阅读说明：本技术 一种生极板孔隙率的测试方法 (Method for testing porosity of green plate ) 是由 马洪涛 闫大龙 李娟� 杨云珍 钱欢 于 2021-08-04 设计创作，主要内容包括：本发明涉及孔隙率测试领域,针对生极板孔隙率的测试结果不准确的问题,提供一种生极板孔隙率的测试方法,先将其中一片生极板编号、称重,记为干态重量M-(11)；再测生极板的长L-(11)、宽S-(11)、厚H-(11)；然后将生极板进行乙醇渗透,取出称重,记为湿态重量M-(12)；接着去除极板上的活性物质,烘干称取板栅质量,记为M-(13)；则第1片生极板孔隙率A-(11)＝(M-(12)-M-(11))/ρ-(乙醇)/(L-(11)*S-(11)*H-(11)-M-(13)/ρ-(板栅))*100％；最后并行在同一位置取若干片生极板,重复前述步骤测得多个孔隙率,取平均值作为这一位置的孔隙率。本发明工艺方法简单、测试方便快捷,测得的生极板孔隙率准确度高。(The invention relates to the field of porosity test, and provides a method for testing the porosity of a green plate aiming at the problem that the test result of the porosity of the green plate is inaccurate 11 (ii) a Measuring the length L of the green plate 11 Width S 11 Thickness of H 11 (ii) a Then the green plate is permeated by ethanol, taken out and weighed, and the wet weight M is recorded 12 (ii) a Removing active substances on the polar plate, drying and weighing the mass of the grid, and recording as M 13 (ii) a The porosity A of the 1 st green plate 11 ＝(M 12 ‑M 11 )/ρ Ethanol /(L 11 *S 11 *H 11 ‑M 13 /ρ Grid ) 100% of the total weight; and finally, taking a plurality of green plates at the same position in parallel, repeating the steps to measure a plurality of porosities, and taking an average value as the porosity at the position. The invention has simple process method, convenient and quick test and measuredThe porosity accuracy of the green plate is high.)

1. A method for testing the porosity of a green plate is characterized by comprising the following steps:

1) one of the green plates was numbered, weighed and recorded as dry weight M₁₁；

2) Measuring the length L of the green plate₁₁Width S₁₁Thickness of H₁₁；

3) Carrying out ethanol infiltration on the green plate, taking out the green plate, weighing the green plate, and recording the weight as wet weight M₁₂；

4) Removing active substances on the polar plate, weighing the mass of the grid after drying, and recording as M₁₃(ii) a The porosity A of the 1 st green plate₁₁＝(M₁₂-M₁₁)/ρ_Ethanol/(L₁₁*S₁₁*H₁₁-M₁₃/ρ_Grid)*100％；

5) Taking a plurality of green plates at the same position in parallel, repeating the steps 1) -4) to measure the porosity, and taking the average value of the measured porosities of all the green plates as the porosity of the position.

2. The method for testing the porosity of the green plate according to claim 1, wherein the step 2) is to test the data of a plurality of different positions of the green plate respectively, and finally, the average value is used as the length, width and thickness values of the green plate.

3. The method for testing the porosity of the green plate according to claim 2, wherein the number of the tests is 4-6.

4. The method for testing the porosity of the green plate according to claim 1, wherein the ethanol in the step 3) is absolute ethanol.

5. The method for testing the porosity of the green plate according to claim 4, wherein the step of penetrating in the step 3) is as follows: and (3) immersing the green plate in absolute ethyl alcohol for 15-25min, taking out, and immediately weighing the mass of the plate after 20-40 s.

6. The method for testing the porosity of the green plate according to claim 5, wherein the infiltration of the step 3) is performed under a negative pressure environment.

7. The method for testing the porosity of the green plate according to claim 1, wherein the drying conditions in the step 4) are as follows: the slab lattice is firstly cleaned by alcohol and then dried for 0.5-1.5h at the temperature of 55-65 ℃.

8. The method for testing the porosity of the green plate according to claim 1 or 7, wherein the number of sheets in the step 5) is 4-6 sheets.

Technical Field

The invention relates to the field of porosity testing, in particular to a method for testing the porosity of a green plate.

Background

The invention of the lead-acid storage battery has the history of more than 150 years, and is widely applied due to the advantages of good reliability, high cost performance, recyclability and the like. The polar plate is an important component of the lead storage battery, and the characteristics of the polar plate play a decisive role in various performances of the battery. The minimum composition unit of the positive pole plate active material structure is lead oxide particles, and a certain number of lead oxide particles are connected with one another to form aggregate lumps with different sizes. The plurality of agglomerates and the individual small particles are connected to one another in certain cases to form an aggregate or a porous mass, with micropores being formed between the agglomerates that make up the aggregate. The porosity has a great influence on the utilization of the active substance, i.e. on the capacity and the lifetime of the active substance. Porosity directly affects H⁺Ions, SO₄ ^2-Ions and H₂O moves inside the active material and in the electrolyte to complete the electrochemical reaction. The porosity of the plate active material is an important characteristic of a battery plate. Through testing the porosity of the plate, the relevant process information in the manufacturing aspect of the plate can be indirectly known from the side surface, and further the performance of the battery can be accurately predicted.

The patent CN111413261A discloses a method for detecting the porosity of an active substance of a green plate, which calculates the porosity of the plate by weighing the dry weight of the plate, soaking the plate in water for 3-4h and taking out the plate and then wet weight, and the plate needs high temperature of 60-90 ℃ during drying for 30-40min, and is cooled for 10-20min after drying, which is greatly different from the actual curing state of the green plate and can not truly reflect the porosity of the green plate. Patent CN105241799B mentions that the method for testing porosity of the green plate is not applicable to the green plate. Other patents and articles about the green plate adopt an underwater test, water can participate in further oxidation of free lead in the green plate when the green plate is dried, weight errors are caused, and when the green plate is weighed in water, the green plate needs to be hung, and active substances of the green plate can be damaged by hanging; in addition, after the water soaking, long-time high-temperature drying treatment is needed, the porosity numerical error and the stability of each test are poor, the test period is long, and the production is judged only by adopting a sampling inspection mode, so that the omission inspection is liable to occur, and the defective products flow into the next procedure. The determination of the porosity of the green plate is necessary for guiding the optimization of the acidification and formation processes and judging the performance of the battery, and in order to solve the problems, a method which can avoid contact with water and quickly and accurately determine the porosity of the green plate needs to be found out, and a quick testing method for the porosity of the green plate is lacked in the existing production process.

Disclosure of Invention

The invention provides a method for testing the porosity of a green plate, aiming at overcoming the problem that the test result of the porosity of the green plate is inaccurate.

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

a method for testing the porosity of a green plate comprises the following steps:

1) one of the green plates was numbered, weighed and recorded as dry weight M₁₁；

2) Measuring the length L of the green plate₁₁Width S₁₁Thickness of H₁₁；

3) Carrying out ethanol infiltration on the green plate, taking out the green plate, weighing the green plate, and recording the weight as wet weight M₁₂；

4) Removing active substances on the polar plate, weighing the mass of the grid after drying, and recording as M₁₃(ii) a The porosity A of the 1 st green plate₁₁＝(M₁₂-M₁₁)/ρ_Ethanol/(L₁₁*S₁₁*H₁₁-M₁₃/ρ_Grid)*100％；

5) Taking a plurality of green plates at the same position in parallel, repeating the steps 1) -4) to measure the porosity, and taking the average value of the measured porosities of all the green plates as the porosity of the position.

The porosity of the active substance of the polar plate is an important characteristic of the battery polar plate, and the relevant process information in the aspect of polar plate manufacturing can be indirectly known from the side surface through testing the porosity of the polar plate, so that the performance of the battery can be accurately predicted. The method has short test time and convenient operation, and is suitable for detecting the porosity of the battery green plate; the currently used slab lattice is a pure lead slab lattice, and the pure lead density value can be directly used, and the lead alloy densities corresponding to other alloy slab lattices can be directly inquired and used. The density of ethanol is also known and is convenient to calculate.

Preferably, step 2) tests data of a plurality of different positions of the plate respectively, and finally takes the average value as the length, width and thickness values of the plate. This may reduce errors. As a further preference, the number of tests is 4 to 6.

Preferably, the ethanol in the step 3) is absolute ethanol. As a further preferred, the step of infiltrating in step 3) is: and (3) immersing the green plate in absolute ethyl alcohol for 15-25min, taking out, and immediately weighing the mass of the plate after 20-40 s. As a further preference, the infiltration of step 3) is carried out under a negative pressure environment.

The invention adopts ethanol to replace water to solve the problem that the water can participate in the reaction in the past, and the green plate is easy to dry after being soaked in the ethanol, so that the test period is greatly shortened, the test quantity can be increased, and the defective products are prevented from flowing into the next procedure.

Preferably, the drying conditions in step 4) are as follows: the slab lattice is firstly cleaned by alcohol and then dried for 0.5-1.5h at the temperature of 55-65 ℃.

Preferably, the number of tablets in step 5) is 4-6 tablets.

Therefore, the beneficial effects of the invention are as follows:

(1) the method has short test time and convenient operation, and is suitable for detecting the porosity of the battery green plate;

(2) the problem that water can participate in reaction in the past is solved by adopting ethanol instead of water, and the green plate is very easy to dry after being soaked in the ethanol, so that the test period is greatly shortened, the test quantity can be increased, and defective products are prevented from flowing into the next procedure;

(3) provides rapid guidance for the optimization of the lead-acid storage curing process and the formation process.

Detailed Description

The technical solution of the present invention is further illustrated by the following specific examples.

In the present invention, unless otherwise specified, all the raw materials and equipment used are commercially available or commonly used in the art, and the methods in the examples are conventional in the art unless otherwise specified.

Example 1

A method for testing the porosity of a green plate comprises the following steps:

1) randomly selecting 1 piece of 6-DZF-20, numbering by using a positive plate, and weighing: recording as a dry weight of 98.5 g;

2) using a vernier caliper to test the length 134.63mm, the width 64.64mm and the thickness 2.36mm of the green pole plate, respectively testing data of 5 different positions of the pole plate for reducing errors, and finally taking the average value as the length, the width and the thickness values of the pole plate;

3) placing the green plate in a negative pressure environment (-0.8MPa) for infiltration in absolute ethyl alcohol, taking out from the absolute ethyl alcohol after 20min, immediately weighing the mass of the plate after 30s, and recording as the wet weight of 105.5 g;

4) removing active substances on the polar plate, cleaning with alcohol, drying the grid in a drying oven at 60 + -2 deg.C for 1h, weighing the grid with a mass of 19.9g, and measuring the porosity A of the 1 st green polar plate₁₁＝(105.5g-98.5g)/ρ_Ethanol/(13.463*6.464*0.236-19.9/ρ_{Lead (II)}) 100% ═ 47.23%, where ρ_EthanolIs 0.789g/cm³；ρ_{Lead (II)}Is 11.34g/cm³；

5) Taking 4 green plates in parallel at the same position, testing the porosity as above to be 47.89%, 46.92%, 47.11%, 47.50%;

6) finally, the porosity value of the 5 green plates is taken as the porosity A of the position₁＝(A₁₁+A₂₁+A₃₁+A₄₁+A₅₁)/5＝47.33％。

Example 2

A method for testing the porosity of a green plate comprises the following steps:

1) randomly selecting 1 piece of 6-DZF-20, numbering with a negative polar plate, and weighing: record as dry weight 68.5 g;

2) testing the length 135.88mm, the width 65.00mm and the thickness 1.72mm of the green polar plate by using a vernier caliper, respectively testing data of 5 different positions of the polar plate for reducing errors, and finally taking the average value as the length, the width and the thickness values of the polar plate;

3) placing the green plate in a negative pressure environment (-0.8MPa) for infiltration in absolute ethyl alcohol, taking out from the absolute ethyl alcohol after 20min, immediately weighing the mass of the plate after 30s, and recording as the wet weight of 73.6 g;

4) removing active substances on the polar plate, cleaning with alcohol, drying the grid in a drying oven at 60 + -2 deg.C for 1h, weighing 13.8g of grid, and measuring porosity A of the 1 st green polar plate₁₁＝(73.6g-68.5g)/ρ_Ethanol/(13.588*6.500*0.172-13.8/ρ_{Lead (II)}) 100% ═ 46.25%, where ρ_EthanolIs 0.789g/cm³；ρ_{Lead (II)}Is 11.34g/cm³；

5) Taking 4 green plates in parallel at the same position, testing the porosity as the above to be 46.79%, 47.78%, 47.16% and 46.50%;

6) finally, the porosity value of the 5 green plates is taken as the porosity A of the position₁＝(A₁₁+A₂₁+A₃₁+A₄₁+A₅₁)/5＝46.90％。

Comparative example 1

The method of embodiment 1 of patent CN111413261A is adopted to test the porosity of the green plate in embodiment 1 of the invention, the measurement result is 30%, compared with the invention, the method needs high temperature of 60-90 ℃ during drying, the time is 30-40min, the green plate is cooled for 10-20min after drying, and the operation is fussy; and the curing state of the green plate is greatly different from the actual green plate, the porosity of the green plate cannot be truly reflected, and the test result is far from 40-50% of the actual cured plate.

Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.