Alkaline secondary battery current collector base band and application thereof

Abstract

The invention discloses an alkaline secondary battery current collector base band and application thereof.The current collector base band comprises a metal base band, a plurality of burr units are evenly distributed on the metal base band in an array mode, and each burr unit is composed of front trapezoid burrs and back trapezoid burrs which are symmetrically arranged; long bottom plates of the front trapezoid burrs and long bottom plates of the back trapezoid burrs are adjacent and parallel to each other, front trapezoid burr long bottom edges formed by the front trapezoid burrs are connected with the metal base band, front trapezoid burr short bottom edges form front trapezoid burr ends, and back trapezoid burr long bottom edges formed by the back trapezoid burrs are connected with the metal base band. And the reverse trapezoidal burr short bottom edge forms a reverse trapezoidal burr end part. The current collector base band adopting a specific trapezoidal burr bidirectional arrangement mode effectively improves the conductivity of the polar plate and reduces the battery resistance, so that the assembled alkaline secondary battery has high rate performance, long cycle service life and other electrical properties and high specific energy, and meanwhile, the requirements of high power and high specific energy of the battery are met.

Description

Technical Field

[0001] The invention belongs to the technical field of alkaline secondary battery current collectors, and in particular relates to an alkaline secondary battery current collector base tape and application thereof. Background Art

[0002] At present, commercial chemical power sources mainly include three battery systems: lithium-ion batteries, lead-acid batteries, and alkaline nickel batteries (nickel hydrogen batteries, nickel cadmium batteries, nickel iron batteries, and nickel zinc batteries). In addition, there are other metal ion batteries such as sodium ion batteries, lithium sulfur batteries, and zinc ion batteries that are in the research and development stage. The preparation of all these batteries is inseparable from the current collector base band to which the positive and negative active materials are attached. The current collector base band not only plays the role of carrying active materials, but also is used to receive electrons transferred from the active materials and transfer them to the external circuit. When charging, the electrons transferred from the external circuit are transferred to the active materials, thereby realizing the mutual conversion of chemical energy and electrical energy. It can be seen that the current collector base band is one of the indispensable and important components of the battery.

[0003] At present, lithium-ion batteries and sodium-ion batteries using organic electrolytes use aluminum foil and copper foil as the current collector base for the positive and negative active materials, respectively. Aluminum foil current collector bases can be used for both positive and negative electrodes of lithium titanate batteries. The active material is mixed with a conductive agent and an adhesive to form a slurry, which is coated on aluminum foil and copper foil, and then dried, rolled and cut to prepare positive and negative electrodes. Batteries such as hydrogen nickel, zinc nickel and iron nickel using aqueous electrolytes mostly use stainless steel mesh, nickel-plated mesh, copper mesh, perforated nickel-plated steel strip, square-hole burred steel strip or copper strip, foam nickel, foam copper and other metal materials as the current collector base for the active material. Since the conductivity of aqueous electrolytes is better than that of organic electrolytes, the thickness of the slurry applied to the current collector base can be more than 10 to 100 times that of organic batteries such as lithium-ion batteries. Therefore, the slurry-pulling process is often used to scrape the active material slurry onto the current collector base, and then dry, roll and cut to make electrodes.

[0004] Among the existing metal current collectors, nickel foam, copper foam, and iron foam are porous three-dimensional structures. The active materials scraped onto them can fully contact the current collector metal and have excellent conductivity, but the cost is high. In addition, the electrode sheet strength is low after rolling, and it is easy to break during the production process, and the active material is also easy to fall off. Flat metal mesh belts and perforated steel belts are relatively cheap, and the active materials can be bonded through perforations to prevent them from falling off, but the amount of sizing is small, and the active materials loaded are small. Under the condition of a certain gram capacity of active materials, equal volume and mass, the number of positive and negative electrode sheets and insulating diaphragms required is greatly increased, resulting in low energy density of the assembled battery and greatly increased battery cost. The burr steel strip is conducive to increasing the sizing amount, increasing the loading amount of active materials, and thus improving the energy density of the battery. However, the traditional burr steel strip has square holes, and the burr shape is triangular, with the tip facing outward. If the burr hole is small, the burr height of the current collector is low, and the sizing amount is naturally low. If the sizing amount is to be increased, the burr height needs to be increased, and the opening area will increase accordingly. The height and diagonal of the quadrilateral after the opening is increased will increase accordingly. In this case, the conductive path of the battery electrode is greatly obstructed, resulting in an increase in the resistance of the pole piece, an increase in the charging voltage of the battery, and a decrease in the discharge platform of the battery, which will greatly affect the gram capacity and rate performance of the battery active material, thereby causing the abnormal expansion of the active material and the de-powdering from the conductive skeleton due to poor conductivity and increased resistance during the charge and discharge process, which seriously affects the cycle life of the battery. Therefore, how to make the current collector base tape meet the requirements of large sizing amount, large active material load, not easy to fall off, and reduce the cost of inactive materials, and improve or at least not reduce the charge and discharge rate performance of the battery, is still a technical problem that needs to be solved.

[0005] The patent previously applied for by the applicant, the patent document with publication number CN115986131A discloses a current collector base tape and a method for preparing an electrode based on the current collector base tape, wherein the current collector base tape includes a metal base tape, and burrs and perforations are distributed on the metal base tape at the same time, and the burrs and perforations are arranged alternately and staggered. The current collector base tape combines the advantages of the burr base tape and the perforated base tape into a current collector base tape, so that the current collector base tape can simultaneously meet the requirements of a large amount of sizing and a large amount of active material loaded. At the same time, the active material of the prepared electrode is not easy to fall off and is relatively low in price, which greatly extends the cycle life of the battery. However, the current collector base tape and the conventional punched current collector base tape have the following technical problems in the subsequent use process: First, the current collector base tape has a wave-like bending and uneven problem caused by the punching and stretching deformation during the punching and forming process, which cannot be overcome; second, the punching surface is formed with a sharp point, which has the hidden danger of causing battery short circuit; third, when the current collector base tape is punched and formed with burrs and perforated at the same time, the processing efficiency is low and the scrap rate is high, so the manufacturing cost is also relatively high; fourth, in order to increase the sizing amount of the current collector base tape and increase the burr height, it is necessary to increase the size of the punching hole, although it can increase the current collector base tape to a certain extent. The amount of sizing, but the increase in the hole margin will lead to the deterioration of the conductivity of the current collector, which will further affect the rate performance, gram capacity of the active material, cycle life and electrical properties of the alkaline secondary battery. In addition, the increase in the opening size of the current collector base belt will also affect the strength of the current collector to a certain extent. At the same time, as the opening size of the current collector base belt increases, the punching deformation causes the base belt to produce wavy bending and unevenness. The fifth is that because the burrs on the steel strip have sharp tips, the height direction strength of the burr steel strip is insufficient. During the punching and winding and electroplating winding and unwinding process, the tip will bend and deform, resulting in inconsistent overall height of the burr steel strip. Summary of the invention

[0006] The technical problem solved by the present invention is to provide an alkaline secondary battery current collector base tape, which adopts a two-way arrangement of trapezoidal burrs, so that the current collector base tape can simultaneously meet the requirements of large sizing amount, good conductivity and high strength. At the same time, the active material of the electrode made based on the current collector base tape is not easy to fall off and the price is relatively low. The alkaline secondary battery current collector base tape can be used to prepare positive and negative electrodes of alkaline secondary batteries.

[0007] In order to solve the above technical problems, the present invention adopts the following technical scheme: an alkaline secondary battery current collector base tape, including a metal base tape, characterized in that: a plurality of burr units are evenly distributed in an array on the metal base tape, and the burr unit is composed of symmetrically arranged front trapezoidal burrs and back trapezoidal burrs, wherein the long bottom plates of the front trapezoidal burrs and the back trapezoidal burrs are adjacent to and parallel to each other, the long bottom side of the front trapezoidal burrs formed by the front trapezoidal burrs is connected to the metal base tape, the short bottom side of the front trapezoidal burrs forms the front trapezoidal burr end, the long bottom side of the back trapezoidal burrs formed by the back trapezoidal burr holes is connected to the metal base tape, and the short bottom side of the back trapezoidal burrs forms the reverse trapezoidal burr end.

[0008] Furthermore, the front trapezoidal burrs and the back trapezoidal burrs are both isosceles trapezoids in shape. The front trapezoidal burrs and the back trapezoidal burrs are evenly arranged on the metal base tape.

[0009] Furthermore, the metal base strip is one or more of a steel strip, a nickel strip, a stainless steel strip, a nickel-plated steel strip, a copper strip or a copper-plated steel strip.

[0010] Furthermore, the thickness of the metal base tape is 0.015-1.0 mm.

[0011] Furthermore, the opening area of ​​the front trapezoidal burr and the back trapezoidal burr are both 0.36-30 mm 2 The total height of the front trapezoidal burr and the back trapezoidal burr after opening is 0.5~10mm, the distance between the adjacent front trapezoidal burrs and the back trapezoidal burrs in the transverse direction is ≤5mm, and the distance between the long bottom edge of the front trapezoidal burr and the long bottom edge of the back trapezoidal burr in a single burr unit is ≤5mm.

[0012] The application of the alkaline secondary battery current collector base tape in the preparation of alkaline secondary battery electrodes is characterized by the specific process of: punching out front trapezoidal burrs and back trapezoidal burrs in a specific arrangement on a metal base tape by design and calculation using a needle punching machine and a punching machine mold respectively to form a current collector base tape; mixing battery active materials, conductive agents, fibers, adhesives and solvents to prepare uniform active material slurry; using a slurry drawing method to scrape the active material slurry onto both sides of the current collector base tape, and preparing positive and negative electrodes through drying, rolling and cutting.

[0013] Furthermore, the thickness of the positive electrode and the negative electrode are both 0.15-6.5 mm.

[0014] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. The current collector base tape of the present invention adopts a bidirectional arrangement of specific trapezoidal burrs, which can greatly increase the burr height of the current collector base tape, so that the current collector base tape can achieve a larger sizing amount and load more active substances. The prepared electrode has a strong adhesion between the active substances and the current collector base tape. During the charge and discharge process, due to the increase of conductive ribs and the greatly shortened conductive path, the active substances will not increase impedance due to the increase in the coating amount and thickness of the battery plate, thereby causing the active substances to fall off, which can effectively improve the cycle life and electrical performance of the alkaline secondary battery.

[0015] 2. The present invention adopts a current collector base tape with a specific bidirectional arrangement of trapezoidal burrs, which increases the controllable range of the burr height, increases the end strength of the front trapezoidal burrs and the back trapezoidal burrs, and effectively reduces the burr bending deformation.

[0016] 3. The present invention adopts a current collector base tape with a specific trapezoidal burr bidirectional arrangement, which can effectively solve the wave bending and unevenness problems of the current collector base tape caused by punching deformation. After the special structure designed by the present invention is punched and formed, the overall flatness of the current collector base tape is better.

[0017] 4. The present invention adopts a current collector base tape with a specific bidirectional arrangement of trapezoidal burrs, so that the effective distance of the reserved edge ribs in the conductive direction is increased. Generally, increasing the burr height will reduce the conductive length of the edge ribs. However, this special structure, that is, all the front trapezoidal burrs and the back trapezoidal burrs are evenly arranged along different angles on the metal base tape, can shorten the conductive path.

[0018] 5. The present invention adopts a specific two-way arrangement of trapezoidal burrs in the current collector base strip, which increases the overall strength of the base strip. The front trapezoidal burrs and the back trapezoidal burrs are evenly arranged along different angles on the metal base strip, increasing the width of the side ribs in the horizontal and vertical directions, effectively increasing the overall strength of the base strip.

[0019] 6. The present invention adopts a current collector base tape with a specific trapezoidal burr bidirectional arrangement, which can increase the sizing amount while ensuring the firm combination of the active material and the skeleton and preventing powder from falling off, and can also improve the capacity of the active material. At the same time, it reduces the hole margin, thereby shortening the conductive path, which can effectively improve the conductivity of the plate and reduce the resistance, thereby improving the rate performance and cycle performance of the alkaline secondary battery, and can ensure the high power requirements and high specific energy requirements of the battery.

[0020] The present invention adopts a current collector base tape with a specific trapezoidal burr bidirectional arrangement. The burrs formed after the holes are opened are trapezoidal without sharp tips, which greatly reduces the risk of battery short circuit caused by sharp tips and improves the battery yield.

[0021] 8. The current collector substrate and the electrode prepared based on the current collector substrate of the present invention are not only suitable for liquid-poor aqueous alkaline secondary batteries, but also suitable for liquid-rich aqueous alkaline secondary batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the planar structure of the current collector base tape in Example 1.

[0023] Figure 2 yes Figure 1 A partial enlarged view of point I in the middle.

[0024] Figure 3 It is a schematic diagram of the three-dimensional structure of the current collector base tape in Example 1.

[0025] Figure 4 It is a schematic diagram of the cross-sectional structure of the current collector base tape in Example 1.

[0026] Figure 5 This is a schematic diagram of the planar structure of the current collector base tape in Comparative Example 1.

[0027] Figure 6 This is a schematic diagram of the three-dimensional structure of the current collector base tape in Comparative Example 1.

[0028] Figure 7 It is the rate performance test curve of the liquid-rich square iron-nickel battery assembled in Example 1 and Comparative Example 1.

[0029] Figure 8 It is the life cycle test curve of the liquid-rich square iron-nickel battery assembled in Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0030] The above contents of the present invention are further described in detail below through examples, but this should not be understood as the scope of the above subject matter of the present invention being limited to the following examples, and all technologies implemented based on the above contents of the present invention belong to the scope of the present invention. Example 1

[0031] Preparation of liquid-rich square iron-nickel battery The positive isosceles trapezoidal burrs and the reverse isosceles trapezoidal burrs were punched out on the 0.025mm thick nickel-plated steel strip using a needle punching machine and a punching machine die. The opening area of ​​the positive isosceles trapezoidal burrs and the reverse isosceles trapezoidal burrs were both 4mm. 2 The total height of the positive isosceles trapezoidal burr and the reverse isosceles trapezoidal burr is 1.5mm. The positive isosceles trapezoidal burr and the reverse isosceles trapezoidal burr are evenly arranged along the 45° tilt direction on the metal base tape. Figure 1. They are used as the positive current collector base and the negative current collector base respectively. The positive electrode ingredients include nickel hydroxide powder, conductive graphite, CMC, PTFE adhesive, etc., add an appropriate amount of deionized water, and mix them in a vacuum mixer to form a uniform positive active material slurry. The negative electrode ingredients include iron oxide powder, conductive graphite, acetylene black, etc., add an appropriate amount of deionized water, and mix them in a vacuum mixer to form a uniform negative active material slurry. The positive active material slurry and the negative active material slurry are applied to the surface of the current collector base respectively, dried and rolled, and then cut into positive and negative electrode sheets of specified sizes. The battery plates are stacked and welded according to a specific process, and then loaded into a PP plastic shell of specified size. Then the positive and negative poles are led out, the cap is sealed, the liquid is injected, the chemical is formed, and the sealing is performed to obtain a 1.2V 500AH iron-nickel battery. The battery has been tested to have a rated capacity of 514AH (0.2C), an operating voltage of 1.2V, a 1C discharge capacity of 475AH, and a cycle life (discharge depth 100%) of more than 2,000 times. Based on the trend, it is estimated that the battery life can reach more than 10,000 times.

[0032] Comparative Example 1 Preparation of liquid-rich square iron-nickel battery A burred nickel-plated steel strip was selected as the positive current collector base strip and the negative current collector base strip. A punching machine die was used to punch out alternating positive and negative burrs on the 0.025 mm thick nickel-plated steel strip. The opening shapes of the positive and negative burrs were both square. The opening areas of the positive and negative burr holes were both 3.9 mm2. The total height of the positive and negative burrs was 1.45 mm. Figure 5 The ingredients, process and operation steps are the same as those in Example 1, and a 1.2V 500AH iron-nickel battery is prepared. After testing, the battery has a rated capacity of 509AH, a voltage of 1.2V, a 1C discharge capacity of 380AH, and a cycle life (discharge depth 100%) of 800 times (attenuation).

[0033] Depend on Figure 7 It can be seen that Example 1 uses a trapezoidal double-sided burr tape current collector, and the capacity is stable in the 2-hour life cycle test; Comparative Example 1 uses a quadrilateral double-sided burr tape current collector, and there is obvious attenuation in the life cycle test. Figure 8 It can be seen that the room temperature 1C rate performance of the liquid-rich square iron-nickel battery assembled in Example 1 is significantly better than that of the liquid-rich square iron-nickel battery assembled in Comparative Example 1.

[0034] The basic principles, main features and advantages of the present invention are shown and described above. Without departing from the spirit and scope of the present invention, the present invention may also be subject to various changes and improvements, which all fall within the scope of the present invention to be protected.

Claims

1. An alkaline secondary battery current collector substrate, comprising a metal substrate, characterized in that: The metal base strip is evenly distributed with a plurality of punching burr units in an array, and the burr units are composed of symmetrically arranged front trapezoidal burrs and rear trapezoidal burrs, wherein the long bottom plates of the front trapezoidal burrs and the rear trapezoidal burrs are adjacent to and parallel to each other, the long bottom side of the front trapezoidal burrs formed by the front trapezoidal burrs is connected to the metal base strip, the short bottom side of the front trapezoidal burrs forms the front trapezoidal burr end, the long bottom side of the rear trapezoidal burrs formed by the rear trapezoidal burrs is connected to the metal base strip, and the short bottom side of the rear trapezoidal burrs forms the reverse trapezoidal burr end.

2. The alkaline secondary battery current collector substrate according to claim 1, characterized in that: The front trapezoidal burrs and the back trapezoidal burrs are both in the shape of isosceles trapezoids, and the front trapezoidal burrs and the back trapezoidal burrs are evenly arranged on the metal base tape.

3. The alkaline secondary battery current collector substrate according to claim 1, characterized in that: The metal base strip is one or more of a steel strip, a nickel strip, a stainless steel strip, a nickel-plated steel strip, a copper strip or a copper-plated steel strip.

4. The alkaline secondary battery current collector substrate according to claim 1, characterized in that: The thickness of the metal base tape is 0.015-1.0 mm.

5. The alkaline secondary battery current collector substrate according to claim 1, characterized in that: The opening area of ​​the front trapezoidal burr and the back trapezoidal burr is 0.36-30mm 2 The total height of the front trapezoidal burr and the back trapezoidal burr after opening is 0.5~10mm, the distance between the adjacent front trapezoidal burrs and the back trapezoidal burrs in the transverse direction is ≤5mm, and the distance between the long bottom edge of the front trapezoidal burr and the long bottom edge of the back trapezoidal burr in a single burr unit is ≤5mm.

6. Use of the alkaline secondary battery current collector substrate according to any one of claims 1 to 5 in the preparation of alkaline secondary battery electrodes.

7. The use according to claim 6, characterized in that The specific process is as follows: by designing and calculating, a needle punching machine and a punching machine mold are used to punch out trapezoidal burrs on the front and back of the metal base tape in a specific arrangement to form a current collector base tape; the battery active material, conductive agent, fiber, adhesive and solvent are mixed to prepare a uniform active material slurry; the active material slurry is completely filled within the burr height on both sides of the current collector base tape by slurry drawing, and the positive and negative electrodes are prepared through drying, rolling and cutting.

8. The use according to claim 7, characterized in that The thickness of the positive electrode and the negative electrode are both 0.15-6.5 mm.

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