A bulge-proof lead-acid storage battery

Abstract

The application discloses a kind of anti-bulging lead-acid battery, it is related to lead-acid battery technical field, including the double-layer lead paste embedded in positive plate, wherein bottom layer is microporous layer, surface layer is macroporous layer, form gradient pore structure to optimize gas discharge path;Graphene-silicon dioxide whisker is embedded in negative plate, constructs three-dimensional conductive network to reduce polarization voltage;Composite separator includes first glass fiber pad of different pore size, puncture-resistant layer and second glass fiber pad, optimize electrolyte distribution and enhance puncture resistance;Composite shell is constituted by polypropylene inner layer, buffer layer and polypropylene-carbon fiber composite outer layer, can produce reversible deformation with pressure change;Through maintaining micro-positive pressure and slow-release gas primary mechanical pressure relief valve and in overcharge or fault condition, instantaneous opening, and timely pressure relief piezoelectric ceramic pressure relief valve two-stage pressure relief unit is formed;Through the synergy of structure and material, improve the bulging of battery, improve cycle life, solve the problem that existing lead-acid battery is easy to bulge.

Description

Technical Field

[0001] The present invention relates to the technical field of lead-acid batteries, in particular to an anti-bulging lead-acid battery. Background Art

[0002] Lead-acid batteries, due to their low cost, high reliability, and mature recycling systems, play a vital role in applications such as vehicle starting, electric vehicle powertrains, energy storage systems, and uninterruptible power supplies (UPS). However, the long-standing problem of lead-acid batteries with bulging severely restricts their performance and safety. During the charge and discharge process, oxygen evolution at the positive electrode and hydrogen evolution at the negative electrode accumulate, leading to increased pressure within the lead-acid battery casing. This, combined with the vaporization of the electrolyte at high temperatures, can easily cause the casing to swell or even rupture, resulting in electrolyte leakage, capacity degradation, and potential safety hazards.

[0003] Current state-of-the-art improvements to the bulging problem focus on the following areas: Electrode structure optimization: Traditional lead-acid batteries utilize uniformly porous electrodes (porosity 45-55%). While this ensures electrolyte infiltration, it provides a single diffusion path for gas, which can easily lead to gas stagnation within the plates. Prior art has proposed adding carbon fibers to the electrodes to enhance conductivity, but these uniformly distributed pores prevent gas from being directed, and the carbon material exacerbates the hydrogen evolution side reaction.

[0004] Electrolyte additives: Adding sodium sulfate, phosphoric acid, etc. can inhibit some gas generation, but it is difficult to balance the effect of conductivity and inhibiting gas release.

[0005] Case pressure relief design: Conventional pressure relief valves (such as rubber check valves) typically open at pressures of 15-20 kPa and have a slow response time (>200 ms), making them unable to cope with sudden overcharge or gas surges at high temperatures. Furthermore, the casing of existing lead-acid batteries is typically made of rigid ABS plastic. This lacks the ability to deform adaptively when pressure increases due to gas release within the casing, making it difficult to recover after deformation and prone to fatigue cracking after repeated deformation.

[0006] Although the above improvements have achieved certain results, the following technical bottlenecks still exist: the contradiction between electrode pores and gas management: the uniform pore structure cannot take into account both high reactivity and rapid exhaust requirements. Gas retention causes local pressure concentration, resulting in expansion and deformation of the plate and shedding of active substances from the plate grid, leading to a decrease in the capacity of the lead-acid battery; side effects of the introduction of carbon materials: although adding carbon black or graphene to the negative electrode improves conductivity, its highly catalytically active surface intensifies the hydrogen evolution reaction, further exacerbating the bulging phenomenon of the lead-acid battery; limitations of static pressure relief: traditional pressure relief valves respond passively and cannot dynamically match the internal pressure of the battery. Frequent pressure relief leads to electrolyte loss, accelerating battery failure; poor adaptability to high temperature environments: the thermal expansion coefficient of existing shell materials does not match that of the plate. Above 45°C, the bulging rate increases, resulting in a sharp drop in the cycle life of the lead-acid battery.

[0007] Therefore, the problems existing in the current prior art are:

[0008] (1) The electrode pore structure is simple and the gas diffusion path is chaotic, which makes it impossible to achieve directional gas conduction. The gas cannot be discharged in time, which easily causes bulging and easily causes the active material on the grid to fall off, affecting the battery capacity; (2) The hydrogen evolution side reaction of the carbon material modified negative electrode is significant, and there is a lack of efficient suppression methods; (3) The shell pressure response is slow, and the static pressure relief mechanism is difficult to match the dynamic internal pressure changes.

[0009] In summary, it is found that the existing technology has at least the following technical problems:

[0010] Existing lead-acid batteries have technical problems such as the inability to discharge gas in a timely manner, difficulty in efficiently suppressing the hydrogen evolution reaction, and the inability to release the pressure inside the shell in a timely manner, which leads to the problem of lead-acid batteries being prone to bulging. Summary of the Invention

[0011] The object of the present invention is to provide an anti-bulging lead-acid battery to solve the technical problems of existing lead-acid batteries, such as the inability to discharge gas in a timely manner, the difficulty in efficiently suppressing hydrogen evolution reaction, and the inability to release pressure in a timely manner.

[0012] The various technical effects that can be produced by the preferred technical solutions among the various technical solutions provided by the present invention are described in detail below.

[0013] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0014] The application provides a bulge-proof lead-acid storage battery, which comprises a positive plate, a double-layer lead paste embedded on the positive plate, a gradient pore structure formed by a microporous layer at a bottom layer and a macroporous layer at a surface layer, and a pore of the double-layer lead paste gradually increasing from inside to outside of the positive plate to form a directional air guide channel; a negative plate, graphene-silicon dioxide whisker embedded on the negative plate to build a three-dimensional conductive network and reduce a polarization voltage; a composite separator, the composite separator comprising a first glass fiber pad, an anti-puncture layer and a second glass fiber pad, a pore size of the second glass fiber pad being larger than that of the first glass fiber pad, the first glass fiber pad facing the positive plate and the second glass fiber pad facing the negative plate during installation; and a composite shell, the composite shell comprising a polypropylene inner layer, a buffer layer, a polypropylene and carbon fiber composite outer layer from inside to outside, for adapting to swelling deformation with an increase of air pressure in the shell and restoring deformation with a decrease of air pressure in the shell; the positive plate, the composite separator and the negative plate are alternately arranged and stacked to form a plate group and arranged in the composite shell; and a two-stage pressure relief unit arranged at a top of the composite shell, the two-stage pressure relief unit comprising a first-stage mechanical pressure relief valve and a second-stage piezoelectric ceramic pressure relief valve; under normal charging, the first-stage mechanical pressure relief valve maintains a slight positive pressure in the composite shell and slowly releases a stable gas; under overcharging or sudden failure, the second-stage piezoelectric ceramic pressure relief valve is instantaneously opened to release pressure, avoiding overexpansion or rupture of the composite shell.

[0015] In one of the embodiments, the positive plate comprises a positive plate grid and the double-layer lead paste; main ribbons of the positive plate grid are arranged radially in a plate frame, and a thickness of a rib at a center of the plate frame is smaller than that of a rib at an edge of the plate frame; the microporous layer of the double-layer lead paste is added with short-cut glass fibers, and the macroporous layer is added with nano carbon fibers.

[0016] In one of the embodiments, the lead paste of the microporous layer is coated on the ribbons of the positive plate grid, and a thickness is controlled at 0.3-0.5 mm, a porosity is controlled at 45-50%, a pore size is controlled at 50-100 μm, and an addition amount of the short-cut glass fibers is controlled at 0.5-1.0 wt%; the lead paste of the macroporous layer is coated on the microporous lead paste, and a thickness is controlled at 1.2-1.5 mm, a porosity is controlled at 30-35%, a pore size is controlled at 20-50 μm, and an addition amount of the nano carbon fibers is controlled at 1.0-1.5 wt%.

[0017] In one of the embodiments, a short-cut length of the short-cut glass fibers is 3-4.5 mm.

[0018] In one embodiment, the negative electrode plate includes a negative electrode grid and a negative electrode lead paste; the ribs of the negative electrode grid are vertically staggered, and the ribs located in the plate frame have a uniform thickness; the graphene-tin dioxide whiskers are composed of nitrogen-doped graphene sheets and tin dioxide, and the tin dioxide is grown on the surface of the graphene sheet by a chemical vapor deposition process to form a composite structure of graphene base + tin dioxide whiskers; and the graphene-tin dioxide whiskers are embedded in the negative electrode lead paste, and the graphene in the graphene-tin dioxide whiskers forms a longitudinal conductive main path in the negative electrode lead paste, and the tin dioxide whiskers vertically penetrate the negative electrode lead paste to form a longitudinal conductive branch path, which is used to improve electron permeability.

[0019] In one embodiment, the buffer layer includes honeycomb aluminum and silica gel, and the silica gel is filled in the honeycomb aluminum and wraps the honeycomb aluminum.

[0020] In one embodiment, the thickness of the first glass fiber mat is controlled to be 0.3-0.4 mm, and the pore size is 5-10 μm. The small pore size is used to prevent lead crystals from puncturing and causing short circuits; the anti-puncture layer is a composite separator of polyethylene and glass fiber mat, and the thickness of the anti-puncture layer is controlled to be 0.5-0.7 mm, and the pore size is 20-30 μm; the thickness of the second glass fiber mat is controlled to be 0.4-0.6 mm, and the pore size is 30-50 μm, and the large pore size is used to guide the gas generated by the negative plate to be discharged from the composite separator; and the pore sizes of the first glass fiber mat, the anti-puncture layer and the second glass fiber mat are increased successively to form a gradient pore size, which is used to promote and guide the flow direction of the electrolyte, and form a liquid storage between the first glass fiber mat and the second glass fiber mat to increase the electrolyte retention.

[0021] In one embodiment, the first glass fiber mat is coated with an alumina coating to reduce the pore size of the first glass fiber mat and improve the compressive strength to avoid lead crystal growth and puncture short circuit, and to improve the thermal stability of the first glass fiber mat and reduce the shrinkage of the composite partition.

[0022] In one embodiment, the first-stage mechanical pressure relief valve includes a silicone diaphragm and a spring, has an opening pressure of 12 kPa, and a response time of 200-300 ms.

[0023] In one embodiment, the secondary piezoelectric ceramic pressure relief valve includes a piezoelectric ceramic sheet, a control unit and a pressure sensor. The pressure sensor and the piezoelectric ceramic sheet are electrically connected to the control unit, and the pressure sensor detects the pressure inside the composite shell. The opening threshold of the secondary piezoelectric ceramic pressure relief valve is that the internal pressure of the composite shell is greater than 20kPa or the pressure change rate is greater than 5kPa / s, and the response time is less than 50ms. It is used to perform emergency pressure relief on the composite shell when the lead-acid battery is overcharged or suddenly fails.

[0024] The beneficial effects of the present invention are as follows:

[0025] The present invention embeds a double-layer lead paste with gradient pores on the positive plate, including a microporous layer at the bottom layer and a macroporous layer at the surface layer. The pores of the double-layer lead paste gradually increase from the inside to the outside of the positive plate to form a directional air guide channel; the composite separator includes a first glass fiber mat, an anti-puncture layer and a second glass fiber mat, and the pore size of the second glass fiber mat is larger than that of the first glass fiber mat; during installation, the first glass fiber mat faces the positive plate and the second glass fiber mat faces the negative plate, and cooperates with the two-stage pressure relief unit arranged on the top of the composite shell to achieve directional gas drainage and dynamic pressure balance.

[0026] (1) Optimize the pore structure of the positive plate to improve gas emission efficiency

[0027] The internal gas of the positive plate of a traditional lead-acid battery is difficult to discharge effectively and easily accumulates during the charge and discharge process, resulting in an increase in the internal pressure of the battery. The present invention embeds a double layer of lead paste in the positive plate, wherein the bottom layer is a microporous layer and the surface layer is a macroporous layer, forming a gradient pore structure, forming a main channel for gas discharge from the positive plate. This structure can guide the precipitated gas to be discharged in a predetermined direction, improve gas discharge efficiency, and reduce the risk of internal gas accumulation; in conjunction with the structure of the composite separator with increasing pore size from the positive plate side to the negative plate side, the gas of the positive plate is guided to enter the space between the puncture-proof layer of the composite separator and the second glass fiber mat, and the gas of the negative plate also passes through the second glass fiber mat and enters the space between the puncture-proof layer and the second glass fiber mat. The gas of the positive and negative plates can be accelerated to overflow from the composite separator and diffuse to the two-stage pressure relief unit, and the gas residence time is shortened from 30s to 8s, thereby reducing the bulging caused by the continuous increase in the internal pressure of the battery due to gas residence, thereby reducing the occurrence of bulging phenomenon; it can also reduce the shedding of active materials on the positive and negative plates due to irregular gas overflow, which leads to a reduction in battery capacity.

[0028] (2) Optimize the composite separator structure to improve battery stability

[0029] The composite separator adopts a multi-layer design, and when installed, the first glass fiber mat is facing the positive plate and the second glass fiber mat is facing the negative plate. This structure can also optimize the distribution of the electrolyte and improve the uniformity of the reaction between the positive and negative plates and the electrolyte. At the same time, compared with the separators of traditional lead-acid batteries, the composite separator of the present application also enhances the puncture resistance, reduces the risk of short circuit due to lead crystal puncture, and improves the overall stability and safety of the battery.

[0030] (3) Using graphene-tin dioxide whisker negative electrode material to reduce polarization voltage

[0031] The negative plates of traditional lead-acid batteries are prone to hydrogen evolution reactions, which leads to increased water loss in the battery and accelerated battery aging. The present invention embeds graphene-tin dioxide whiskers in the negative plates to form a three-dimensional conductive network, thereby improving the overall conductivity and specific surface area of ​​the negative plates, thereby improving electron transmission efficiency and reducing internal resistance, thereby achieving a reduction in polarization voltage, reducing the driving force of the hydrogen evolution reaction, reducing the occurrence of the hydrogen evolution reaction, and improving the cycle life and charge and discharge performance of the lead-acid battery.

[0032] (4) Innovative composite shell design to enhance pressure regulation capability

[0033] Traditional battery casings are prone to irreversible deformation or rupture when internal pressure increases. The composite casing of the present invention adopts a multi-layer structure, comprising, from the inside out, an inner polypropylene layer, a buffer layer, and an outer polypropylene and carbon fiber composite layer. The buffer layer can absorb deformation caused by internal pressure changes, allowing the casing to expand and deform when air pressure increases, and return to its original shape when air pressure decreases. It also reduces the impact of external high-frequency vibration on the active materials on the positive and negative plates (especially when used as a power battery in electric vehicles), reducing additional loss of battery capacity. This deformable casing design can effectively reduce the irreversible expansion of the battery casing caused by internal gas accumulation and the impact of external vibration transmission on the battery capacity, thereby improving the safety and durability of the battery.

[0034] (5) Double-stage pressure relief unit to improve safety

[0035] The two-stage pressure relief valve unit realizes graded pressure management of the composite shell by setting a first-stage mechanical pressure relief valve and a second-stage piezoelectric ceramic pressure relief valve; the pressure inside the composite shell is maintained by the first-stage mechanical pressure relief valve to form a micro-positive pressure. Under the micro-positive pressure, it helps to maintain the efficiency of oxygen recombination, and when the pressure inside the composite shell reaches the pressure at which the mechanical pressure relief valve opens, it can also slowly release the steady-state gas in the shell to avoid excessive accumulation of internal gas.

[0036] Through the secondary piezoelectric ceramic pressure relief valve, when the battery is overcharged or suddenly fails, there is a sudden overpressure in the composite shell. The valve body can be opened instantaneously to relieve pressure with an extremely high response speed, quickly releasing the internal pressure and avoiding excessive expansion of the composite shell due to overpressure, which may lead to irreversible shell deformation or shell rupture.

[0037] (6) Improved battery cycle life and capacity retention

[0038] The lead-acid battery of the present invention has a cycle life increased from 400 times to 435 times, and a capacity attenuation rate reduced, while maintaining the battery temperature below 45°C and cycling at 90% of the charge and discharge capacity. Furthermore, the capacity retention rate of the lead-acid battery of the present invention is approximately 85%, which is an improvement compared to the capacity retention rate of only approximately 70% of conventional lead-acid batteries. The lead-acid battery of the present invention is suitable for use in a start-stop system with high-frequency oil start-stop requirements.

[0039] The present invention provides an anti-bulging lead-acid battery. By optimizing the plate structure, separator structure and material and shell design, and introducing a two-stage pressure relief unit, the present invention effectively solves the bulging problem caused by the inability to discharge gas in time, high polarization voltage, and accumulated shell pressure during use of the lead-acid battery. The bulging phenomenon can be effectively suppressed, and the service life, safety and charge and discharge performance of the battery are improved. The battery has significant technical advantages and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solution of the present invention, the following is a brief introduction to the drawings required for use in the implementation. Obviously, the drawings described below are only some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0041] Figure 1 It is a structural schematic diagram of the anti-bulging lead-acid battery of the present invention;

[0042] Figure 2 Schematic diagram of the structure of the negative electrode grid of the present invention;

[0043] Figure 3 Schematic diagram of the structure of the positive electrode grid of the present invention;

[0044] Figure 4 It is a schematic diagram of the combined structure of the positive electrode plate, the negative electrode plate and the composite separator of the present invention.

[0045] The accompanying drawings are numerals as follows:

[0046] 1. Positive plate; 11. Positive grid; 111. Main rib; 112. Secondary rib;

[0047] 2. Negative plate; 21. Negative grid;

[0048] 3. Composite partition;

[0049] 4. Composite shell;

[0050] 5. Two-stage pressure relief unit; 51. First-stage mechanical pressure relief valve; 52. Second-stage piezoelectric ceramic pressure relief valve. DETAILED DESCRIPTION

[0051] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention.

[0052] In a specific embodiment, an anti-bulging lead-acid battery is provided, which effectively solves the technical problems of existing lead-acid batteries, such as the inability to discharge gas in a timely manner, the difficulty in efficiently suppressing hydrogen evolution reaction, and the inability to release pressure in the shell in a timely manner, thereby avoiding the problem of lead-acid batteries being prone to bulging.

[0053] The first embodiment of the anti-bulging lead-acid battery is as follows Figures 1 to 4 As shown, it includes a positive plate 1, on which a double layer of lead paste including a microporous layer at the bottom layer and a macroporous layer at the surface layer is embedded, forming a gradient pore structure, and the pores of the double layer of lead paste gradually increase from the inside to the outside of the positive plate 1 to form a directional air guide channel; and a negative plate 2, on which graphene-tin dioxide whiskers are embedded to construct a three-dimensional conductive network to reduce the polarization voltage; and a composite separator 3, which includes a first glass fiber mat, an anti-puncture layer and a second glass fiber mat, and the pore size of the second glass fiber mat is larger than that of the first glass fiber mat; when installed, the first glass fiber mat faces the positive plate 1 and the second glass fiber mat faces the negative plate 2; and a composite shell 4, which is composed of an inner and outer shell. The outer structure includes a polypropylene inner layer, a buffer layer, and a polypropylene and carbon fiber composite outer layer, which are used to adapt to expansion deformation as the air pressure in the shell increases and recovery deformation as the air pressure in the shell decreases; the positive plate 1-composite separator 3-negative plate 2 are alternately arranged and stacked to form a plate group, and are arranged in the composite shell 4; and a two-stage pressure relief unit 5 is arranged on the top of the composite shell 4. The two-stage pressure relief unit 5 includes a first-stage mechanical pressure relief valve 51 and a second-stage piezoelectric ceramic pressure relief valve 52; under normal charging, the first-stage mechanical pressure relief valve 51 maintains a slightly positive pressure in the composite shell 4 and slowly releases steady-state gas; in the case of overcharging or sudden failure, the second-stage piezoelectric ceramic pressure relief valve 52 opens instantly to relieve pressure to prevent excessive expansion or rupture of the composite shell 4.

[0054] The present invention provides a bulging-resistant lead-acid battery. By optimizing the plate structure, separator structure and materials, and housing design, and introducing a dual-stage pressure relief unit 5, the present invention effectively solves the bulging problem of lead-acid batteries during use caused by the inability to promptly discharge gassing, high polarization voltage, and accumulated housing pressure. The bulging phenomenon can be effectively suppressed, and the battery's service life, safety, and charge-discharge performance can be improved. Specifically, the improvements are:

[0055] By optimizing the pore structure of the positive plate, the gas emission efficiency is improved; the internal gas of the positive plate 1 of the traditional lead-acid battery is difficult to be effectively discharged and is easily accumulated during the charge and discharge process, resulting in an increase in the internal pressure of the battery. The present invention embeds a double layer of lead paste in the positive plate 1, wherein the bottom layer is a microporous layer and the surface layer is a macroporous layer, forming a gradient pore structure, forming a main channel for gas discharge from the positive plate 1, this structure can guide the precipitated gas to be discharged in a predetermined direction, thereby improving the gas emission efficiency and reducing the risk of internal gas accumulation; in combination with the structure of the composite separator 3 with an enlarged pore size from the positive plate 1 side to the negative plate 2 side, The gas of the positive plate 1 is guided to enter between the anti-puncture layer of the composite separator 3 and the second glass fiber mat, and the gas of the negative plate 2 also passes through the second glass fiber mat and enters between the anti-puncture layer and the second glass fiber mat. The gas of the positive and negative plates 2 is accelerated to overflow from the composite separator 3 and diffuse to the two-stage pressure relief unit 5. The gas residence time is shortened from 30s to 8s, reducing the bulging caused by the continuous increase in the internal pressure of the battery due to gas retention, thereby reducing the occurrence of bulging. It can also reduce the shedding of active materials on the positive and negative plates 2 caused by irregular gas overflow, which leads to a reduction in battery capacity.

[0056] The battery stability is improved by optimizing the composite separator structure; the composite separator 3 adopts a multi-layer design, and when installed, the first glass fiber mat is directed toward the positive plate 1, and the second glass fiber mat is directed toward the negative plate 2. This structure can also optimize the distribution of the electrolyte and improve the uniformity of the reaction between the positive and negative plates 2 and the electrolyte; at the same time, compared with the separator of traditional lead-acid batteries, the composite separator 3 of the present application also enhances the puncture resistance, reduces the risk of short circuit due to lead crystal puncture, and improves the overall stability and safety of the battery.

[0057] By adopting a graphene-tin dioxide whisker negative electrode material, the polarization voltage is reduced. The negative plate 2 of a conventional lead-acid battery is prone to hydrogen evolution reaction, which leads to increased water loss in the battery and thus accelerated battery aging. The present invention embeds graphene-tin dioxide whiskers in the negative plate 2 to form a three-dimensional conductive network, thereby improving the overall conductivity and specific surface area of ​​the negative plate 2, thereby improving electron transmission efficiency and reducing internal resistance, thereby achieving a reduction in polarization voltage, reducing the driving force of the hydrogen evolution reaction, reducing the occurrence of the hydrogen evolution reaction, and improving the cycle life and charge and discharge performance of the lead-acid battery.

[0058] By adopting a composite structure of a composite shell, the pressure regulation capability is enhanced; conventional battery shells are prone to irreversible deformation or rupture when the internal pressure increases. The composite shell 4 of the present invention adopts a multi-layer structure, which includes, from the inside to the outside, a polypropylene inner layer, a buffer layer, and a polypropylene and carbon fiber composite outer layer; wherein the buffer layer can absorb the deformation caused by internal pressure changes, so that the shell can expand and deform when the air pressure increases, and return to its original shape when the air pressure decreases, and reduce the impact of external high-frequency vibration on the active materials on the positive and negative plates 2 (especially when used as a power battery in electric vehicles), thereby reducing the additional loss of battery capacity; this deformable shell design can effectively reduce the irreversible expansion of the battery shell caused by internal gas accumulation and the impact of external vibration transmission on the battery capacity, thereby improving the safety and durability of the battery.

[0059] Safety is improved by using a bipolar pressure relief unit; the two-stage pressure relief valve unit implements graded pressure management of the composite shell 4 by setting a first-stage mechanical pressure relief valve 51 and a second-stage piezoelectric ceramic pressure relief valve 52; the pressure inside the composite shell 4 is maintained by the first-stage mechanical pressure relief valve 51 to form a micro-positive pressure, which helps to maintain the efficiency of oxygen recombination under the micro-positive pressure, and when the pressure inside the composite shell 4 reaches the pressure at which the mechanical pressure relief valve opens, it can also slowly release the steady-state gas in the shell to avoid excessive accumulation of internal gas.

[0060] Through the secondary piezoelectric ceramic pressure relief valve 52, when the battery is overcharged or suddenly fails, when there is a sudden overpressure in the composite shell 4, the valve body can be opened instantaneously with an extremely high response speed to relieve the pressure, quickly release the internal pressure, and avoid the composite shell 4 from being over-pressurized and over-expanding, resulting in irreversible shell deformation or shell rupture.

[0061] Improve the performance of battery cycle life and capacity retention rate; the lead-acid battery of the present invention, when maintaining the battery temperature below 45°C and cycling at 90% of the charge and discharge capacity, has a cycle life increased from 400 times to 435 times, and the capacity attenuation rate is reduced; and the capacity retention rate of the lead-acid battery of the present invention is about 85%, which is an improvement compared to the capacity retention rate of only about 70% of traditional lead-acid batteries; the lead-acid battery of the present invention is suitable for use in start-stop systems with high-frequency start-stop requirements of oil.

[0062] As an optional implementation method

[0063] Regarding the specific structure of the positive electrode plate 1, this embodiment Figure 3 As shown, the positive plate 1 includes a positive grid 11 and a double-layer lead paste; the main ribs 111 of the positive grid 11 are arranged radially in the plate frame, and the thickness of the ribs located at the center of the plate frame is less than the thickness of the ribs located at the edge of the plate frame; short glass fibers are added to the microporous layer of the double-layer lead paste, and nano-carbon fibers are added to the macroporous layer.

[0064] Among them, the width of the main ribs 111 of the positive electrode grid 11 is 1.0-1.2mm, and the positive electrode grid 11 also has secondary ribs 112, which are perpendicular to the opposite sides of the plate frame and intersect with the main ribs 111; the width of the secondary ribs 112 is 0.6-0.8mm; the thickness of the ribs located at the center of the plate frame is 2.0mm, and the thickness of the ribs located at the edge of the plate frame is 2.5mm, which helps to optimize the current distribution of the positive plate 1, reduce the edge effect, and improve the charge and discharge performance of the positive plate 1.

[0065] The chopped length of the chopped glass fibers is 3-4.5 mm.

[0066] During application, the positive electrode grid 11 is made of lead-calcium-tin alloy as a whole, which helps to improve the corrosion resistance of the positive electrode grid 11; the chopped glass fiber has the performance of enhancing mechanical support. In the lead paste of the microporous layer, the chopped glass fiber can enhance the creep resistance of the positive plate 1, so that the expansion rate of the positive plate 1 is lower than that of the traditional positive plate 1, and prevent the material on the positive electrode grid 11 from falling off; and the nano-carbon fibers added in the macroporous layer help to expand the pores and improve the lead paste forming of the macroporous layer, avoid the falling off of active substances, and at the same time achieve rapid gas conduction and reduce gas retention.

[0067] The above-mentioned double-layer lead paste adopts a layered coating process. Specifically, the microporous layer of lead paste is coated on the ribs of the positive plate grid, and the thickness is controlled at 0.3-0.5mm, the porosity is controlled at 45-50%, the pore size is controlled at 50-100μm, and the amount of chopped glass fiber added is controlled at 0.5-1.0wt%; the macroporous layer of lead paste is coated on the microporous lead paste, and the thickness is controlled at 1.2-1.5mm, the porosity is controlled at 30-35%, the pore size is controlled at 20-50μm, and the amount of nano-carbon fiber added is controlled at 1.0-1.5wt%.

[0068] Here, wt% refers to mass percentage.

[0069] Regarding the specific structure of the negative electrode plate 2, this embodiment Figure 2 As shown, the negative plate 2 includes a negative electrode grid 21 and a negative electrode lead paste; the ribs of the negative electrode grid 21 are vertically staggered, and the ribs located in the plate frame are of uniform thickness; the graphene-tin dioxide whiskers are composed of nitrogen-doped graphene sheets and tin dioxide, and tin dioxide whiskers are grown on the surface of the graphene sheets through a chemical vapor deposition process to form a composite structure of graphene base + tin dioxide whiskers; and the graphene-tin dioxide whiskers are embedded in the negative electrode lead paste, and the graphene in the graphene-tin dioxide whiskers forms a longitudinal conductive main path in the negative electrode lead paste, and the tin dioxide whiskers vertically penetrate the negative electrode lead paste to form a longitudinal conductive branch path, which is used to improve electron permeability.

[0070] The ribs of the negative plate grid 21 are vertically staggered, and the ribs located in the plate frame have consistent thickness, which ensures uniform distribution of current and maintains stability of current density. Nitrogen doping treatment of the graphene sheet can increase its surface hydrophilicity and promote electrolyte infiltration.

[0071] In application, the negative plate grid 21 adopts lead-calcium alloy, and the surface is plated with tin 2-5 μm, so that the hydrogen evolution overpotential of the negative plate 2 is increased by 50 mV. The higher the overpotential is, the greater the energy barrier required for the hydrogen evolution reaction is, and the more difficult the reaction is to occur, thereby reducing the generation of hydrogen and reducing the bulging phenomenon and safety risk of the battery.

[0072] Since the dangling bonds at the edges of the graphene are high active sites for hydrogen evolution, the SnO2 whiskers are vertically grown on the surface of the graphene to cover the edges and reduce the exposed catalytically active sites, thereby controlling the generation of the hydrogen evolution reaction. Meanwhile, the graphene sheet has ultrahigh electrical conductivity and high specific surface area, providing a high-speed electron transport channel to compensate for the poor intrinsic conductivity of tin dioxide, anchoring the tin dioxide whiskers on the surface of the graphene, and embedding the graphene-tin dioxide whiskers in the negative plate paste in a vertical manner to prevent the formation of stacking when the graphene-tin dioxide whiskers are embedded in the negative plate paste, thereby maintaining a high specific surface area and improving the overall conductivity of the negative plate 2, thereby improving the electron transport efficiency and reducing the internal resistance, thereby reducing the polarization voltage, reducing the driving force of the hydrogen evolution reaction, reducing the occurrence of the hydrogen evolution reaction, and improving the cycle life and charge-discharge performance of the lead-acid battery.

[0073] The specific structure of the buffer layer of the composite shell 4 includes honeycomb aluminum and silica gel, and the silica gel is filled in the honeycomb aluminum and wrapped around the honeycomb aluminum.

[0074] In application, the honeycomb aluminum provides high compression resistance to maintain strength, and the elasticity of the filled and wrapped silica gel provides recovery force for plastic deformation, and can also absorb the energy of high-frequency vibration, thereby improving the deformation ability and safety of the composite shell 4 and helping to improve the charge-discharge performance stability of the lead-acid battery.

[0075] The specific structure of the composite separator 3 includes a first glass fiber pad with a thickness of 0.3-0.4 mm and a pore size of 5-10 μm, a puncture-resistant layer composed of polyethylene and a glass fiber pad with a thickness of 0.5-0.7 mm and a pore size of 20-30 μm, and a second glass fiber pad with a thickness of 0.4-0.6 mm and a pore size of 30-50 μm. The small pore size is used to prevent short circuit caused by lead crystal puncture, the large pore size is used to guide the gas generated by the negative plate 2 to be discharged from the composite separator 3, and the pore sizes of the first glass fiber pad, the puncture-resistant layer, and the second glass fiber pad are gradually increased to form a gradient pore size, which is used to promote and guide the flow direction of the electrolyte and form a liquid storage between the first glass fiber pad and the second glass fiber pad to increase the electrolyte retention.

[0076] During use, the structure of the composite separator 3 with gradually increasing aperture from the positive plate 1 side to the negative plate 2 side can guide the gas of the positive plate 1 into the space between the anti-puncture layer of the composite separator 3 and the second glass fiber mat, and the gas of the negative plate 2 also passes through the second glass fiber mat and enters the space between the anti-puncture layer and the second glass fiber mat. The gas of the positive and negative plates 2 can be accelerated to overflow from the composite separator 3 and diffuse to the two-stage pressure relief unit 5.

[0077] Regarding the specific structure and performance of the above-mentioned first-stage mechanical pressure relief valve 51, the first-stage mechanical pressure relief valve 51 includes a silicone diaphragm and a spring, the opening pressure is 12kPa, and the response time is 200-300ms.

[0078] When a trace amount of gas is released during the float charge stage of the lead-acid battery, the internal pressure of the composite shell 4 accumulates to greater than 12 kPa, which can trigger the opening condition of the first-level mechanical pressure relief valve 51. The steady-state gas in the composite shell 4 is slowly released by opening the first-level mechanical pressure relief valve 51, preventing frequent triggering of the second-level piezoelectric ceramic pressure relief valve 52, which leads to excessive release of gas and the loss of water in the electrolyte (in the form of hydrogen and oxygen).

[0079] Regarding the specific structure and performance of the above-mentioned secondary mechanical pressure relief valve, the secondary piezoelectric ceramic pressure relief valve 52, the secondary piezoelectric ceramic pressure relief valve 52 includes a piezoelectric ceramic sheet, a control unit and a pressure sensor. The pressure sensor and the piezoelectric ceramic sheet are electrically connected to the control unit. The pressure sensor detects the pressure inside the composite shell 4; the opening threshold of the secondary piezoelectric ceramic pressure relief valve 52 is that the internal pressure of the composite shell 4 is greater than 20kPa or the pressure change rate is greater than 5kPa / s, and the response time is <50ms. It is used to perform emergency pressure relief on the composite shell 4 when the lead-acid battery is overcharged or suddenly fails.

[0080] During application, the internal pressure of the composite shell 4 is monitored in real time by the pressure sensor, and the control unit receives the pressure signal fed back by the pressure sensor. When the internal pressure of the composite shell 4 is greater than 20 kPa, the control unit applies voltage to the piezoelectric ceramic piece, the piezoelectric ceramic piece is deformed, and the secondary piezoelectric ceramic pressure relief valve 52 is instantly deformed and opened, releasing the gas in the composite shell 4 for emergency pressure relief.

[0081] The second embodiment of the anti-bulging lead-acid battery is different from the first embodiment in that the first glass fiber mat is structurally reinforced and coated with an alumina coating to reduce the pore size of the first glass fiber mat and improve the compressive strength to prevent lead crystal growth from puncturing the composite partition 3 and causing a short circuit, and to improve the thermal stability of the first glass fiber mat and reduce the shrinkage of the composite partition 3.

[0082] During application, the alumina coating can enhance the compressive resistance of the first glass fiber mat in the composite separator 3, reduce the degree of compression of the composite separator 3 due to thermal expansion and contraction and high pressure inside the shell during battery charging and discharging, and help extend the life of the composite separator 3; when the lead-acid battery is float-charged or overcharged at high temperature, it avoids short circuit between the positive plate 1 and the negative plate 2 due to shrinkage of the composite separator 3, thereby extending the life of the lead-acid battery.

[0083] The technical features of the above embodiments may be combined arbitrarily. To simplify the description, not all possible combinations of the technical features in the above embodiments are described.

Claims

1. An anti-bulging lead-acid battery, characterized in that: The invention comprises a positive electrode plate, wherein a double-layer lead paste including a microporous layer at the bottom layer and a macroporous layer at the surface layer is embedded in the positive electrode plate to form a gradient pore structure, wherein the pores of the double-layer lead paste gradually increase from the inside to the outside of the positive electrode plate to form a directional air guide channel; and a negative electrode plate, wherein graphene-tin dioxide whiskers are embedded in the negative electrode plate to construct a three-dimensional conductive network to reduce polarization voltage; and a composite separator, the composite separator comprising a first glass fiber mat, a puncture-proof layer, and a second glass fiber mat, wherein the second glass fiber mat has a larger pore size than the first glass fiber mat; when installed, the first glass fiber mat faces the positive electrode plate, and the second glass fiber mat faces the negative electrode plate; and a composite shell, the composite shell comprising, from the inside out, a polypropylene inner layer, a buffer layer, and a polypropylene and carbon fiber composite outer layer, adapted to expand and deform as the air pressure inside the shell increases, and recover and deform as the air pressure inside the shell decreases; The positive electrode plate, the composite separator, and the negative electrode plate are alternately arranged and stacked to form a plate group, which is then disposed in the composite shell; and a double-stage pressure relief unit provided on the top of the composite shell, the double-stage pressure relief unit comprising a first-stage mechanical pressure relief valve and a second-stage piezoelectric ceramic pressure relief valve; Under normal charging, the first-level mechanical pressure relief valve maintains a slight positive pressure in the composite shell and slowly releases steady-state gas; under overcharging or sudden failure, the second-level piezoelectric ceramic pressure relief valve opens instantaneously to release pressure to prevent the composite shell from over-expansion or rupture.

2. The anti-bulging lead-acid battery according to claim 1, characterized in that: The positive plate includes a positive grid and the double-layer lead paste; The main ribs of the positive electrode grid are arranged radially in the plate frame, and the thickness of the ribs located in the center of the plate frame is smaller than the thickness of the ribs located at the edge of the plate frame; The microporous layer of the double-layer lead paste is added with short-cut glass fibers, and the macroporous layer is added with nano-carbon fibers.

3. The anti-bulging lead-acid battery according to claim 2, characterized in that: The lead paste of the microporous layer is coated on the ribs of the positive grid, and the thickness is controlled to be 0.3-0.5 mm, the porosity is controlled to be 45-50%, the pore size is controlled to be 20-50 μm, and the amount of chopped glass fiber added is controlled to be 0.5-1.0 wt%; The lead paste of the macroporous layer is coated on the lead paste of the microporous layer, and the thickness is controlled at 1.2-1.5 mm, the porosity is controlled at 30-35%, the pore size is controlled at 50-100 μm, and the amount of nano-carbon fiber added is controlled at 1.0-1.5 wt%.

4. The anti-bulging lead-acid battery according to claim 3, characterized in that: The chopped length of the chopped glass fibers is 3-4.5 mm.

5. The anti-bulging lead-acid battery according to claim 1, characterized in that: The negative plate includes a negative grid and negative lead paste; the ribs of the negative grid are vertically staggered, and the ribs located within the plate frame are of uniform thickness; The graphene-tin dioxide whiskers are composed of nitrogen-doped graphene sheets and tin dioxide, and the tin dioxide whiskers are grown on the surface of the graphene sheets through a chemical vapor deposition process to form a composite structure of graphene base + tin dioxide whiskers; The graphene-tin dioxide whiskers are embedded in the negative electrode lead paste, the graphene in the graphene-tin dioxide whiskers forms a longitudinal conductive main path in the negative electrode lead paste, and the tin dioxide whiskers vertically penetrate the negative electrode lead paste to form a longitudinal conductive branch path, which is used to improve electron permeability.

6. The anti-bulging lead-acid battery according to claim 1, characterized in that: The buffer layer includes honeycomb aluminum and silica gel, and the silica gel is filled in the honeycomb aluminum and wraps the honeycomb aluminum.

7. The anti-bulging lead-acid battery according to claim 1, characterized in that: The thickness of the first glass fiber mat is controlled to be 0.3-0.4 mm, and the pore size is 5-10 μm. The small pore size is used to prevent lead crystals from puncturing and causing short circuits. The puncture-proof layer is a composite layer of polyethylene and glass fiber mat, and the thickness of the puncture-proof layer is controlled to be 0.5-0.7 mm and the pore size is 20-30 μm; The thickness of the second glass fiber mat is controlled to be 0.4-0.6 mm, and the pore size is 30-50 μm. The large pore size is used to guide the gas generated by the negative plate to be discharged from the composite separator; The pore sizes of the first glass fiber mat, the puncture-proof layer and the second glass fiber mat increase successively to form a gradient pore size, which is used to promote and guide the flow direction of the electrolyte, and form a liquid storage between the first glass fiber mat and the second glass fiber mat to increase the electrolyte retention.

8. The anti-bulging lead-acid battery according to claim 7, characterized in that: The first glass fiber mat is coated with an alumina coating, which is used to reduce the pore size of the first glass fiber mat and improve the compressive strength to avoid lead crystal growth puncture short circuit, and to improve the thermal stability of the first glass fiber mat and reduce the shrinkage of the composite partition.

9. The anti-bulging lead-acid battery according to claim 1, characterized in that: The first-stage mechanical pressure relief valve includes a silicone diaphragm and a spring, has an opening pressure of 12 kPa, and a response time of 200-300 ms.

10. The anti-bulging lead-acid battery according to claim 9, characterized in that: The secondary piezoelectric ceramic pressure relief valve includes a piezoelectric ceramic sheet, a control unit and a pressure sensor. The pressure sensor and the piezoelectric ceramic sheet are both electrically connected to the control unit. The pressure sensor detects the pressure inside the composite shell. The opening threshold of the secondary piezoelectric ceramic pressure relief valve is that the internal pressure of the composite shell is greater than 20kPa or the pressure change rate is greater than 5kPa / s, and the response time is less than 50ms. It is used to provide emergency pressure relief for the composite shell when the lead-acid battery is overcharged or suddenly fails.

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