Single-sided punching burr belt for coating liquid-rich alkaline secondary battery pole plate and application of single-sided punching burr belt

Abstract

The invention discloses a single-side punching burr band for coating an alkaline secondary battery pole plate and application thereof, the single-side punching burr band comprises a metal base band, single-side punching burr units and punched holes are simultaneously distributed on the metal base band, the single-side punching burr units and the punched holes are alternately arranged in a staggered manner, and the single-side punching burr units and the punched holes are uniformly distributed on the metal base band. The single-side punching burr unit comprises at least one polygonal punching burr. According to the invention, a trapezoidal burr and punching mode is adopted to improve the aperture ratio of a punching burr belt, ions can pass through the punching burr belt, the internal resistance of the battery is reduced, the burrs have certain height and density, and a permanent exhausting and liquid supplementing channel is formed between the positive and negative pole pieces and the diaphragm, so that electro-liquid can easily enter a pole group, gas can be easily exhausted, and the service life of the battery is prolonged. Effective heat dissipation can be realized; and meanwhile, as the single-sided burr punching belt is good in strength and balanced in contact force, the single-sided burr punching belt is coated on the surface of the pole piece, so that expansion of the pole piece caused by unsmooth exhausting and liquid supplementing can be reduced, the internal resistance is reduced, the charge-discharge efficiency of the battery is greatly improved, the cycle life of the battery is greatly prolonged, and the stability of electrical performance is greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of alkaline secondary battery electrodes, and in particular relates to a single-sided punched burr tape for coating a liquid-rich alkaline secondary battery plate and an application thereof. Background Art

[0002] The iron-nickel battery is a secondary battery with an iron electrode as the negative electrode and nickel oxyhydroxide as the positive electrode. Compared with the cadmium and lead materials used in the negative electrodes of cadmium-nickel batteries and lead-acid batteries, it does not pollute the environment. Compared with the hydrogen storage alloy mainly composed of rare earths used in the negative electrodes of hydrogen-nickel batteries, the cost advantage is very obvious. The iron electrode and nickel electrode of the iron-nickel battery traditionally adopt a bag structure, that is, the mixed powders of positive and negative active materials, additives and conductive agents are respectively wrapped in bag-shaped plate strips made of nickel-plated steel strips by mechanical equipment, and then cut into plate blanks of different widths according to the required size, and then the blanks are placed in the plate frame, and the positive and negative plates are formed by embossing respectively. Then, according to the size of the battery capacity, according to the principle of the negative electrode on the outside and the positive electrode on the inside, the required number of positive and negative plates and plastic grids are stacked together in sequence, and finally the positive and negative plates are welded or assembled on the collector to form a complete electrode group. The plastic grid replaces the diaphragm to separate the positive and negative electrodes, and also has the function of exhaust. However, the thickness of the plastic grid is generally between 1.5mm and 3mm, which increases the distance between the positive and negative plates and increases the internal resistance of the battery. At the same time, the width of the plastic grid is also between 1.5mm and 3mm. In the structure where the opening rate of the positive and negative plates of the pouch battery does not exceed 18%, a considerable part of the opening rate of the positive and negative plates is blocked, which makes the battery performance very poor, such as high charging voltage, inability to charge and discharge quickly, failure to discharge at 0°C, particularly poor battery rate performance, energy efficiency less than 50%, and very low utilization rate of active substances, only about 60% of the rated capacity, resulting in high cost, heavy weight, large volume and other vicious consequences, resulting in no progress in iron-nickel batteries for more than 120 years and slowly being abandoned.

[0003] The patent document with announcement number CN203910930U discloses a coated iron electrode, whose electrode plate is mainly composed of a foamed nickel matrix or a foamed iron matrix and an active material coated on the foamed nickel matrix or the foamed iron matrix, and the two sides of the electrode plate are respectively coated with a cut-pull mesh, a punched mesh belt, a woven mesh or a microporous metal sheet, and the cut-pull mesh, the punched mesh belt, the woven mesh or the microporous metal sheet are mechanically rolled or seam welded or mechanically rolled and seam welded so that the electrode plate is coated in the cut-pull mesh, the punched mesh belt, the woven mesh or the microporous metal sheet. The patent document with announcement number CN203910912U discloses a coated nickel electrode, wherein the electrode plate is a foamed nickel electrode or a burred steel strip slurry-drawn nickel electrode, and the electrode plate is coated with a cut-drawn mesh, a perforated mesh belt, a woven mesh or a microporous metal sheet, and then mechanically rolled or seam-welded or mechanically rolled and seam-welded to make the electrode plate coated in the cut-drawn mesh, perforated mesh belt, woven mesh or microporous metal sheet, and then formed corresponding protrusions and grooves on the electrode plate and the cut-drawn mesh, perforated mesh belt, woven mesh or microporous metal sheet coated on both sides of the electrode plate by pressing grooves. The above two patent documents are two patents applied for by the applicant in the early stage. The perforated mesh belt used for coating the electrode plate in the patent document is a conventional thin mesh belt. Although the mesh belt can form a gas exhaust channel, the exhaust channel cannot be permanently unobstructed. Compared with pouch batteries, although the battery life is increased to more than 800 times, the final attenuation of the battery is still because this structure cannot prevent the final expansion of the electrode, which results in the electrolyte being unable to enter the electrode group and gas stagnation and inability to be discharged, aggravating the expansion and heat of the electrode, and ultimately causing the electrode group to dry up and end its life. Summary of the invention

[0004] The technical problem solved by the present invention is to provide a single-sided punched burr belt for coating the pole plate of an alkaline secondary battery. The trapezoidal single-sided punched burr belt adopts polygonal burrs and through holes, which can effectively improve the opening rate of the punched burr belt. Due to the existence of burrs, an exhaust channel is formed between the single-sided burr punched belt and the pole piece, which can ensure that the electrolyte easily enters the pole group, the gas is easily discharged, and the heat can be effectively dissipated; at the same time, since the single-sided burr punched belt has good strength, it is coated on the surface of the pole piece, which can reduce the expansion of the pole piece and reduce the internal resistance, thereby effectively improving the charging and discharging efficiency and cycle stability of the alkaline secondary battery. The single-sided punched burr belt can be used to coat the pole plate of the alkaline secondary battery to form a coated electrode, which can greatly improve the electrical performance of the battery. According to the pilot batch test data, the current cycle life of the battery has exceeded 2,000 times, and the capacity is still maintained at more than 95%. According to theoretical calculations, the subsequent cycle life can reach more than 10,000 times. .

[0005] In order to solve the above technical problems, the present invention adopts the following technical scheme: a single-sided punching burr tape for coating alkaline secondary battery plates, comprising a metal base tape, characterized in that: single-sided punching burr units and punchings are distributed on the metal base tape at the same time, the single-sided punching burr units and the punchings are arranged alternately and staggered, and the single-sided punching burr unit includes at least one polygonal punching burr.

[0006] Furthermore, the punching burr in the single-sided punching burr unit is any polygon.

[0007] Furthermore, the punched holes are circular holes, elliptical holes or polygonal holes.

[0008] Furthermore, the metal base strip is one or more of iron, nickel, stainless steel strip, nickel-plated steel strip, copper strip or copper mesh, copper-plated steel strip or copper-plated steel mesh.

[0009] Furthermore, the thickness of the metal base tape is 0.015-1.2 mm.

[0010] Furthermore, the opening area of ​​the polygonal punching burr is 0.36-35 mm 2 The height of the polygonal punching burr is above 0.5mm and can reach up to 12mm (the supported plate thickness exceeds 5mm). As the thickness of the large-capacity battery plate increases, the channel required for exhaust will also increase accordingly, which requires a higher punching burr height. The distance between adjacent punchings in the horizontal direction is ≤5mm, and the distance between adjacent punchings in the vertical direction is ≤5mm.

[0011] The single-sided punched burr tape for coating the liquid-rich alkaline secondary battery plate of the present invention is used for coating the liquid-rich alkaline secondary battery plate to prepare a coated electrode.

[0012] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. The punching burrs of the single-sided punching burr belt of the present invention have a certain height and density, forming a permanent exhaust and liquid replenishment channel between the positive and negative electrode sheets and the diaphragm, which can ensure that the electrolyte can easily enter the electrode group and the gas can be easily discharged. At the same time, it can effectively dissipate heat and ensure that the electrode group is in a moist state during the long-term cycle of the battery, thereby improving the battery life; 2. The single-sided burr punching belt of the present invention has good strength, balanced contact force, and is coated on the surface of the pole piece, which can reduce the expansion of the pole piece caused by poor exhaust and rehydration, reduce internal resistance, and effectively improve the charging and discharging efficiency and cycle life of the alkaline secondary battery and the stability of electrical performance; 3. The present invention can greatly increase the open porosity of the steel strip, which is beneficial to the passage of ions, reduces the internal resistance of the battery, and improves the gram capacity of the active material and the rate performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the planar structure of the single-sided punched burr belt in Example 1.

[0014] Figure 2 yes Figure 1 A partial enlarged view of point I in the middle.

[0015] Figure 3 It is a schematic diagram of the three-dimensional structure of the single-sided punched burr belt in Example 1.

[0016] Figure 4 It is a schematic diagram of the cross-sectional structure of the single-sided punched burr belt in Example 1.

[0017] Figure 5 This is a schematic diagram of the plastic grid used in the battery in Comparative Example 2.

[0018] Figure 6 It is the life cycle test curve of the liquid-rich square iron-nickel battery assembled in Example 1 and Comparative Example 1 and Comparative Example 2. DETAILED DESCRIPTION

[0019] 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

[0020] Preparation of liquid-rich square iron-nickel battery Use a needle punching machine and a punching machine mold to punch out double-sided isosceles trapezoidal burr steel strips on a 0.045mm thick nickel-plated steel strip, respectively, and use them as the positive current collector base strip and the negative current collector base strip, 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 respectively applied to the surface of the current collector base strip, dried and rolled, and then cut into positive and negative electrode sheets of specified sizes, and the single-sided punched burr belt of the present invention is used to coat the electrode sheet, wherein the burrs face the electrode plate side. The coated pole pieces and diaphragms are stacked alternately to form pole groups, and then the positive and negative poles of the pole groups are welded separately, and then loaded into a PP plastic shell of a specified size. Then the positive pole and negative pole are led out, capped, injected, formed, and sealed to obtain a 1.2V 300AH iron-nickel battery. After testing, the battery has a rated capacity of 320AH (0.2C), an operating voltage of 1.2V, a 1C discharge capacity of 285AH, and a cycle life (discharge depth 100%) of more than 10,000 times (to 70% of the rated capacity).

[0021] Comparative Example 1 Preparation of liquid-rich square iron-nickel battery Use a punching machine die to punch out double-sided isosceles trapezoidal burr steel strips on 0.045mm thick nickel-plated steel strips, which are used as positive current collector base strips and negative current collector base strips respectively. Its ingredients, process and operation steps are the same as those in Example 1. The positive and negative electrode sheets are coated with 0.06mm cut and pulled nets, and the coated positive and negative electrode sheets and diaphragms are cross-laminated and assembled, and then loaded into a PP plastic shell of a specified size. Then the positive and negative poles are led out, the caps are sealed, the liquid is injected, the formation is formed, and the sealing is performed to obtain a 1.2V300AH iron-nickel battery. After testing, the battery has a rated capacity of 309AH, a voltage of 1.2V, a 1C discharge capacity of 228AH, and a cycle life (discharge depth 100%) of 300 times (attenuation).

[0022] Comparative Example 2 The positive active material nickel hydroxide, conductive agent acetylene black or graphite, a small amount of polytetrafluoro emulsion, and the negative active material iron oxide powder, conductive agent graphite, a small amount of polytetrafluoro emulsion are respectively packed in a bag-shaped plate strip made of nickel-plated steel strip by mechanical equipment, and then cut into plate blanks of different widths according to the required size, and then the blanks are placed in the plate frame, and the positive and negative plates are formed by embossing. According to the principle of the negative electrode on the outside and the positive electrode on the inside, the required calculated number of positive and negative plates and plastic grids are stacked together in sequence, and finally the positive and negative plates are welded or assembled on the collector plate to form a complete electrode group, which is placed in a PP plastic shell of a specified size. Then the positive pole and negative pole are led out, the cap is sealed, the liquid is injected, the formation is carried out, and the sealing is carried out to obtain a 1.2V300AH iron-nickel battery. After testing, the battery has a rated capacity of 301AH, a voltage of 1.2V, a 1C discharge capacity of 218AH, and a cycle life (discharge depth 100%) of 300 times (attenuation).

[0023] Depend on Figure 6 It can be seen that Example 1 adopts the "coating single-sided burr tape" process. In the 2-hour rate life cycle test, the capacity is still very stable after 2000 cycles. It can be theoretically calculated that it can be cycled for more than 10,000 times. Comparative Example 1 adopts the "coating cut and drawn mesh" process. After more than 800 2-hour rate life cycle tests, it began to decay. Comparative Example 2 uses a bag-type battery structure with a plastic grid, which underwent significant decay after 550 cycles.

[0024] The above embodiments describe the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for illustrating the principles of the present invention. Without departing from the scope of the principles of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of protection of the present invention.

Claims

1. A single-sided punched burr tape for coating a liquid-rich alkaline secondary battery plate, comprising a metal base tape, characterized in that: The metal base strip is provided with single-sided punching burr units and punchings at the same time. The single-sided punching burr units and the punchings are arranged alternately and staggered. The single-sided punching burr unit includes at least one polygonal punching burr.

2. The single-sided punched burr tape for coating the polar plate of the rich liquid alkaline secondary battery according to claim 1, characterized in that: The punching burr in the single-sided punching burr unit is any polygon.

3. The single-sided punched burr tape for coating the liquid-rich alkaline secondary battery plate according to claim 1, characterized in that: The punched holes are circular holes, elliptical holes or polygonal holes.

4. The single-sided punched burr tape for coating the liquid-rich alkaline secondary battery plate according to claim 1, characterized in that: The metal base strip is one or more of iron, nickel, stainless steel strip, nickel-plated steel strip, copper strip or copper mesh, copper-plated steel strip or copper-plated steel mesh.

5. The single-sided punched burr tape for coating the alkaline secondary battery plate according to claim 1, characterized in that: The thickness of the metal base tape is 0.015-1.2 mm.

6. The single-sided punched burr tape for coating the polar plate of a liquid-rich alkaline secondary battery according to claim 1, characterized in that: The opening area of ​​the polygonal punching burr is 0.36~35mm 2 The height of the polygonal punching burr is 0.5~12mm, the distance between adjacent punching holes in the horizontal direction is ≤5mm, and the distance between adjacent punching holes in the vertical direction is ≤5mm.

7. The single-sided punched burr tape for coating a liquid-rich alkaline secondary battery plate according to any one of claims 1 to 8 is used for coating a liquid-rich alkaline secondary battery plate to prepare a coated electrode.

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