CN113363502A - Unequal-thickness grid and preparation method thereof - Google Patents
Unequal-thickness grid and preparation method thereof Download PDFInfo
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/64—Carriers or collectors
- H01M4/70—Carriers or collectors characterised by shape or form
- H01M4/72—Grids
- H01M4/73—Grids for lead-acid accumulators, e.g. frame plates
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/64—Carriers or collectors
- H01M4/70—Carriers or collectors characterised by shape or form
- H01M4/72—Grids
- H01M4/74—Meshes or woven material; Expanded metal
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/64—Carriers or collectors
- H01M4/82—Multi-step processes for manufacturing carriers for lead-acid accumulators
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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Abstract
The invention relates to the technical field of lead-acid batteries, in particular to a grid with different thicknesses and a preparation method thereof. A grid with different thicknesses comprises a pole lug, a bus bar positioned at the root of the pole lug and a punching part; the punching part sequentially comprises a first punching part to an Nth punching part with sequentially decreasing thickness from top to bottom, and N is more than or equal to 2; and a plurality of reinforcing ribs are arranged between the Nth punching part and the N-1 th punching part. The technical problems that the weight of the grid can be increased and the specific energy of the grid can be reduced when the aperture is reduced are solved, the method 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 when the specific surface area of the grid is improved, and the performance of the battery manufactured by the polar plate is comprehensively improved.
Description
Technical Field
The invention relates to the technical field of lead-acid batteries, in particular to a grid with different thicknesses and a preparation method thereof.
Background
Lead-acid batteries are storage batteries, which have been developed for hundreds of years so far, and the main principle of the lead-acid batteries is the conversion of chemical energy into electric energy. The lead-acid battery mainly comprises an electrolytic bath, 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 consists of a grid and active substances on the grid, and the grid mainly has the functions of fixing the active substances and inputting or outputting current of electrochemical reaction of the active substances.
Chinese patents CN104868176B (a 3D lead-acid battery and a manufacturing method thereof) and CN104882616B (a 3D current collector of a lead-acid battery and a manufacturing method thereof) have studied a method capable of increasing the volume specific surface area of a grid, and the volume specific surface area (pore slope) of the grid is increased by reducing the pore diameter of open pores of the grid, so as to reduce the internal resistance of current transmission, and improve the efficiency of converting chemical energy into effective electrical energy and the utilization rate of active substances. However, under the condition of certain volume and thickness, the increase of the volume specific surface area of the grid tends to increase the weight of the grid. According to research, when the volume specific surface area of the grid is increased by 150-200%, the weight of the grid is increased by 16-35%. The increase of the weight of the grid will inevitably lead to the increase of the specific energy (energy generated per unit weight) of the battery, and the advantage brought by the increase of the volume specific surface area is offset by the great increase of the weight of the grid. How to overcome the negative surface effect caused by the weight increase of the grid, and simultaneously, 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 invention aims to provide a grid with different thicknesses 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 purpose, the invention adopts the following technical scheme:
a grid with different thicknesses comprises a tab, a bus bar and a punching part; the punching part comprises a first punching part to an Nth punching part which are sequentially decreased in thickness from top to bottom, and N is more than or equal to 2; a plurality of reinforcing ribs are arranged between the Nth punching part and the N-1 th punching part; a plurality of reinforcing ribs are also arranged between the first punching hole part and the bus bar.
The scheme also provides a preparation method of the grid with different thicknesses, which comprises the following steps in sequence:
s1: preparing and obtaining a grid initial blank;
s2: obtaining a gradient thickness punching blank through multiple times of cold rolling, wherein the gradient thickness punching blank comprises a lug, a bus bar and a gradient thickness punching part;
s3: punching the gradient thickness punching part to obtain a 3D structure pre-blank;
s4: and pressing the 3D structure front punching hole part of the 3D structure front blank into a wavy shape to obtain the grid with different thicknesses.
The principle and the advantages of the scheme are as follows: this scheme has set up the portion of punching a hole that thickness degressive in proper order from top to bottom, and utmost point ear and busbar keep former thickness unchangeable, when guaranteeing the current-carrying capacity of grid, have alleviateed the weight of grid, and then have increased the specific energy of battery. The method utilizes the gradient thickness cold rolling mode to increase the specific surface area by 150-200% (by reducing the aperture) and simultaneously make the weight of the grid equal to or less than about 15% of the weight of the original grid (cast grid or drawn 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 structure. Experiments prove that the high-current performance of the grid with the structure at 4.5 multiplying power, 8 multiplying power and 10 multiplying power is not different from that of the grid with the traditional structure, and the requirements of national standards on corrosion resistance and cycle life are met.
In order to increase the volume specific surface area of the grid, the inventor tries to reduce the punching diameter, and finds that the weight of the grid is increased by 16-35% when the volume specific surface area of the grid is increased by 150-200%. The advantages of increased volume-specific surface area are offset by the large increase in grid weight. In order to overcome the technical problems, the inventor tries a method for reducing the thickness of the whole grid, and the reduction of the thickness of the whole grid (the thickness of a lug, a lug root bus bar and a punching part is reduced) can completely meet the requirement that the ratio of the grid to the plate is in a range of 0.31-0.40 (namely the weight of the grid is in a range of 31-35% of the weight of the whole plate, which is a conventional requirement in the industry). However, since the overall thickness of the grid becomes thin, the conductivity becomes poor and the grid strength becomes poor.
Aiming at the problem of grid strength: the weight of the whole polar plate is more than three times of that of the grid after the grid is pasted, the polar plate cannot be greatly deformed in the production of the battery, the battery is assembled into a pressure tight assembly, the polar plate of the battery needs to be welded in series and parallel, and the technological processes all require that the grid has technological strength meeting technological requirements. The above requirements cannot be met if the grid is too thin. Although the left and right ends of the grid and the tabs are reinforced by the resin bonding material, the mechanical strength can be ensured, and the defects can be overcome, but the process is complicated. Because the left end and the right end of the grid are used for fixing the grid in the electrolytic bath, and the lug is required to be fixed with a wire and other structures, the grid needs to bear certain force, and therefore reinforcement is needed.
Aiming at the problem of conductivity, after the grid is integrally thinned under the normal temperature condition, the 4.5-multiplying-power, 8-multiplying-power and 10-multiplying-power large-current performance of the grid has no advantages compared with the grid with the traditional structure, the thin grid is completely in a disadvantage in a 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 tab and the busbar does not reach the current-carrying capacity of the traditional structure. In addition, grids near the ears are particularly susceptible to decay. The thickness of the lug and the thickness of the busbar at the root of the lug are increased in a welding material increasing mode, so that the high-magnification large-current carrying capacity of the grid can be improved. However, there is a problem in that the process is complicated, and the conductive property of the welded material is inferior to that of the integrally molded material.
Because the whole thinnings of grid is realized to the demand that lightens weight, and then in order to overcome the whole not good problem of intensity and current-carrying capacity that thins of grid and bring, need adopt two kinds of different solutions to overcome simultaneously, this has just increased the technology degree of difficulty, has increased the cost of manufacture and has reduced maneuverability. The inventors have tried various solutions and found that the grid of the present invention formed by sequentially decreasing the thickness of the punched portion from top to bottom without performing the thickness decreasing process on the tab and the bus bar can completely overcome the above problems. Due to the reduced thickness of the part, the whole 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, can not appear the overheated problem of battery yet. The inventors analyzed that the upper portion of the grid was relatively current-intensive, while the lower portion did not require excessive thickness to maintain a relatively large current-carrying capacity. In addition, the thickness of the pole lug is not reduced, and the problem that the pole lug is not strong enough and is not convenient to fix 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 set to be of a structure with the upper part thick and the lower part thin, so that the three problems influencing the quality of the storage battery and the difficulty degree of processing can be solved at the same time, and the purpose of killing three birds with one stone is achieved.
In addition, because the punched parts have thickness difference, the punched parts are easy to break at the connecting position of the Nth punched part and the (N-1) th punched part and the connecting position of the first punched part and the bus bar, and a plurality of reinforcing ribs are arranged between the Nth punched part and the (N-1) th punched part and between the first punched part and the bus bar so as to increase the integral strength of the grid.
Furthermore, the width of one end of the reinforcing rib close to the tab is 1.5-2.5mm, and the width of one end far away from the tab is 0.5-1 mm; the distance between one end of the reinforcing rib close to the pole lug and one end of the reinforcing rib far away from the pole lug is 4-6 mm. The reinforcing rib with the size can better avoid the occurrence of metal material metallographic fracture (or crack) at the junction with the thickness difference, and the reinforcing rib with the shape is easy to manufacture. For widths close to the extreme ear end and far from the extreme ear end, if the widths are too narrow, the reinforcing effect on the junction of the thickness difference is insufficient; if it is too wide, it will excessively increase the self weight of the grid, waste materials and reduce the specific energy of the battery.
Further, the punching part is wavy; the distance between the adjacent wave crests and the wave troughs of the punching part is 0.9-2.5mm, and the distance between the adjacent wave crests is 1.5-5.5 mm. 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 to form the lead-acid battery is facilitated. If the distance between the adjacent wave crests and wave troughs and the distance between the adjacent wave crests and wave crests are too large, the effect of increasing the contrast surface area is insufficient; if too small, the processing operation becomes too difficult.
Furthermore, a plurality of punched holes are arranged on the punched part, and the size of each punched hole is 2.5 multiplied by 2.5mm, 3.5 multiplied by 3.5mm or 5 multiplied by 5 mm. The punched holes with the sizes are convenient to punch and form, and the ideal hole slope and the utilization rate of active substances of the grid are maintained. The punching size is the conventional size in the prior art and can be obtained by utilizing 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 hole part is reduced by 35-40% relative to the thickness of the tab, the thickness of the second punching hole part is reduced by 25-30% relative to the thickness of the first punching hole part, and the thickness of the third punching hole part is reduced by 20-25% relative to the thickness of the second punching hole part. By adopting the thickness gradient, smaller energy loss and grid weight can be ensured, and ideal specific energy and performance of the battery can be finally obtained.
Further, the first punched hole portion, the second punched hole portion and the third punched hole portion are formed by machining the first pre-machining punched hole portion, the second pre-machining punched hole portion and the third pre-machining punched hole portion respectively; the height ratio of the first, second and third pre-piercing portions is 5-7: 15-25: 70-75. The punched part with the height ratio can ensure that the grid has larger current carrying capacity and is not easy to corrode.
Furthermore, the thicknesses of the lugs and the bus bar are both 0.7-0.8 mm.
By adopting the technical scheme, the tab and the busbar are maintained to be of certain thickness, the current is ensured to flow smoothly in the grid (the current-carrying capacity of the tab and the busbar is ensured), and the problem that the temperature of the battery rises faster than that of the traditional structure due to overlarge current or overlow ambient temperature is avoided.
Further, in S2, the equal-thickness punched part of the grid starting blank is placed between an upper roll and a cold-rolled plate, the upper roll and the cold-rolled plate cold-roll the equal-thickness punched part to a prescribed thickness, and the gradient thickness punched part is obtained by a plurality of cold-rolling. Through the matching of the upper roll and the cold rolling flat plate and multiple cold rolling, the uniform-thickness punching part can be processed into a gradient-thickness punching part with a smooth surface and thickness difference, and conditions are created for the subsequent processing of the punching part into a finished product. The grid with the gradient thickness prepared by adopting the method of cold rolling (pack rolling) in sequence has the following advantages: and the multiple-overlapping rolling ensures that the weight of the grid with different thicknesses manufactured by accurate quantification is smaller than that of the traditional cast grid. The grid formed by sequential pack rolling is slightly larger in density than the grid formed by casting due to multiple rolling, so that the corrosion resistance of the grid is better. Although grids of gradient thickness can be obtained by other means (such as casting), it is difficult to obtain by casting in order to prepare ultra-thin grids with the thickness decreasing from 0.7 to 0.8 mm. Once the target thickness is reduced, the liquid lead alloy is difficult to uniformly distribute in the whole casting mould during casting, so that bubbles are easy to generate, and the phenomenon of uneven density of the finished grid is easy to occur. The thin plate grid formed by casting has poor conductivity and corrosion resistance. The grid is formed by repeated pack rolling, a compact metallographic structure is formed inside the grid material, a 'slurry coating corrosion-resistant layer' can be formed on the surface of the cold-rolled material, and the corrosion-resistant requirement of the grid under the experimental condition specified by the national standard is met. The improvement of the overall specific energy of the battery (the overall weight of the battery is reduced) is realized by repeatedly performing rolling and rolling compaction under the condition that the 3D structure performance advantage is embodied.
Furthermore, a plurality of grooves for preparing reinforcing ribs are formed in the upper surface of one end, close to the pole lug, of the cold-rolled flat plate. In the process of using the matching of the upper roll and the cold rolling flat plate and carrying out cold rolling, reinforcing ribs can be formed at the grooves, and the condition that the punched part is broken at the junction is avoided. When the thickness gradient is formed by cold rolling, the cold rolling shear stress is easy to cause stress cracks on a deformation section, which seriously influences the service life of the plate grid and finally influences the service life of a battery. The reinforcing ribs are formed simultaneously with the cold rolling, and the material breakage during the cold rolling is prevented.
Drawings
Fig. 1 is a top view of a differential thickness grid of example 1.
Fig. 2 is a left side view of the gradient thickness punch blank of example 1.
Fig. 3 is an enlarged view of section a (showing the reinforcing bars).
Figure 4 is a top view of section a of figure 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 a tandem rolling apparatus according to 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 further detailed by way of specific embodiments:
reference numerals in the drawings of the specification include: the punching device comprises a tab 1, a bus bar 2, a punching part 3, a punching hole 4, a first punching part 5, a second punching part 6, a third punching part 7, a first pre-machining punching part 8, a second pre-machining punching part 9, a third pre-machining punching part 10, a cold-rolled flat plate 12, an upper roller 13, a lower roller 14, a crawler belt 15, a bottom surface 16, a groove 17, a reinforcing rib 18, an equal-thickness punching part 19, a 3D structure front punching part 20, a wave crest 21 and a wave trough 22.
Example 1
As shown in fig. 1, the grid with different thicknesses of the embodiment includes a tab 1, a busbar 2 and a punching part 3 which are integrally formed, and a plurality of punching holes 4 are arranged on the punching part 3. The punched holes 4 may be one or more of square, rectangular and diamond-shaped, and in this case, the punched holes 4 are uniformly distributed on the punched part 3 (uniformly distributed along both the length and width directions of the punched part 3). The size of the punch 4 may be 2.5 x 2.5mm or 3.5 x 3.5mm or 5 x 5 mm. Preferably, the punched holes 4 are diamond-shaped, and the extension lines of the side edges of the diamond-shaped punched holes form an angle of 45 degrees with the busbar 2. As shown in fig. 5, the punched portions 3 of the finished unequal-thickness grid are corrugated to increase the specific surface area of the unequal-thickness grid. The corrugated punching part 3 comprises wave crests 21 and wave troughs 22, the distance between the adjacent wave crests 21 and wave troughs 22 is 0.9-2.5mm, and the distance between the adjacent wave crests 21 and wave crests 21 is 1.5-5.5 mm. 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 and gradually reduced in thickness and integrally formed from top to bottom. The bus bar 2 and the tab 1 are equal in thickness, the thickness is 0.7-0.8mm, and the height of the bus bar 2 (in fig. 1, the distance from the top to the bottom of the bus bar 2) is 1.5-4 mm.
The preparation method of the grid with different thicknesses comprises the following steps:
the method comprises the following steps: the lead alloy is made into a casting lead plate (the 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) by a gravity casting mode, and the casting lead plate is taken out after solidification and crystallization are stable.
Step two: and (3) cold rolling the cast lead plate, carrying out multiple cold rolling to the thickness of 0.7-0.8mm, and winding and slitting to obtain the initial blank of the grid according to the requirements on width and length.
Step three (i.e. the pack rolling step): the grid starting blank (see fig. 6) already has the tab 1 and the busbar 2 and also includes the punched part 19 of equal thickness integrally formed with the busbar 2. The uniform thickness punched hole portion 19 has a single thickness equal to the thicknesses of the tab 1 and the bus bar 2, and a thickness gradient is not formed yet, the thickness of which is the same as the thickness of the tab 1 and the bus bar 2. The equal-thickness punched part 19 of the initial grid blank is subjected to the cold-rolling for three times, and then is cut according to the size requirement, and then a punched blank with gradient thickness (also called a blank before punching, shown in fig. 2) is formed. The gradient thickness punching blank comprises a tab 1, a bus bar 2 and a gradient thickness punching part 3 (formed by machining an equal thickness punching part 19) which are integrally formed, and the gradient thickness punching part 3 comprises a first pre-machining punching part 8, a second pre-machining punching part 9 and a third pre-machining punching part 10 which are integrally formed. The thickness of the punching part 8 before the first processing is reduced by 35-40% relative to the equal-thickness punching part 19; the thickness of the second pre-piercing part 9 is reduced by 25 to 30% relative to the thickness of the first pre-piercing part 8; the thickness of the third pre-pierce portion 10 is reduced by 20-25% with respect to the second pre-pierce portion 9. The height of the first pre-pierce portion 8 (the distance from the top to the bottom of the first pre-pierce portion 8 in fig. 2) is 5-7% of the height of the gradient-thickness pierce portion 3, the height of the second pre-pierce portion 9 is 15-25% of the height of the gradient-thickness pierce portion 3, and the height of the third pre-pierce portion 10 is 70-75% of the height of the gradient-thickness pierce portion 3.
As shown in fig. 6, a specific process of cold rolling (pack rolling) is to perform a process of forming the equal-thickness piercing part 19 with a gradient thickness by using a cold rolling apparatus. The cold rolling equipment comprises an upper roller 13 and a track structure, wherein the track structure is a conventional structure in the prior art and comprises a lower roller 14 and a track 15, the track 15 is driven by the rolling of the lower roller 14 to move anticlockwise, and the upper roller 13 and the lower roller 14 are both rotationally connected on a rack. A cold-rolled flat plate 12 (with the thickness of 5-6mm) is fixed on the upper surface of the crawler belt 15 through screws, the equal-thickness punched hole part 19 is placed between the upper roller 13 and the cold-rolled flat plate 12, the crawler belt 15 drives the grid initial blank to move from right to left, the equal-thickness punched hole 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 first pre-processing punched hole part 8 formed after the first cold rolling. And after the first cold rolling is finished, performing second cold rolling again, placing the initial blank of the grid subjected to the first cold rolling between the cold-rolled flat plate 12 and the upper roller 13, keeping a certain distance between the left end of the cold-rolled flat plate 12 and the busbar 2 (according to the height required by the first machining front punching part 8), adjusting the distance between the cold-rolled flat plate 12 and the upper roller 13 to be close, starting the crawler belt 15 to rotate anticlockwise, driving the initial blank of the grid to move leftwards, and finishing the second cold rolling. And performing third cold rolling on the grid initial blank subjected to the second cold rolling in the same manner to finally obtain the gradient thickness punching blank shown in fig. 2. Namely, the uniform-thickness punching portion 19 is processed by three times of cold rolling (i.e., the double rolling) to form the gradient-thickness punching blank shown in fig. 2.
In order to prevent the piercing section 3 from being broken, a plurality of reinforcing ribs 18 are provided in parallel as shown in fig. 3 between the first and second piercing sections 8 and 9. As shown in fig. 4, the maximum width of the reinforcing bead 18 is 1.5 to 2.5mm (near the first machining-leading-hole portion 8), and the minimum width of the reinforcing bead 18 is 0.5 to 1mm (near the second machining-leading-hole portion 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 2-3 mm. The included angle formed by the inclined surface of the rib 18 and the side surface of the first pilot hole portion 8 adjacent to the rib 18 in fig. 3 is 65 to 75 °. The reinforcing rib 18 is integrally formed with the first and second pre-pierce portions 8, 9, and is specifically formed by: referring to fig. 7, a plurality of grooves 17 for forming reinforcing ribs 18 by pressing are provided in the cold-rolled flat plate 12 (left end), and the reinforcing ribs 18 are formed by cold-rolling. When the gradient thickness punching part 3 is formed by pack 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. A reinforcing rib 18 is similarly provided between the second and third pre-working hole portions 9 and 10, and a reinforcing rib 18 (not shown) is similarly provided between the first pre-working hole portion 8 and the bus bar 2. The rib 18 between the first pre-machined hole 8 and the bus bar 2 may penetrate the entire first pre-machined hole 8 in the height direction of the first pre-machined hole 8. Because the first pre-processing punched hole part 8 is close to the bus bar 2 and has higher requirement on current-carrying capacity, the reinforcing rib 18 not only plays a role of preventing two adjacent parts with different thicknesses from being broken, but also plays a role of improving the current-carrying capacity of the grid at the part.
The grid with gradient thickness prepared by adopting the scheme in the mode of sequentially rolling has the following advantages: and the manufactured grid with different thicknesses is ensured to be lighter than the traditional cast grid by multiple times of overlapping rolling. The grid formed by sequentially rolling is formed by rolling, and the grid is formed by multiple times of rolling and is slightly larger than the grid formed by casting in density, so that the corrosion resistance of the grid is better. Although other methods (such as casting) can obtain grids with gradient thickness, the method of casting is difficult to obtain when an ultrathin grid with the thickness gradually decreasing from 0.7 to 0.8mm is prepared. Once the thickness to be processed and formed is reduced, the whole casting die cavity is difficult to uniformly distribute liquid lead alloy during casting, bubbles are easy to generate, and the phenomenon of uneven density of the finished grid is easy to occur. The thin grid formed by casting has poor conductivity and corrosion resistance. The grid is formed by repeated pack rolling, a compact metallographic structure is formed inside the grid material, a 'slurry coating corrosion-resistant layer' can be formed on the surface of the cold-rolled material, and the corrosion-resistant requirement of the grid under the experimental condition specified by the national standard is met. The improvement of the overall specific energy of the battery (the overall weight of the battery is reduced) is realized by repeated pack rolling and rolling under the condition that the advantage of 3D structure performance is embodied. The arrangement of the grooves 17 and the reinforcing ribs 18 avoids the occurrence of metallographic fracture (or crack) of the metal material at the boundary where the thickness difference exists.
Step four (punching 4 step): the graded thickness punched blank (also referred to as 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 punches 4 are diamond shaped holes, the size of the punches 4 may be 2.5 x 2.5mm or 3.5 x 3.5mm or 5 x 5mm, the width of the ribs between adjacent punches 4 is 1-1.25mm and in fig. 8 the ribs are at an angle of 45 ° to the busbar 2. The 3D structure front blank comprises a tab 1, a bus bar 2 and a 3D structure front punching part 20 which are integrally formed. The punch heads of the grinding tool for preparing the punched holes 4 are arranged within 150mm in width, the nearest distance between the punch heads is 0.1-0.125mm, the punched holes 4 with the size of 2.5 multiplied by 2.5mm are prepared, and 57-58 punch heads are arranged in double rows (the two rows are added to form 57-58 punch heads); 5X 5mm punches 4 are made, and 34-35 punches are arranged in double rows.
Step five: and (3) placing the 3D structure pre-blank in a conventional double-roller structure in the prior art, and performing corrugated structure rolling to finally form a gradient thickness corrugated unequal-thickness grid structure (namely the unequal-thickness grid structure shown in figure 1). In the process, the thickness of the 3D structure front punching part 20 is kept unchanged (the control tolerance is 0.05-0.1). That is, ideally, the thickness of the first pre-pierce working portion 8 is equal to the thickness of the first piercing portion 5, the thickness of the second pre-pierce working portion 9 is equal to the thickness of the second piercing portion 6, and the thickness of the third pre-pierce working portion 10 is equal to the thickness of the third piercing portion 7.
Examples of the experiments
Preparing a grid with unequal thickness according to the method of the embodiment 1, wherein the specific parameters of the obtained grid with unequal thickness are as follows: the thicknesses of the lug 1 and the busbar 2 are both 0.8mm, and the width of the busbar 2 is equal to that of a pole plate of a lead-acid battery (the lead-acid battery conforms to the specification of 7AH and 60AH ranges). The punched part 3 occupies 85% of the height of the slab lattice (not including the height of the tab 1). The height of the first pre-pierce portion 8 is 5% of the height of the gradient-thickness pierce portion 3, the height of the second pre-pierce portion 9 is 25% of the height of the gradient-thickness pierce portion 3, and the height of the third pre-pierce portion 10 is 70% of the height of the gradient-thickness pierce portion 3. The thickness of the first pre-machined piercing section 8 is approximately 0.7mm, the thickness of the second pre-machined piercing section 9 is reduced by 30% relative to the first pre-machined piercing section 8, and the thickness of the third pre-machined piercing section 10 is reduced by 25% relative to the second pre-machined piercing section 9. The punched parts 3 of the whole grid with different thicknesses except the bus bar 2 and the lugs 1 are wavy, straight lines where the wave crests 21 and the wave troughs 22 are located are parallel to the bus bar 2, and the distance between the adjacent wave crests 21 and the wave troughs 22 is 0.9-2.5 mm. The size of the punched hole 4 is 3.5mm multiplied by 3.5mm or 5mm multiplied by 5 mm; the width of the ribs between adjacent punched holes 4 is 1.25 mm.
The method for preparing the polar plate of the lead-acid battery by using the grids with different thicknesses comprises the following specific steps:
(1) active material coating: and (3) coating the two sides of the manufactured grid with different thicknesses by using positive and negative lead pastes in a manual coating mode respectively, and compacting to obtain the cured green plate.
(2) And (3) curing: and respectively putting the anode plate and the cathode plate into a closed oven for moisturizing and curing, wherein the curing time is 24 hours, the initial temperature of the oven is 45 ℃, the temperature is increased to 80 ℃ at the speed of 3 ℃/h, the temperature is kept, the humidity is kept above 95%, and the anode plate and the cathode plate are dried for 12 hours in an environment of 70 ℃ after curing is completed. And (3) carrying out slicing, weighing, polishing of the electrode lugs 1, sheet wrapping, battery assembly and welding (parallel welding) on the dried electrode plates to obtain the 2V test single battery.
(3) Formation: and adding the monomer (2V) battery assembled according to the test requirement into sulfuric acid with the density of 1.26, standing for 30-40min, and forming for 19 hours according to a 5-charge-1-discharge mode to obtain the cooked pole plate.
Various experimental tests are carried out on the cooked polar plate, and the experimental results are detailed in tables 1-4. The grids in tables 1 and 2 were compared for equal area and equal thickness of bus bars and tabs. Table 1 shows the comparison of the specific surface area of the grid with different thickness prepared by the present scheme with the traditional cast grid and the expanded grid. The grid with different thicknesses manufactured by the scheme has larger hole slope, so that the internal resistance of current transmission can be reduced, and the efficiency of converting chemical energy into effective electric energy and the utilization rate of active substances are improved. Table 2 shows a comparison in weight of the unequal-thickness grids prepared according to the present scheme with conventional cast grids and expanded grids. The grid with different thicknesses manufactured by the scheme has smaller weight, the increase of the volume specific surface area can not bring the increase of the weight of the grid, and meanwhile, the specific energy and the utilization rate of active substances of the lead-acid storage battery are fully improved. Table 3 shows the comparison of the corrosion-resistant cycle life of the grid, and the corrosion-resistant cycle life of the grid with different thickness prepared by the scheme is obviously superior to that of the existing cast grid and expanded grid compared with that of the traditional cast grid and expanded grid. The results of the high-rate low-temperature experiment are shown in table 4, and multiple experiments show that the grid with different thicknesses prepared by the scheme meets the national standard and shows excellent properties in the high-rate low-temperature experiment.
Table 1: specific surface area comparison
Table 2: weight comparison of grids
Table 3: comparison of grid Corrosion resistant cycle life
Table 4: high rate low temperature experimental results
The foregoing is merely an example of the present invention and common general knowledge in the art of designing and/or characterizing particular aspects and/or features is not described in any greater detail herein. It should be noted that, for those skilled in the art, without departing from the technical solution of the present invention, several variations and modifications can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicability of the patent. The scope of the claims of the present application shall be determined by the contents of the claims, and the description of the embodiments and the like in the specification shall be used to explain the contents of the claims.
Claims (10)
1. A grid with different thicknesses is characterized in that: comprises a tab, a bus bar and a punching part; the punching part comprises a first punching part to an Nth punching part which are sequentially decreased in thickness from top to bottom, and N is more than or equal to 2; a plurality of reinforcing ribs are arranged between the Nth punching part and the N-1 th punching part; a plurality of reinforcing ribs are also arranged between the first punching hole part and the bus bar.
2. The unequal-thickness grid according to claim 1, wherein: the width of one end of the reinforcing rib close to the pole lug is 1.5-2.5mm, and the width of one end far away from the pole lug is 0.5-1 mm; the distance between one end of the reinforcing rib close to the pole lug and one end of the reinforcing rib far away from the pole lug is 4-6 mm.
3. The unequal-thickness grid according to claim 1, wherein: the punching part is wavy; the distance between the adjacent wave crests and the adjacent wave troughs of the punching part is 0.9-2.5mm, and the distance between the adjacent wave crests and the adjacent wave crests is 1.5-5.5 mm.
4. The unequal-thickness grid according to claim 1, wherein: the punching hole part is provided with a plurality of punching holes, and the size of each punching hole is 2.5 multiplied by 2.5mm, 3.5 multiplied by 3.5mm or 5 multiplied by 5 mm.
5. The unequal-thickness grid according to claim 1, wherein: the punching part comprises a first punching part, a second punching part and a third punching part; the thickness of the first punching hole part is reduced by 35-40% relative to the thickness of the tab, the thickness of the second punching hole part is reduced by 25-30% relative to the thickness of the first punching hole part, and the thickness of the third punching hole part is reduced by 20-25% relative to the thickness of the second punching hole part.
6. The unequal-thickness grid according to claim 5, wherein: the first punching hole part, the second punching hole part and the third punching hole part are respectively formed by machining a first machining front punching hole part, a second machining front punching hole part and a third machining front punching hole part; the height ratio of the first, second and third pre-piercing portions is 5-7: 15-25: 70-75.
7. The unequal-thickness grid according to claim 1, wherein: the thicknesses of the lugs and the bus bar are both 0.7-0.8 mm.
8. A method for producing a differential thickness grid for use in producing a differential thickness grid according to any one of claims 1 to 7, comprising: comprises the following steps in sequence:
s1: preparing and obtaining a grid initial blank;
s2: obtaining a gradient thickness punching blank through multiple times of cold rolling, wherein the gradient thickness punching blank comprises a lug, a bus bar and a gradient thickness punching part;
s3: punching the gradient thickness punching part to obtain a 3D structure pre-blank;
s4: and pressing the 3D structure front punching hole part of the 3D structure front blank into a wavy shape to obtain the grid with different thicknesses.
9. The method for preparing a grid with unequal thicknesses according to claim 8, characterized in that: in S2, the equal-thickness punched part of the grid starting blank is placed between an upper roller and a cold-rolled plate, the upper roller and the cold-rolled plate cold-roll the equal-thickness punched part to a prescribed thickness, and the gradient-thickness punched part is obtained by a plurality of cold-rolling.
10. The method for preparing a grid with unequal thicknesses according to claim 9, characterized in that: and a plurality of grooves for preparing reinforcing ribs are formed in the upper surface of one end, close to the lug, of the cold-rolled flat plate.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104821402A (en) * | 2014-08-15 | 2015-08-05 | 骆驼集团襄阳蓄电池有限公司 | Lead-acid storage battery plate grid and forming surface treatment method |
| CN104868176A (en) * | 2015-05-19 | 2015-08-26 | 李毛丁 | 3D lead-acid battery and production method thereof |
| CN208433468U (en) * | 2018-04-28 | 2019-01-25 | 代朋岳 | A kind of ultra-thin plate railings of anode and cathode of lead-acid accumulator |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104821402A (en) * | 2014-08-15 | 2015-08-05 | 骆驼集团襄阳蓄电池有限公司 | Lead-acid storage battery plate grid and forming surface treatment method |
| CN104868176A (en) * | 2015-05-19 | 2015-08-26 | 李毛丁 | 3D lead-acid battery and production method thereof |
| CN208433468U (en) * | 2018-04-28 | 2019-01-25 | 代朋岳 | A kind of ultra-thin plate railings of anode and cathode of lead-acid accumulator |
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