial to improving the energy density of the electrode. The thickness H2 of the transition layer satisfies: 0.5μm≤H2≤3μm, to improve the buffering performance and bonding strength of the transition layer and reduce space waste generated by the transition layer, which is beneficial to improving the energy density of the electrode. The thickness H3 of the active material layer satisfies: 60μm≤H3≤160μm, to control the internal resistance of the electrode and reduce space waste generated by the active material layer, which is beneficial to improving the energy density of the electrode.

[0021] In some embodiments of this application, 7μm≤H1≤9μm is used to further meet the structural strength requirements of the current collector and reduce space waste generated by the current collector, which is beneficial to improving the energy density of the electrode. 1μm≤H2≤1.5μm is used to further improve the buffering performance and bonding strength of the transition layer and reduce space waste generated by the transition layer, which is beneficial to improving the energy density of the electrode. 90μm≤H3≤110μm is used to further control the internal resistance of the electrode and reduce space waste generated by the active material layer, which is beneficial to improving the energy density of the electrode.

[0022] In some embodiments of this application, the resistance R of the transition layer satisfies: 1 mohm ≤ R ≤ 20 mohm, in order to improve the conductivity of the transition layer.

[0023] Embodiments of this application also provide a battery cell, which includes an electrode assembly, and the electrode assembly includes any of the electrode sheets in the above embodiments.

[0024] Embodiments of this application also provide an electrical device, including any of the electrode sheets or any of the battery cells described in the above embodiments.

[0025] In the aforementioned electrode, cell, and electrical device, one transition layer is disposed between at least a portion of the first conductive layer and the corresponding active material layer, protruding along the second direction from the peripheral edge of the corresponding active material layer. Another transition layer is disposed between at least a portion of the second conductive layer and the corresponding active material layer, also protruding along the second direction from the peripheral edge of the corresponding active material layer. This allows the portion of the transition layer corresponding to the edge of the active material layer to alleviate the shear force experienced by the current collector during cold pressing, thereby reducing the risk of damage to the current collector due to excessive shear force and improving the structural strength of the electrode. By limiting the average particle size of the active material particles to 5 μm to 20 μm, the cycle performance, energy density, and lithium plating performance of the electrode are improved. Solid particles are less prone to expansion when in contact with the electrolyte compared to active material particles, allowing the transition layer to buffer deformation caused by the expansion of the corresponding active material layer. By limiting the average particle size of the solid particles to 500 nm to 1500 nm, production costs are controlled and interfacial resistance is reduced. Furthermore, the average particle size of the solid particles is smaller than that of the active material particles, which helps the solid particles to act as a buffer between the active material particles and the current collector, reducing the risk of the active material particles with larger average particle sizes directly contacting the current collector and causing compression damage to the first or second conductive layer, thereby improving the structural strength of the electrode. Attached Figure Description

[0026] Figure 1 This is a planar schematic diagram of the electrode sheet in one embodiment of this application.

[0027] Figure 2 yes Figure 1 A sectional view along section line AA.

[0028] Figure 3 This is a planar schematic diagram of the electrode sheet in another embodiment of this application.

[0029] Figure 4 yes Figure 3 A sectional view along section line BB.

[0030] Figure 5 This is a schematic diagram showing the arc-shaped projection of the hole wall of the electrode in one embodiment of this application.

[0031] Figure 6 This is a schematic diagram showing the wavy shape of the projection of the hole wall of the electrode in one embodiment of this application.

[0032] Figure 7 This is a schematic diagram showing the serrated shape of the projection of the hole wall of the electrode in one embodiment of this application.

[0033] Figure 8 This is a schematic diagram of the battery cell structure in one embodiment of this application.

[0034] Figure 9 This is a schematic diagram of the structure of an electrical device in one embodiment of this application.

[0035] Explanation of main component symbols

[0036] Electrode 100a, 100b

[0037] 200 cells

[0038] 300 electrical appliances

[0039] Current collector 10

[0040] Support layer 11

[0041] First conductive layer 12

[0042] Second conductive layer 13

[0043] First end face 101

[0044] Fourth end face 102

[0045] Active material layer 20

[0046] Second end face 21

[0047] Fifth end face 22

[0048] Transition layer 30

[0049] Connecting part 31

[0050] Through hole 311

[0051] Extension 32

[0052] Third end face 301

[0053] Sixth end face 302

[0054] Projection overlap area 40

[0055] 41 inner perimeter

[0056] 42 outer perimeter

[0057] Electrode assembly 201

[0058] First Extreme Film 202

[0059] Second pole piece 203

[0060] Diaphragm 204

[0061] JE205

[0062] First direction Z

[0063] Second direction X

[0064] Third direction Y

[0065] The following detailed description, in conjunction with the accompanying drawings, will further illustrate this application. Detailed Implementation

[0066] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0067] It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or may also have a component positioned in between. When a component is considered to be "set" on another component, it can be directly set on the other component or may also have a component positioned in between. When a value is considered to be "equal" to another value, it means that the two are equal within a set deviation range, which is within 5%. In other words, when at least one of the two values ​​fluctuates within the set deviation range, even if their values ​​are not equal, they are still considered to be approximately equal. When a value is considered to be in a "1:1" ratio with another value, it means that the two are equal within a set deviation range, which is within 5%. In other words, when at least one of the two values ​​fluctuates within the set deviation range, even if their values ​​are not equal, they are still considered to be in a 1:1 ratio.

[0068] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0069] It should be understood that, considering actual machining tolerances, the term "perpendicular" in the technical solution of this application is used to describe the ideal state between two components. In actual production or use, two components may exist in a state that is approximately perpendicular. For example, combined with numerical description, perpendicularity can refer to the angle between two straight lines within the range of 90°±10°, perpendicularity can also refer to the dihedral angle between two planes within the range of 90°±10°, and perpendicularity can also refer to the angle between a straight line and a plane within the range of 90°±10°. The two components described as "perpendicular" do not have to be absolutely straight lines or planes, but can be approximately straight lines or planes. From a macroscopic perspective, if the overall extension direction is a straight line or plane, the component can be considered a "straight line" or "plane".

[0070] In this article, the term "average particle size" refers to the particle size that, as measured by a laser particle size analyzer, reaches 50% of the total volumetric particle size in the particle distribution of a material on a volume basis. It can also be referred to as "D50".

[0071] One embodiment of this application provides an electrode, which includes a current collector, two active material layers, and two transition layers. The current collector includes a support layer, and a first conductive layer and a second conductive layer disposed on both sides of the support layer in a first direction, the first direction being the thickness direction of the current collector. One active material layer is disposed on the side of the first conductive layer opposite to the support layer, and the other active material layer is disposed on the side of the second conductive layer opposite to the support layer. One transition layer is disposed between at least a portion of the first conductive layer and the corresponding active material layer, and protrudes from the peripheral edge of the corresponding active material layer along a second direction, the other transition layer being disposed between at least a portion of the second conductive layer and the corresponding active material layer, and protruding from the peripheral edge of the corresponding active material layer along a second direction, the second direction being perpendicular to the first direction. The active material layers include active material particles with an average particle size of 5 μm to 20 μm; the transition layers include solid particles, the solid particles including at least one selected from alumina, silicon oxide, silicon carbide, tin oxide, indium oxide, titanium dioxide, cobalt oxide, chromium trioxide, boehmite, amorphous carbon, lithium phosphorus oxynitride, and titanium diboride. The average particle size of the solid particles ranges from 500 nm to 1500 nm.

[0072] In the aforementioned electrode, one transition layer is disposed between at least a portion of the first conductive layer and the corresponding active material layer, protruding along the second direction from the peripheral edge of the corresponding active material layer. Another transition layer is disposed between at least a portion of the second conductive layer and the corresponding active material layer, also protruding along the second direction from the peripheral edge of the corresponding active material layer. This design alleviates the shear force experienced by the current collector at the edge of the transition layer corresponding to the active material layer during cold pressing, thereby reducing the risk of damage to the current collector due to excessive shear force and improving the structural strength of the electrode. Solid particles are less prone to expansion when in contact with the electrolyte compared to active material particles, allowing the transition layer to buffer deformation caused by the expansion of the corresponding active material layer. By limiting the average particle size of the active material particles to 5 μm to 20 μm, the cycle performance, energy density, and lithium plating performance of the electrode are improved. By limiting the average particle size of the solid particles to 500 nm to 1500 nm, production costs are controlled and interfacial resistance is reduced. Furthermore, the average particle size of the solid particles is smaller than that of the active material particles, which helps the solid particles to act as a buffer between the active material particles and the current collector, reducing the risk of the active material particles with larger average particle sizes directly contacting the current collector and causing compression damage to the first or second conductive layer, thereby improving the structural strength of the electrode.

[0073] The embodiments of this application will be further described below with reference to the accompanying drawings.

[0074] Example 1

[0075] Please refer to the following: Figure 1 and Figure 2 One embodiment of this application provides an electrode 100a, which is used to form a battery cell for use in a secondary battery. A secondary battery is a battery that can be used again after being discharged by recharging to activate the active materials. Optionally, the electrode 100a can be a positive electrode or a negative electrode.

[0076] The electrode 100a includes a current collector 10, two active material layers 20, and two transition layers 30. The current collector 10 is a composite current collector used to collect current. Specifically, the current collector 10 includes a support layer 11, and a first conductive layer 12 and a second conductive layer 13 disposed on both sides of the support layer 11 in a first direction Z. The first direction Z is the thickness direction of the current collector 10.

[0077] The support layer 11 is made of a high-molecular insulating material, which has high structural strength and low density and mass, thus reducing the thickness and weight of the current collector 10. The first conductive layer 12 and the second conductive layer 13 are made of metallic materials. Compared with conventional metal current collectors, the thickness of the first conductive layer 12 and the second conductive layer 13 disposed on both sides of the support layer 11 is reduced. When the current collector 10 is subjected to mechanical damage by external force impact, it helps to reduce the generation of metal burrs, thereby reducing the risk of short circuit.

[0078] Optionally, the polymeric insulating material includes one or more of polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), polyimide (PI), polyetherketone (PEK), and polyphenylene sulfide (PPS).

[0079] Optionally, the metallic material includes one or more of aluminum, copper, nickel, silver, gold, and iron.

[0080] Please refer to the following: Figure 1 and Figure 2One active material layer 20 is disposed on the side of the first conductive layer 12 opposite to the support layer 11, and the other active material layer 20 is disposed on the side of the second conductive layer 13 opposite to the support layer 11. The two active material layers 20 are used to generate current and collect it onto the current collector 10. Specifically, the active material layers 20 are coated on one side of the first conductive layer 12 or one side of the second conductive layer 13 using methods such as extrusion coating, transfer coating, or spray coating.

[0081] Optionally, when viewed along the first direction Z, the two active material layers 20 are continuously arranged in both the length and width directions of the electrode 100a.

[0082] One transition layer 30 is disposed between at least a portion of the first conductive layer 12 and the corresponding active material layer 20, and protrudes along the second direction X from the peripheral edge of the corresponding active material layer 20. The other transition layer 30 is disposed between at least a portion of the second conductive layer 13 and the corresponding active material layer 20, and protrudes along the second direction X from the peripheral edge of the corresponding active material layer 20. The active material layer 20 corresponding to the first conductive layer 12 refers to the active material layer 20 located on the side of the first conductive layer 12 facing away from the support layer 11, and the active material layer 20 corresponding to the second conductive layer 13 refers to the active material layer 20 located on the side of the second conductive layer 13 facing away from the support layer 11. The current generated by the active material layer 20 is collected onto the current collector 10 through the corresponding transition layer 30. The portion of the transition layer 30 corresponding to the edge of the active material layer 20 is used to alleviate the shear force on the corresponding position of the current collector 10 during cold pressing, thereby reducing the risk of damage to the current collector 10 due to excessive shear force and improving the structural strength and conductivity of the electrode 100a. The first direction Z is perpendicular to the second direction X. Optionally, the second direction X is the width direction of the current collector 10.

[0083] The active material layer 20 includes active material particles with an average particle size of 5 μm to 20 μm. When the average particle size of the active material particles is too small (less than 5 μm), it easily leads to difficulties in slurry dispersion, affecting the cycle performance of the electrode 100a. When the average particle size of the active material particles is too large (greater than 20 μm), it easily leads to increased solid-phase diffusion resistance of active ions and increased polarization, affecting the energy density and lithium plating performance of the electrode 100a. By limiting the average particle size of the active material particles to 5 μm to 20 μm, the cycle performance, energy density, and lithium plating performance of the electrode 100a are improved.

[0084] Optionally, the average particle size of the active material particles can be one of 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, or any other value within the range of 5 μm to 20 μm.

[0085] Furthermore, the average particle size of the active material particles is 10 μm to 15 μm to further improve the cycle performance, energy density and lithium plating performance of the electrode 100a.

[0086] The transition layer 30 includes solid particles. Specifically, the transition layer 30 is a layered structure formed by a slurry of solid particles on the first conductive layer 12 and the second conductive layer 13. This layered structure has lithium-ion conductivity. The solid particles are a solid electrolyte that does not contain positive electrode active material particles or negative electrode active material particles. For example, the solid electrolyte is an oxide solid electrolyte or a sulfide solid electrolyte, etc. It is understood that, as materials constituting the transition layer 30, in addition to the solid electrolyte, conductive additives, sintering aids, and binders may also be included to improve the structural strength of the transition layer 30. The solid particles are less likely to expand when in contact with the electrolyte than the active material particles, so that the transition layer 30 can buffer the deformation caused by the expansion of the corresponding active material layer 20 and reduce the risk of the active material layer 20 detaching from the current collector 10.

[0087] Optionally, the solid particles include at least one of alumina, silicon oxide, silicon carbide, tin oxide, indium oxide, titanium dioxide, cobalt oxide, chromium trioxide, boehmite, amorphous carbon, lithium phosphorus oxynitride, and titanium diboride.

[0088] The average particle size of the solid particles is between 500 nm and 1500 nm. When the average particle size is too small (less than 500 nm), production costs increase. When the average particle size is too large (greater than 1500 nm), it can easily affect the conductive contact between the active material layer 20 and the current collector 10, resulting in a higher interfacial resistance. By limiting the average particle size of the solid particles to between 500 nm and 1500 nm, production costs are controlled and interfacial resistance is reduced. Furthermore, when the average particle size of the solid particles is smaller than that of the active material particles, the solid particles act as a buffer between the active material particles and the current collector 10, reducing the risk of large-sized active material particles directly contacting the current collector 10 and causing crush damage to the first conductive layer 12 or the second conductive layer 13, thus improving the structural strength of the electrode 100.

[0089] Optionally, the average particle size of the solid particles can be one of 500nm, 600nm, 700nm, 800nm, 900nm, 1000nm, 1100nm, 1200nm, 1300nm, 1400nm, 1500nm, or any other value in the range of 500nm to 1500nm.

[0090] Furthermore, the average particle size of the solid particles is 800 nm to 1000 nm, which further controls production costs and reduces interfacial resistance. In addition, it is beneficial for the solid particles to act as a buffer between the active material particles and the current collector 10, reducing the risk of the active material particles with larger average particle size directly contacting the current collector 10 and causing crush damage to the first conductive layer 12 or the second conductive layer 13, thereby improving the structural strength of the electrode 100a.

[0091] In the aforementioned electrode 100a, one transition layer 30 is disposed between at least a portion of the first conductive layer 12 and the corresponding active material layer 20 and protrudes along the second direction X from the peripheral edge of the corresponding active material layer 20. Another transition layer 30 is disposed between at least a portion of the second conductive layer 13 and the corresponding active material layer 20 and protrudes along the second direction X from the peripheral edge of the corresponding active material layer 20. This allows the portion of the transition layer 30 corresponding to the edge of the active material layer 20 to alleviate the shear force experienced by the current collector 10 during cold pressing, thereby reducing the risk of damage to the current collector 10 due to excessive shear force and improving the structural strength and conductivity of the electrode 100a. Solid particles are less prone to expansion when in contact with the electrolyte compared to active material particles, allowing the transition layer 30 to buffer the deformation caused by the expansion of the corresponding active material layer 20. By limiting the average particle size of the active material particles to 5 μm to 20 μm, the cycle performance, energy density, and lithium plating performance of the electrode 100a are improved. By limiting the average particle size of the solid particles to 500 nm to 1500 nm, production costs are controlled and interfacial resistance is reduced. Furthermore, the average particle size of the solid particles is smaller than that of the active material particles, which helps the solid particles to act as a buffer between the active material particles and the current collector 10. This reduces the risk of the active material particles with larger average particle sizes directly contacting the current collector 10 and causing crush damage to the first conductive layer 12 or the second conductive layer 13, thereby improving the structural strength of the electrode 100a.

[0092] Please refer to the following: Figure 1 and Figure 2 In some embodiments, the compaction density of the active material layer 20 is 3 g / cm³. 3 Up to 4.5 g / cm 3 The compaction density of transition layer 30 is 1.6 g / cm³. 3 Up to 3g / cm 3It should be noted that the active material layer 20 and the corresponding transition layer 30 are simultaneously subjected to cold pressing. The difference in materials between the active material layer 20 and the transition layer 30 results in different compaction densities for the active material layer 20 and the transition layer 30. These compaction densities are roughly positively correlated. During the cold pressing process, the compaction density of the active material layer 20 is the primary consideration. If the compaction density of the active material layer 20 is too low (less than 3 g / cm³), the energy density of the electrode 100a is likely to be too low. If the compaction density of the active material layer 20 is too high (greater than 4.5 g / cm³), the current collector 10 is at risk of being damaged due to excessive shear force, affecting the structural strength of the electrode 100a. Furthermore, it can reduce the ion transport channels, impacting the cycle performance of the electrode 100a.

[0093] By limiting the compaction density of the active material layer 20 to 3 g / cm3 to 4.5 g / cm3, the energy density and cycle performance of the electrode 100a are improved, and the risk of damage caused by excessive shear force on the current collector 10 is reduced.

[0094] Furthermore, the compaction density of the active material layer 20 is 4.1 g / cm³. 3 Up to 4.3 g / cm 3 The compaction density of transition layer 30 is 2.2 g / cm³. 3 Up to 2.4 g / cm 3 This is to further improve the energy density and cycle performance of the electrode 100a, and reduce the risk of damage caused by excessive shear force on the current collector 10.

[0095] Optionally, the compaction density of the active material layer 20 can be 3 g / cm³. 3 3.1g / cm 3 3.2g / cm 3 3.3g / cm 3 3.4g / cm 3 3.5g / cm 3 3.6g / cm 3 3.7g / cm 3 3.8g / cm 3 3.9g / cm 3 4g / cm 3 4.1g / cm 3 4.2g / cm 3 4.3g / cm 3 4.4g / cm 3 4.5g / cm 3 and 3g / cm 3 Up to 4.5 g / cm 3 One of any other values ​​within the range.

[0096] Optionally, the compaction density of the transition layer 30 can be 2.2 g / cm³. 3 2.3g / cm 3 2.4g / cm 3 and 2.2g / cm 3 Up to 2.4 g / cm 3 One of any other values ​​within the range.

[0097] In some embodiments, the resistance R of the transition layer 30 satisfies: 1 mohm ≤ R ≤ 20 mohm, so as to improve the conductivity of the transition layer 30.

[0098] Optionally, R can be any value within the range of 1 mohm, 2 mohm, 3 mohm, 4 mohm, 5 mohm, 6 mohm, 7 mohm, 8 mohm, 9 mohm, 10 mohm, 01 mohm, 12 mohm, 13 mohm, 14 mohm, 15 mohm, 16 mohm, 17 mohm, 18 mohm, 19 mohm, 20 mohm, and any other value within the range of 1 mohm ≤ R ≤ 20 mohm.

[0099] Please refer to the following: Figure 1 and Figure 2 In some embodiments, the transition layer 30 includes a connecting portion 31 and an extension portion 32 that are interconnected. Along the first direction Z, the projection of the connecting portion 31 coincides with the projection of the corresponding active material layer 20, which helps reduce the risk of compression damage to the first conductive layer 12 or the second conductive layer 13 caused by direct contact between active material particles and the current collector 10, thereby improving the structural strength of the electrode 100a. The projection of the extension portion 32 is disposed around the periphery of the projection of the corresponding active material layer 20, and the projection of the extension portion 32 is also located within the projection of the current collector 10. This allows the portion of the transition layer 30 corresponding to the edge of the active material layer 20 to alleviate the shear force on the corresponding position of the current collector 10 during cold pressing, thereby reducing the risk of damage to the current collector 10 due to excessive shear force, and improving the structural strength and conductivity of the electrode 100a.

[0100] Please refer to the following: Figure 1 and Figure 2In some embodiments, the current collector 10 includes two first end faces 101 disposed opposite each other along the second direction X, the active material layer 20 includes two second end faces 21 disposed opposite each other along the second direction X, and the transition layer 30 includes two third end faces 301 disposed opposite each other along the second direction X. Along the second direction X, among the first end faces 101, second end faces 21, and third end faces 301 located on one side of the active material layer 20, the current collector 10 between the first end faces 101 and the third end faces 301 forms a hollow foil area for connecting the electrode terminals, and the transition layer 30 between the second end faces 21 and the third end faces 301 is a partial extension 32. The electrode terminals may be, but are not limited to, tabs.

[0101] The distance L1 between the first end face 101 and the third end face 301 satisfies the condition: 0.2mm ≤ L1 ≤ 1.8mm, to limit the area of ​​the empty foil region. When L1 is too small (less than 0.2mm), the area connecting the empty foil region to the electrode terminal is too small, which may result in a weak connection strength. When L1 is too large (greater than 1.8mm), the empty foil region occupies a large space in the second direction X, resulting in wasted space and affecting the energy density of the electrode 100a. By limiting L1 to 1.8mm (0.2mm ≤ L1 ≤ 1.8mm), the connection strength between the empty foil region and the electrode terminal is improved, and the wasted space in the second direction X is reduced, which is beneficial to improving the energy density of the electrode 100a. It is understood that the connection between the empty foil region and the electrode terminal can be, but is not limited to, welding to form a solder mark.

[0102] The distance L2 between the second end face 21 and the third end face 301 satisfies: 0 < L2 ≤ 1.5 mm, so as to facilitate visual detection of whether the transition layer 30 protrudes from the edge of the corresponding active material layer 20 along the second direction X, and reduce the space waste caused by the large space occupied by the extension 32 in the second direction X.

[0103] Optionally, L1 can be any value within the range of 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, and any other value within the range of 0.2mm≤L1≤1.8mm.

[0104] Optionally, L2 can be any value within the range of 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, and any other value within the range of 0 < L2 ≤ 1.5mm.

[0105] Furthermore, 0.4mm≤L1≤0.6mm is used to further improve the connection strength between the empty foil area and the electrode terminal, and to reduce the space waste generated by the empty foil area in the second direction X, which is beneficial to improving the energy density of the electrode 100a.

[0106] Furthermore, 0.2mm≤L2≤0.5mm is used to facilitate visual detection of whether the transition layer 30 protrudes from the edge of the corresponding active material layer 20 along the second direction X, and to reduce the space waste caused by the large space occupied by the extension 32 in the second direction X.

[0107] Please refer to the following: Figure 1 and Figure 2 In some embodiments, the current collector 10 includes two fourth end faces 102 disposed opposite each other along a third direction Y, the active material layer 20 includes two fifth end faces 22 disposed opposite each other along a third direction Y, and the transition layer 30 includes two sixth end faces 302 disposed opposite each other along a third direction Y. The first direction Z, the second direction X, and the third direction Y are perpendicular to each other. Optionally, the third direction Y is the length direction of the current collector 10.

[0108] Along the third direction Y, in the fourth end face 102, fifth end face 22, and sixth end face 302 located on the other side of the active material layer 20, the current collector 10 between the fourth end face 102 and the sixth end face 302 forms a hollow foil area for connecting the electrode terminals, and the transition layer 30 between the fifth end face 22 and the sixth end face 302 is a partial extension 32. The electrode terminals may be, but are not limited to, tabs.

[0109] The distance L3 between the fourth end face 102 and the sixth end face 302 satisfies the condition 0.2mm ≤ L3 ≤ 1.8mm to limit the area of ​​the empty foil region. When L3 is too small (less than 0.2mm), the area connecting the empty foil region to the electrode terminal is too small, which may result in a weak connection strength. When L3 is too large (greater than 1.8mm), the empty foil region occupies a large space in the third direction Y, resulting in wasted space and affecting the energy density of the electrode 100a. By limiting L3 to 0.2mm ≤ L3 ≤ 1.8mm, the connection strength between the empty foil region and the electrode terminal is improved, and the wasted space in the third direction Y is reduced, which is beneficial to improving the energy density of the electrode 100a.

[0110] The distance L4 between the fifth end face 22 and the sixth end face 302 satisfies: 0 < L4 ≤ 1.5 mm, so as to facilitate visual detection of whether the transition layer 30 protrudes from the edge of the corresponding active material layer 20 along the third direction Y, and to reduce the space waste caused by the large space occupied by the extension 32 in the third direction Y.

[0111] Optionally, L3 can be any value within the range of 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, and any other value within the range of 0.2mm≤L3≤1.8mm.

[0112] Optionally, L4 can be any value within the range of 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, and any other value within the range of 0 < L4 ≤ 1.5mm.

[0113] Furthermore, 0.4mm≤L3≤0.6mm is used to further improve the connection strength between the empty foil area and the electrode terminal, and to reduce the space waste generated by the empty foil area, which is beneficial to improving the energy density of the electrode 100a.

[0114] Furthermore, 0.2mm≤L4≤0.5mm is used to facilitate visual detection of whether the transition layer 30 protrudes from the edge of the corresponding active material layer 20 along the third direction Y, and to reduce the space waste caused by the large space occupied by the extension 32 in the second direction X.

[0115] It is understood that the first end face 101, the second end face 21, the third end face 301, the fourth end face 102, the fifth end face 22 and the sixth end face 302 can be one of the planar structure, the arc structure and the irregular structure, respectively, wherein the shortest distance between two end faces is used as the distance that defines the above range.

[0116] It is understood that in other embodiments, the edge portion of the active material layer 20 also has a thinning region, with the second end face 21 or the fifth end face 22 located at the end of the corresponding thinning region.

[0117] Please refer to the following: Figure 1 and Figure 2 In some embodiments, along the first direction Z, the two transition layers 30 located on both sides of the current collector 10 have equal widths in the second direction X. The projections of the two transition layers 30 are staggered in the second direction X, and each transition layer 30 includes a staggered region that does not overlap with the other transition layer 30. The two staggered regions are spaced apart in the second direction X, and the widths of the two staggered regions in the second direction X are equal and both less than or equal to 0.3 mm to meet the requirements of machining tolerances.

[0118] Optionally, the width of each misaligned region in the second direction X is one of 0, 0.1 mm, 0.2 mm, 0.3 mm, or any other value within the range of less than 0.3 mm.

[0119] Please refer to the following: Figure 1 and Figure 2 In some embodiments, along the first direction Z, the thickness H1 of the current collector 10 satisfies: 4μm≤H1≤20μm, in order to meet the structural strength requirements of the current collector 10 and reduce the space waste generated by the current collector 10, which is beneficial to improving the energy density of the electrode 100a.

[0120] Optionally, H1 can be any one of the following values: 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, and any other value within the range of 4μm to 20μm.

[0121] Furthermore, 7m≤H1≤9m is used to further meet the structural strength requirements of the current collector 10 and reduce the space waste caused by the large space occupied by the current collector 10, which is conducive to improving the energy density of the electrode 100a.

[0122] In some embodiments, along the first direction Z, the thickness H2 of the transition layer 30 satisfies: 0.5 μm ≤ H2 ≤ 3 μm. When H2 is too small (less than 0.5 μm), it easily affects the buffering performance and bonding strength of the transition layer 30; when H2 is too large (greater than 3 μm), it easily leads to a large space occupied by the transition layer 30, resulting in space waste and affecting the energy density of the electrode 100a. By limiting 0.5 μm ≤ H2 ≤ 3 μm, the buffering performance and bonding strength of the transition layer 30 are improved, and the space waste generated by the transition layer 30 is reduced, which is beneficial to improving the energy density of the electrode 100a.

[0123] Optionally, H2 can be any value within the range of 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm, 2μm, 2.1μm, 2.2μm, 2.3μm, 2.4μm, 2.5μm, 2.6μm, 2.7μm, 2.8μm, 2.9μm, 3μm, and any other value within the range of 0.5μm≤H2≤3μm.

[0124] Furthermore, 1μm≤H2≤1.5μm is used to further improve the buffering performance and bonding strength of the transition layer 30, and reduce the space waste generated by the transition layer 30, which is beneficial to improving the energy density of the electrode 100a.

[0125] In some embodiments, along the first direction Z, the thickness H3 of the active material layer 20 satisfies: 60 μm ≤ H3 ≤ 160 μm. When H3 is too small (less than 60 μm), the energy density of the electrode 100a is easily too low; when H3 is too large (greater than 160 μm), the internal resistance of the electrode 100a is easily increased and the space occupied by the active material layer 20 is large, resulting in wasted space. By limiting 60 μm ≤ H3 ≤ 160 μm, the internal resistance of the electrode 100a is controlled and the wasted space generated by the active material layer 20 is reduced, which is beneficial to improving the energy density of the electrode 100a.

[0126] Optionally, H3 can be any one of the following values: 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, 100μm, 105μm, 110μm, 115μm, 120μm, 125μm, 130μm, 135μm, 140μm, 145μm, 150μm, 155μm, 160μm, and any other value within the range of 60μm to 160μm.

[0127] Furthermore, 90μm≤H3≤110μm is used to further control the internal resistance of electrode 100a and reduce the space waste generated by active material layer 20, which is beneficial to improving the energy density of electrode 100a.

[0128] In some embodiments, the coating weight of the active material layer 20 is 100 mg / 1540.25 mm. 2 Up to 400mg / 1540.25mm 2 When the coating weight is too small (less than 100mg / 1540.25mm), 2 This can easily lead to excessively low energy density of the 100a electrode; when the coating weight is too high (greater than 400mg / 1540.25mm), it can also cause this problem. 2 This can easily lead to material waste, and in severe cases, may even result in overcapacity, causing dendrite precipitation, puncturing the separator, and short circuits, affecting the safety of the cell containing electrode 100a. The coating weight of the active material layer 20 is limited to 100mg / 1540.25mm. 2 Up to 400mg / 1540.25mm 2 This can improve the energy density of electrode 100a, reduce material waste, and improve the safety of the cell containing electrode 100a.

[0129] Optionally, the coating weight of the active material layer 20 can be any value within the range of 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, or any other value between 100 and 400, with the corresponding coating weight unit being mg / 1540.25 mm. 2 .

[0130] Example 2

[0131] Please refer to the following: Figure 3 and Figure 4 An embodiment of this application also provides an electrode 100b. The difference between electrode 100b and electrode 100a is that the connecting portion 31 is provided with a through hole 311 that runs through the connecting portion 31 along the first direction Z. The active material layer 20 passes through the through hole 311 and connects to the corresponding first conductive layer 12 or second conductive layer 13. The shear force exerted on the current collector 10 by the edge of the active material layer 20 during the cold pressing process is greater than the shear force on other parts of the current collector 10. By providing the through hole 311, the transition layer 30 is adapted to the part of the current collector 10 that is subjected to greater shear force, thereby reducing the risk of the active material particles at the edge of the active material layer 20 directly contacting the current collector 10 and causing extrusion damage to the first conductive layer 12 or second conductive layer 13. In addition, the shear force on the corresponding position of the current collector 10 is relieved during the cold pressing process, thereby reducing the risk of damage to the current collector 10 due to excessive shear force, and improving the structural strength and conductivity of electrode 100b. Furthermore, the active material layer 20 has a larger thickness at the portion through the through hole 311, which is beneficial for improving the energy density of the electrode 100b.

[0132] In some embodiments, along the first direction Z, the projection of the through hole 311 is located within the projection range of the corresponding active material layer 20. The overlapping area 40 of the projection of the connecting part 31 and the corresponding active material layer 20 includes an inner periphery 41 and an outer periphery 42. The inner periphery 41 is the projection of the edge of the hole wall of the through hole 311, and the outer periphery 42 is the projection of the end face of the corresponding active material layer 20. The outer periphery 42 is disposed around the periphery of the inner periphery 41. The distance L5 between the inner periphery 41 and the outer periphery 42 satisfies: 0 < L5 ≤ 1 mm. Since the edge stress of the active material layer 20 is large, it is beneficial to provide a transition layer at the edge position to play a buffering role between the edge of the active material layer 20 and the current collector 10, and to increase the volume of the part of the active material layer 20 that passes through the through hole 311, thereby increasing the volume of the part with a larger thickness in the active material layer 20 and increasing the energy density of the electrode 100b.

[0133] Optionally, L5 can be any value within the range of 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, and any other value within the range of 0 < L5 ≤ 1mm.

[0134] Furthermore, 0 < L5 ≤ 0.5 mm, which further facilitates increasing the volume of the active material layer 20 passing through the through hole 311, thereby facilitating the increase of the volume of the thicker portion of the active material layer 20 and improving the energy density of the electrode 100b.

[0135] In some embodiments, the projected shape of the through-hole 311 along the first direction Z is rectangular, so that the transition layer 30 can form the through-hole 311 during the coating process.

[0136] Please see Figure 5 , Figure 6 and Figure 7 It is understood that in other embodiments, the projection of the hole wall of the through hole 311 is arc-shaped, wavy, sawtooth-shaped, etc., so as to increase the connection area between the hole wall of the through hole 311 and the corresponding active material layer 20, thereby increasing the connection strength between the transition layer 30 and the corresponding active material layer 20.

[0137] It should be noted that, apart from the differences mentioned above, the parameters of electrode 100b and electrode 100a are roughly the same, and the description of electrode 100a above can be referred to.

[0138] Please see Figure 8 An embodiment of this application also provides a battery cell 200, including an electrode assembly 201, which includes the electrode 100a (100b) in any of the above embodiments.

[0139] In some embodiments, the electrode assembly 201 includes a first electrode 202, a diaphragm 204, and a second electrode 203 sequentially stacked along a first direction Z. The first electrode 202 is positively polarized, and the second electrode 203 is negatively polarized. At least one of the first electrode 202 and the second electrode 203 is electrode 100a (100b).

[0140] In some embodiments, the first electrode 202 is an electrode 100a (100b), and the battery cell 200 further includes a plurality of tabs 205, one end of each tab 205 being connected to the empty foil area of ​​the first electrode 202, and the other end of each tab 205 extending outward.

[0141] It is understood that in other embodiments, the electrode assembly 201 includes a first electrode 202, a diaphragm 204, and a second electrode 203 sequentially wound together. The first electrode 202 is positively polarized, and the second electrode 203 is negatively polarized. At least one of the first electrode 202 and the second electrode 203 is electrode 100a (100b).

[0142] Please see Figure 9 An embodiment of this application also provides an electrical device 300, including the electrode 100a (100b) of any of the above embodiments or the battery cell 200 of any of the above embodiments. The electrical device 300 may be a vehicle, mobile phone, portable device, laptop computer, ship, spacecraft, electric toy, and power tool, etc.

[0143] In summary, in the aforementioned electrode 100a (100b), battery cell 200, and electrical device 300, one transition layer 30 is disposed between at least a portion of the first conductive layer 12 and the corresponding active material layer 20 and protrudes along the second direction X from the peripheral edge of the corresponding active material layer 20; the other transition layer 30 is disposed between at least a portion of the second conductive layer 13 and the corresponding active material layer 20 and protrudes along the second direction X from the peripheral edge of the corresponding active material layer 20. This allows the portion of the transition layer 30 corresponding to the edge of the active material layer 20 to alleviate the shear force experienced by the current collector 10 during cold pressing, thereby reducing the risk of damage to the current collector 10 due to excessive shear force and improving the structural strength and conductivity of the electrode 100a (100b). By limiting the average particle size of the active material particles to 5 μm to 20 μm, the cycle performance, energy density, and lithium plating performance of the electrode 100a (100b) are improved. Solid particles are less prone to expansion when in contact with the electrolyte compared to active material particles, thus allowing the transition layer 30 to buffer the deformation caused by the expansion of the corresponding active material layer 20. By limiting the average particle size of the solid particles to 500 nm to 1500 nm, production costs are controlled and interfacial resistance is reduced. Furthermore, the average particle size of the solid particles is smaller than that of the active material particles, which helps the solid particles to act as a buffer between the active material particles and the current collector 10, reducing the risk of the larger active material particles directly contacting the current collector 10 and causing crush damage to the first conductive layer 12 or the second conductive layer 13, thereby improving the structural strength of the electrode 100a (100b).

[0144] The present application will be specifically described below based on the embodiments through Tables 1-3, but the present application is not limited to these embodiments.

[0145] The tensile strength of the tab is used as a parameter for comparison. It should be noted that one end of the tab is connected to the empty foil area of ​​the electrode 100a (100b), and the other end extends outward. The edge portion of the electrode 100a (100b) (the portion of the current collector 10 corresponding to the edge of the active material layer 20) has a weaker tensile strength compared to other parts of the electrode 100a (100b). During the stretching process of the tab, the edge portion of the electrode 100a (100b) is more likely to break and separate first. Therefore, the tensile strength of the tab reflects the structural strength of the electrode 100a (100b). The higher the tensile strength of the tab, the higher the structural strength of the electrode 100a (100b), and the lower the tensile strength of the tab, the lower the structural strength of the electrode 100a (100b).

[0146] The tensile strength of the tabs in each embodiment and comparative example was measured by the following method. The electrode 100a (100b) was cut into a 20mm*10cm strip with the electrode and tab at both ends. The two ends of the strip were fixed by a tensile testing machine and stretched at a constant rate of 50mm / min. The maximum tensile stress at the edge of the electrode 100a (100b) when it broke was recorded. The ratio of the maximum tensile stress to the cross-sectional area at the fracture point is the tensile strength of the tab.

[0147] The battery energy density of each embodiment and comparative example was measured as follows: At 25°C, the battery was charged to 3.9V at a constant current of 0.5C, then charged to 0.05C at a constant voltage. The thickness, width, and length of the battery made of electrode 100a (100b) were measured. At 25°C, the battery was charged to 4.45V at a constant current of 0.5C, then charged to 0.025C at a constant voltage. After resting for 5 minutes, the battery was discharged to 3.0V at a constant current of 0.1C, and the discharge energy was recorded. Energy density (Wh / L) = Discharge energy (Wh) / (Battery thickness mm × Battery width mm × Battery length mm × 10) -6 ).

[0148] The testing standard is: the tensile strength of the tab is greater than or equal to 26 N / mm. 2 A score of 28 N / mm² is considered passing; a score of 700 Wh / L or higher is considered excellent. An energy density of 720 Wh / L or higher is considered excellent.

[0149] Example 1

[0150] Please see Figure 2The transition layer 30 includes a connecting portion 31 and an extension portion 32 that are interconnected. Along the first direction Z, the projection of the connecting portion 31 coincides with the projection of the corresponding active material layer 20, and the projection of the extension portion 32 is disposed around the periphery of the projection of the corresponding active material layer 20. The projection of the extension portion 32 is also located within the projection of the current collector 10. L1 = 1.8 mm; L2 = 0.2 mm; L3 = 0.2 mm; L4 = 0.2 mm; H1 = 8 μm; H2 = 2 μm; H3 = 60 μm; the compaction density of the active material layer 20 is 3 g / cm³; the compaction density of the transition layer 30 is 1.6 g / cm³; the average particle size of the active material particles is 5 μm; the average particle size of the solid particles is 500 nm; the solid particles include alumina, tin oxide, silicon oxide, boehmite, and calcium carbonate.

[0151] Example 2

[0152] Except for the average particle size of the active material particles being 10 μm, everything else is the same as in Example 1.

[0153] Example 3

[0154] Except for the average particle size of the active material particles being 15 μm, everything else is the same as in Example 1.

[0155] Example 4

[0156] Except for the average particle size of the active material particles being 20 μm, everything else is the same as in Example 1.

[0157] Comparative Example 1

[0158] Except for the average particle size of the active material particles being 2 μm, everything else is the same as in Example 1.

[0159] Comparative Example 2

[0160] Except for the average particle size of the active material particles being 30 μm, everything else is the same as in Example 1.

[0161] Example 5

[0162] Except for the average particle size of the solid particles being 800 nm, everything else is the same as in Example 1.

[0163] Example 6

[0164] Except for the average particle size of the solid particles being 1000 nm, everything else is the same as in Example 1.

[0165] Example 7

[0166] Except for the average particle size of the solid particles being 1500 nm, everything else is the same as in Example 1.

[0167] Comparative Example 3

[0168] Except for the average particle size of the active material particles being 200 nm, everything else is the same as in Example 1.

[0169] Comparative Example 4

[0170] Except for the average particle size of the active material particles being 2000 nm, the rest is the same as in Example 1.

[0171] Example 8

[0172] Please see Figure 4 Except that the connecting part 31 is provided with a through hole 311 that runs through the connecting part 31 in the first direction Z, the active material layer 20 passes through the through hole 311 and connects to the corresponding first conductive layer 12 or second conductive layer 13, and L5 is 0.2mm, the rest is the same as in Example 1.

[0173] Example 9

[0174] Except for L5 being 0.5mm, the rest is the same as in Example 8.

[0175] Example 9

[0176] Except for L5 being 1 mm, the rest is the same as in Example 8.

[0177] Example 10

[0178] Except for L5 being 1.5mm, the rest is the same as in Example 8.

[0179] Comparative Example 5 is the same as Example 1, except that the transition layer 30 is composed of active material particles.

[0180] Table 1

[0181]

[0182]

[0183] As shown in Table 1:

[0184] As can be seen from Examples 1-4 and Comparative Examples 1-2, by limiting the average particle size of the active material particles to 5 μm to 20 μm, the battery energy density (above 700 Wh / L) and the structural strength of the electrode (above 26 N / mm2) can meet the standards.

[0185] As can be seen from Examples 1, 5-7 and Comparative Examples 3-4, by limiting the average particle size of the solid particles to 500 nm to 1500 nm, the battery energy density and the structural strength of the electrode can meet the standards.

[0186] As shown in Examples 1 and 8-11, by providing through holes 311 and limiting 0 < L5 ≤ 1 mm, the battery energy density and electrode structural strength meet the standards. As shown in Examples 1 and Comparative Example 5, by providing a transition layer 30, the battery energy density and electrode structural strength meet the standards.

[0187] Examples 12-16 are identical to Example 1 except for the parameters mentioned in Table 2.

[0188] Table 2

[0189]

[0190] As shown in Table 2, and as seen in Examples 1 and 12-16, by limiting the compaction density of the active material layer 20 to 3 g / cm3 to 4.5 g / cm3 and the compaction density of the transition layer 30 to 1.6 g / cm3 to 3 g / cm3, the battery energy density and the structural strength of the electrode meet the standards.

[0191] Examples 17-40 are identical to Example 1 except for the parameters mentioned in Table 3.

[0192] Table 3

[0193]

[0194]

[0195] As shown in Table 3, and as seen in Examples 1 and 17-21, by limiting 0.2mm≤L1≤1.8mm, the battery energy density and electrode structural strength meet the standards.

[0196] As can be seen from Examples 1 and 22-25, by limiting 0 < L2 ≤ 1.5 mm, the battery energy density and the structural strength of the electrode can meet the standards.

[0197] As can be seen from Examples 1 and 26-30, by limiting 4μm≤H1≤20μm, the battery energy density and electrode structural strength can meet the standards.

[0198] As can be seen from Examples 1 and 31-35, by limiting 0.5μm≤H2≤3μm, the battery energy density and the structural strength of the electrode can meet the standards.

[0199] As can be seen from Examples 1 and 36-40, by limiting 60μm≤H3≤160μm, the battery energy density and electrode structural strength can meet the standards.

[0200] It should be noted that the test results using L3 as a test parameter are similar to those using L1, therefore the test results using L3 as a test parameter can be referred to Examples 1, 17-21; similarly, the test results using L4 as a test parameter are similar to those using L2, therefore the test results using L4 as a test parameter can be referred to Examples 1, 22-25. Furthermore, those skilled in the art can make other changes within the spirit of this application; of course, all such changes made in accordance with the spirit of this application should be included within the scope disclosed in this application.

Claims

1. An electrode sheet, characterized in that, The electrode includes: The current collector includes a support layer, and a first conductive layer and a second conductive layer disposed on both sides of the support layer in a first direction, wherein the first direction is the thickness direction of the current collector. Two active material layers, one of which is disposed on the side of the first conductive layer away from the support layer, and the other active material layer is disposed on the side of the second conductive layer away from the support layer; Two transition layers, one of which is disposed between at least a portion of the first conductive layer and the corresponding active material layer, and the other of which is disposed between at least a portion of the second conductive layer and the corresponding active material layer. The active material layer includes active material particles, the average particle size of which is 5 μm to 20 μm. The transition layer comprises solid particles, which include at least one of alumina, silicon oxide, silicon carbide, tin oxide, indium oxide, titanium dioxide, cobalt oxide, chromium trioxide, boehmite, amorphous carbon, lithium phosphorus oxynitride, and titanium diboride; the average particle size of the solid particles is 500 nm to 1500 nm. The transition layer includes a connecting portion. Along the first direction, the projection of the connecting portion coincides with the projection of the corresponding active material layer. The connecting portion is provided with a through hole that penetrates the connecting portion along the first direction. The active material layer passes through the through hole and connects to the corresponding first conductive layer or second conductive layer. Along the first direction, the projection of the through hole is located within the projection range of the corresponding active material layer.

2. The electrode sheet as described in claim 1, characterized in that, Along the second direction, the transition layer protrudes from the edge of the peripheral side of the corresponding active material layer, and the second direction is perpendicular to the first direction.

3. The electrode sheet as described in claim 2, characterized in that, The average particle size of the active material particles is 5 to 15 μm; the average particle size of the solid particles is 500 nm to 1000 nm.

4. The electrode sheet as described in claim 3, characterized in that, The average particle size of the active material particles is 10 μm to 15 μm; the average particle size of the solid particles is 800 nm to 1000 nm.

5. The electrode sheet as described in claim 1, characterized in that, The compaction density of the active material layer is 3 g / cm³. 3 Up to 4.5 g / cm 3 The compaction density of the transition layer is 1.6 g / cm³. 3 Up to 3g / cm 3 .

6. The electrode sheet as described in claim 5, characterized in that, The compaction density of the active material layer is 4.1 g / cm³. 3 Up to 4.3 g / cm 3 The compaction density of the transition layer is 2.2 g / cm³. 3 Up to 2.4 g / cm 3 .

7. The electrode sheet according to any one of claims 1, 4, and 6, characterized in that, The transition layer further includes an extension portion, which is connected to the connecting portion. Along the first direction, the projection of the extension portion is disposed around the periphery of the projection of the corresponding active material layer, and the projection of the extension portion is also located within the projection of the current collector.

8. The electrode sheet as described in claim 7, characterized in that, Along the first direction, the overlapping area of ​​the projection of the connecting part and the corresponding active material layer includes an inner periphery and an outer periphery. The outer periphery is disposed around the periphery of the inner periphery, and the distance L5 between the inner periphery and the outer periphery satisfies: 0 < L5 ≤ 1 mm.

9. The electrode sheet as described in claim 8, characterized in that, 0 < L5 ≤ 0.5 mm.

10. The electrode sheet as described in claim 2, characterized in that, The current collector includes two first end faces disposed opposite to each other along the second direction, the active material layer includes two second end faces disposed opposite to each other along the second direction, and the transition layer includes two third end faces disposed opposite to each other along the second direction. Along the second direction, among the first end face, the second end face, and the third end face located on one side of the active material layer, the distance L1 between the first end face and the third end face satisfies: 0.2mm≤L1≤1.8mm; the distance L2 between the second end face and the third end face satisfies: 0<L2≤1.5mm.

11. The electrode sheet as described in claim 10, characterized in that, 0.4mm≤L1≤0.6mm; 0.2mm≤L2≤0.5mm.

12. The electrode sheet as described in claim 10, characterized in that, The current collector includes two fourth end faces arranged opposite each other along a third direction, the active material layer includes two fifth end faces arranged opposite each other along the third direction, and the transition layer includes two sixth end faces arranged opposite each other along the third direction. The first direction, the second direction, and the third direction are perpendicular to each other. Along the third direction, among the fourth end face, the fifth end face, and the sixth end face located on the other side of the active material layer, the distance L3 between the fourth end face and the sixth end face satisfies: 0.2mm≤L3≤1.8mm; the distance L4 between the fifth end face and the sixth end face satisfies: 0<L4≤1.5mm.

13. The electrode sheet as described in claim 11, characterized in that, 0.4mm≤L3≤0.6mm; 0.2mm≤L4≤0.5mm.

14. The electrode sheet as described in claim 1, characterized in that, Along the first direction, the thickness H1 of the current collector satisfies: 4μm≤H1≤16μm; the thickness H2 of the transition layer satisfies: 0.5μm≤H2≤3μm; and the thickness H3 of the active material layer satisfies: 60μm≤H3≤160μm.

15. The electrode sheet as described in claim 14, characterized in that, 7μm≤H1≤9μm; 1μm≤H2≤1.5μm; 90μm≤H3≤110μm.

16. The electrode sheet according to any one of claims 1, 4, 11, and 15, characterized in that, The resistance R of the transition layer satisfies: 1 mohm ≤ R ≤ 20 mohm.

17. A battery cell, characterized in that, It includes an electrode assembly, the electrode assembly comprising an electrode sheet as described in any one of claims 1 to 16.

18. An electrical appliance, characterized in that, Includes the electrode sheet as described in any one of claims 1 to 16 or the cell as described in claim 17.

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