Sampling and testing method for electrolyte in wet separator

Abstract

The invention provides a method for sampling and testing electrolyte in a wet separator, which comprises the following steps: S1, dissecting a battery, then taking out a to-be-detected separator, cutting the separator into a plurality of sections along the vertical direction during assembly and use, and respectively extruding and taking out the electrolyte in each section of separator; s2, detecting and calculating by using an acid-base titration method to obtain the mass fraction of sulfuric acid in the electrolyte from each section of the separator; wherein an electrolyte collecting device is used for sampling, the electrolyte collecting device comprises a partition plate cutting unit and a partition plate extruding unit, and the partition plate cutting unit comprises a first placing table, a cutter and a first driving mechanism; and the partition plate extruding unit comprises a second placing table, a pressing head and a second driving mechanism. According to the invention, through the uniquely designed electrolyte collection device, each part of the partition plate can be accurately sampled, the concentration of sulfuric acid in the electrolyte is measured, and the measured data is more accurate.

Description

Technical Field

[0001] This invention belongs to the field of lead-acid battery technology, specifically relating to a method for sampling and testing electrolyte in a wet separator. Background Technology

[0002] In valve-regulated lead-acid batteries, the electrolyte is stored in AGM separators. There is no flowing liquid inside the battery case. During charge-discharge cycles, a concentration difference in the electrolyte within the separator occurs. Due to gravity, the electrolyte concentration is consistently higher at the top of the separator and lower at the bottom. When disassembling and analyzing the battery, it is necessary to measure the sulfuric acid concentration in the electrolyte at the top, middle, and bottom of the separator. Currently, this is done manually, which is difficult and results in uneven sampling.

[0003] Patent application CN110967277A discloses a method for determining the sulfuric acid content and proportion in battery separators and plates. This method involves first soaking the positive and negative plates in pure water and repeatedly washing and squeezing the separators to obtain a filtrate. The plates and separators are then dried under vacuum. The H2SO4 content is calculated by measuring the weight change of the plates and separators before and after drying, and the mass fraction of H2SO4 in the filtrate is also measured to calculate the proportion of H2SO4 in the plates and separators. However, this method involves multiple treatments of the plates and separators. In practice, this often leads to issues such as lead paste peeling off the plates and separator damage, resulting in significant errors in the determination of the H2SO4 content.

[0004] Patent application CN119666654A discloses a method for determining the sulfuric acid concentration of electrolyte stored in the plates or separators of a lead-acid battery. This method first immerses the plates or separators in pure water, and then uses a vacuum to remove residual gas from the micropores within the plates or separators, causing H2SO4 to mix thoroughly with the pure water, resulting in solution 1. Using a measuring device, the mass of the electrolyte in the plates or separators is obtained by calculating the difference between the mass of the plates or separators suspended in pure water and the mass of the pure water mixed with H2SO4 at the bottom. Simultaneously, the mass fraction of H2SO4 in solution 1 is measured, and the mass percentage of H2SO4 in the plates or separators is obtained by calculating the dilution ratio. However, this method does not accurately measure the sulfuric acid concentration by sampling the lower and middle portions of the separator. Summary of the Invention

[0005] To address the aforementioned technical problems in the prior art, this invention provides a method for sampling and testing electrolyte in a wetted partition.

[0006] This invention provides a method for sampling and testing electrolyte in a wetted separator, comprising the following steps: S1. After dissecting the battery, remove the separator to be tested, cut the separator into multiple sections along the vertical direction used during assembly, and squeeze out the electrolyte from each section of the separator. S2, the mass fraction of sulfuric acid in the electrolyte from each section of the partition was determined and calculated using acid-base titration. The sampling process utilizes an electrolyte collection device, which includes a partition cutting unit and a partition squeezing unit. The partition cutting unit includes: a first placement platform for placing partitions; a cutter, including at least one, for cutting the partitions; and a first driving mechanism for driving the cutter to cut the partitions into multiple segments along the vertical direction during assembly and use. The partition extrusion unit includes: a second placement platform with pressing holes, the number of which is the same as the number of segments after the partition is cut; a pressing head located above the pressing holes, with a pressing head above each pressing hole; and a second driving mechanism for driving the pressing head to extrude the electrolyte from the partition placed in the pressing hole.

[0007] Preferably, in step S2, acid-base titration is performed using a standard sodium hydroxide solution. An acid-base indicator is added to the electrolyte sourced from each partition, and the standard sodium hydroxide solution is added dropwise until the solution color changes. The mass fraction A of sulfuric acid in the electrolyte is then calculated as follows: Where Mr is the molecular weight of sulfuric acid; c is the concentration of the sodium hydroxide standard solution in mol / L; V is the volume of sodium hydroxide standard solution consumed in mL; and m is the mass of the electrolyte from which the separator to be tested originates in g.

[0008] More preferably, the acid-base indicator is methyl red indicator solution.

[0009] Preferably, the partition cutting unit includes a first bracket disposed on one side of the first placement platform, and the first driving mechanism includes a first cylinder disposed on the first bracket and driving the cutter to move vertically. The first driving mechanism drives the cutter to move vertically, thereby cutting the partition. The cylinder achieves extreme simplification in structure, cost, and maintenance while ensuring sufficient cutting capacity and production efficiency. Furthermore, the cylinder can operate stably in dusty, humid, or slightly corrosive environments, ensuring high safety.

[0010] Preferably, the partition extrusion unit includes a second bracket disposed on one side of the second placement platform, and the second driving mechanism includes a second cylinder disposed on the second bracket for driving the pressure head to move vertically. The second cylinder drives the pressure head to move vertically downward, thereby squeezing the electrolyte in the partition downward and removing it.

[0011] Preferably, the cutter comprises two spaced-apart blades that cut the separator vertically into three equal sections (top, middle, and bottom) for assembly and use; correspondingly, there are three pressure holes and three pressure heads. This allows for the measurement of sulfuric acid concentration in the electrolyte at the bottom, middle, and bottom of the separator, making it more suitable for the dissection and analysis of lead-acid batteries.

[0012] More preferably, the interval between the two cutters is adjustable, allowing for the selection of specific sections of the partition for sulfuric acid concentration measurement as needed.

[0013] More preferably, the partition cutting unit includes a mounting guide post for mounting the cutter. The cutter has a mounting hole through which the mounting guide post passes, and the cutter is fixed to the mounting guide post by a positioning screw. The two cutters can move horizontally on the mounting guide post, thereby adjusting the interval between the two cutters.

[0014] Preferably, both the pressing hole and the pressing head are conical, with the bottom surface of the pressing hole having a through hole for electrolyte outflow. The conical shape of both the pressing hole and the pressing head allows for automatic alignment and guidance. As the pressing head is pressed in, the conical surfaces fit tightly together, achieving a smooth transition and uniform distribution of pressure, preventing localized stress damage to the workpiece. The through hole on the bottom surface ensures smooth electrolyte outflow during the extrusion process, avoiding accuracy deviations caused by liquid accumulation and preventing the formation of a sealed pressure chamber, thus ensuring the continuity and stability of the process flow.

[0015] Preferably, the first and second placement platforms use the same platform, with the partition cutting unit and the partition extrusion unit located at opposite ends of this platform. Using the same platform not only saves costs but also facilitates smoother operation of the partition cutting and extrusion processes.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention utilizes a uniquely designed electrolyte collection device to accurately sample various parts of the separator, thereby determining the concentration of sulfuric acid in the electrolyte and providing more accurate measurement data. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the electrolyte collection device of the present invention.

[0018] Figure 2 This is a cross-sectional view of the electrolyte collection device of the present invention.

[0019] Figure 3 This is a schematic diagram of the structure when the partition is placed on the first placement platform in the electrolyte collection device.

[0020] Figure 4 for Figure 3 A schematic diagram of the structure when the middle partition is cut and placed on the second placement platform in the electrolyte collection device.

[0021] Figure 5 This is a schematic diagram of the electrolyte being squeezed and collected from the separator in the separator squeezing unit.

[0022] Figure label: 1. Partition plate; 2. First placement platform; 3. Cutter; 4. First cylinder; 5. First bracket; 6. Mounting guide post; 7. Second placement platform; 8. Pressing hole; 9. Pressing head; 10. Sampling cup; 11. Second cylinder; 22. Second bracket. Detailed Implementation

[0023] like Figures 1-5 As shown, this embodiment provides an electrolyte collection device, including a partition cutting unit and a partition squeezing unit.

[0024] The partition cutting unit includes a first placement table 2, a cutter 3, and a first driving mechanism. The first placement table 2 is used to place the partition 1; the cutter 3 includes at least one for cutting the partition 1; the first driving mechanism is used to drive the cutter 3 to cut the partition 1 into multiple segments along the vertical direction during assembly and use.

[0025] The partition cutting unit also includes a first bracket 5 disposed on one side of the first placement platform 2, and a first drive mechanism including a first cylinder 4 disposed on the first bracket 5 and driving the cutter 3 to move vertically. The first drive mechanism drives the cutter 3 to move vertically, thereby cutting the partition 1. The cylinder achieves extreme simplification in structure, cost, and maintenance while ensuring sufficient cutting capacity and production efficiency. Furthermore, the cylinder can work stably in dusty, humid, or slightly corrosive environments, ensuring high safety.

[0026] The partition extrusion unit includes a second placement platform 6, a pressure head 7, and a second driving mechanism. The second placement platform 6 has pressure holes 61, the number of which is consistent with the number of segments after the partition 1 is cut; the pressure head 7 is located above the pressure holes 61, with one pressure head 7 above each pressure hole 61; the second driving mechanism is used to drive the pressure head 7 to extrude the electrolyte from the partition 1 placed in the pressure hole 61.

[0027] Both the pressing hole 61 and the pressing head 7 are conical. The bottom surface of the pressing hole 61 has a through hole for electrolyte to flow out, and a sampling cup 8 can be placed below the through hole to receive the flowing electrolyte. The conical shape of the pressing hole 61 and the pressing head 7 allows for automatic alignment and guidance. As the pressing head 7 is pressed in, the conical surfaces fit tightly together, achieving a smooth transition and uniform distribution of pressure, avoiding damage to the workpiece from localized stress. The through hole on the bottom surface ensures smooth flow of electrolyte during the extrusion process, preventing accuracy deviations caused by liquid accumulation and preventing the formation of a sealed pressure chamber, thus ensuring the continuity and stability of the process flow.

[0028] The partition extrusion unit also includes a second support 10 disposed on one side of the second placement platform 6, and a second drive mechanism including a second cylinder 9 disposed on the second support 10 and driving the pressure head 7 to move vertically. The second cylinder 9 drives the pressure head 7 to move vertically downward, which can squeeze the electrolyte in the partition 1 downward and remove it.

[0029] The first placement table 2 and the second placement table 6 use the same placement table, with the partition cutting unit and the partition extrusion unit located at opposite ends of this placement table. Using the same placement table not only saves costs but also facilitates the smooth operation of the two processes of partition 1 cutting and extrusion.

[0030] To facilitate the dissection and analysis of lead-acid batteries, the cutter 3 includes two spaced-apart blades that cut the separator 1 vertically into three equal sections: upper, middle, and lower. Correspondingly, there are three pressure holes 61 and three pressure heads 7, which allows for the measurement of the concentration of sulfuric acid in the electrolyte at the upper, middle, and lower parts of the separator 1.

[0031] The interval between the two cutters 3 is adjustable, allowing for the selection of specific locations on the partition 1 for sulfuric acid concentration measurement as needed. Specifically, a mounting guide post 51 for mounting the cutters 3 is provided on the first bracket 5 of the partition cutting unit. The cutters 3 have mounting holes through which the mounting guide post 51 passes, and the cutters 3 are fixed to the mounting guide post 51 by positioning screws. The two cutters 3 move horizontally on the mounting guide post 51, thereby adjusting the interval between the two cutters 3.

[0032] This embodiment also provides a method for sampling and testing the electrolyte in the wet partition 1, using the above-mentioned electrolyte collection device, including the following steps: (1) After dissecting the battery, take out the separator 1 to be tested and place it on the first placement platform 2. Adjust the position of the cutter 3 on the mounting guide post 51 so that the cutter 3 is on the three-part line of the separator 1 to be cut. The first cylinder 4 drives the cutter 3 to descend and cut the separator 1 into three sections: upper, middle and lower.

[0033] (2) Place the cut partition 1 on the three pressure holes 61 on the second placement platform 6 respectively. The second cylinder 9 drives the pressure head 7 to descend and squeeze the partition 1 into the pressure hole 61. The sampling cup 8 below the pressure hole 61 collects the electrolyte from each extruded partition until no electrolyte drips down, and the sampling is completed.

[0034] (3) Use slow qualitative filter paper (maximum pore size 10-15µm, filtration speed 100mL / 140s) to completely filter the electrolyte in sampling cup 8 to remove impurities.

[0035] (4) The mass fraction of sulfuric acid in the electrolyte from each partition source was determined and calculated using acid-base titration. The following operations were performed on the electrolytes from the three sources: Weigh a clean and dried ground glass stoppered weighing bottle (60×30) to constant weight using an analytical balance, accurate to 0.0001 g. Pipette 20 drops of electrolyte sample into the bottle and weigh it on the balance, accurate to 0.0001 g. Record the mass of the sample after subtracting the mass of the ground glass stoppered weighing bottle. Transfer the sample from the weighing bottle to a ground glass stoppered conical flask (250 mL). Wash the remaining liquid in the weighing bottle into the conical flask with distilled water. Dilute the sample in the conical flask to about 50 mL. Add 2 drops of methyl red indicator solution (1 g / L) and use c （NaOH） Titrate with a 0.5 mol / L sodium hydroxide standard solution until the solution turns yellow.

[0036] Calculate the mass fraction A of sulfuric acid in the electrolyte as follows: Where Mr is the molecular weight of sulfuric acid; c is the concentration of the sodium hydroxide standard solution in mol / L; V is the volume of sodium hydroxide standard solution consumed in mL; and m is the mass of the electrolyte from which the separator to be tested originates in g.

[0037] Table 1 The sulfuric acid content of the upper, middle and lower sections of 10 partitions was tested using the above method, and the results are shown in Table 1.

Claims

1. A method for sampling and testing electrolyte in a wet separator, characterized by, The method comprises the following steps: S1, after disassembling the battery, the separator to be detected is taken out, the separator is cut into multiple sections along the vertical direction during assembly and use, and electrolyte in each section of the separator is squeezed and taken out; S2, the mass fraction of sulfuric acid in the electrolyte from each section of the separator is detected and calculated by using acid-base titration; The sampling uses an electrolyte collecting device, and the electrolyte collecting device comprises a separator cutting unit and a separator squeezing unit, The separator cutting unit comprises: a first placement table for placing the separator; a cutter comprising at least one for cutting the separator; a first driving mechanism for driving the cutter to cut the separator into multiple sections along the vertical direction during assembly and use; The separator squeezing unit comprises: a second placement table, the second placement table is provided with pressing holes, the number of the pressing holes is consistent with the number of sections of the separator after being cut; a pressing head arranged above the pressing holes, and one pressing head is arranged above each pressing hole; a second driving mechanism for driving the pressing head to squeeze out the electrolyte in the separator placed in the pressing hole.

2. The method for sampling and testing the electrolyte in a wetted partition according to claim 1, characterized in that, In step S2, the acid-base titration is performed by using a sodium hydroxide standard solution, an acid-base indicator is added to the electrolyte from each section of the separator, the sodium hydroxide standard solution is added dropwise until the color of the solution changes, and the mass fraction A of sulfuric acid in the electrolyte is calculated as follows: wherein Mr is the molecular weight of sulfuric acid, c is the concentration of the sodium hydroxide standard solution, the unit is mol / L, V is the consumption volume of the sodium hydroxide standard solution, the unit is mL, and m is the mass of the electrolyte from the separator to be detected, the unit is g.

3. The method of claim 1, wherein the sampling and testing of the electrolyte in the wet separator is performed by a method comprising: The separator cutting unit comprises a first support arranged on one side of the first placement table, and the first driving mechanism comprises a first cylinder arranged on the first support and driving the cutter to move vertically. ​ 4. The method for sampling and testing the electrolyte in a wetted partition according to claim 1, characterized in that, The separator squeezing unit comprises a second support arranged on one side of the second placement table, and the second driving mechanism comprises a second cylinder arranged on the second support and driving the pressing head to move vertically.

5. The method for sampling and testing the electrolyte in a wetted partition according to claim 1, characterized in that, The cutter comprises two cutters arranged at intervals, and the two cutters cut the separator into three sections of upper, middle and lower along the vertical direction during assembly and use; correspondingly, the pressing holes and the pressing heads are all three.

6. The method for sampling and testing the electrolyte in a wetted partition according to claim 5, characterized in that, The interval of the two cutters is adjustable.

7. The method for sampling and testing the electrolyte in a wetted partition according to claim 6, characterized in that, The separator cutting unit comprises mounting guide columns for mounting the cutter, the cutter is provided with mounting holes for the mounting guide columns to pass through, and the cutter is fixed with the mounting guide columns through positioning screws.

8. The method for sampling and testing the electrolyte in a wetted partition according to claim 1, characterized in that, The pressing holes and the pressing heads are all conical, and the bottom surface of the pressing hole is provided with a through hole for the electrolyte to flow out.

9. The method for sampling and testing the electrolyte in a wetted partition according to claim 1, characterized in that, The first placement table and the second placement table use the same placement table, and the separator cutting unit and the separator squeezing unit are located at two ends of the placement table, respectively.

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