CN113363502B

CN113363502B - Unequal-thickness grid and preparation method thereof

Info

Publication number: CN113363502B
Application number: CN202110736286.XA
Authority: CN
Inventors: 李毛丁; 谭毅
Original assignee: Chongqing Leichi New Energy Technology Co ltd
Current assignee: Chongqing Guanzhi E Commerce Co ltd
Priority date: 2021-06-30
Filing date: 2021-06-30
Publication date: 2023-08-29
Anticipated expiration: 2041-06-30
Also published as: CN113363502A

Abstract

The application relates to the technical field of lead-acid batteries, in particular to a grid with unequal thickness and a preparation method thereof. A plate grid with unequal thickness comprises a lug, a busbar positioned at the root of the lug and a punching part; the punching part sequentially comprises a first punching part, a second punching part and a third punching part from top to bottom, wherein the thickness of the first punching part to the third punching part is gradually decreased, and N is more than or equal to 2; a plurality of reinforcing ribs are arranged between the N punching part and the N-1 punching part. The technical problems that the weight of the grid is increased and the specific energy of the grid is reduced when the aperture of the grid is reduced are solved, the grid can be applied to practical operation of prolonging the cycle life of the battery and improving the performance of the battery, the weight of the grid is not increased while the specific surface area of the grid is increased, and the performance of the battery manufactured by the polar plate is comprehensively improved.

Description

Unequal-thickness grid and preparation method thereof

Technical Field

The application relates to the technical field of lead-acid batteries, in particular to a grid with unequal thickness and a preparation method thereof.

Background

Lead acid batteries are a type of storage battery, which has been developed for hundreds of years so far, and the main principle of which is the conversion of chemical energy into electrical energy. The lead-acid battery mainly comprises an electrolytic tank, electrolyte and a polar plate, wherein the polar plate is a core component of the whole battery and determines the main performance of the lead-acid battery. The polar plate is composed of a grid and active substances on the grid, and the grid is mainly used for fixing the active substances and inputting or outputting current of electrochemical reaction of the active substances.

Chinese patent CN104868176B (a 3D lead-acid battery and a method for manufacturing the same) and CN104882616B (a 3D current collector of a lead-acid battery and a method for manufacturing the same) have studied a method for increasing the volume specific surface area of a grid, and the volume specific surface area (Kong Xielv) of the grid is increased by reducing the aperture of the opening of the grid, so as to reduce the internal resistance of current transmission and increase the efficiency of chemical energy conversion into effective electric energy and the utilization rate of active materials. However, under the conditions of certain volume and thickness, increasing the specific surface area of the grid volume tends to increase the weight of the grid. The research shows that when the specific surface area of the grid is increased by 150-200%, the weight of the grid is increased by 16-35%. The increase in the weight of the grid tends to result in an increase in the specific energy (energy per unit weight) of the battery, and the advantage of the increase in the volumetric specific surface area is offset by the substantial increase in the weight of the grid. The negative effect caused by the increase of the weight of the grid is overcome, the specific energy and the active material utilization rate of the lead-acid storage battery are fully improved, and the method has important significance for improving the cycle life and the performance of the battery.

Disclosure of Invention

The application aims to provide a grid with unequal thickness so as to solve the technical problem that the specific energy of the grid is reduced when the aperture of the grid is reduced.

In order to achieve the above purpose, the application adopts the following technical scheme:

a plate grid with unequal thickness comprises a lug, a busbar and a punching part; the punching part comprises a first punching part, a N punching part and a second punching part from top to bottom, wherein the thickness of the first punching part to the N punching part is gradually decreased, and N is more than or equal to 2; a plurality of reinforcing ribs are arranged between the N punching part and the N-1 punching part; a plurality of reinforcing ribs are also arranged between the first punching part and the busbar.

The scheme also provides a preparation method of the grid with different thickness, which comprises the following steps in sequence:

s1: preparing and obtaining an initial slab lattice blank;

s2: obtaining a gradient thickness punching blank through multiple cold rolling, wherein the gradient thickness punching blank comprises a tab, a busbar and a gradient thickness punching part;

s3: punching the gradient thickness punching part to obtain a 3D structure front blank;

s4: and pressing the 3D structure front punching part of the 3D structure front blank into waves to obtain the grid with different thickness.

The principle and the advantages of the scheme are as follows: this scheme has set up the punching part that reduces in proper order from top to bottom thickness, and utmost point ear and busbar keep former thickness unchanged, when guaranteeing the current-carrying capacity of grid, have alleviateed the weight of grid, and then have increased the specific energy of battery. The gradient thickness cold rolling mode is utilized to solve the problem that the specific surface area is increased by 150-200 percent (by reducing the aperture), and the weight of the grid is equal to or less than about 15 percent of that of the original plate grid (the cast grid or the expanded grid with the same specification). The specific energy of the 3D engineering sample battery manufactured by the structure is improved by 15-25% compared with the traditional battery. Experiments prove that the high-current performance of the structural grid with 4.5 multiplying power, 8 multiplying power and 10 multiplying power is not different from that of the traditional structural grid, and the requirements of national standards on corrosion-resistant cycle life are met.

The inventor has found that when the volume specific surface area of the grid is increased by 150-200% in an attempt to reduce the punching diameter, the weight of the grid is increased by 16-35%. The advantage of increasing the volume specific surface area is offset by the substantial increase in weight of the grid. In order to overcome the technical problems, the inventor tries to reduce the thickness of the grid integrally, and the reduction of the thickness of the grid integrally (the thickness of the lug, the lug root bus bar and the punching part is reduced) can completely meet the requirement that the ratio of the grid to the pole plate is in the range of 0.31-0.40 (namely, the weight of the grid is in the range of 31-35% of the weight of the whole pole plate, which is the conventional requirement of industry). But the conductivity is deteriorated and the strength of the grid is deteriorated due to the overall thickness of the grid being thinned.

Aiming at the strength problem of the grid: the weight of the whole polar plate is more than three times of that of the plate after the plate grid is pasted, the polar plate is required to be incapable of being deformed greatly in the production of the battery, the battery is assembled into a tight assembly, the polar plates of the battery are required to be welded in series and parallel, and the technological processes all require that the plate grid has technological strength meeting the technological requirements. The grid is too thin to meet the above requirements. The reinforcing treatment of the left and right ends of the grid and the tab portions by the resin adhesive material can ensure mechanical strength and overcome defects, but can lead to complicated processes. Because the left and right ends of the grid are fixed in the electrolytic tank, and the lug positions need to be fixed with structures such as wires, the positions need to bear certain force, so reinforcement is needed.

Aiming at the problem of conductivity, after the whole grid is thinned under normal temperature, the 4.5-multiplying power, 8-multiplying power and 10-multiplying power large current performance of the grid is not superior to that of the grid with the traditional structure, the thin grid is completely in the disadvantage in the low-temperature test at-10 to-18 ℃, and the temperature rise of the battery is faster than that of the traditional structure. The current carrying capacity of the tabs and the bus bars does not reach that of the conventional structure. In addition, grids in the vicinity of the tabs are particularly prone to corrosion. The thickness of the lug and the thickness of the bus bar at the root of the lug are increased in a welding and material increasing mode, so that the high-magnification and high-current carrying capacity of the grid can be improved. However, there is a problem in that the process is complicated, and the electrical conductivity of the welded material is inferior to that of the integrally formed material.

Because the demand of weight reduction is with the whole thinning of grid, and then in order to overcome the not good problem of intensity and current-carrying capacity that the whole thinning of grid brought, need adopt two kinds of different solutions to overcome simultaneously, this has just increased the technology degree of difficulty, has increased cost of manufacture and has reduced maneuverability. The inventors tried various solutions and found that the above problems could be completely overcome by forming the grid according to the present embodiment by performing the thickness reduction treatment of the punching portion in order from top to bottom without performing the thickness reduction treatment of the tab and the bus bar. Due to the reduction of the partial thickness, the overall weight of the grid is reduced, so that the specific energy of the battery is increased. And the grid structure of this scheme can not reduce its current-carrying capacity, also can not appear the overheated problem of battery. The inventor has analyzed that the upper portion of the grid is more current, while the lower portion does not require excessive thickness to maintain a larger current carrying capacity. In addition, the thickness of the lug is not reduced, and the problem that the strength is not enough and the fixing is inconvenient is solved. When the two ends of the punching part are fixed in the storage battery, the upper part of the punching part bears larger force, and the upper part of the punching part is thicker, so that the strength of the punching part is ensured. Therefore, the punching part of the grid is arranged to be of a structure with thick upper part and thin lower part, so that the problems of influencing the quality and the processing difficulty of the storage battery can be solved simultaneously.

In addition, because the punching parts have thickness difference, the part where the N punching part and the N-1 punching part are connected and the part where the first punching part and the bus bar are connected are easy to break, so a plurality of reinforcing ribs are arranged between the N punching part and the N-1 punching part and between the first punching part and the bus bar so as to increase the overall strength of the grid.

Further, the width of one end of the reinforcing rib close to the lug is 1.5-2.5mm, and the width of one end of the reinforcing rib far away from the lug is 0.5-1mm; the distance between one end of the reinforcing rib close to the lug and one end of the reinforcing rib far away from the lug is 4-6mm. The reinforcing rib with the size can better avoid metallographic fracture (or crack) of the metal material at the junction with the thickness difference, and the reinforcing rib with the shape is easy to manufacture. For the widths close to the tab end and far from the tab end, if the widths are too narrow, the reinforcing effect on the junction of the thickness differences is insufficient; if too wide, the dead weight of the grid can be excessively increased, wasting material and reducing the specific energy of the battery.

Further, the punching part is wavy; the distance between adjacent wave crests and wave troughs of the punching part is 0.9-2.5mm, and the distance between adjacent wave crests and wave troughs is 1.5-5.5mm. The wavy design can increase the volume specific surface area of the grid, thereby increasing the utilization rate of active substances. By adopting the arrangement, the ideal effect of increasing the volume specific surface area of the grid can be obtained, and meanwhile, the grid also has certain strength, so that the subsequent processing of the grid is convenient for the process of forming the lead-acid battery. Aiming at the distance between adjacent wave crests and wave troughs and the distance between adjacent wave crests, if the distance between adjacent wave crests and wave crests is too large, the effect of increasing the specific surface area is insufficient; if too small, the difficulty of the machining operation is too great.

Further, a plurality of punched holes are arranged on the punching part, and the size of the punched holes is 2.5X2.5 mm or 3.5X3.5 mm or 5X 5mm. The punched holes of the above dimensions facilitate the stamping formation and maintain the desired Kong Xielv and active material utilization of the grid. The above-mentioned punched hole size is conventional in the prior art, and can be obtained by using the existing die.

Further, the punching part comprises a first punching part, a second punching part and a third punching part; the thickness of the first punching part is reduced by 35-40% relative to the thickness of the tab, the thickness of the second punching part is reduced by 25-30% relative to the thickness of the first punching part, and the thickness of the third punching part is reduced by 20-25% relative to the thickness of the second punching part. By adopting the thickness gradient, smaller energy loss and grid weight can be ensured, and the ideal specific energy and performance of the battery can be finally obtained.

Further, the first punching portion, the second punching portion and the third punching portion are formed by processing the first pre-processing punching portion, the second pre-processing punching portion and the third pre-processing punching portion, respectively; the height ratio of the first pre-processing punching part, the second pre-processing punching part and the third pre-processing punching part is 5-7:15-25:70-75. The punching part of Gao Dubi can ensure that the grid has larger current carrying capacity and is not easy to corrode.

Further, the thickness of each of the tab and the bus bar is 0.7-0.8mm.

By adopting the technical scheme, the lug and the busbar are maintained to be of a certain thickness, so that smooth current flowing in the grid is ensured (namely, the current carrying capacity of the lug and the busbar is ensured), and the problem that the temperature rise of the battery is faster than that of the traditional structure due to overlarge current or overlarge environmental temperature is avoided.

Further, in S2, the uniform thickness punched section of the initial blank of the grid is placed between the upper roller and the cold-rolled flat plate, the upper roller and the cold-rolled flat plate cold-roll the uniform thickness punched section to a specified thickness, and the gradient thickness punched section is obtained by multiple cold-rolling. The uniform-thickness punching part can be processed into a gradient-thickness punching part with a flat surface and a thickness difference by matching the upper roller with the cold-rolled flat plate and carrying out cold rolling for a plurality of times, thereby creating conditions for the subsequent processing of the punching part into a finished product. The grid with gradient thickness prepared by adopting the mode of sequential cold rolling (pad rolling) of the scheme has the following advantages: the multiple rolling ensures that the weight of the manufactured grid with different thickness is smaller than that of the traditional cast grid. The slab lattice formed by sequential rolling is slightly larger in density than the slab lattice formed by casting due to multiple rolling, so that the corrosion resistance of the slab lattice is better. While other means (e.g., casting) may obtain grids of graded thickness, it is difficult to obtain such means by casting in order to produce ultra-thin grids of successively decreasing thickness from 0.7 to 0.8mm. Because once the thickness of the object becomes smaller, the liquid lead alloy is difficult to uniformly distribute in the whole casting mould, bubbles are easy to generate, and the density of the finished grid is easy to be uneven. The sheet grid formed by casting has poor conductivity and corrosion resistance. The grid formed by multiple times of rolling is compact in metallographic structure, and the surface of the cold-rolled material can form a slurry-coated corrosion-resistant layer, so that the corrosion resistance requirement of the grid under the experimental conditions specified by national standards is met. Through repeated rolling compaction, the improvement of the overall specific energy of the battery (the reduction of the overall weight of the battery) is realized under the condition of embodying the 3D structural performance advantage.

Further, the upper surface of one end of the cold-rolled flat plate, which is close to the tab, is provided with a plurality of grooves for preparing reinforcing ribs. In the process of using the cooperation of the upper roller and the cold-rolled flat plate and carrying out cold rolling, reinforcing ribs can be formed at the grooves, so that the situation that the punching part breaks at the junction is avoided. When cold rolling forms thickness gradient, cold rolling shearing stress is very easy to cause stress crack on the deformed section, which has serious influence on the service life of the plate grid and finally influences the service life of the battery. The reinforcing ribs are formed at the same time of cold rolling, so that the breakage of materials during cold rolling is prevented.

Drawings

Fig. 1 is a top view of a grid of unequal thickness of example 1.

Fig. 2 is a left side view of the gradient thickness punched blank of example 1.

Fig. 3 is an enlarged view of the portion a (showing the reinforcing bars).

Fig. 4 is a plan view of the portion a in fig. 2 (showing the reinforcing bars).

Fig. 5 is a left side view of the unequal thickness grid of fig. 1.

Fig. 6 is a schematic structural view of the rolling apparatus of embodiment 1.

Fig. 7 is a longitudinal sectional view of the cold rolled flat plate of fig. 6.

Fig. 8 is a front view of the 3D structured pre-blank of example 1.

Detailed Description

The following is a further detailed description of the embodiments:

reference numerals in the drawings of the specification include: tab 1, bus bar 2, punching section 3, punching section 4, first punching section 5, second punching section 6, third punching section 7, first pre-processing punching section 8, second pre-processing punching section 9, third pre-processing punching section 10, cold-rolled flat plate 12, upper roller 13, lower roller 14, crawler 15, bottom surface 16, groove 17, stiffener 18, equal thickness punching section 19, 3D structure pre-punching section 20, crest 21, trough 22.

Example 1

As shown in fig. 1, the grid with different thickness of the present embodiment includes an integrally formed tab 1, a busbar 2 and a punching portion 3, and a plurality of punching holes 4 are provided on the punching portion 3. The punched holes 4 may be one or more of square, rectangular and diamond-shaped, and in this embodiment, the punched holes 4 are uniformly distributed on the punching portion 3 (uniformly distributed along the length and width directions of the punching portion 3). The punched holes 4 may be 2.5X2.5 mm or 3.5X3.5 mm or 5X 5mm in size. Preferably, the punched holes 4 are diamond-shaped with the extension of the sides at 45 ° to the busbar 2. As shown in fig. 5, the punching portion 3 of the final non-uniform thickness grid is corrugated to increase the specific surface area of the non-uniform thickness grid. The corrugated punching part 3 comprises wave crests 21 and wave troughs 22, wherein the distance between the adjacent wave crests 21 and wave troughs 22 is between 0.9 and 2.5mm, and the distance between the adjacent wave crests 21 and wave crests 21 is between 1.5 and 5.5mm. The punching part 3 sequentially comprises a first punching part 5, a second punching part 6 and a third punching part 7 which are sequentially decreased in thickness and integrally formed from top to bottom. The bus bar 2 and the tab 1 are equal in thickness and 0.7-0.8mm in thickness, and the height of the bus bar 2 (the distance from the top to the bottom of the bus bar 2 in fig. 1) is 1.5-4mm.

The preparation method of the grid with different thickness comprises the following steps:

step one: the lead alloy is manufactured into cast lead plates (weight is controlled to be 4-5 kg/piece) with the dimensions of 300mm multiplied by 200mm multiplied by 6mm (length multiplied by width multiplied by thickness) in a gravity casting mode, and the cast lead plates are taken out after solidification and crystallization are stabilized.

Step two: cold rolling the cast lead plate, namely cold rolling for a plurality of times to a thickness of 0.7-0.8mm, and winding and slitting according to the requirements on width and length to obtain the initial slab lattice blank.

Step three (i.e., the step of lapping): the grid initial blank (see fig. 6) already has tabs 1 and buss bars 2, and also includes an equal thickness punch 19 integrally formed with buss bars 2. The thickness-equalizing punched portion 19 has a single thickness equal to the thickness of the tab 1 and the bus bar 2, and has not yet formed a thickness gradient, and its thickness is identical to the thickness of the tab 1 and the bus bar 2. The equal thickness punching portion 19 of the panel initial blank is subjected to three-pass cold rolling and is sheared as required in size, and then a gradient thickness punched blank (also referred to as a pre-punched blank, shown in fig. 2) is formed. The gradient thickness punching blank comprises an integrally formed tab 1, a busbar 2 and a gradient thickness punching portion 3 (formed by processing an equal thickness punching portion 19), and the gradient thickness punching portion 3 comprises an integrally formed first pre-processing punching portion 8, a second pre-processing punching portion 9 and a third pre-processing punching portion 10. The thickness of the punching part 8 before the first processing is thinned by 35-40% relative to the thickness of the equal-thickness punching part 19; the thickness of the second pre-processing punching part 9 is thinned by 25-30% relative to the thickness of the first pre-processing punching part 8; the thickness of the third pre-machining punch 10 is reduced by 20-25% relative to the second pre-machining punch 9. The height of the first pre-process punch 8 (the distance from the top to the bottom of the first pre-process punch 8 in fig. 2) is 5-7% of the height of the gradient thickness punch 3, the height of the second pre-process punch 9 is 15-25% of the height of the gradient thickness punch 3, and the height of the third pre-process punch 10 is 70-75% of the height of the gradient thickness punch 3.

The specific process of cold rolling (lap rolling) is to perform a process of gradient thickness on the equal thickness punching portion 19 using a cold rolling machine, as shown in fig. 6. The cold rolling equipment comprises an upper roller 13 and a crawler belt structure, the crawler belt structure is a conventional structure in the prior art and comprises a lower roller 14 and a crawler belt 15, the crawler belt 15 is driven to move anticlockwise by the rolling of the lower roller 14, and the upper roller 13 and the lower roller 14 are both connected to a frame in a rotating manner. The upper surface of the caterpillar band 15 is fixedly provided with a cold-rolled flat plate 12 (the thickness is 5-6 mm) through a screw, a uniform-thickness punching part 19 is arranged between the upper roller 13 and the cold-rolled flat plate 12, the caterpillar band 15 drives an initial blank of a grid to move from right to left, the uniform-thickness punching part 19 is subjected to first cold rolling, and the distance between the cold-rolled flat plate 12 and the upper roller 13 is the thickness of the punching part 8 before first processing formed after the first cold rolling. After the first cold rolling is finished, the second cold rolling is carried out, the grid initial blank subjected to the first cold rolling is placed between the cold rolling flat plate 12 and the upper roller 13, the left end of the cold rolling flat plate 12 and the busbar 2 are separated by a certain distance (depending on the height required by the punching part 8 before the first machining), the distance between the cold rolling flat plate 12 and the upper roller 13 is adjusted to be close, the crawler belt 15 is started to rotate anticlockwise, the grid initial blank is driven to move leftwards, and the second cold rolling is finished. And then carrying out third cold rolling on the grid initial blank subjected to the second cold rolling in the same way, and finally obtaining the gradient thickness punching blank shown in fig. 2. That is, the uniform thickness punching portion 19 is processed by three cold rolling (i.e., multiple cold rolling is rolling), to form a gradient thickness punching blank shown in fig. 2.

In order to prevent breakage of the punching portion 3, the reinforcing ribs 18 as shown in fig. 3 are provided between the first pre-processing punching portion 8 and the second pre-processing punching portion 9, and the reinforcing ribs 18 are provided in a number of parallel. As shown in fig. 4, the maximum width of the reinforcing rib 18 is 1.5 to 2.5mm (near the first pre-processing punch 8), and the minimum width of the reinforcing rib 18 is 0.5 to 1mm (near the second pre-processing punch 9); the distance from the top to the bottom of the reinforcing ribs 18 is 4-6mm, and the distance between adjacent reinforcing ribs 18 is 2-3mm. The angle formed by the bevel of the reinforcing rib 18 in fig. 3 with the side of the first pre-machining punch 8 adjacent to the reinforcing rib 18 is 65-75 °. The reinforcing rib 18 is integrally formed with the first pre-processing punching part 8 and the second pre-processing punching part 9, and is specifically processed by the following modes: as shown in fig. 7, a plurality of grooves 17 for pressing the reinforcing beads 18 are provided on the cold-rolled flat plate 12 (left end), and the reinforcing beads 18 are formed by cold-rolling pressing. When the gradient thickness punching part 3 is formed by the rolling, the reinforcing ribs 18 can be formed at the same time, so that the gradient thickness punching part 3 is prevented from being broken. In the same way, a reinforcing rib 18 is provided between the second pre-processing punch 9 and the third pre-processing punch 10, and in the same way, a reinforcing rib 18 (not shown) is provided between the first pre-processing punch 8 and the busbar 2. The reinforcing rib 18 between the first pre-process punch 8 and the bus bar 2 may penetrate the entire first pre-process punch 8 in the height direction of the first pre-process punch 8. Because the punching part 8 is close to the busbar 2 before the first processing, the requirement on the current-carrying capacity is higher, and the reinforcing rib 18 not only plays a role in preventing two adjacent parts with different thicknesses from being broken, but also plays a role in improving the current-carrying capacity of the grid at the part.

The grid with gradient thickness prepared by adopting the sequential rolling mode of the scheme has the following advantages: the multiple rolling ensures that the weight of the manufactured grid with different thickness is smaller than that of the traditional cast grid. According to the scheme, the grids formed by sequential rolling are slightly larger in density than the grids formed by casting due to repeated rolling, so that the corrosion resistance of the grids is better. While other means (e.g., casting) may obtain grids of graded thickness, it is difficult to obtain such means by casting in order to produce ultra-thin grids of successively decreasing thickness from 0.7 to 0.8mm. Because once the thickness of the formed plate to be processed becomes smaller, the liquid lead alloy is difficult to uniformly distribute in the whole casting mould cavity during casting, bubbles are easy to generate, and the density of the finished plate grid is easy to be uneven. The sheet grid formed by casting has poor conductivity and corrosion resistance. The grid formed by multiple times of rolling is compact in metallographic structure, and the surface of the cold-rolled material can form a slurry-coated corrosion-resistant layer, so that the corrosion resistance requirement of the grid under the experimental conditions specified by national standards is met. Through repeated rolling compaction, the improvement of the overall specific energy of the battery (the reduction of the overall weight of the battery) is realized under the condition of embodying the 3D structural performance advantage. The arrangement of the grooves 17 and the reinforcing ribs 18 prevents metallographic fracture (or crack) of the metal material from occurring at the junction where the thickness difference exists.

Step four (punching 4 step): the gradient thickness punched blank (also referred to as a pre-punched blank) is fed into a grinding tool and subjected to a punching operation to obtain a 3D structured pre-blank (as shown in fig. 8). In fig. 8, the punched holes 4 are diamond-shaped holes, the punched holes 4 may be 2.5×2.5mm or 3.5×3.5mm or 5×5mm in size, the width of the ribs between adjacent punched holes 4 is 1-1.25mm, and in fig. 8 the ribs are at a 45 ° angle to the busbar 2. The 3D structure front blank includes an integrally formed tab 1, a busbar 2 and a 3D structure front punching portion 20. The arrangement width of the grinding tool punches for preparing the punched holes 4 is within 150mm, the nearest distance between the punches is 0.1-0.125mm, the punched holes 4 with the size of 2.5X2.5 mm are manufactured, and 57-58 punches are arranged in double rows (the total of 57-58 punches are added together in two rows); the punched holes 4 with the length of 5 multiplied by 5mm are manufactured, and 34 to 35 punches are arranged in double rows.

Step five: the 3D structured pre-blank is placed in a conventional twin roll structure in the prior art, corrugated, and finally a gradient thickness corrugated non-uniform thickness grid structure (i.e., the non-uniform thickness grid structure shown in fig. 1) is formed. In this process, the thickness of the front punch 20 of the 3D structure is kept as constant as possible (control tolerance is 0.05-0.1). That is, in an ideal state, the thickness of the first pre-processing punch 8 is equal to the thickness of the first punch 5, the thickness of the second pre-processing punch 9 is equal to the thickness of the second punch 6, and the thickness of the third pre-processing punch 10 is equal to the thickness of the third punch 7.

Experimental example

The method of example 1 was used to prepare grids of varying thickness, the specific parameters of which were: the thickness of the lug 1 and the bus bar 2 is 0.8mm, and the width of the bus bar 2 is equal to the width of a polar plate of the lead-acid battery (accords with the specification of the lead-acid battery in the range of 7AH and 60 AH). The punching part 3 occupies 85% of the height of the grid (without tab 1) with unequal thickness. The height of the first pre-processing punch 8 is 5% of the height of the gradient thickness punch 3, the height of the second pre-processing punch 9 is 25% of the height of the gradient thickness punch 3, and the height of the third pre-processing punch 10 is 70% of the height of the gradient thickness punch 3. The thickness of the first pre-machining punch 8 is about 0.7mm, the thickness of the second pre-machining punch 9 is reduced by 30% relative to the first pre-machining punch 8, and the thickness of the third pre-machining punch 10 is reduced by 25% relative to the second pre-machining punch 9. The punching part 3 of the whole grid with different thickness except the busbar 2 and the tab 1 is wave-shaped, the straight lines of the wave crest 21 and the wave trough 22 are parallel to the busbar 2, and the distance between the wave crest 21 and the wave trough 22 of the adjacent wave is 0.9-2.5 mm. The punched hole 4 has the dimensions of 3.5mm by 3.5mm or 5mm by 5mm; the width of the ribs between adjacent punched holes 4 is 1.25mm.

The polar plate of the lead-acid battery is prepared by using the unequal-thickness slab lattice, and the specific process is as follows:

(1) Active material coating: and the positive and negative lead plaster is respectively coated on two sides of the manufactured grid with different thickness in a manual coating mode, and the cured green polar plate is obtained by compacting.

(2) Curing: and respectively placing the anode plate and the cathode plate into a closed oven for moisture preservation and curing for 24 hours, wherein the initial temperature of the oven is 45 ℃, and after the initial temperature is raised to 80 ℃ at the speed of 3 ℃/h, the anode plate and the cathode plate are kept at the temperature, the humidity is kept at more than 95%, and after the curing is finished, the anode plate and the cathode plate are dried for 12 hours in the environment of 70 ℃. And (3) slicing, weighing, polishing the electrode lug 1, packaging the sheet, assembling and welding (parallel welding) the battery to obtain the 2V test single battery.

(3) And (3) formation: adding the assembled monomer (2V) battery according to the test requirement into sulfuric acid with the density of 1.26, standing for 30-40min, and performing formation for 19 hours according to a 5 charge-1 discharge mode to obtain the cooked polar plate.

Each experimental test was performed on the cooked electrode plate, and the experimental results are shown in tables 1 to 4. The grids in tables 1 and 2 were compared with equal areas and equal thicknesses of the bus bars and tabs. Table 1 shows the comparison of the specific surface area of the non-uniform thickness grids prepared according to the present scheme with conventional cast and expanded grids. The grid with different thickness manufactured by the scheme has larger hole slope, can reduce internal resistance of current transmission, and improves efficiency of converting chemical energy into effective electric energy and utilization rate of active substances. Table 2 shows the weight comparison of the non-uniform thickness grids prepared according to the present scheme with conventional cast and expanded grids. The unequal-thickness grid manufactured by the scheme has smaller weight, the increase of the volume specific surface area does not bring about the increase of the grid weight, and meanwhile, the specific energy and the active material utilization rate of the lead-acid storage battery are fully improved. Table 3 shows the corrosion cycle life comparison of grids, and the unequal thickness grids prepared by the scheme are significantly better than the conventional cast grids and expanded grids in corrosion cycle life. The high-rate low-temperature experiment results are shown in Table 4, and multiple experiments show that the unequal-thickness grid prepared by the scheme meets the national standard and shows excellent properties in the high-rate low-temperature experiment.

Table 1: specific surface area contrast

Table 2: grid weight comparison

Table 3: grid corrosion-resistant cycle life comparison

Table 4: high-rate low-temperature experimental result

The foregoing is merely exemplary of the present application, and specific technical solutions and/or features that are well known in the art have not been described in detail herein. It should be noted that, for those skilled in the art, several variations and modifications can be made without departing from the technical solution of the present application, and these should also be regarded as the protection scope of the present application, which does not affect the effect of the implementation of the present application and the practical applicability of the patent. The protection scope of the present application is subject to the content of the claims, and the description of the specific embodiments and the like in the specification can be used for explaining the content of the claims.

Claims

1. The utility model provides a thick grid of inequality which characterized in that: comprises a tab, a busbar and a punching part; the punching part comprises a first punching part, a second punching part, a third punching part, a fourth punching part and a fifth punching part, wherein the thickness of the first punching part is gradually decreased from top to bottom, and N=3; a plurality of reinforcing ribs are arranged between the N punching part and the N-1 punching part; a plurality of reinforcing ribs are also arranged between the first punching part and the busbar;

the thickness of the first punching part is reduced by 35-40% relative to the thickness of the tab, the thickness of the second punching part is reduced by 25-30% relative to the thickness of the first punching part, and the thickness of the third punching part is reduced by 20-25% relative to the thickness of the second punching part; the first punching part, the second punching part and the third punching part are respectively formed by processing a first pre-processing punching part, a second pre-processing punching part and a third pre-processing punching part;

the width of one end of the reinforcing rib, which is close to the lug, is 1.5-2.5mm, and the width of one end of the reinforcing rib, which is far away from the lug, is 0.5-1mm; the distance between one end of the reinforcing rib close to the lug and one end of the reinforcing rib far from the lug is 4-6mm; the distance between adjacent reinforcing ribs is 2-3mm; the inclined plane of the reinforcing rib and the side surface of the punching part before the first processing, which is close to the reinforcing rib, form an included angle of 65-75 degrees;

the preparation method comprises the following steps:

s1: preparing a grid initial blank, wherein the grid initial blank comprises a punching part with equal thickness;

s2: obtaining a gradient thickness punching blank through multiple cold rolling, wherein the gradient thickness punching blank comprises a tab, a busbar and a gradient thickness punching part; the gradient thickness punching part comprises a first pre-processing punching part, a second pre-processing punching part and a third pre-processing punching part which are thinned in a gradient manner;

the process of the multiple cold rolling is as follows: placing the equal-thickness punching part between the upper roller and the cold-rolled flat plate, and carrying out first cold rolling on the equal-thickness punching part, wherein the distance between the cold-rolled flat plate and the upper roller is the thickness of the first pre-processing punching part formed after the first cold rolling; secondly, cold rolling is carried out, the initial blank of the grid subjected to the first cold rolling is placed between a cold rolling flat plate and an upper roller, the distance between the cold rolling flat plate and the upper roller is adjusted to be close, and a crawler belt is started to drive the initial blank of the grid to move leftwards, so that the second cold rolling is completed; thirdly cold rolling the grid initial blank subjected to the second cold rolling in a second cold rolling mode to obtain a gradient thickness punching blank;

the upper surface of one end of the cold-rolled flat plate, which is close to the lug, is provided with a plurality of grooves for preparing reinforcing ribs;

2. The non-uniform thickness grid according to claim 1, wherein: the punching part is wavy; the distance between adjacent wave crests and wave troughs of the punching part is 0.9-2.5mm, and the distance between adjacent wave crests and wave troughs is 1.5-5.5mm.

3. The non-uniform thickness grid according to claim 2, wherein: the punching part is provided with a plurality of punched holes, and the size of the punched holes is 2.5X2.5 mm or 3.5X3.5 mm or 5X 5mm.

4. A variable thickness grid according to claim 3, wherein: the height ratio of the first pre-processing punching part, the second pre-processing punching part and the third pre-processing punching part is 5-7:15-25:70-75.

5. The non-uniform thickness grid according to claim 1, wherein: the thickness of the lug and the bus bar is 0.7-0.8mm.

6. A method for preparing a non-uniform thickness grid, for preparing a non-uniform thickness grid as defined in any one of claims 1-5, comprising: the method comprises the following steps of:

s1: preparing and obtaining an initial slab lattice blank;

7. The method for preparing the grid with different thickness according to claim 6, wherein the method comprises the following steps: in S2, the equal-thickness punching part of the initial blank of the grid is placed between an upper roller and a cold-rolling flat plate, the upper roller and the cold-rolling flat plate cold-roll the equal-thickness punching part to a specified thickness, and the gradient-thickness punching part is obtained through multiple cold-rolling.