Current collector, battery pole piece, secondary battery and electrical device

Abstract

The present invention discloses a current collector, a battery pole piece, a secondary battery and an electrical device, and relates to the field of batteries. The current collector includes: a first conductive wire and a second conductive wire interwoven into a mesh, and at least one of the first conductive wire and the second conductive wire is made of a flexible substrate coated with a metal layer. In the present application, a mesh structure is adopted, which can effectively increase the roughness of the surface of the current collector sheet, improve the adhesion of the active material on the substrate, and avoid cracking, film peeling, etc. compared with traditional copper foil or aluminum foil; the current collector is set to a mesh shape, so that the electrolyte can more easily penetrate the current collector, improve its wetting performance and battery rate performance, and at least one of the first conductive wire and the second conductive wire is made of a flexible substrate with a metal layer on the surface, which can improve the conductivity of the current collector, reduce costs, and effectively reduce the weight of the current collector.

Description

Technical Field

[0001] The present application relates to the field of batteries, and in particular to a current collector, a battery pole piece, a secondary battery and an electrical device. Background Art

[0002] As we all know, the positive and negative current collectors of the battery are important components of the battery, as they are carriers of the positive and negative active materials and can conduct electricity during the charging and discharging process. Currently, the current collectors are usually made of copper foil or aluminum foil, and the active material slurry is directly coated on the surface of the copper foil or aluminum foil. However, the current collectors produced by this method are prone to cracking and demolding, and have poor wetting performance. Summary of the invention

[0003] The main purpose of the present application is to provide a current collector, a battery pole piece, a secondary battery and an electrical device, aiming to provide a current collector that is not easy to crack, demould, and has good wettability.

[0004] In a first aspect, the present application provides a current collector, comprising: first conductive wires and second conductive wires interwoven into a mesh, wherein at least one of the first conductive wires and the second conductive wires is made of a flexible substrate coated with a metal layer.

[0005] In the technical solution of the embodiment of the present application, the current collector is composed of a first conductive wire and a second conductive wire interwoven into a mesh, and adopts a mesh structure. Compared with traditional copper foil or aluminum foil, it can effectively increase the roughness of the surface of the current collector sheet, improve the adhesion of the active material on the substrate, and avoid cracking, demolding, etc.; in addition, the current collector is set to a mesh shape, so that the electrolyte can more easily penetrate the current collector, thereby improving its wetting performance and battery rate performance.

[0006] In addition, at least one of the first conductive wire and the second conductive wire is made of a flexible substrate with a metal layer coated on the surface, which can improve the conductivity of the current collector, reduce costs, and effectively reduce the weight of the current collector.

[0007] In some embodiments, the material of the first conductive wire is a flexible substrate coated with a metal layer, and the material of the second conductive wire includes at least one of platinum, gold, silver, copper, aluminum, nickel and iron. The metal layer includes at least one of a platinum layer, a gold layer, a silver layer, a copper layer, an aluminum layer, a nickel layer and an iron layer; the above-mentioned metals such as platinum, gold, silver, copper, aluminum, nickel and iron have strong conductivity and flexibility, and are adapted to the characteristics of different batteries. Different metals or metal layers can be selected according to the parameter requirements of the battery.

[0008] In some embodiments, the material of the flexible substrate includes at least one of polyethylene, polypropylene, polyimide, glass fiber, cotton and linen. The above materials have the advantages of light weight, good toughness and low cost. When used in the current collector, it can effectively reduce its weight and reduce its manufacturing cost.

[0009] In some embodiments, the diameter of the flexible substrate is 500nm~20μm, and the thickness of the metal layer is 10nm~1μm. In this way, the thickness of the current collector can be moderate and the size of the formed mesh can be moderate, thereby improving the adhesion of the active material on the substrate and avoiding cracking, demolding, etc.

[0010] In some embodiments, at least one of the transverse conductive wires and the longitudinal conductive wires is made of a flexible substrate coated with a metal layer. This can effectively reduce weight and significantly reduce the manufacturing cost of the current collector.

[0011] In a second aspect, the present application provides a method for preparing a current collector, comprising the following steps:

[0012] The first conductive wire and the second conductive wire are interwoven into a mesh to obtain a current collector.

[0013] Setting the current collector into a mesh structure can effectively increase the roughness of the current collector surface compared to traditional copper foil or aluminum foil, improve the adhesion of the active material on the substrate, and avoid cracking, peeling, etc.; in addition, setting the current collector into a mesh structure makes it easier for the electrolyte to penetrate the current collector, improving its wetting performance and battery rate performance.

[0014] In some embodiments, the flexible substrate coated with a metal layer is prepared by the following method:

[0015] A metal layer is prepared on the outer surface of the flexible substrate by magnetron sputtering, chemical plating or electroplating.

[0016] By adopting the above method, a metal layer is prepared on the outer surface of the flexible substrate, so that the metal layer can be more closely attached to the surface of the flexible substrate, which can improve the conductivity of the current collector, reduce costs, and effectively reduce the weight of the current collector.

[0017] In a third aspect, the present application provides a battery electrode, comprising the current collector in the above embodiment.

[0018] In a fourth aspect, the present application provides a secondary battery, comprising the battery electrode in the above-mentioned embodiment.

[0019] In some embodiments, the secondary battery is a wound battery, and in the current collector of the secondary battery, the first conductive wire extends along the length direction of the current collector, and the material of the first conductive wire is metal, and the second conductive wire extends along the width direction of the current collector, and the material of the second conductive wire is a flexible substrate with a metal layer coated on the surface. In this way, when the current collector is wound, it is wound along the length direction of the current collector, and the flexible substrate with a metal layer coated on the surface can effectively improve the toughness of the current collector, making the current collector not easy to break, and the material of the longitudinal conductive wire is metal, which maintains the high conductivity and low ductility of the current collector and reduces the ductility of the current collector in the width direction.

[0020] In a fifth aspect, the present application provides an electrical device, comprising the secondary battery in the above-mentioned embodiment. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 A schematic diagram comparing a wound battery in an embodiment of the present application with a common wound battery;

[0023] Figure 2 This is a schematic diagram of the preparation process of a flexible substrate coated with a metal layer according to Example 1 of the present application;

[0024] Figure 3 This is a schematic diagram of the preparation process of the current collector of Example 1 of the present application.

[0025] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0027] It should be noted that, in the embodiments, those without specifying specific conditions are carried out according to normal conditions or conditions recommended by the manufacturer. Those without specifying the manufacturer of reagents or instruments used are conventional products that can be purchased commercially. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes, and "A and / or B" is taken as an example, including schemes A, B, or A and B that meet the same time. In addition, the technical schemes between the various embodiments can be combined with each other, but must be based on the ability of ordinary technicians in the field to achieve. When the combination of the technical schemes is contradictory or cannot be achieved, it should be considered that the combination of such technical schemes does not exist, and is not within the scope of protection required by the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work, all belong to the scope of protection of the present invention.

[0028] As we all know, the positive and negative current collectors of the battery are important components of the battery, as they are carriers of the positive and negative active materials and can conduct electricity during the charging and discharging process. Currently, the current collectors are usually made of copper foil or aluminum foil, and the active material slurry is directly coated on the surface of the copper foil or aluminum foil. However, the current collectors produced by this method are prone to cracking and demolding, and have poor wetting performance.

[0029] Therefore, researchers in related fields have made improvements to the current collector. For example, ultrasonic treatment of the metal substrate in an acidic or alkaline solution is used to make its surface have an impermeable nanoporous metal, which can effectively improve the adhesion of the active material on the substrate surface, reduce shedding, reduce the weight of the substrate, and improve the battery mass energy density; another example is the use of a metal mesh sheet as the current collector, so that the active materials on both sides of the current collector form a whole, improving the battery's wetting performance and rate performance; but the above two methods have obvious disadvantages: the current collector is highly brittle and has low toughness, which makes the electrode prone to rupture, edge breakage, burrs and other undesirable phenomena during the production process, resulting in material waste, poor product consistency and even safety issues.

[0030] Some researchers have also plated a layer of metal material on the surface of a flexible substrate to make the battery more flexible and improve the safety performance of secondary batteries. However, problems such as low surface viscosity and poor wettability have not been solved.

[0031] The inventors noticed that how to make the current collector have good flexibility and wettability, not easy to crack and demold, and at the same time have good conductivity, is a key technical point. That is, even if the current collector has the characteristics of both metal and flexible substrate, how to blend the two materials together is the key technical point of this application.

[0032] Based on the above analysis, the inventors found after a large number of repeated experiments that weaving the conductive wires into a mesh to form a current collector can simultaneously meet the requirements of flexibility, wettability and conductivity. Furthermore, the inventors further improved the conductive wires through creative analysis and a large amount of theoretical research, and made the conductive wires into a flexible substrate with a metal layer coated on the surface. In this way, on the one hand, the weight of the conductive wires and the current collector can be reduced. On the other hand, the cost of the flexible substrate is low, which can greatly reduce the cost of the conductive wires and the current collector.

[0033] Specifically, the current collector, the first conductive wire and the second conductive wire proposed in the present application, at least one of which is made of a flexible substrate coated with a metal layer. Compared with the prior art, the present application has the following beneficial effects:

[0034] In the technical solution of the embodiment of the present application, the current collector is composed of a first conductive wire and a second conductive wire interwoven into a mesh, and adopts a mesh structure. Compared with traditional copper foil or aluminum foil, it can effectively increase the roughness of the surface of the current collector sheet, improve the adhesion of the active material on the substrate, and avoid cracking, demolding, etc.; in addition, the current collector is set to a mesh shape, so that the electrolyte can more easily penetrate the current collector, thereby improving its wetting performance and battery rate performance.

[0035] In addition, at least one of the first conductive wire and the second conductive wire is made of a flexible substrate coated with a metal layer. The use of a flexible substrate makes the pole piece more plastic, avoiding the breakage of the strip and the cracking of the pole piece during the processing; the flexible substrate has a low density and low cost, and can effectively improve the energy density of the battery.

[0036] It can be understood that there are four types of current collectors proposed in this application: (1) the first conductive wire and the second conductive wire are both made of a flexible substrate with a metal layer coated on the surface; (2) the first conductive wire is made of metal, and the second conductive wire is made of a flexible substrate coated with a metal layer; (3) the first conductive wire is made of a flexible substrate with a metal layer coated on the surface, and the second conductive wire is made of metal. The above three types of current collectors are all within the scope of protection of this application. At least one of the first conductive wire and the longitudinal conductive wire is made of a flexible substrate coated with a metal layer. In this way, on the one hand, it can effectively reduce the weight, and on the other hand, it can greatly reduce the manufacturing cost of the current collector.

[0037] It should be noted that the present application does not impose any restrictions on the extension direction of the first conductive thread and the second conductive thread, which can extend along the length direction of the current collector (longitudinal direction) and along the width direction of the current collector (transverse direction), respectively, or can be inclined in both directions. In the embodiment of the present application, the first direction is the transverse direction, which refers to the TD direction, that is, perpendicular to the mechanical direction, and the second direction is the longitudinal direction, which refers to the MD direction, that is, the mechanical stretching direction of the mesh silk fabric.

[0038] In addition, in some embodiments, the diameters of the first conductive filament and the second conductive filament are the same or similar, so that the mesh and surface roughness of the current collector are more uniform, thereby improving the stability of the current collector.

[0039] In some embodiments, the material of the first conductive wire is a flexible substrate coated with a metal layer, and the material of the second conductive wire includes at least one of platinum, gold, silver, copper, aluminum, nickel and iron. The metal layer includes at least one of a platinum layer, a gold layer, a silver layer, a copper layer, an aluminum layer, a nickel layer and an iron layer; the above-mentioned metals such as platinum, gold, silver, copper, aluminum, nickel and iron have strong conductivity and flexibility, and are adapted to the characteristics of different batteries. Different metals or metal layers can be selected according to the parameter requirements of the battery.

[0040] It can be understood that the metals of the metal and the flexible substrate coated with a metal layer can be the same or different, and the present application does not limit this. In addition, the metal layer can also be an alloy layer made of an alloy of platinum, gold, silver, copper, aluminum, nickel and iron. When the metal layer has multiple layers, the present application does not limit the stacking order of the above multiple layers. As long as it is an embodiment including the above-mentioned platinum layer, gold layer, silver layer, copper layer, aluminum layer, nickel layer and iron layer, it is within the protection scope of the present application.

[0041] In some embodiments, the material of the flexible substrate includes at least one of polyethylene, polypropylene, polyimide, glass fiber, cotton and linen. The above materials have the advantages of light weight, good toughness and low cost. When used in the current collector, it can effectively reduce its weight and reduce its manufacturing cost.

[0042] Polyethylene (PE) is one of the five major synthetic resins. It is the variety with the largest production capacity and the largest import volume in my country. It can be seen that its preparation process is relatively mature and easy to obtain. Low-density polyethylene has good softness, elongation, impact strength and permeability. It is non-toxic, tasteless, odorless, and has a matte surface. The density is 0.916~0.930g / cm 3, it is relatively soft, has good elongation, electrical insulation, chemical stability, processing performance and low temperature resistance (can withstand -70℃7; Polypropylene (PP for short) is a semi-crystalline thermoplastic plastic with high impact resistance, strong mechanical properties, resistance to a variety of organic solvents and acid and alkali corrosion, and is one of the most common polymer materials; Polyimide (PI7 for short refers to a class of polymers containing an imide ring (-CO-NR-CO-7) on the main chain. It is one of the organic polymer materials with the best comprehensive performance. High temperature resistance is above 400℃, and the long-term use temperature range is -200~300℃; glass fiber is glass fiber (Fiberglass7, which is an inorganic non-metallic material with excellent performance and a wide variety. Its advantages are good insulation, strong heat resistance, good corrosion resistance, high mechanical strength, high elastic coefficient and good rigidity; cotton is cotton fiber, which is natural cotton tissue with good moisture absorption and flexibility; hemp is a plant fiber, which comes from various crude fiber plants, has a natural spindle-shaped structure and unique pectin bevel holes, resulting in excellent moisture absorption and flexibility.

[0043] In some embodiments, the diameter of the flexible substrate is 500nm to 20μm, where 1μm=1000nm. When the cross section of the flexible substrate is circular, the diameter is the diameter of the cross section circle. For example, the diameter of the flexible substrate can be 500nm, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm. , 19μm, 20μm, etc., the thickness of the metal layer is 10nm~1μm, for example, it can be 10nm, 20nm, 50nm, 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, 1μm, etc., so that the thickness of the current collector can be moderate and the size of the formed mesh can be moderate, thereby improving the adhesion performance of the active material on the substrate and avoiding cracking, demolding, etc.

[0044] It can be understood that the diameter of the flexible substrate and the thickness of the metal layer may satisfy only one of the above-mentioned ranges or both. In the embodiment of the present application, the above-mentioned two ranges are satisfied at the same time, so that the surface roughness of the obtained current collector is better and the active material can be efficiently adhered thereto.

[0045] In a second aspect, the present application provides a method for preparing a current collector, comprising the following steps:

[0046] The first conductive wire and the second conductive wire are interwoven into a mesh to obtain a current collector.

[0047] When interweaving, the current collector can be woven into a mesh structure. Compared with traditional copper foil or aluminum foil, it can effectively increase the roughness of the current collector surface, improve the adhesion of active materials on the substrate, and avoid cracking, demolding, etc.; in addition, setting the current collector to a mesh shape makes it easier for the electrolyte to penetrate the current collector, thereby improving its wetting performance and battery rate performance.

[0048] In some embodiments, the flexible substrate coated with a metal layer is prepared by the following method:

[0049] A metal layer is prepared on the outer surface of the flexible substrate by magnetron sputtering, chemical plating or electroplating.

[0050] The magnetron sputtering method is to fill a proper amount of argon gas in a high vacuum, apply a DC voltage of several hundred K between the cathode (columnar target or flat target) and the anode (coating chamber wall), generate a magnetron type abnormal glow discharge in the coating chamber, and ionize the argon gas. The magnetron sputtering method has the advantages of strong bonding between the coating layer and the substrate, dense and uniform coating layer, etc.; Chemical plating (Chemical plating), also known as electroless plating (Electroless plating) or autocatalytic plating (Autocatalytic plating), is a plating method that uses a suitable reducing agent to reduce metal ions in the plating solution to metal and deposit them on the surface of parts without an external current. Chemical plating has a wide range of uses, and the gold plating layer is uniform and decorative; the electroplating method is in the electroplating tank, the drill bit to be plated is the cathode, under the action of the electric field force, the metal ions in the electrolyte swim to the cathode, and are reduced and deposited as neutral atoms of the metal at the plated part of the drill bit to form a coating, and the plated material is firmly encased, and finally a coating that meets the drill bit size requirements is formed.

[0051] By using any of the above methods to prepare a metal layer on the outer surface of the flexible substrate, the metal layer can be more closely attached to the surface of the flexible substrate, which can improve the conductivity of the current collector, reduce costs, and effectively reduce the weight of the current collector.

[0052] The preparation method of the current collector proposed in the present application is simple, easy to operate, and has all the beneficial effects of the above-mentioned current collector, which will not be described in detail here.

[0053] In a third aspect, the present application provides a battery electrode, comprising the current collector in the above embodiment.

[0054] As an example, the battery pole piece includes a current collector as in the above embodiment and an active material disposed on at least one surface of the current collector.

[0055] When the battery pole piece is specifically prepared, the active material is made into a slurry and evenly coated on both sides of the above-mentioned current collector, and then the battery pole piece is obtained through drying, cold pressing and slitting.

[0056] The battery pole piece proposed in this application has all the beneficial effects of the above-mentioned current collector, which will not be described in detail here.

[0057] In a fourth aspect, the present application provides a secondary battery, comprising the battery electrode in the above-mentioned embodiment.

[0058] The secondary battery may be a battery cell, which includes the battery pole pieces (positive pole piece, negative pole piece), electrolyte and separator as described in the above embodiments. The secondary battery cell mainly relies on the movement of lithium ions between the positive pole piece and the negative pole piece to work. The thin film structure of the three layers of material in the cylindrical battery cell is wound into a cylindrical electrode assembly, while the thin film structure in the rectangular battery cell is wound or stacked into an electrode assembly having a roughly rectangular shape.

[0059] In a common battery cell structure, the battery cell includes a shell, an electrode assembly and an electrolyte. The electrode assembly is contained in the shell of the battery cell, and the electrode assembly includes a positive electrode sheet, a negative electrode sheet and a separator. The shell includes a shell and an end cap. The shell includes a housing formed by a plurality of walls and an opening. The end cap is arranged at the opening to close the housing chamber. In addition to the electrode assembly, the housing chamber also contains an electrolyte. The positive electrode sheet and the negative electrode sheet in the electrode assembly include tabs. In order to ensure that a large current passes without melting, the number of positive tabs is multiple and stacked together, and the number of negative tabs is multiple and stacked together. The tabs are electrically connected to the electrode terminals located outside the battery cell through connecting members, and the electrode terminals generally include a positive electrode terminal and a negative electrode terminal. For a rectangular battery cell, the electrode terminal is generally arranged at the end cap portion. A plurality of battery cells are connected in series and / or in parallel via the electrode terminals for application in various applications.

[0060] In some embodiments, the secondary battery is a wound battery, and in the current collector of the secondary battery, the first conductive wire is a transverse conductive wire, and the material of the transverse conductive wire is a flexible substrate with a metal layer coated on the surface, and the second conductive wire is a longitudinal conductive wire, and the material of the longitudinal conductive wire is metal. In this way, when the current collector is wound, it is wound in the longitudinal direction, and the flexible substrate with a metal layer coated on the surface can effectively improve the toughness of the current collector, making the current collector not easy to break, and the material of the longitudinal conductive wire is metal, which maintains the high conductivity and low ductility of the current collector and reduces the ductility of the current collector in the width direction.

[0061] See also Figure 1In a secondary battery made of ordinary current collector copper foil and aluminum foil, due to the blocking effect of copper foil and aluminum foil, the electrolyte can only enter from the two ends of the reel. However, in the present application, the first conductive wire and the second conductive wire are woven into a mesh to form a conductive metal mesh current collector. The electrolyte can enter not only from the two ends, but also from the mesh holes of the metal mesh, achieving infiltration in four directions, with higher infiltration efficiency, making it easier for the electrolyte to penetrate the current collector, thereby improving its infiltration performance and battery rate performance.

[0062] The battery composed of cells formed by winding is called a wound battery. Wound batteries are also called cells, and battery industry insiders call them roll cores. Compared with flat batteries, wound batteries are made of high-voltage winding of plates with a thickness of only about 1mm. Through special process means, the battery has many characteristics: super high-rate discharge capability, with a maximum discharge rate of 18C~30C; excellent high and low temperature performance, can work at -55℃~150℃; stable high output voltage, higher energy density; strong structure, with excellent seismic resistance; no free electrolyte (such as colloidal acid 7, can be placed in any direction for work; can be quickly charged, more than 95% of the power can be charged in 40 minutes (1C charging 7; ultra-long life, the designed floating charge life can reach more than 8 years; extremely high resistance to low current deep discharge.

[0063] The manufacturing method of the above-mentioned wound battery of the present application is as follows:

[0064]

Preparation of flexible substrate coated with metal layer

[0065] A flexible substrate is prepared, the material of which is at least one of polyethylene, polypropylene, polyimide, glass fiber, cotton and linen, and the diameter of which is 500nm to 20μm; a conductive metal layer is plated on the flexible silk fabric substrate by magnetron sputtering, chemical plating or electroplating, wherein the metal layer includes at least one of a platinum layer, a gold layer, a silver layer, a copper layer, an aluminum layer, a nickel layer and an iron layer, and the thickness of the metal layer is 10nm to 1μm, to obtain a flexible substrate coated with a metal layer.

[0066]

Preparation of current collector

[0067] The flexible substrate coated with a metal layer prepared as above is used as the mechanical stretching direction (MD direction) of the mesh silk fabric, and the pure metal wire is used as the direction perpendicular to the mechanical direction (TD direction), wherein the material of the metal wire includes at least one of platinum, gold, silver, copper, aluminum, nickel and iron, and the diameter is 500nm to 20μm; and it is woven into a current collector by a weaving method.

[0068]

Pole piece preparation

[0069] The active material is made into slurry and evenly coated on both sides of the current collector, and then dried, cold pressed and cut to obtain the wound battery cell pole pieces.

[0070]

Preparation of wound batteries

[0071] The positive and negative pole pieces and the isolation film are produced into a wound dry cell by a winding machine, and then cold pressed and shaped. The MD direction uses a composite conductive wire material, which is flexible and not easy to break during the shaping process, solving the problem of easy cracking at the corners of the wound cell. The TD direction uses pure metal with good conductivity, good conductivity, and strong current capacity, so that the current of the cell is evenly distributed during the charging and discharging process.

[0072] The secondary battery proposed in this application has all the beneficial effects of the above-mentioned current collector, which will not be described in detail here.

[0073] A secondary battery can be a battery module. A battery module is formed by electrically connecting a certain number of battery cells together and placing them in a frame in order to protect the battery cells from external impact, heat, vibration, etc. A commonly used battery module generally includes two end plates, and a plurality of battery cells (secondary batteries) are arranged between the two end plates. The end plate provided with the output pole of the battery module is also called the output pole end plate, and the end plate not provided with the output pole of the battery module is also called the non-output pole end plate.

[0074] Secondary batteries can also be battery packs. In some battery production and processing technologies, multiple battery cells are first integrated into battery modules, and then the battery modules are packaged in the battery box to form a battery pack. A battery pack can be packaged in one row of multiple battery modules, or multiple rows of multiple battery modules. The arrangement of multiple rows of multiple battery modules can be double rows and multiple columns, multiple rows and double columns, multiple rows and multiple columns, etc. Taking a battery pack that packages double rows and multiple columns of battery modules as an example, the first end plate of each column is generally the head output extreme plate, the two adjacent end plates between the two rows of battery modules are the middle non-output extreme plates, and the last end plate of each column is the tail non-output extreme plate. The head output extreme plate and one of the middle non-output extreme plates belong to the first row of battery modules, and one of the middle non-output extreme plates and the tail output extreme plate belong to the second row of battery modules.

[0075] In a fifth aspect, the present application provides an electrical device, comprising the secondary battery in the above-mentioned embodiment.

[0076] The electrical devices proposed in the present application include but are not limited to: mobile phones, portable devices, laptop computers, electric vehicles, electric vehicles, ships, spacecraft, electric toys and electric tools, etc. For example, spacecraft include airplanes, rockets, space shuttles and spacecraft, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric vehicle toys, electric ship toys and electric airplane toys, etc. Electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators and electric planers.

[0077] The electrical device proposed in this application has all the beneficial effects of the above-mentioned current collector, which will not be described in detail here.

[0078] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments and drawings. It should be understood that the following embodiments are only used to explain the present invention, and are not used to limit the present invention.

[0079] The current collector compositions of Examples 1 to 8 and Comparative Examples 1 to 2 are as shown in Table 1:

[0080] Table 1 Current collector compositions of Examples 1 to 8 and Comparative Examples 1 to 2

[0081]

[0082] Example 1

[0083]

Preparation of flexible substrate coated with metal layer

[0084] See also Figure 2 , take a flexible substrate, and use magnetron sputtering to plate a conductive metal layer on the flexible silk fabric substrate to obtain a flexible substrate coated with a metal layer (i.e., the composite conductive wire in the figure).

[0085]

Preparation of current collector

[0086] See also Figure 3 , take the above-prepared flexible substrate coated with a metal layer as the mechanical stretching direction (MD direction) of the mesh silk fabric, take the metal wire as the perpendicular direction to the mechanical direction (TD direction), wherein the diameter of the metal wire is 20 μm; and use a weaving method to weave it into a current collector (i.e., a conductive metal mesh).

[0087] From the XRD pattern of the conductive metal mesh, it can be seen that the conductive metal mesh has a uniform grid.

[0088]

Pole piece preparation

[0089] The active material is made into slurry and evenly coated on both sides of the current collector, and then dried, cold pressed and cut to obtain the wound battery cell pole pieces.

[0090]

Preparation of wound batteries

[0091] The positive and negative electrode sheets and the isolation film are produced into a dry battery cell with a wound structure through a winding machine, and then cold pressed and shaped.

[0092] Example 2

[0093]

Preparation of flexible substrate coated with metal layer

[0094] A flexible substrate is taken, and a conductive metal layer is plated on the flexible silk fabric substrate by chemical plating to obtain a flexible substrate coated with a metal layer.

[0095]

Preparation of current collector

[0096] The flexible substrate coated with a metal layer prepared above is used as the mechanical stretching direction (MD direction) of the mesh silk fabric, and the metal wire is used as the perpendicular direction to the mechanical direction (TD direction), wherein the diameter of the metal wire is 20 μm; and it is woven into a current collector by a weaving method.

[0097]

Pole piece preparation

[0098] The active material is made into slurry and evenly coated on both sides of the current collector, and then dried, cold pressed and cut to obtain the wound battery cell pole pieces.

[0099]

Preparation of wound batteries

[0100] The positive and negative electrode sheets and the isolation film are produced into a dry battery cell with a wound structure through a winding machine, and then cold pressed and shaped.

[0101] Example 3

[0102]

Preparation of flexible substrate coated with metal layer

[0103] A flexible substrate is taken and a conductive metal layer is plated on the flexible silk fabric substrate by electroplating to obtain a flexible substrate coated with a metal layer.

[0104]

Preparation of current collector

[0105] The flexible substrate coated with a metal layer prepared above is used as the mechanical stretching direction (MD direction) of the mesh silk fabric, and the metal wire is used as the perpendicular direction (TD direction), wherein the diameter of the metal wire is 8 μm; and it is woven into a current collector by a weaving method.

[0106]

Pole piece preparation

[0107] The active material is made into slurry and evenly coated on both sides of the current collector, and then dried, cold pressed and cut to obtain the wound battery cell pole pieces.

[0108]

Preparation of wound batteries

[0109] The positive and negative electrode sheets and the isolation film are produced into a dry battery cell with a wound structure through a winding machine, and then cold pressed and shaped.

[0110] Example 4

[0111]

Preparation of flexible substrate coated with metal layer

[0112] A flexible substrate is taken and a conductive metal layer is plated on the flexible silk fabric substrate by electroplating to obtain a flexible substrate coated with a metal layer.

[0113]

Preparation of current collector

[0114] The flexible substrate coated with a metal layer prepared above is used as the mechanical stretching direction (MD direction) of the mesh silk fabric, and the metal wire is used as the perpendicular direction to the mechanical direction (TD direction), wherein the diameter of the metal wire is 13 μm; and it is woven into a current collector by a weaving method.

[0115]

Pole piece preparation

[0116] The active material is made into a slurry and evenly coated on both sides of the current collector, and then dried, cold pressed and cut to obtain battery pole pieces.

[0117]

Preparation of wound batteries

[0118] The positive and negative electrode sheets and the isolation film are produced into a dry battery cell with a wound structure through a winding machine, and then cold pressed and shaped.

[0119] Example 5

[0120]

Preparation of flexible substrate coated with metal layer

[0121] A flexible substrate is taken, and a conductive metal layer is plated on the flexible silk fabric substrate by a magnetron sputtering method to obtain a flexible substrate coated with a metal layer.

[0122]

Preparation of current collector

[0123] The flexible substrate coated with a metal layer prepared above is used as the mesh silk fabric perpendicular to the mechanical direction (TD direction), and the metal wire is used as the mechanical stretching direction (MD direction), wherein the diameter of the metal wire is 10 μm; and it is woven into a current collector by a weaving method.

[0124]

Pole piece preparation

[0125] The active material is made into slurry and evenly coated on both sides of the current collector, and then dried, cold pressed and cut to obtain the wound battery cell pole pieces.

[0126]

Preparation of wound batteries

[0127] The positive and negative electrode sheets and the isolation film are produced into a dry battery cell with a wound structure through a winding machine, and then cold pressed and shaped.

[0128] Example 6

[0129]

Preparation of flexible substrate coated with metal layer

[0130] A flexible substrate is taken, and a conductive metal layer is plated on the flexible silk fabric substrate by a magnetron sputtering method to obtain a flexible substrate coated with a metal layer.

[0131]

Preparation of current collector

[0132] The flexible substrate coated with a metal layer prepared above is used as the mesh silk fabric perpendicular to the mechanical direction (TD direction), and the metal wire is used as the mechanical stretching direction (MD direction), wherein the diameter of the metal wire is 15 μm; and it is woven into a current collector by a weaving method.

[0133]

Pole piece preparation

[0134] The active material is made into slurry and evenly coated on both sides of the current collector, and then dried, cold pressed and cut to obtain the wound battery cell pole pieces.

[0135]

Preparation of wound batteries

[0136] The positive and negative electrode sheets and the isolation film are produced into a dry battery cell with a wound structure through a winding machine, and then cold pressed and shaped.

[0137] Example 7

[0138]

Preparation of flexible substrate coated with metal layer

[0139] A flexible substrate is taken, and a conductive metal layer is plated on the flexible silk fabric substrate by a magnetron sputtering method to obtain a flexible substrate coated with a metal layer.

[0140]

Preparation of current collector

[0141] The flexible substrate coated with a metal layer prepared above is used as the mesh silk fabric perpendicular to the mechanical direction (TD direction), and the flexible substrate coated with a metal layer prepared above is used as the mechanical stretching direction (MD direction), and is woven into a current collector by a weaving method.

[0142]

Pole piece preparation

[0143] The active material is made into slurry and evenly coated on both sides of the current collector, and then dried, cold pressed and cut to obtain the wound battery cell pole pieces.

[0144]

Preparation of wound batteries

[0145] The positive and negative electrode sheets and the isolation film are produced into a dry battery cell with a wound structure through a winding machine, and then cold pressed and shaped.

[0146] Example 8

[0147]

Preparation of flexible substrate coated with metal layer

[0148] A flexible substrate is taken, and a conductive metal layer is plated on the flexible silk fabric substrate by a magnetron sputtering method to obtain a flexible substrate coated with a metal layer.

[0149]

Preparation of current collector

[0150] The flexible substrate coated with a metal layer prepared above is used as the mesh silk fabric perpendicular to the mechanical direction (TD direction), and the flexible substrate coated with a metal layer prepared above is used as the mechanical stretching direction (MD direction), and is woven into a current collector by a weaving method.

[0151]

Pole piece preparation

[0152] The active material is made into slurry and evenly coated on both sides of the current collector, and then dried, cold pressed and cut to obtain the wound battery cell pole pieces.

[0153]

Preparation of wound batteries

[0154] The positive and negative electrode sheets and the isolation film are produced into a dry battery cell with a wound structure through a winding machine, and then cold pressed and shaped.

[0155] Comparative Example 1

[0156] The preparation method is the same as that of Example 1, and the diameter of the copper is 21 μm.

[0157] Comparative Example 2

[0158] The preparation method is the same as that of Example 1, and the diameter of the aluminum is 21 μm.

[0159] A commercially available copper foil current collector is used as comparative example 3, and an aluminum foil current collector is used as comparative example 4. Pole sheets and batteries are made according to the preparation method of the pole sheet in Example 1. The negative electrode active material of Examples 1 to 8 is graphite. The positive and negative pole sheets obtained in Examples 1 to 8 and Comparative Examples 1 to 4 are tested for resistivity, adhesion, and brittle fracture performance, and the wetting performance and rate performance of the corresponding batteries are measured, and Table 2 is obtained.

[0160] Among them, the resistivity test is detected by a resistivity tester, the bonding force determination method is to fix the prepared positive electrode plate on the test bench, use adhesives with different bonding forces to stick the plate, and determine the force when the active material and the current collector are separated; the brittle fracture performance determination method is to fold the positive electrode plate along the middle and then unfold it, repeat the above operation and count the number of times when cracks appear on the plate; the wetting performance determination method is to soak the battery, observe whether the electrolyte enters the current collector every 1 hour, and record the time when the electrolyte completely enters the current collector; the rate performance determination method is to measure the battery retention rate at 0.5C and 4C on the charger and discharge machine respectively, take 0.5C as 100%, and convert the retention rate of 4C to the rate performance.

[0161] Table 2 Performance test of current collector and battery

[0162]

[0163]

[0164] It can be seen from Table 2 that the conductivity of the positive and negative electrodes of the secondary battery prepared by the process of the present application is not significantly deteriorated compared with the existing copper foil and aluminum foil, and the rate performance, adhesion, brittle fracture performance and wettability are significantly improved.

[0165] Compared with Comparative Examples 1 and 2, the diameter (diameter) of the flexible substrate of the positive electrode sheet of Examples 1 to 10 of the present application is in the range of 500nm to 20μm, while Comparative Examples 1 and 2 are not in the range, then their rate performance, adhesion, brittle fracture performance and wettability are significantly lower than those of the embodiments, which shows that the diameter of the flexible substrate is crucial.

[0166] In addition, the batteries prepared in Examples 1 to 8 of the present application have significantly higher rate performance, adhesion, brittle fracture performance and wettability than those of conventional batteries made of copper foil and aluminum foil, indicating that the use of a mesh structure can effectively increase the roughness of the surface of the current collector and improve the adhesion of the active material on the substrate, thereby avoiding cracking, demolding, etc., compared with traditional copper foil or aluminum foil; the electrolyte can pass through the current collector to improve the wettability and battery rate performance; the use of a flexible substrate makes the electrode have stronger plasticity, thereby avoiding band breakage and electrode cracking during processing; the flexible substrate has a low density and low cost, and can effectively improve the battery energy density.

[0167] In summary, the mesh structure adopted in the present application can effectively increase the roughness of the surface of the current collector sheet and improve the adhesion of the active material on the substrate to avoid cracking, peeling, etc. compared with the traditional copper foil or aluminum foil; the electrolyte can pass through the current collector to improve the wetting performance and battery rate performance; the flexible substrate is used to make the electrode have stronger plasticity to avoid breaking and cracking of the electrode during the processing process; the flexible substrate has low density and low cost, which can effectively improve the battery energy density.

[0168] The above are only preferred embodiments of the present invention, and do not limit the patent scope of the present invention. For those skilled in the art, the present invention may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the patent protection scope of the present invention.

Claims

1. A secondary battery, characterized in that: It includes an electrode plate, an electrolyte and an isolation membrane. The secondary battery is a wound battery. The current collector of the electrode plate includes a first conductive wire and a second conductive wire interwoven into a mesh. The first conductive wire extends along the length direction of the current collector and is made of metal. The second conductive wire extends along the width direction of the current collector and is made of a flexible substrate whose surface is completely covered with a metal layer.

2. The secondary battery according to claim 1, wherein: The material of the metal layer includes at least one of platinum, gold, silver, copper, aluminum, nickel and iron.

3. The secondary battery according to claim 1, wherein: The material of the flexible substrate includes at least one of polyethylene, polypropylene, polyimide, glass fiber, cotton and linen.

4. The secondary battery according to claim 1, wherein: The diameter of the flexible substrate is 500 nm to 20 μm.

5. The secondary battery according to claim 1, wherein: The thickness of the metal layer is 10 nm to 1 μm.

6. The secondary battery according to any one of claims 1 to 5, characterized in that: The current collector is prepared by the following steps: The first conductive wire and the second conductive wire are interwoven into a mesh to obtain a current collector.

7. The secondary battery according to claim 6, characterized in that: The flexible substrate coated with a metal layer is prepared by the following method: A metal layer is prepared on the outer surface of the flexible substrate by magnetron sputtering, chemical plating or electroplating.

8. An electrical device, characterized in that: A secondary battery comprising the secondary battery according to any one of claims 1 to 7.

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