Thin bag-type puncture-resistant AGM separator and preparation method therefor

Abstract

The present invention belongs to the technical field of battery separators, and relates to a thin bag-type puncture-resistant AGM separator and a preparation method therefor. The thin bag-type puncture-resistant AGM separator comprises the following raw materials in percentages by mass: 50%-70% of high-alkali glass fibers and 30%-50% of reinforced fibers, wherein the high-alkali glass fibers comprise high-alkali glass fibers having a beating degree of 29-44°SR and high-alkali glass fibers having a beating degree of 19-29°SR; and the reinforced fibers are sheath-core-type fibers with dual melting points. In the present invention, a thin bag-type puncture-resistant AGM separator suitable for a barren-liquor-type lead-acid storage battery is prepared; and same has a bag-type structure, can completely cover a electrode sheet, and has high puncture resistance, thin and uniform thickness, high air permeability and low electrical resistance.

Description

A thin, bag-type puncture-resistant AGM septum and its preparation method Technical Field

[0001] This invention relates to the field of battery separator technology, specifically to a thin, pouch-type puncture-resistant AGM separator and its preparation method. Background Technology

[0002] In lead-acid batteries, sulfuric acid acts as the electrolyte, directly participating in the charge and discharge reactions. In traditional lead-acid batteries, except for the plates and separators, the entire space is filled with sulfuric acid electrolyte, resulting in a flooded state, hence the name EFB (Enhanced Flooded Battery). Flooded batteries use PE pouch separators, with the plates completely immersed in the electrolyte-filled pouch separators and separated from the other plates. However, flooded batteries require regular water replenishment, are prone to gas and acid mist generation, and pose a risk of electrolyte leakage, presenting safety hazards during transportation and use. With the release of relevant national environmental protection policies, the development of lead-acid batteries is gradually shifting from EFB flooded batteries to AGM (Average Mutual Acid, Starved Battery) batteries.

[0003] AGM (Aluminum Gland Energy) lead-acid batteries use ultra-fine glass fiber mat as separators to separate the positive and negative electrodes, provide oxygen recombination channels, and absorb the electrolyte within the separators. There is no flowing electrolyte, resulting in maintenance-free operation and higher safety. However, compared to the pouch-type PE separators used in EFB (Electrode Feeder) batteries, the glass fiber separators in ordinary AGM batteries, while covering both sides of the plates, leave the sides completely exposed. This means that when active material detaches from the plates, it reduces the battery's cycle life. Furthermore, the primary failure mode of AGM batteries is short circuits, mainly caused by lead dendrites puncturing the separator.

[0004] At present, valve-regulated maintenance-free starved electrolyte batteries are the mainstream direction of lead-acid battery development at home and abroad. However, with the development of the industry, the main technical development direction of lead-acid batteries is to improve energy density and lifespan. Energy density is achieved by designing thinner electrode plates to increase the surface area and utilization efficiency of active materials. Existing separators also limit the improvement of battery performance to a certain extent, and there are the following problems: (1) Puncture resistance: In order to increase the number of electrode plates assembled in the battery, the thickness of the separator needs to be designed to be thinner. However, the thinner the separator, the higher the risk of being punctured by lead dendrites. Therefore, the separator needs to have high puncture resistance to prevent the separator from being punctured by dendrites and causing short circuits between the positive and negative electrodes; (2) Resistance: The resistance of the separator directly affects the charging and discharging characteristics of lead-acid batteries, such as charging and discharging efficiency, output power, battery life, etc.; (3) Electrode plates are not covered: When the battery is charged and discharged, the positive and negative electrode plates will expand or contract. The separator with a certain elasticity can adhere well to the electrode plates to prevent the active materials from falling off, but the sides are in an open state.

[0005] In summary, it is essential to research and develop a thin-film puncture-resistant AGM septum and its preparation method.

[0006] Summary of the Invention

[0007] To address one or more technical problems existing in current lead-acid batteries with low electrolyte content, such as poor separator puncture resistance, inconsistent thickness, and uncoated plates, this invention provides a thin-film pouch-type puncture-resistant AGM separator and its preparation method.

[0008] The present invention provides a thin bag-type puncture-resistant AGM separator in a first aspect, comprising the following raw materials in weight percentages: 50% to 70% high-alkali glass fiber and 30% to 50% reinforcing fiber; wherein the high-alkali glass fiber comprises high-alkali glass fiber with a tapping degree of 29 to 44°SR and high-alkali glass fiber with a tapping degree of 19 to 29°SR; and the reinforcing fiber is a core-sheath type double melting point fiber.

[0009] Preferably, the thin bag-type puncture-resistant AGM separator comprises the following raw materials in weight percentages: 30%–40% high-alkali glass fiber with a freeness of 29–44°SR, 20%–40% high-alkali glass fiber with a freeness of 19–29°SR, and 30%–50% reinforcing fiber.

[0010] Preferably, the high-alkali glass fiber with a knockout degree of 29–44°SR is obtained by flame processing.

[0011] Preferably, the high-alkali glass fiber with a knockout degree of 19–29°SR is obtained by centrifugation.

[0012] Preferably, the raw materials used in the core-sheath type dual-melting-point fiber include at least one of polyethylene terephthalate, polypropylene, and polyethylene.

[0013] Preferably, the sheath-core type dual-melting-point fiber has a sheath melting point of 100-165°C and a core melting point of not less than 180°C.

[0014] A method for preparing a thin, pouch-type puncture-resistant AGM septum includes:

[0015] (1) High alkali glass fiber with a knockout degree of 29-44°SR, high alkali glass fiber with a knockout degree of 19-29°SR and reinforcing fiber are added to acidic dewatering water for dewatering to obtain slurry;

[0016] (2) The slurry is diluted and then fed to a forming wire and dehydrated under vacuum to obtain a wet fiber felt; the wet fiber felt is then heated in an oven and cooled to obtain a partition.

[0017] (3) Fold or stack the partition and heat-press the edges to obtain the thin bag-type puncture-resistant AGM partition.

[0018] Preferably, in step (1): the desolvation time is 10 to 20 minutes, and the fiber concentration in the slurry is 10 to 15 g / L.

[0019] Preferably, in step (1): the pH value of the acidic ionization water is 2 to 3.

[0020] Preferably, in step (1): high alkali glass fiber with a knockout degree of 29-44°SR and high alkali glass fiber with a knockout degree of 19-29°SR are added to acidic dewatering water and dispersed for 5-10 minutes, and then the reinforcing fiber is added and dispersed for 5-10 minutes for dewatering.

[0021] Preferably, in step (2), the fiber concentration in the diluted slurry is 1.4 to 3.6 g / L.

[0022] Preferably, in step (2): the heating temperature is higher than the sheath melting point and lower than the core melting point of the sheath-core type dual melting point fiber.

[0023] Preferably, in step (3): the temperature of the hot-press sealing is higher than the melting point of the sheath layer of the core-shell type dual-melting-point fiber and lower than the melting point of the core layer.

[0024] Preferably, in step (3): the temperature of the hot-press sealing is 100-200℃ and the pressure is 0.1-0.5MPa.

[0025] Compared with the prior art, the present invention has at least the following beneficial effects:

[0026] (1) In this invention, the low-resolution glass fiber plays a skeletal role in the thin bag-type puncture-resistant AGM separator, ensuring the acid absorption capacity of the separator and increasing the ion and reactant transport channels in the separator; the addition of reinforcing fiber improves the puncture resistance of the prepared AGM separator, thereby avoiding the decrease in puncture strength caused by the thinning of the separator and the increase of low-resolution glass fiber, and preventing lead dendrite puncture short circuit.

[0027] (2) The thin pouch-type puncture-resistant AGM separator prepared by this invention is used in lead-acid batteries with low electrolyte content. Therefore, the thin pouch-type puncture-resistant AGM separator needs to have a certain electrolyte adsorption capacity. Glass fiber has a better adsorption capacity for acidic electrolyte than chemical fiber, so glass fiber is still used as the main component in the formulation. Experiments have confirmed that by limiting the above raw material components, the prepared separator has a poor electrolyte adsorption capacity when the amount of glass fiber is too small, and the puncture resistance of the separator is poor or even leads to lead dendrite puncture and short circuit when the amount of glass fiber is too large.

[0028] (3) In this invention, the puncture resistance of the thin bag-type puncture-resistant AGM separator is improved by adding double melting point reinforcing fibers. During the preparation process, the low melting point skin layer melts first, and the melted part is bonded to the high alkali glass fiber to form a mesh structure. At this time, the core layer has a higher melting point and plays the role of skeleton fiber together with the high alkali glass fiber in the thin bag-type puncture-resistant AGM separator. At the same time, it further improves the resilience, wear resistance and puncture resistance of the separator.

[0029] (4) In this invention, since the reinforcing fiber is a flexible chemical fiber, the integrity of the AGM separator can still be guaranteed after folding or stacking. Then, the edge of the separator is pressed and bonded under a certain pressure and a certain temperature by a hot-press sealing machine. The temperature during hot-press sealing can melt the skin of the reinforcing fiber, thereby sealing the edge under a certain pressure by means of the melted skin, and obtaining a thin bag-type puncture-resistant AGM separator, which is applied to lead-acid batteries with low electrolyte levels. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0031] This invention provides a thin, bag-type puncture-resistant AGM separator, comprising the following raw materials in weight percentages: 50%–70% high-alkali glass fiber (e.g., 50%, 52%, 54%, 55%, 56%, 58%, 60%, 62%, 64%, 65%, 66%, 68%, or 70%) and 30%–50% reinforcing fiber (e.g., 30%, 32%, 34%, 35%, 36%, 38%, 40%, 42%, 44%, 45%, 46%, 48%, or 50%); the high-alkali glass fiber includes high-alkali glass fiber with a beating degree of 29–44°SR and high-alkali glass fiber with a beating degree of 19–29°SR; the reinforcing fiber is a core-sheath type double-melting-point fiber.

[0032] Specifically, a solubility of 29 to 44°SR refers to any value from 29°SR to 44°SR, such as 29°SR, 30°SR, 32°SR, 34°SR, 35°SR, 36°SR, 38°SR, 40°SR, 42°SR, or 44°SR.

[0033] A resolution of 19–29°SR refers to any value between 19°SR and 29°SR, such as 19°SR, 20°SR, 22°SR, 24°SR, 25°SR, 26°SR, 28°SR, or 29°SR.

[0034] In this invention, low-method glass fiber acts as a skeleton in the thin-film puncture-resistant AGM separator, ensuring the separator's acid absorption capacity and increasing the ion and reactant transport channels in the separator. The addition of reinforcing fiber improves the puncture resistance of the prepared AGM separator, thereby avoiding the decrease in puncture strength caused by the thinning of the separator and the increase of low-method glass fiber, and preventing lead dendrite puncture short circuit.

[0035] According to some preferred embodiments, a thin bag-type puncture-resistant AGM diaphragm comprises the following raw materials in weight percentages: 30% to 40% (e.g., 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, or 40%) of high alkali glass fiber with a freeness of 29 to 44°SR, 20% to 40% (e.g., 20%, 22%, 24%, 25%, 26%, 28%, 30%, 32%, 34%, 35%, 36%, 38%, or 40%) of high alkali glass fiber with a freeness of 19 to 29°SR, and 30% to 50% (e.g., 30%, 32%, 34%, 35%, 36%, 38%, 40%, 42%, 44%, 45%, 46%, 48%, or 50%) of reinforcing fiber.

[0036] The thin, pouch-type puncture-resistant AGM separator prepared by this invention is used in lead-acid batteries with low electrolyte content. Therefore, the thin pouch-type puncture-resistant AGM separator needs to have a certain electrolyte adsorption capacity. Glass fiber has a better adsorption capacity for acidic electrolytes than chemical fibers, so glass fiber is still used as the main component in the formulation. Experiments have confirmed that by limiting the above raw material components, the separator's electrolyte adsorption capacity is avoided when the amount of glass fiber is too small, while the puncture resistance of the separator or even the problem of lead dendrite puncture and short circuit is avoided when the amount of glass fiber is too large. Meanwhile, by further limiting the mass percentage of high-alkali glass fibers with different low degrees of beating dissociation in the thin-type bag-type puncture-resistant AGM separator, under the premise that the amount of other raw materials remains unchanged, it is possible to further avoid the excessively large pore size in the separator when the amount of high-alkali glass fibers with a beating dissociation of 29-44°SR is less than 30%, which would cause the active material of the electrode plate to penetrate into the separator; it is also possible to avoid the increase in separator resistance and the decrease in ion transfer efficiency and oxygen recombination capacity between the positive and negative electrodes when the amount of high-alkali glass fibers with a beating dissociation of 29-44°SR is more than 40%.

[0037] According to some preferred embodiments, high-alkali glass fibers with a knockout degree of 29–44°SR are obtained by flame processing.

[0038] According to some preferred embodiments, high-alkali glass fibers with a knockout degree of 19–29°SR are obtained by centrifugation.

[0039] In this invention, due to the molecular forces between fibers, the water molecules cause less damage to these forces during the hydrolytic dispersibility process, resulting in relatively poor dispersion. The centrifugally produced high-alkali glass fibers have more uniform diameter and length, leading to a smoother separator surface and improved thickness consistency. Higher beating degree means larger dimensions, weaker molecular forces, and better dispersion. During separator molding, these fibers, together with reinforcing fibers, form a skeletal structure, ensuring the overall uniformity of the thin, puncture-resistant AGM separator meets requirements.

[0040] This invention does not have special requirements for high-alkali glass fibers; existing products that meet the beating degree requirements can be used. Specifically, flame-processed high-alkali glass fibers are mainly 29-44°SR, while centrifugally processed high-alkali glass fibers are mainly 19-29°SR. The production processes are relatively mature, and their application in the AGM separator industry has reached a certain scale, with corresponding controllable costs.

[0041] According to some preferred embodiments, the raw materials used in the core-sheath type dual melting point fiber include at least one of polyethylene terephthalate, polypropylene, and polyethylene.

[0042] According to some preferred embodiments, the sheath melting point of the core-sheath dual-melting-point fiber is lower than that of the core melting point.

[0043] According to some preferred embodiments, the sheath melting point of the core-sheath type dual melting point fiber is 100-165°C (e.g., it can be 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C or 165°C), and the core melting point is not lower than 180°C (e.g., it can be 180°C, 185°C, 190°C, 195°C, 200°C, 205°C, 210°C, 220°C, 240°C, 250°C, etc.).

[0044] In this invention, the puncture resistance of a thin bag-type puncture-resistant AGM separator is improved by adding dual-melting-point reinforcing fibers. During the preparation process, the low-melting-point outer layer melts first, and the melted part bonds with the high-alkali glass fiber to form a mesh structure. At this time, the core layer has a higher melting point and together with the high-alkali glass fiber, it plays the role of a skeleton fiber in the thin bag-type puncture-resistant AGM separator. At the same time, it further improves the resilience, wear resistance and puncture resistance of the separator.

[0045] Specifically, the core-sheath type dual melting point fiber can be polyethylene with different melting points, polyethylene terephthalate with different melting points, polypropylene with different melting points, polyethylene and polyethylene terephthalate, polypropylene and polyethylene terephthalate, polyethylene and polypropylene.

[0046] Ordinary AGM separators are typically designed with a thickness of 1.0 mm or more at 10 kPa to ensure a certain level of puncture resistance. The AGM separator prepared in this invention improves the puncture resistance of the separator through dual-melting-point reinforcing fibers. Therefore, the thickness of the prepared AGM separator at 10 kPa can be designed between 0.6 and 1.0 mm (for example, it can be 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm, 0.8 mm, 0.85 mm, 0.9 mm, 0.95 mm, or 1.0 mm), thereby obtaining lower resistance and a greater number of electrode plates.

[0047] This invention also provides a method for preparing a thin, pouch-type puncture-resistant AGM septum, the method comprising:

[0048] (1) High alkali glass fiber with a knockout degree of 29-44°SR, high alkali glass fiber with a knockout degree of 19-29°SR and reinforcing fiber are added to acidic dewatering water for dewatering to obtain slurry;

[0049] (2) The slurry is diluted and then fed to the forming mesh and dehydrated under vacuum to obtain wet fiber felt; the wet fiber felt is then transferred to an oven for heating and cooling to obtain a partition.

[0050] (3) Fold or stack the partitions and heat-press the edges to obtain a thin bag-type puncture-resistant AGM partition.

[0051] According to some preferred embodiments, in step (1):

[0052] The descaling time is 10–20 min (e.g., 10 min, 11 min, 12 min, 15 min, 16 min, 18 min, or 20 min), and the fiber concentration in the slurry is 10–15 g / L (e.g., 10 g / L, 10.5 g / L, 11 g / L, 11.5 g / L, 12 g / L, 12.5 g / L, 13 g / L, 13.5 g / L, 14 g / L, 14.5 g / L, or 15 g / L).

[0053] In this invention, the pulping process for the AGM separator mainly employs hydraulic desiccation and dispersion. Fiber dispersion relies on the flow of water molecules and the mutual shear forces between fibers. Therefore, considering the uniformity of fiber dispersion, the fiber concentration in the pulp is limited to ensure the desiccation effect. Experiments have confirmed that if the fiber concentration is too low, the fibers will not be able to exert mutual shearing force, while if the fiber concentration is too high, the fibers will not be sufficiently and uniformly dispersed.

[0054] According to some preferred embodiments, in step (1):

[0055] The pH value of the acidic ionization water is 2 to 3 (for example, it can be 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9 or 3).

[0056] In this invention, the pH of the slurry is maintained at a low level by adjusting the pH of the acidic dispersing water, thereby weakening the molecular forces between fibers and improving the dispersion effect.

[0057] According to some preferred embodiments, in step (1):

[0058] High-alkali glass fibers with a beating degree of 29–44°SR and high-alkali glass fibers with a beating degree of 19–29°SR are added to acidic dewatering water and dispersed for 5–10 minutes (e.g., 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes or 10 minutes). Then, reinforcing fibers are added and dispersed for 5–10 minutes (e.g., 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes or 10 minutes) for dewatering.

[0059] In this invention, the specific dispersing method during slurry preparation can be centralized pulping or multiple pulping processes. By first dispersing the high-alkali glass fibers and then adding and dispersing the reinforcing fibers, thorough mixing of the high-alkali glass fibers and the reinforcing fibers is achieved.

[0060] It should be noted that the acidic dewatering water in step (1) is preferably a mixed solution of plain water and sulfuric acid (e.g., with a concentration of 65-85%), with a pH value of 2-3. Plain water refers to the recycled water used in the manufacture of AGM separators, which is initially a mixed solution of pure water and sulfuric acid. This invention does not impose a specific limit on the amount of sulfuric acid used to adjust the pH of the acidic dewatering water, as long as the pH of the acidic dewatering water is adjusted to the target range.

[0061] According to some preferred embodiments, in step (2):

[0062] The fiber concentration in the diluted pulp is 1.4–3.6 g / L (for example, it can be 1.4 g / L, 1.5 g / L, 1.6 g / L, 1.8 g / L, 2.0 g / L, 2.2 g / L, 2.5 g / L, 2.8 g / L, 3.0 g / L, 3.2 g / L, 3.4 g / L, 3.5 g / L or 3.6 g / L).

[0063] According to some preferred embodiments, step (2) further includes:

[0064] The slurry after descaling is diluted for the first time to obtain a slurry with a fiber concentration of 2-5 g / L; then the slurry is diluted for the second time to obtain a sizing slurry with a fiber concentration of 1.4-3.6 g / L.

[0065] In this invention, in order to balance the good dispersion performance of the fiber and the high descaling efficiency, the fiber concentration in the slurry is limited to 10-15 g / L; the slurry is further diluted for the first time to ensure the dispersion performance of the fiber, and a second dilution is performed during the sizing process in step (2) to further ensure the dispersion of the fiber.

[0066] According to some preferred embodiments, in step (2):

[0067] The heating temperature is higher than the melting point of the sheath layer of the core-sheath dual-melting-point fiber but lower than the melting point of the core layer.

[0068] In this invention, the shaped wet fiber felt is further conveyed into an oven and heated. The heating causes the outer layer of the reinforcing fiber to reach its melting point and melt, enhancing the adhesion with the high-alkali glass fiber and forming a network structure. The felt is then removed from the oven and cooled to solidify, resulting in a partition.

[0069] According to some preferred embodiments, in step (3):

[0070] The temperature of hot-press sealing is higher than the melting point of the sheath layer of the core-shell type dual-melting-point fiber but lower than the melting point of the core layer.

[0071] According to some preferred embodiments, in step (3):

[0072] The temperature for hot-press sealing is 100–200℃ (e.g., 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, 130℃, 135℃, 140℃, 150℃, 160℃, 170℃, 180℃, 190℃, or 200℃), and the pressure is 0.1–0.5MPa (e.g., 0.1MPa, 0.15MPa, 0.2MPa, 0.25MPa, 0.3MPa, 0.35MPa, 0.4MPa, 0.45MPa, or 0.5MPa).

[0073] In this invention, since the reinforcing fiber is a flexible chemical fiber, the integrity of the AGM partition can still be guaranteed after folding or stacking. Then, the edge of the partition is pressed and bonded together by a hot-press sealing machine under a certain pressure and temperature. The temperature during hot-press sealing can melt the skin of the reinforcing fiber, thereby achieving sealing under a certain pressure with the help of the melted skin, resulting in a thin bag-type puncture-resistant AGM partition.

[0074] Unless otherwise specified, the raw materials used in this invention can be commercially available products or synthesized by existing methods;

[0075] In this invention, the use of "and / or" between multiple technical features indicates that these technical features are connected by an "and / or" relationship, meaning that it can be any one of these technical features, or any combination of two or more of these technical features.

[0076] The present invention will be further described below by way of examples, but the scope of protection of the present invention is not limited to these embodiments.

[0077] Example 1

[0078] A thin, bag-type puncture-resistant AGM separator comprises the following raw materials by weight percentage: 30% flame-processed high-alkali glass fiber with a freeness of 29°SR, 40% centrifugally processed high-alkali glass fiber with a freeness of 19°SR, and 30% reinforcing fiber; the reinforcing fiber is a core-sheath type dual-melting-point fiber with a polyethylene sheath and a polyethylene terephthalate core.

[0079] Preparation method of thin-walled puncture-resistant AGM septum:

[0080] (1) According to the above dosage, flame-made high-alkali glass fiber with a knockout degree of 29°SR, centrifugally-made high-alkali glass fiber with a knockout degree of 19°SR and reinforcing fiber are added to acidic dissolving water (a mixed solution of white water and sulfuric acid) with pH=2 and dissolved for 6 minutes. Then, reinforcing fiber is added and dissolving is continued for 6 minutes to obtain a slurry with a fiber concentration of 12 g / L.

[0081] (2) After diluting the slurry (fiber concentration of 3.0 g / L), the slurry is evenly fed to the polyester forming mesh through a slurry distributor and a headbox. After vacuum dehydration, the slurry is conveyed forward from the forming mesh to the drying oven. In the drying oven, the wet fiber felt after forming and dehydration is conveyed into the oven and then conveyed to the oven outlet through the transmission device inside the oven. The oven is heated by a burner to the melting point of polyethylene +10°C, so that the moisture in the wet fiber felt is evaporated when passing through the oven. At the same time, the outer layer of the reinforcing fiber melts after reaching the melting point and cools and solidifies after exiting the oven to obtain the partition.

[0082] (3) Cut the dried separator into sheets according to the required size, then fold or stack the sheet separators and send them into a hot press edge sealing machine. Press and seal the edges of the separators at 150℃ and 0.5MPa. After cooling and solidification, a thin bag-type puncture-resistant AGM separator that can completely cover the electrode plate is produced.

[0083] Example 2

[0084] A thin, bag-type puncture-resistant AGM separator comprises the following raw materials by weight percentage: 35% flame-processed high-alkali glass fiber with a freeness of 34°SR, 35% centrifugally processed high-alkali glass fiber with a freeness of 24°SR, and 30% reinforcing fiber; the reinforcing fiber is a core-sheath type dual-melting-point fiber with a low-melting-point polyethylene terephthalate outer layer and a high-melting-point polyethylene terephthalate core layer;

[0085] Preparation method of thin-walled puncture-resistant AGM septum:

[0086] (1) According to the above dosage, flame-made high-alkali glass fiber with a knockout degree of 34°SR, centrifugally-made high-alkali glass fiber with a knockout degree of 24°SR and reinforcing fiber are added to acidic dissolving water (a mixed solution of white water and sulfuric acid) with pH=2.5 and dissolve for 5 minutes. Then, reinforcing fiber is added and dissolved for another 5 minutes to obtain a slurry with a fiber concentration of 14 g / L.

[0087] (2) After diluting the slurry (fiber concentration of 3.2 g / L), the slurry is evenly fed to the polyester forming mesh through a slurry distributor and a headbox. After vacuum dehydration, the slurry is conveyed forward from the forming mesh to the drying oven. In the drying oven, the wet fiber felt after forming and dehydration is conveyed into the oven and then conveyed to the oven outlet through the transmission device inside the oven. The oven is heated to the melting point temperature of 130°C + 10°C by a burner so that the moisture in the wet fiber felt is evaporated when passing through the oven. At the same time, the outer layer of the reinforcing fiber melts after reaching the melting point and cools and solidifies after exiting the oven to obtain the partition.

[0088] (3) Cut the dried separator into sheets according to the required size, then fold or stack the sheet separators and send them into a hot press edge sealing machine. Press and seal the edges of the separators at 160℃ and 0.4MPa. After cooling and solidification, a thin bag-type puncture-resistant AGM separator that can completely cover the electrode plate is produced.

[0089] Example 3

[0090] A thin, bag-type puncture-resistant AGM separator comprises the following raw materials by weight percentage: 30% flame-processed high-alkali glass fiber with a freeness of 44°SR, 35% centrifugally processed high-alkali glass fiber with a freeness of 19°SR, and 35% reinforcing fiber. The reinforcing fiber is a core-sheath type dual-melting-point fiber with a polyethylene sheath and a polypropylene core.

[0091] Preparation method of thin-walled puncture-resistant AGM septum:

[0092] (1) According to the above dosage, flame-made high-alkali glass fiber with a knockout degree of 44°SR, centrifugally-made high-alkali glass fiber with a knockout degree of 19°SR and reinforcing fiber were added to acidic dissolving water (a mixed solution of white water and sulfuric acid) with pH=2.6 and dissolved for 7 minutes. Then, reinforcing fiber was added and dissolving was continued for 5 minutes to obtain a slurry with a fiber concentration of 14 g / L.

[0093] (2) After diluting the slurry (fiber concentration of 3.2 g / L), the slurry is evenly fed to the polyester forming mesh through a slurry distributor and a headbox. After vacuum dehydration, the slurry is conveyed forward from the forming mesh to the drying oven. In the drying oven, the wet fiber felt after forming and dehydration is conveyed into the oven and then conveyed to the oven outlet through the transmission device inside the oven. The oven is heated to the melting point temperature of 110°C + 10°C by a burner so that the moisture in the wet fiber felt is evaporated when passing through the oven. At the same time, the outer layer of the reinforcing fiber melts after reaching the melting point and cools and solidifies after exiting the oven to obtain the partition.

[0094] (3) Cut the dried separator into sheets according to the required size, then fold or stack the sheet separators and send them into a hot press sealing machine. Press and seal the edges of the separators at 140℃ and 0.5MPa. After cooling and solidification, a thin bag-type puncture-resistant AGM separator that can completely cover the electrode plate is produced.

[0095] Example 4

[0096] Example 4 is basically the same as Example 2, except that:

[0097] A thin, bag-type puncture-resistant AGM separator comprises the following raw materials in weight percentages: 25% flame-processed high-alkali glass fiber with a freeness of 34°SR, 25% centrifugally processed high-alkali glass fiber with a freeness of 29°SR, and 50% reinforcing fiber; the reinforcing fiber is a core-sheath type dual-melting-point fiber with a low-melting-point polyethylene terephthalate outer layer and a high-melting-point polyethylene terephthalate core layer.

[0098] Example 5

[0099] Example 5 is basically the same as Example 2, except that:

[0100] A thin, bag-type puncture-resistant AGM separator comprises the following raw materials in weight percentages: 33% flame-processed high-alkali glass fiber with a freeness of 34°SR, 33% centrifugally processed high-alkali glass fiber with a freeness of 24°SR, and 34% reinforcing fiber; the reinforcing fiber is a core-sheath type dual-melting-point fiber with a low-melting-point polyethylene terephthalate outer layer and a high-melting-point polyethylene terephthalate core layer.

[0101] Example 6

[0102] Example 6 is basically the same as Example 2, except that:

[0103] A thin, bag-type puncture-resistant AGM separator comprises the following raw materials in weight percentages: 30% flame-processed high-alkali glass fiber with a freeness of 44°SR, 30% centrifugally processed high-alkali glass fiber with a freeness of 29°SR, and 40% reinforcing fiber. The reinforcing fiber is a core-sheath type dual-melting-point fiber with a polyethylene sheath and a polypropylene core.

[0104] Comparative Example 1

[0105] Comparative Example 1 is basically the same as Example 2, except that:

[0106] The raw materials used to prepare the thin bag-type puncture-resistant AGM separator do not contain reinforcing fibers, and no reinforcing fibers are added during the preparation of the thin bag-type puncture-resistant AGM separator.

[0107] Comparative Example 2

[0108] Comparative Example 2 is basically the same as Example 2, except that:

[0109] The raw material for preparing the thin bag-type puncture-resistant AGM separator is not a core-sheath type dual-melting-point fiber, but rather a low-melting-point polyethylene terephthalate fiber containing only the sheath material.

[0110] Comparative Example 3

[0111] Comparative Example 3 is basically the same as Example 2, except that:

[0112] The raw materials used in the preparation of thin bag-type puncture-resistant AGM separators are all high-alkali glass fibers produced by flame processing, i.e., high-alkali glass fibers produced by centrifugation are not used.

[0113] Comparative Example 4

[0114] Comparative Example 4 is basically the same as Example 2, except that:

[0115] The amount of reinforcing fiber used in the raw materials for preparing thin bag-type puncture-resistant AGM separators is 25%.

[0116] Comparative Example 5

[0117] Comparative Example 5 is basically the same as Example 2, except that:

[0118] The amount of reinforcing fiber used in the raw materials for preparing thin bag-type puncture-resistant AGM separators is 60%.

[0119] The present invention compares and evaluates the performance of AGM separators prepared in various embodiments and comparative examples. The testing methods for various performance aspects of the AGM separators refer to the national standard GB / T 28535-2018 Lead-acid Battery Separators. The performance of the obtained separator products is shown in Table 1.

[0120] Table 1

[0121] As can be seen from the experimental data in Table 1, the air permeability further ensures the acid absorption capacity and electrical resistance of the thin bag-type puncture-resistant AGM separator prepared by this invention. The addition of low-beating-degree high-alkali glass fiber and centrifugally prepared high-alkali glass fiber during pulping improves the surface of the separator and increases the consistency of thickness. At the same time, the low-beating-degree fiber provides a skeleton structure for the separator, improving the air permeability and porosity of the separator. Meanwhile, the addition of core-sheath type double-melting-point fiber plays a role in bonding the fiber and enhancing the puncture resistance of the separator, so that the prepared AGM separator has excellent puncture resistance even when the thickness is less than 1.0 mm at 10 kPa. Moreover, the core-sheath type double-melting-point fiber can also melt the skin layer during hot pressing to obtain a tightly fitted irregular edge, thereby increasing the contact area of ​​the edge and improving the bonding force to obtain a thin bag-type puncture-resistant AGM separator.

[0122] The parts of this invention not described in detail are techniques known to those skilled in the art.

[0123] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A thin, bag-type puncture-resistant AGM diaphragm, characterized in that, The raw materials include the following percentages by weight: 50%–70% high-alkali glass fiber and 30%–50% reinforcing fiber; the high-alkali glass fiber includes high-alkali glass fiber with a tapping degree of 29–44°SR and high-alkali glass fiber with a tapping degree of 19–29°SR; the reinforcing fiber is a core-sheath type double melting point fiber.

2. The thin-walled, puncture-resistant AGM diaphragm according to claim 1, characterized in that, The raw materials include the following percentages by weight: 30%–40% high alkali glass fiber with a knockout degree of 29–44°SR, 20%–40% high alkali glass fiber with a knockout degree of 19–29°SR, and 30%–50% reinforcing fiber.

3. The thin-walled, puncture-resistant AGM diaphragm according to claim 1, characterized in that, High-alkali glass fibers with a knockout degree of 29–44°SR are obtained by flame processing.

4. The thin-film puncture-resistant AGM diaphragm according to claim 1, characterized in that, High-alkali glass fibers with a knockout degree of 19–29°SR are obtained by centrifugation.

5. The thin-film puncture-resistant AGM diaphragm according to claim 1, characterized in that, The core-sheath type dual-melting-point fiber uses at least one of polyethylene terephthalate, polypropylene, and polyethylene as raw materials.

6. The thin-walled, puncture-resistant AGM diaphragm according to any one of claims 1 to 5, characterized in that, The core-sheath type dual-melting-point fiber has a sheath melting point of 100-165°C and a core melting point of not less than 180°C.

7. A method for preparing a thin-film puncture-resistant AGM septum according to any one of claims 1 to 6, characterized in that, include: (1) High alkali glass fiber with a knockout degree of 29-44°SR, high alkali glass fiber with a knockout degree of 19-29°SR and reinforcing fiber are added to acidic dewatering water for dewatering to obtain slurry; (2) The slurry is diluted and then fed to a forming wire and dehydrated under vacuum to obtain a wet fiber felt; the wet fiber felt is then heated in an oven and cooled to obtain a partition. (3) Fold or stack the partition and heat-seal the edges to obtain the thin bag-type waterproof material. Puncture the AGM septum.

8. The preparation method according to claim 7, characterized in that, In step (1): The dissolution time is 10-20 min, and the fiber concentration in the slurry is 10-15 g / L.

9. The preparation method according to claim 7, characterized in that, In step (1): The pH value of the acidic decontamination water is 2 to 3.

10. The preparation method according to claim 7, characterized in that, In step (1): High-alkali glass fibers with a knockout degree of 29–44°SR and high-alkali glass fibers with a knockout degree of 19–29°SR were added to acidic dewatering water and dispersed for 5–10 minutes. Then, the reinforcing fibers were added and dispersed for 5–10 minutes for dewatering.

11. The preparation method according to claim 7, characterized in that, In step (2): The fiber concentration in the diluted slurry is 1.4–3.6 g / L.

12. The preparation method according to claim 7, characterized in that, In step (2): The heating temperature is higher than the sheath melting point of the core-sheath dual-melting-point fiber but lower than the core melting point.

13. The preparation method according to any one of claims 7 to 12, characterized in that, In step (3): The temperature of the hot-press sealing is higher than the melting point of the sheath layer of the core-shell type dual-melting-point fiber but lower than the melting point of the core layer, and the pressure is 0.1 to 0.5 MPa.

14. The preparation method according to any one of claims 7 to 12, characterized in that, In step (3): the temperature of the hot-press sealing edge is 100-200℃.

Images