CN107703167B - PAM analysis and test method for positive active material of lead-acid battery - Google Patents

Abstract

The invention relates to a lead-acid storage battery positive active material PAM analysis and test method, which comprises the steps of carrying out layered sampling on positive active materials PAM with different charge states, analyzing by X-ray powder diffraction (XRD), and carrying out data processing by a Rietveld reference tool to obtain PbO of each sample₂The mass percentage of the component (A) is that a Gaussian distribution function is adopted to carry out the mass percentage of PbO under different charge states and different layers₂The optimum charge state (depth of discharge) of the active material of the positive electrode plate or the charge performance of different plates is represented by the change rate of the reaction depth of the active material through fitting of the content distribution curve of the positive electrode plate. The analysis method of the invention evaluates the cycle life of the battery and the quality of the design scheme through the reaction depth, and determines the proper discharge depth of various design batteries through the change rate of the reaction depth.

Description

PAM analysis and test method for positive active material of lead-acid battery

technical field

The invention relates to the field of industrial lead-acid batteries, in particular to a PAM analysis and testing method for positive active substances of lead-acid batteries.

Background technique

At present, there is no systematic analysis and evaluation method for the active material of lead _- acid battery plates. Only by observing the appearance, shape and color, or analyzing the percentage of PbO2 in the positive plate, it is impossible to quantitatively analyze the reaction of the active material of the plate under different states of charge. The size of the depth, the design life of the battery can only be determined by the cycle life test results, the research and development cycle is too long, and the performance of the active material of the plate cannot be pre-evaluated to guide the research and development and design improvement of the product. Therefore, a method for analyzing the performance of PAM, a positive active material for lead-acid batteries, was invented to analyze the design scheme and pre-assess the life of the battery, further optimize the product structure and performance design, shorten the research and development cycle, reduce design errors, and design a long-life cycle battery. Very necessary.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the defects existing in the prior art, and to provide a solution to the problem of the analysis method of the active material of the positive electrode plate of the battery. PAM analysis and test method for positive active material of lead-acid battery to ensure product reliability and best use effect.

The technical scheme for realizing the object of the present invention is: a PAM analysis and testing method for the positive electrode active material of a lead-acid battery, comprising the following steps:

1) Stratified sampling of the positive active material PAM with different charge states,

2) by X-ray powder diffraction analysis (XRD),

3) Use the Rietveld Refinement tool for data processing,

4) Obtain the mass percentage content of PbSO ₄ and PbO ₂ of each sample,

5) Using Gaussian distribution function to fit the content distribution curve of PbO ₂ under different charge states and under different layers,

6) The depth of discharge of the active material of the positive electrode plate or the charging performance of different plates is represented by the rate of change of the active material reaction depth.

The step 1) described in the above technical solution is specifically: the positive electrode plate of the lead-acid battery is discharged according to the discharge amount of different percentages, and N kinds of positive electrode plates with different states of charge are respectively made, one for each type, and one for each electrode. The plate is evenly divided into 5 layers along the thickness d (mm) direction, the thickness sampling point coordinates are 0.1d, 0.3d, 0.5d, 0.7d, 0.9d, the thickness of each layer is 0.2d (mm), and sampling is taken in the middle of each layer , the sampling position in the length L direction is 0.25L ~ 0.75L, and the sampling position in the width B direction is 0.25B ~ 0.75B. The samples were mixed and used as standard samples, and were numbered according to the percentage of charge state and the number of layers.

The step ₅ ) described in the above technical solution is specifically: using a Gaussian distribution function to fit the content distribution curve of PbO , taking

σ=2.25-w/2, mm,

Among them, _A is the integral area of the fitted Gaussian function curve, Z is the average content (%) of PbO2 in the positive electrode active material PAM of the electrode plate, σ is the average reaction depth in the thickness direction of the electrode plate (mm), y ₀ Represents coefficients for statistical calculations, and w represents the weighted half-peak width.

According to the above technical solution, the positive electrode plate is discharged according to different discharge quantities, and 40%, 50%, 60%, 70%, 80%, 90%, 100% of seven different charge states of the positive electrode plate are respectively made. piece.

After adopting above-mentioned technical scheme, the present invention has following positive effect:

(1) PbSO ₄ of the present invention is the main component that characterizes the electrode plate, and has a great relationship with the battery life. During the test, the test obtains the mass percentage content of PbSO 4 and PbO ₂ of each sample, and the activity of the electrode plate is determined by measuring the The reaction depth of the material PAM is used to pre-evaluate the cycle life of the battery and the pros and cons of various product design schemes. Through the rate of change of the reaction depth, the appropriate depth of discharge for various designed batteries is determined.

(2) The present invention solves the problem of the analysis method of the active material of the positive electrode plate of the battery. By analyzing and evaluating the performance of the electrode plate, comparing the depth of discharge, the depth of reaction of the electrode plate and the cycle life, the optimal design is found and the cycle life of the product is improved. life, to ensure product reliability and the best use effect.

Detailed ways

(Example 1)

The present invention discharges the positive electrode plate of the lead-acid battery according to different discharge quantities, and makes 40%, 50%, 60%, 70%, 80%, 90%, 100% and other positive electrode plates with different states of charge respectively. The plates are represented by 1, 2, 3, 4, 5, 6, 7 in turn. Each plate is divided into 5 layers along the thickness d (mm) direction, and the thickness of each layer is 0.2d (mm), in the middle of each layer. Sampling, the thickness sampling point coordinates are 0.1d, 0.3d, 0.5d, 0.7d, 0.9d, and the sampling positions in the length and width directions are within the range of 0.25L~0.75L, 0.25B~0.75B, and the upper and middle , down, or left, middle, and right, sample 3 points, and mix the 3 samples as standard samples, which are represented by -1, -2, -3, -4, -5 respectively, according to the state of charge and The number of layers is numbered respectively. For example, 4-3 represents the third layer sample of the 70% charged state plate. The sample taken is subjected to X-ray powder diffraction (XRD), and Rietveld Refinement is used for data processing to obtain the value of each sample. The mass percentage of PbSO ₄ and PbO ₂ .

A Gaussian distribution function was used to fit the content distribution curve of PbO ₂ .

σ=2.25-w/2, mm,

Among them, A is the integral area of the Gaussian function curve obtained by fitting, Z is the average content (%) of PbO ₂ in the positive electrode active material PAM of the electrode plate, σ is the average reaction depth in the thickness direction (mm), and y ₀ is the statistical Calculated coefficient, w represents the weighted half-peak width. The optimal state of charge (depth of discharge) of the active material of the electrode plate or the charging performance of different electrode plates is characterized by the rate of change of the reaction depth of the active material.

The following will further illustrate the content of the present invention and its beneficial effects through the examples of PAM analysis and testing methods for positive active materials of A-type and B-type lead-acid batteries with different design schemes.

1. Discharge the A-type and B-type lead-acid battery samples according to the depth of discharge of 0%, 10%, 20%, 30%, 40%, 50%, and 60% respectively. 100%, 90%, 80%, 70%, 60%, 50%, 40%.

2. Dissect the A-type and B-type lead-acid batteries, sample the plates and dry them, and mark each plate. Each plate is sampled in 5 layers, and 3 samples are taken from each layer. down, or left, middle, and right, sampling 3 points, and mixing the 3 samples as standard samples, numbering according to the state of charge and the number of layers, respectively, the samples taken are analyzed by X-ray powder diffraction (XRD), And using Rietveld Refinement tool for data processing, the mass percentage content of PbO ₂ in each sample is obtained as shown in Table 1 and Table 2.

Table 1 shows the layered PbO _{2 content under different charge states of the A-type battery, and Table 2 shows the layered PbO 2 content} under different charge states of the B-type battery.

Table 1

Table 2

The Gaussian distribution function was used to fit the content distribution curve of PbO ₂ in different states of charge and under different layers. Z was used to represent the average content of PbO ₂ in the positive electrode active material PAM, and σ was the average reaction depth in the thickness direction. , R represents the confidence of the post-preparation results, and the post-preparation results are credible, as shown in Table 3.

table 3

3. Analyze the change trend of the PAM reaction depth of the positive plate during the discharge process. It is found that when the charge state of the A-type battery is 40% (the discharge depth is 60%), the reaction depth is 1.582, and the charge state is 60% (the discharge depth is 60%). 40%), the reaction depth is 1.193, the discharge depth is reduced by 24.6%, the rate of change of the reaction depth is large, and the discharge depth is deepened. The reaction depth of the B-type battery when the state of charge is 40% (discharge depth of 60%) is 1.202, which is close to the reaction depth of 1.193 when the state of charge of the A-type battery is 60% (discharge depth of 40%). Under the deep discharge depth of 60%, it can still maintain a good cycle life, and it can be pre-evaluated that the design of the B-type battery is better than that of the A-type.

1. Analysis of capacity decay rate and cycle life of A-type and B-type batteries

The 40% DOD discharge cycle system is:

a) 0.1C for 4h;

b) 2.35V/pc, current limit 0.25C, charge for 3h;

c) Continue the steps a) and b) to circulate 100 times;

d) After 100 cycles, charge at 2.35V/cell, with a current limit of 0.2C for 24h, and then perform C10 capacity detection after charging;

e) Repeat a) to d) until the check capacity detection is less than 80% C10.

The 60% DOD discharge cycle system is:

a) 0.1C for 6h;

b) 2.35V/piece, current limit 0.25C, charge for 5h;

c) Continue the steps a) and b) to circulate 100 times;

d) After 100 cycles, charge at 2.35V/cell, with a current limit of 0.2C for 24h, and then perform C10 capacity detection after charging;

e) Repeat a) to d) until the check capacity detection is less than 80% C10.

(1) Capacity decay rate

The actual discharge capacity of the A-type battery is 99.2% of the initial capacity when it is cycled to the 500th time according to the DOD cycle system with a depth of discharge of 40%, and the actual discharge capacity is 87.5% of the initial capacity when it is cycled to the 500th time according to the depth of discharge 60% DOD cycle system. , the actual discharge capacity of the B-type battery is 99.4% of the initial capacity when it is cycled to the 500th cycle according to the depth of discharge 60% DOD cycle,

The test shows that the capacity decay rate of the A-type battery is 40% DOD and the B-type battery is 60% DOD, indicating that the A-type battery is suitable for 40% shallow cycle, and the B-type battery is suitable for 60% deep cycle.

(2) Cycle life times

A type battery with a depth of discharge of 40% has 1800 DOD cycles, while a 60% depth of discharge battery has only 800 DOD cycles. close in number.

Comprehensive comparison of discharge depth, plate reaction depth and cycle life, when the discharge depth of A-type battery is 60%, the plate reaction depth is 1.582, and when the discharge depth is 40%, the plate reaction depth is 1.193, which is reduced by 24.6%. The corresponding The cycle life was increased to 2.1 times, while the plate reaction depth of the B-type battery at a depth of discharge of 60% was 1.202, which was similar to the plate reaction depth of 1.193 at a depth of discharge of 40% of the A-type battery, and the number of cycle life was similar. This shows that the cycle life of the battery and the pros and cons of various product design schemes can be pre-evaluated by measuring the reaction depth of the active material PAM, and the appropriate discharge depth of the battery can be designed through the rate of change of the reaction depth.

The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present invention in further detail. It should be understood that the above descriptions are only specific embodiments of the present invention, and are not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (4)

1. a lead-acid battery positive electrode active material PAM analysis test method, is characterized in that, comprises the steps: 1) Stratified sampling of the positive active material PAM with different charge states, 2) Analysis by X-ray powder diffraction, 3) Use the Rietveld Refinement tool for data processing, 4) Obtain the mass percentage content of PbSO ₄ and PbO ₂ of each sample, 5) Using Gaussian distribution function to fit the content distribution curve of PbO ₂ under different charge states and under different layers, 6) The depth of discharge of the active material of the positive electrode plate or the charging performance of different plates is represented by the rate of change of the active material reaction depth. 2. lead-acid battery positive electrode active material PAM analysis test method according to claim 1, is characterized in that: described step 1) is specially: the positive electrode plate of lead-acid battery is discharged according to different percentages of discharge electricity, respectively. Make N kinds of positive electrode plates with different states of charge, one for each, and each plate is evenly divided into 5 layers along the thickness d direction, the thickness of each layer is 0.2d, and samples are taken in the middle of each layer, and the length L direction The sampling position is 0.25L～0.75L, and the sampling position in the width B direction is 0.25B～0.75B. Press the upper, middle, lower, or left, middle, and right of each layer to sample 3 points, and mix the 3 samples. As a standard sample, numbered according to the percentage of charge state and the number of layers. 3. lead-acid battery positive electrode active material PAM analysis test method according to claim 1, is characterized in that: described step 5) is specifically: adopt Gaussian distribution function to PbO ₂ the content distribution curve is fitted, get σ=2.25-w/2, mm,

Among them, A is the integral area of the Gaussian function curve obtained by fitting, Z is the average content of PbO ₂ in the positive electrode active material PAM of the electrode plate, σ is the average reaction depth in the thickness direction of the electrode plate, y ₀ is the coefficient of statistical calculation, w represents the weighted half-peak width. 4. The method for analyzing and testing the positive active material PAM of a lead-acid battery according to claim 2, characterized in that: the positive electrode plate is discharged according to different discharge quantities, and 40%, 50%, 60%, 70% are respectively made , 80%, 90%, 100% of seven different charge states of the positive plate each 1 piece.