A method of improving inconsistency of lead acid battery packs

Abstract

The application discloses a method for improving inconsistency of lead-acid battery group, and belongs to the technical field of lead-acid batteries. The method solves the problems of low efficiency, poor effect, inability to improve inconsistency of lead-acid battery group or even deterioration of inconsistency in the prior art by using reverse polarity charging and discharging or polarity reversal to improve inconsistency of lead-acid battery group. The method comprises the following steps: discharging the lead-acid battery group; reverse polarity charging the lead-acid battery group; reverse polarity discharging the lead-acid battery group; sequentially charging the lead-acid battery group to a threshold voltage; before, during and after the implementation, the electrolyte of each single cell in the lead-acid battery group is excessive, and the electrolyte level or amount of each single cell is the same as each other, or the excessive amount of electrolyte of each single cell in the battery group is controlled in a specific range. The method can be used to improve inconsistency of lead-acid battery group.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of lead-acid storage batteries, and particularly relates to a method for improving inconsistency of a lead-acid storage battery pack. BACKGROUND

[0002] The lead-acid storage battery pack includes two or more single cells (i.e. monobatteries), each of which is connected in series or / and parallel with each other. On the one hand, during use, the failure modes (such as water loss or liquid loss, positive electrode softening or / and shedding, negative electrode sulfuration, electrode passivation, etc.) of the single cells will lead to performance degradation of the single cells or even the battery pack, and even the end of life. On the other hand, during use, due to the influence of manufacturing process deviation, use condition difference, environmental condition difference, etc., the types and degrees of the failure modes of the single cells in the lead-acid storage battery pack are often inconsistent with each other, which increases the inconsistency in charge-discharge performance and characteristics among the single cells. The above two types of inconsistency belong to inconsistency of the lead-acid storage battery pack, and greater inconsistency of the battery pack will significantly and accelerate the reduction of the cycle life, capacity, charge-discharge efficiency of the lead-acid storage battery pack, and even lead to the end of life of the battery pack.

[0003] According to the prior art, after dripping 2-10 ml of distilled water, the lead-acid storage battery is charged and discharged at 1-100% depth of charge and discharge, and the positive and negative direction charge-discharge is repeated 1-8 times, which can increase the average capacity of the lead-acid storage battery with capacity degradation or end of life by 50%-100%, and the best one can be close to the nominal capacity (rated capacity, C), thereby prolonging the service life of the lead-acid storage battery. For the battery with sulfurization or capacity loss of the remaining electrolyte, the positive and negative direction charging is carried out at a small current and a low temperature to remove the sulfurization and activate the battery, and the capacity of the battery can be restored to the rated capacity. Under the condition of no electrolyte loss, the polarity reversal of the lead-acid storage battery can prevent, repair and alleviate the problem of positive electrode softening or / and shedding of the lead-acid storage battery, etc.

[0004] However, in actual application, the lead-acid storage battery pack with capacity degradation or end of life has great difference or inconsistency in liquid loss, sulfuration, softening, charge acceptance, state of charge, discharge output capacity, etc. among the single cells, which makes it difficult to directly or simply use the above-mentioned prior art to improve the inconsistency of the battery pack, and the results are low efficiency, inapplicability, poor improvement of the inconsistency, inability to improve the inconsistency of the lead-acid storage battery pack, or even worsening of the inconsistency. SUMMARY

[0005] In view of the above analysis, the present application aims to provide a method for improving the inconsistency of lead-acid battery pack, solving the problem that the effect of improving the inconsistency of lead-acid battery pack by using reverse polarity charging or polarity reversal is inefficient, unable to improve the inconsistency of lead-acid battery pack or even leading to the deterioration of inconsistency in the prior art.

[0006] The purpose of the present application is mainly achieved by the following technical solutions:

[0007] The present application provides a method for improving the inconsistency of lead-acid battery pack, the lead-acid battery pack comprising 2 or more single cells connected in series or / and parallel, the method comprising the following steps:

[0008] Step 1: discharging the lead-acid battery pack, so that the voltage of the lead-acid battery pack decreases from a positive voltage to 0V;

[0009] Step 2: reverse polarity charging (i.e. reverse charging) of the lead-acid battery pack, i.e. the original positive electrode of the lead-acid battery pack as a negative electrode, and the original negative electrode as a positive electrode, charging in this state;

[0010] Step 3: reverse polarity discharging of the lead-acid battery pack, so that the voltage of the lead-acid battery pack increases from a negative voltage to 0V;

[0011] Step 4: forward polarity charging (i.e. forward charging) of the lead-acid battery pack, i.e. the original positive electrode of the lead-acid battery pack as a positive electrode, and the original negative electrode as a negative electrode, charging in this state, to a threshold voltage;

[0012] Before, during and after the implementation, the electrolyte of each single cell in the lead-acid battery pack is in excess; the electrolyte in excess includes: always keeping the electrolyte in excess.

[0013] The lead-acid battery includes but is not limited to a liquid-starved type, a sealed lead-acid battery, such as a valve-regulated sealed lead-acid battery, or the lead-acid battery pack includes but is not limited to a lead-acid battery pack with single cells connected in series.

[0014] The electrolyte in excess means that the electrolyte level of each single cell is higher than the original electrolyte level of the single cell, or / and the liquid amount (volume amount or / and mass amount) of the electrolyte of each single cell is greater than the original electrolyte amount of the single cell; the original electrolyte level or amount of the single cell refers to the level or amount of the electrolyte of the single cell as set or rated in the product design and production scheme of the battery pack, or the level or amount of the electrolyte of the single cell possessed by the brand-new battery pack product obtained after the product production is completed.

[0015] Generally, the excess electrolyte level is not lower than the top of the electrode or the electrode active material.

[0016] Further, when the lead-acid battery is a battery pack, the electrolyte levels or volumes of each single cell are made the same as or as close as possible to each other during the liquid supplementing;

[0017] Alternatively, the excess amounts (volume or mass) of electrolyte of each single cell in the battery pack are controlled to be within a range where the minimum amount ÷ the maximum amount of the excess amounts is greater than or equal to 50%, the excess amounts being mass or volume; or the maximum difference between the electrolyte levels of each single cell is less than the distance from the average value of the electrolyte levels of each single cell to the top of the electrode or active material; the reason for this is:

[0018] 1) Before repair, the single cells of the battery pack have obvious inconsistencies in electrode state, liquid loss, etc. Based on the repair practice effect, the above-mentioned difference control range of the electrolyte volumes or levels of each single cell can basically guarantee that it does not worsen the original inconsistency of the battery pack.

[0019] 2) During the repair process of the battery pack, the existing inconsistency of the battery pack will cause the liquid loss of each single cell during the repair process to be inconsistent, which will cause the consistency of the liquid volumes or levels of each single cell during the repair process to change to some extent. If the liquid volumes or levels of each single cell are kept absolutely the same at all times during the repair process, it will bring a considerable workload (including workload, difficulty, etc.) to the actual operation, therefore, based on the repair practice effect, the above-mentioned difference control range of the electrolyte volumes or levels of each single cell is determined to provide a balanced and suitable operation reference or principle between the workload of the actual operation and the beneficial technical effect (improving the consistency of the battery pack).

[0020] Further, the excess amount of electrolyte is not less than 5% of the original electrolyte volume of the battery to meet the needs of heating, cooling, circulating electrolyte, gas evolution, and diluting electrolyte (accelerating the removal of sulfuration by diluting the electrolyte concentration) during the repair process of the application.

[0021] Further, in the above-mentioned step 4, the threshold voltage is 0.4-1.1 times the oxygen evolution voltage of the single cell × n. n is the number of single cells connected in series in the lead-acid battery pack, when the single cells in the lead-acid battery pack are connected in parallel, n is 1.

[0022] Further, before, during, and after steps 1, 2, 3, and 4, the liquid level or volume, concentration of the electrolyte of the battery is adjusted by liquid supplementing or / and liquid removal operation;

[0023] The above-mentioned liquid supplementing of each single cell in the lead-acid battery pack includes the following steps:

[0024] The electrolyte level or volume in each single cell is obtained. In practical application, the operator can observe or measure the weight of the cell, or the observation can be performed once every certain time, for example, more than 1 minute.

[0025] It is determined whether the electrolyte level or volume in each single cell is lower than a threshold value, i.e., whether it is lower than the level or volume of the original electrolyte or a certain excess electrolyte. If yes, the liquid is added to the single cell with electrolyte level or volume lower than the threshold value until the threshold value is reached. If no, the liquid is not added. The liquid is an aqueous liquid, including but not limited to water, sulfuric acid solution, and aqueous solution containing additives. It should be noted that in practical application, the liquid is added when the electrolyte level is lower than a certain excess level to prevent liquid deficiency accidents.

[0026] Further, the above liquid removal from each single cell in the lead-acid battery includes the following steps:

[0027] The following steps can be further included before step 1, during steps 1 to 4, and after step 4:

[0028] The electrolyte level or volume in each single cell is obtained. In practical application, the operator can observe or measure the weight of the cell, or the observation can be performed once every certain time, for example, more than 1 minute.

[0029] It is determined whether the electrolyte level or volume in each single cell is higher than a threshold value. If yes, the liquid is removed from the single cell with electrolyte level or volume higher than the threshold value, so that the electrolyte level or volume of each single cell is reduced to the threshold value. If no, the electrolyte volume is not reduced.

[0030] Further, the liquid removal is performed by evaporation, overcharge gas evolution, mechanical liquid removal, or liquid absorption.

[0031] Further, the liquid addition and removal operation further includes the following steps during steps 1 to 4 or / and after step 4:

[0032] The concentration of the electrolyte is measured and adjusted before the liquid addition and removal. The concentration of the electrolyte in the lead-acid battery is adjusted to a target value by adding an aqueous solution (such as water or sulfuric acid solution) to the lead-acid battery. The electrolyte concentration target value can be the concentration value of the original electrolyte or other values. When the lead-acid battery is a battery pack, the concentration of the electrolyte in each single cell in the battery pack is consistent or tends to be consistent by the above electrolyte concentration adjustment.

[0033] Further, the liquid supplementing and liquid removing operation further comprises: before, during and after the liquid supplementing and liquid removing operation, performing a vacuum pumping operation on the lead-acid battery, so that some gas in the battery is pumped out, and the electrolyte can enter the battery more fully; because the used battery may have experienced thermal runaway, dry liquid and gas evolution, some of the gas in the battery is difficult to be replaced by the electrolyte, and when the gas evolution reaction occurs during the repair process, the gas generated is also easy to occupy part of the pore structure in the battery. In order to make the electrolyte fully contact with the active material, prevent the loss of liquid and thermal runaway after repair, better improve the consistency of the battery pack, and improve the production efficiency, success rate or quality of the battery repair, it is necessary to perform a vacuum pumping operation on the lead-acid battery before, during and after the liquid supplementing and liquid removing operation.

[0034] Further, at least one overcharging is performed on the lead-acid battery pack during or after step 4 and before liquid removal.

[0035] Further, after step 4, the electrolyte of the single battery of the lead-acid battery pack is excessive, and overcharging is performed on the lead-acid battery pack; the excessive electrolyte already exists in the single battery after step 4, or water or water-containing liquid is added to the single battery of the lead-acid battery pack to make the electrolyte excessive.

[0036] Further, the overcharging amount is not less than 1.5 times the rated capacity of the lead-acid battery pack or the single battery, and the voltage of the battery pack reaches at least the gas evolution potential determined by the electrochemical system of the battery pack, wherein the hydrogen evolution potential is n×2.44V, and n is the number of single batteries connected in series in the lead-acid battery pack. When the single batteries in the lead-acid battery pack are connected in parallel, n is 1.

[0037] Further, at least one charging and discharging cycle is performed on the lead-acid battery pack after step 4 and before liquid removal, and the depth of the charging and discharging cycle can be more than 30%.

[0038] Further, in step 2, the lead-acid battery pack is subjected to reverse polarity charging, so that the voltage of the lead-acid battery pack decreases from 0V to ≤n×(-1.75±0.1)V.

[0039] And / or, in step 4, the lead-acid battery pack is subjected to forward polarity charging, so that the voltage of the lead-acid battery pack increases from 0V to n×(1.75±0.1)V or more.

[0040] n is the number of single batteries connected in series in the lead-acid battery pack. When the single batteries in the lead-acid battery pack are connected in parallel, n is 1.

[0041] Further, in the step 2, the lead-acid battery is subjected to the reverse polarity charging process to cause the single cell to generate the gas evolution reaction.

[0042] Further, in the step 2 and / or 4, the lead-acid battery is heated to make the temperature of the battery or the temperature of the electrolyte in the single cell higher than the room temperature (20-30℃) or higher than the upper limit of the temperature control range (45±5℃) during the conventional use or repair of the lead-acid battery.

[0043] Further, the heating of the lead-acid battery includes the following steps:

[0044] First, the lead-acid battery is heated by using the heat generated from the inside to the outside of the single cell during the reverse polarity charging and the forward polarity charging to make the temperature of the battery or the temperature of the electrolyte rise;

[0045] When the heat generated from the inside to the outside of the single cell during the reverse polarity charging and the forward polarity charging is not enough to make the temperature of the battery or the temperature of the electrolyte reach the predetermined value or range, the lead-acid battery is heated by using an external heating source to make the temperature of the battery or the temperature of the electrolyte rise.

[0046] Further, before, during or after the implementation of the steps 1, 2, 3 and 4, the following steps are further included:

[0047] The space for accommodating the electrolyte in the single cell is opened to make the heat and the gas generated in the single cell discharged from the inside of the battery through the liquid injection port or the slot of the battery tank. For example, the upper cover of the battery is opened, or the liquid injection port of the battery is opened, or the liquid injection port at the top of the lead-acid battery is connected with a container, and the container can be opened to the external environment of the battery. The container connected with the liquid injection port of the battery has multiple functions: first, it is beneficial to discharge the heat and the gas in the battery; second, it is used to accommodate the excess electrolyte and is beneficial to observe and judge the amount or level of the excess electrolyte; and third, it can prevent the electrolyte from overflowing or splashing to the external environment of the battery during the charging and the gas evolution of the battery.

[0048] Further, the electrolyte level includes the electrolyte level in the battery tank and the electrolyte level in the container connected with the battery tank or the liquid injection port.

[0049] Compared with the prior art, the present application can at least achieve one of the following beneficial effects:

[0050] a) The method for improving the inconsistency of lead-acid battery provided by the present application can be applied to the repair of lead-acid batteries and battery packs, and prolong the service life of lead-acid batteries and battery packs. It can not only ensure that the electrochemical reaction is sufficiently and completely conducted in steps 1 to 4, and the liquid is not lacking, but also be conducive to reducing the concentration of lead sulfate salt in the electrolyte, increasing the dissolution amount of sulfate in the electrolyte, removing or alleviating the sulfidation problem due to the reduction of the saturation degree of lead sulfate salt solution, thereby accelerating the removal rate of the inconsistency of the battery pack, reducing the short circuit problem caused by the deposition of sulfate under over-discharge or reverse polarity state; at the same time, the excess electrolyte can provide sufficient water for the temperature rise of reverse polarity charging (the reverse polarity charging process involves the release of a large amount of heat and the evaporation of electrolyte water), the water or liquid amount for over-charging gas evolution, and the prevention of reverse polarity charging thermal runaway; the excess electrolyte is also conducive to the actual operation of finding the liquid level of each single cell, so that the liquid level or liquid amount of each single cell is more easily achieved or tends to be consistent; the excess electrolyte is also conducive to the gas channel in the closed separator, and is conducive to preventing the gas from promoting sulfidation or scouring softening of the electrode during the gas evolution reaction of the electrode.

[0051] b) The method for improving the inconsistency of lead-acid battery provided by the present application can form an effective cooling source on the physical position of the top or the periphery of the single cell through liquid supplementing or / and liquid removing, which is conducive to forming a heat distribution state of upper cold and lower hot or outer cold and inner hot of the electrolyte during the charging and discharging process of steps 1 to 4, cooperating with the charging and discharging process, promoting the circulation of the electrolyte on the upper and lower electrode plates, and realizing the uniform mixing and uniform distribution of the electrolyte in the single cell. At the same time, the liquid level or liquid amount or concentration of the electrolyte of each single cell is the same, wherein the liquid level or liquid amount includes the liquid level or liquid amount in the battery tank and the liquid level or liquid amount in the container. The same liquid level or liquid amount or concentration of the electrolyte of each single cell through liquid supplementing is conducive to the good consistency of the total amount and concentration of the electrolyte contained in each single cell after liquid supplementing.

[0052] c) The method for improving the inconsistency of lead-acid battery provided by the present application has differences in reaction activation energy and reaction rate in different reaction processes, and increasing the temperature can reduce the difference degree of the reaction rate or reduce the influence of the difference. Specifically, the reaction of removing sulfidation is obviously slower than the reaction of removing softening, the coarse lead sulfate salt has small specific surface area, low solubility and very low reactivity, and is generally not easy to be converted, so the reaction of removing sulfidation is generally the control step for improving the inconsistency; when the battery temperature or the electrolyte temperature is increased, the solubility of lead sulfate salt can be greatly increased, and the reactivity of lead sulfate salt can be increased, thereby accelerating the removal rate of sulfidation and simultaneously removing softening and sulfidation in a relatively shorter time period.

[0053] d) The method for improving the inconsistency of lead-acid battery provided by the present application, on the one hand, the gas generated by the gas evolution reaction has a stirring effect on the electrolyte, which can make the electrolyte concentration uniform and evenly distributed in the battery, and at the same time, because it is in step 2 or has undergone the process of step 2, it will not or is not easy to cause the original positive active material to soften and fall off, or further, it also makes it possible to use larger current (such as current above 0.125C, C for the rated capacity of the battery), larger voltage (such as n×2.55V above) for reverse constant current and constant voltage charging gas evolution reaction, allowing the gas evolution reaction to proceed more vigorously; on the other hand, the heat generated during the gas evolution reaction can accelerate the dissolution of the original negative lead sulfate salt crystals and accelerate the removal or mitigation of the sulfuration problem; on the other hand, when the gas evolution reaction occurs, the battery is in the overcharge or high voltage state of reverse charging, which can also accelerate the electrochemical conversion speed of the original negative lead sulfate salt, and is conducive to the conversion or complete conversion of the irreversible lead sulfate salt deep inside the electrode.

[0054] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the present application. The objects and other advantages of the present application can be achieved and obtained by the structure particularly pointed out in the written description. DETAILED DESCRIPTION

[0055] The preferred embodiments of the present application are described in detail below.

[0056] Example 1

[0057] The present embodiment provides a method for improving the inconsistency of lead-acid battery, which includes two or more single batteries in series or / and parallel, the method comprising the following steps:

[0058] Step 1: Discharge the lead-acid battery, so that the voltage of the lead-acid battery decreases from positive voltage to 0V;

[0059] Step 2: Reverse charging (i.e. reverse charging) of the lead-acid battery, i.e. the original positive electrode of the lead-acid battery as negative electrode, the original negative electrode as positive electrode, charging in this state;

[0060] Step 3: Reverse discharge of the lead-acid battery, so that the voltage of the lead-acid battery rises from negative voltage to 0V;

[0061] Step 4: Forward charging (i.e. forward charging) of the lead-acid battery to the threshold voltage, which is 0.4-1.1 times of n (usually, when n=6, it is 13.8v) of the oxygen evolution voltage of the single battery, i.e. the original positive electrode of the lead-acid battery as positive electrode, the original negative electrode as negative electrode, charging in this state;

[0062] Before step 1, during steps 1 to 4, and after step 4, the following steps are further included: supplementing the electrolyte in each single cell in the lead-acid battery pack, so that the electrolyte in each single cell in the lead-acid battery pack is in excess, the electrolyte level is not lower than the top of the electrode, and the electrolyte levels of each single cell are the same; or, the excess amount of electrolyte in each single cell in the battery pack is controlled within the following range:

[0063] The minimum amount of excess amount ÷ the maximum amount of excess amount ≥ 50%, and the excess amount is in mass or volume; for example, a battery pack contains 6 single cells, and the excess amount of electrolyte in the 6 single cells is 20g, 24g, 28g, 32g, 36g, and 40g respectively, then the minimum amount of excess amount 20g ÷ the maximum amount of excess amount 40g = 50%;

[0064] Or, the maximum difference between the electrolyte levels of each single cell is less than the distance from the average value of the electrolyte levels of each single cell to the top of the electrode or active material;

[0065] And the excess amount of electrolyte is not less than 5%, 10%, 15%, 20%, 30%, 50%, 70%, or 100% of the original electrolyte volume of the battery.

[0066] It should be noted that the voltage value > 0V is called positive voltage value, and the voltage value < 0V is called negative voltage value.

[0067] In addition, it should be noted that the excess amount of electrolyte means that the actual electrolyte level of each single cell is higher than the original electrolyte level of the single cell, or the actual electrolyte volume (volume or / and mass) of each single cell is greater than the original electrolyte volume of the single cell. The original electrolyte level or volume of the single cell refers to the electrolyte level or volume set or rated in the design and production scheme of the battery product, or the electrolyte level or volume when the product is just put into use after production.

[0068] Compared with the prior art, the method for improving inconsistency of lead-acid battery provided by the application can be applied to repair of lead-acid batteries and battery groups and prolong the service life of lead-acid batteries and battery groups. The method can not only ensure that the electrochemical reaction is sufficiently and completely performed in the process of steps 1 to 4 and the electrolyte is not lost, but also is beneficial to reducing the concentration of lead sulfate in the electrolyte, increasing the dissolution amount of the sulfate in the electrolyte, removing or relieving the sulfuration problem due to the reduction of the saturation degree of the lead sulfate solution, thereby accelerating the removal rate of the inconsistency of the battery group, reducing the short circuit problem caused by the deposition of the sulfate in the over-discharge or reverse polarity state, and facilitating the prevention of the gas from promoting sulfuration of the opposite electrode (when oxygen is generated) or scouring and softening of the opposite electrode during the gas generation reaction of a certain electrode.

[0069] In addition, by adding the electrolyte, an effective cooling source can be formed at the physical position of the top of the single cell, which is beneficial to forming a heat distribution state in which the electrolyte is hot at the top and cold at the bottom during the charging and discharging process of steps 1 to 4, cooperating with the charging and discharging process, promoting the circulation of the electrolyte on the upper and lower electrode plates, and realizing uniform mixing and distribution of the electrolyte in the single cell. Meanwhile, the liquid levels of the electrolyte in the single cells are selected to be the same, wherein the liquid level includes the liquid level in the battery tank and the liquid level in the container. By adding the electrolyte to make the liquid levels of the electrolyte in the single cells the same, the total amount and concentration of the electrolyte contained in the single cells after adding water are beneficial to having good consistency with each other.

[0070] Specifically, the above adding the electrolyte to the single cells in the lead-acid battery group includes the following steps:

[0071] The liquid level or liquid amount of the electrolyte in each single cell is obtained, which can be observed by the naked eye of an operator or observed once every 1 min or more in actual application, or the weight of the battery is weighed to calculate the liquid storage and loss.

[0072] It is judged whether the liquid level or liquid amount of the electrolyte in each single cell is lower than a threshold value, i.e., whether it is lower than the liquid level or liquid amount of the original electrolyte or a certain excess electrolyte. If yes, the liquid (for example, water, sulfuric acid solution, or other aqueous solution containing additives) is added to the single cell with the liquid level or liquid amount of the electrolyte lower than the threshold value until the threshold value is reached, or / and the liquid levels or liquid amounts of the electrolytes in the single cells are made the same. If no, the electrolyte does not need to be added.

[0073] In this way, the electrolyte contained in each single cell is in an excess or non-loss state before, during and after steps 1 to 4, the role of the electrolyte or the excess electrolyte is played, and the state of the electrolyte is kept as consistent as possible among the single cells.

[0074] Generally, for the convenience of operation and good results, each single cell is supplemented with electrolyte to a certain excess electrolyte level or volume before step 1 is performed, and then whether the electrolyte level or volume in each single cell is below the threshold value is determined during or after the process of steps 1-4, and whether to supplement or not is determined according to the determination.

[0075] In order to avoid excessive electrolyte from causing electrolyte overflow during charging and discharging, or to solve or alleviate the problem of inconsistency of each single cell in the process of steps 1-4 due to the inconsistency of the battery pack, or to restore the electrolyte state of each single cell to the original state (level or / and volume) as much as possible after steps 1-4, the following steps can be included before step 1, during the process of steps 1 to 4, and after step 4:

[0076] The electrolyte level or volume in each single cell is obtained, which can be observed by the naked eye or measured by weight in actual application, or observed every 1 min or more;

[0077] Determine whether the electrolyte level or volume in each single cell is above the threshold value, if so, the single cell with electrolyte level or volume above the threshold value is dehydrated, for example, evaporation, overcharge gas evolution, mechanical drainage or suction can be used to reduce the electrolyte level or volume of each single cell to the domain value, or / and have the same level or volume, if not, the electrolyte volume does not need to be reduced.

[0078] The concentration of the battery electrolyte can also be adjusted before, during, and after steps 1, 2, 3, and 4 by supplementing or / and dehydrating.

[0079] The supplementing or / and dehydrating operation also includes:

[0080] The lead-acid battery is subjected to air extraction.

[0081] Thus, by means of liquid supplementing and liquid removing, the problems of electrolyte shortage and electrolyte concentration increase caused by electrolyte shortage during charging and discharging are avoided, the problems of electrolyte overflow caused by excessive electrolyte are avoided, the problems of liquid loss and inconsistent liquid loss of each single cell caused by inconsistency of the battery pack before step 1 are solved or alleviated, the problems of inconsistent liquid loss and inconsistent properties of electrolyte of each single cell during steps 1-4 caused by inconsistent electrochemical reaction performance of each single cell caused by inconsistency of the battery pack are solved or alleviated, or / and, after steps 1-4, the properties of electrolyte remaining in each single cell are consistent with each other or as consistent as possible, the state of electrolyte in the battery is restored to the original state of electrolyte of each single cell as much as possible, the original state of electrolyte of each single cell refers to the state (liquid level, liquid amount, concentration, consistency between each single cell) of electrolyte of each single cell when the battery product is designed, produced, or just put into use after production, and consistency of lead-acid battery pack in terms of electrolyte is achieved, and the properties of electrolyte remaining in each single cell are consistent with each other.

[0082] Correspondingly, when the consistency problem of electrolyte and the problem of restoring to the original state are solved or alleviated, the consistency problem of electrodes or electrode state interacting with electrolyte in each single cell and the problem of restoring to the original state are also favorably solved or improved.

[0083] It should be noted that after step 4, before liquid removal, the lead-acid battery pack is subjected to at least one charging and discharging cycle, and the depth of the charging and discharging cycle is more than 30%. Thus, after the liquid level and / or liquid amount are consistent, before liquid removal and after reverse polarity, the electrolyte is more fully involved in the reaction, mixed uniformly, and distributed consistently, so that the battery consistency between each single cell is better, the electrolyte remaining in the battery after liquid removal is more consistent, and the state of charge of the battery active material is also more consistent.

[0084] In order to remove the softening, removal of sulfuration and other failure modes of the process to achieve synchronization as possible, in step 2 and / or 4, the lead-acid battery is heated, the battery temperature or the temperature of the electrolyte in the single cell is higher than room temperature (for example, 20-30℃ or higher than the upper limit of the temperature control range of the lead-acid battery during normal use and repair (45±5℃), for example, not less than 20℃, 30℃, 40℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, one of them. Because of the difference in the reaction activation energy, reaction rate, the difference between the reaction rate can be reduced or the impact of the difference can be reduced by increasing the temperature. Specifically, the removal of sulfuration is significantly slower than the removal of softening. The coarse lead sulfate salt has small specific surface area, low solubility and low reactivity, so it is not easy to be converted and the reaction time is long. Therefore, the removal of sulfuration is generally a control step for improving consistency. When the battery temperature is increased, the solubility of lead sulfate salt can be greatly increased, the reactivity of lead sulfate salt can be increased, and the removal rate of sulfuration can be accelerated. Softening and sulfuration can be removed simultaneously in a relatively short period of time. For example, the original softening is removed in 1 hour, and the sulfuration is removed in 10 hours. After increasing the temperature, the softening may be removed in 0.5 hour, and the sulfuration may be removed in 5 hours. As can be seen, the difference between the removal of softening and the removal of sulfuration is smaller after increasing the temperature, and the synchronization is increased, thereby accelerating and strengthening the implementation of the consistency of the lead-acid battery.

[0085] It should be noted that the lead-acid battery is heated by the following steps:

[0086] First, the heat generated by the single cell from the inside to the outside during reverse polarity charging is used to heat the lead-acid battery, so that the temperature of the lead-acid battery or the temperature of the electrolyte is increased. It should be noted that the heat generated by the single cell from the inside to the outside during reverse polarity charging includes the heat generated by the chemical reaction, electrochemical reaction and current passing through the internal resistance of the battery during reverse polarity charging.

[0087] When the heat generated by the single cell from the inside to the outside during reverse polarity charging and forward polarity charging is not enough to make the temperature of the lead-acid battery or the temperature of the electrolyte reach the predetermined range, an external heating source (such as a liquid heater) is used to heat the lead-acid battery, so that the temperature of the lead-acid battery is increased.

[0088] Among them, the heat generated by the single cell from the inside to the outside during reverse polarity charging is the main heat source, which accounts for more than 50% of the required heat. This is beneficial to form the temperature inside the single cell higher than the temperature outside or on the surface of the battery, thereby improving the reaction temperature inside the single cell as much as possible under the premise of ensuring that the battery shell (usually plastic) does not deform.

[0089] The first use of single cell in the reverse pole charging, the positive pole charging, the heat generated by itself from the inside to the outside of the lead-acid battery heating, so that the temperature of the lead-acid battery or electrolyte temperature rises, on the one hand, it is beneficial to make the battery form the temperature distribution of internal heat and external cold, so that the internal reaction temperature of the battery can be higher than the temperature limit of the battery shell, and a relatively higher electrochemical reaction temperature and a better electrochemical reaction heating response rate are obtained; on the other hand, the energy consumed in repair can be fully utilized, the energy or heat can be fully utilized, the heating equipment can be saved, the cooling work burden can be reduced, and when the battery is allowed to carry out electrochemical reaction at a large current (0.125-0.3C or more), the normal reaction process does not need to be frequently paused for overheating removal and cooling, thereby significantly improving the production efficiency.

[0090] In order to further improve the inconsistency of the lead-acid battery, in the above step 2, the lead-acid battery is reversely charged, so that the voltage of the lead-acid battery decreases from 0V to ≤n×(-1.75±0.1)V, n is the number of single cells in series in the lead-acid battery, and when each single cell in the lead-acid battery is in parallel, n is 1. It is found that when the voltage of the lead-acid battery reaches this value, the consistency of the battery begins to be obviously improved, and before reaching this value, for example, when the voltage of the battery is between n×(1.75±0.1)V and n×(-1.75±0.1)V, the consistency of the battery is not obviously improved, and even becomes worse; and when the voltage of the battery is lower than this value (n×(-1.75±0.1)V), it is beneficial to further improve the inconsistency of the battery, and it is also beneficial to relatively completely eliminate the inconsistency of the activity of the active material, sulfuration, softening, passivation and the like among the single cells, which also lays a foundation for the battery to obtain good consistency during subsequent recovery of the positive charging, and at the same time, this value is also a symbol of the relatively better consistency of the battery, that is, when the voltage of the battery reaches this value, it indicates that the reverse state of charge of each single cell is relatively consistent and there is no short circuit problem. It should be noted that when in parallel, the total voltage of the lead-acid battery is equal to the voltage of each single cell, the voltage of each single cell is equal to each other and equal to the voltage of the battery and changes synchronously, therefore, no matter how many are in parallel, the voltage is equal to the voltage of a single cell, and when the lead-acid battery is composed of two or more single cells in parallel, n=1.

[0091] In order to improve the uniformity of electrolyte during the reverse polarity charging process, improve the thoroughness, rapidity, synchronism, result consistency and the like of removing the failure source of the battery, in the above step 2, the single cell is caused to generate the gas evolution reaction during the reverse polarity charging process of the lead-acid battery pack. In this way, on the one hand, the gas generated by the gas evolution reaction has the stirring effect on the electrolyte, which can make the electrolyte uniform in concentration and distribution in the battery, but will not cause the original positive active material to soften and fall off; on the other hand, the heat generated during the gas evolution reaction can be used to accelerate the dissolution of the original negative lead sulfate salt crystal, accelerate the removal or relief of the sulfuration problem; on the other hand, the battery is in the overcharge or high voltage state during the reverse polarity charging when the gas evolution reaction occurs, which can also accelerate the electrochemical conversion speed of the original negative lead sulfate salt, and is beneficial to the irreversible lead sulfate salt in the deep inside of the electrode to be converted or completely converted.

[0092] In order to avoid the electrolyte overflow during the charging and discharging or the gas evolution reaction process, the following step is further included between the above step 1 and step 2 or between step 3 and step 4:

[0093] The injection port of each single cell is connected to the outside environment through a container, that is, the container has two through holes, one of which is connected to the injection port of the single cell, and the other is connected to the outside environment, so that the accommodation space of the battery tank in each single cell is connected to the accommodation space of the container. Because in the process of steps 1 to 4, the heat generated inside the single cell is transmitted upward at a speed and intensity greater than downward, horizontal, etc. (especially in the case of gas evolution), the temperature rise of the upper part of the battery or the cover of the shell due to heating will be greater than that of other parts of the battery or the shell. When the temperature rise is large enough, the upper cover of the battery shell will be deformed and damaged by heat before other parts of the battery shell. If the battery is not opened, in the case that the battery cover is not opened, in order to prevent the upper cover from being damaged by heat, the reaction temperature inside the battery needs to be reduced, thereby reducing the temperature rise on the upper cover of the battery. However, a lower reaction temperature inside the battery is not conducive to improving the inconsistency of the lead-acid battery. In addition, this also makes the reaction temperature inside the single cell inconsistent in the vertical direction, and the reaction speed and degree of the electrode in the vertical direction are inconsistent. Through the arrangement of the container, on the one hand, it provides accommodation space for the excess electrolyte, especially when the electrolyte is excessive, the battery tank cannot accommodate it, the electrolyte increases when overcharging or gas evolution charging, and the volume increases after containing bubbles; on the other hand, it prevents the increased gas pressure in the electrolytic tank from causing the electrolyte to splash out of the electrolytic tank and pollute the environment; and on the other hand, it provides an outlet or cooling source for the heat or hot gas propagating upward in the single cell, so that the reaction temperature inside the battery is as high as possible and the reaction temperature inside the battery is as uniform as possible, and the sulfuration problem of the electrode at the bottom of the single cell is alleviated or solved.

[0094] Alternatively, in order to avoid excessive heat or excessive gas pressure in the single cell during reverse polarity charging, the following method can also be used: between step 1 and step 2, the following steps are further included:

[0095] The space for accommodating electrolyte in the single cell is opened (for example, the injection port cover covering the injection port can be opened or the battery cover covering the battery tank can be removed as a whole), so that the heat and gas generated in the single cell are discharged from the injection port or the tank opening of the battery tank. On the one hand, by opening the space for accommodating electrolyte in the single cell, it is beneficial to realize that the reaction in step 2 is carried out at the highest reaction temperature in the battery or the highest reaction temperature allowed by the battery shell, so that the reaction is carried out at a high temperature in a fast manner. On the other hand, when step 2 is carried out, the upper part of the shell has the highest temperature rise and is most susceptible to thermal deformation, so that the heat and gas generated in the battery are discharged from the discharge channel at the upper part of the battery shell. Under the premise of ensuring that the shell and the upper cover of the battery are not damaged and deformed by the heat and gas pressure generated during the process, the internal reaction of the battery is carried out at the highest temperature as possible, and the consistency of the battery is improved as quickly and as well as possible.

[0096] To further improve the consistency of the above lead-acid battery, in the above step 4, the lead-acid battery pack is charged in the forward direction, so that the voltage of the lead-acid battery pack rises from 0V to n x (1.75 ± 0.1) V or above, where n is the number of single cells connected in series in the lead-acid battery pack, and n is 1 when all single cells in the lead-acid battery pack are connected in parallel. It is found that from this value, the consistency of the lead-acid battery pack during forward charging begins to improve relatively obviously, that is, relative to the consistency degree of the battery pack when the battery pack is in the state of n x (1.75 ± 0.1) V to n x (-1.75 ± 0.1) V, or relative to the consistency degree of the battery pack before step 1 of the operation; and when the state of charge of the battery pack reaches or is higher than this voltage value, the improvement of the consistency degree of the battery pack is more practically meaningful.

[0097] To further improve the capacity of the lead-acid battery pack in the forward charging and discharging state, the following step is further included during or after the above step 4 and before liquid removal:

[0098] The electrolyte in the single cell is overcharged, and the lead-acid battery pack is overcharged, and the overcharge is not less than 1.5 times the rated capacity of the lead-acid battery pack. The overcharge refers to charging the battery pack and making the voltage of the battery pack reach at least the gas (oxygen or / and hydrogen) evolution potential determined by the electrochemical system of the battery pack, wherein the hydrogen evolution potential is n x 2.44V, and n is the number of single cells connected in series in the lead-acid battery pack, and n is 1 when all single cells in the lead-acid battery pack are connected in parallel. This is because it can eliminate or alleviate the negative effects (such as sulfuration, change of porosity, etc.) of the battery polarity reversal operation on each single cell, and more fully and completely eliminate or alleviate the residues of the original failure mode of each single cell, improve the consistency of the state of charge and the state of charge of the battery pack, and improve the capacity of the battery pack. After the lead-acid battery is reversed and restored to the forward charging and discharging state, because the reverse charging process will cause new lead sulfate saltization phenomenon when the battery returns to the forward charging and discharging state, which will cause the capacity of the battery in the forward charging and discharging state to be lower than the rated capacity (C) of the battery, therefore, after the reverse charging, the battery needs to be overcharged in time after returning to the forward charging and discharging state to remove the lead sulfate saltization phenomenon, improve the capacity of the lead-acid battery pack in the forward charging and discharging state, and not less than the discharge capacity at the end of the life of the lead-acid battery pack or even reach or exceed the rated capacity of the lead-acid battery pack. Test data shows that the capacity of the lead-acid battery pack during overcharging is about 0.75-0.9C, while after overcharging, the capacity can reach 1.0C or above, and the capacity is increased by more than 10%.

[0099] Example 1

[0100] The lead-acid battery pack of this embodiment is a used valve-regulated lead-acid battery pack, model 6-DZF-20, which is composed of 6 single cells connected in series, i.e., n = 6, n is the number of single cells connected in series in the battery pack, the 6 single cells are connected together, the single cells are No. 1 single cell, No. 2 single cell, No. 3 single cell, No. 4 single cell, No. 5 single cell and No. 6 single cell, respectively, the rated voltage and the rated capacity of the lead-acid battery pack are 12V and 20Ah (2h, 25℃, the same below), respectively, the specifications and models of the 6 single cells contained in the lead-acid battery pack are the same as each other, the rated voltage and the rated capacity of each single cell are 2V and 20Ah, respectively; each single cell of the lead-acid battery pack of this embodiment does not lack electrolyte. The single cell is a valve-regulated sealed lead-acid battery.

[0101] Before the method for improving the inconsistency degree of the lead-acid battery pack is implemented on the lead-acid battery pack of this embodiment, it is necessary to judge the inconsistency degree between the 6 lead-acid battery single cells of the lead-acid battery pack, if the inconsistency exceeds the threshold value, the method for improving the inconsistency degree of the lead-acid battery pack is implemented, and the inconsistency degree method is as follows: the lead-acid battery pack is subjected to charge and discharge, and in the process of charge and discharge, the voltage, current and other electrical properties and differences of each single cell are measured and compared, and the specific process is as follows:

[0102] Under room temperature conditions, the lead-acid battery pack of this embodiment is subjected to charge and discharge according to the following charge and discharge system:

[0103] Step a: the lead-acid battery pack is discharged to 10.5V at a current of 10A (0.5C rate current, C is the rated capacity of the battery pack, the same below), then constant current charging is carried out at a current of 10A to 14.8V (n x 2.466V), then constant voltage charging is carried out at 14.8V to a total cumulative time of 3.5 hours of constant current charging and constant voltage charging, and standing for 1 hour;

[0104] Step b: the lead-acid battery pack is subjected to constant current discharge at a current of 10A, and when the voltage reaches 10.5V (n x 1.75V), the discharge is stopped, and standing for 10 min;

[0105] Step c: the lead-acid battery pack is subjected to constant current charging at a current of 10A (0.5C rate) to 14.8V;

[0106] Step d: the lead-acid battery pack is subjected to constant voltage charging at a voltage of 14.8V, and when the cumulative charging time of step c constant current charging and step d constant voltage charging reaches 3.5 hours, the charging is stopped.

[0107] In the above step b, when the lead-acid battery pack of this embodiment is subjected to constant current discharge at a current of 10A to the battery pack voltage reaches 10.5V (t DC终 , the discharge is terminated), the voltage, current and other electrical properties of the lead-acid battery pack and each single cell thereof at tDC终 The voltage value at a given moment.

[0108] In step c above, when the lead-acid battery pack is charged to 14.8V (t CC终 At the moment when charging is completed, the lead-acid battery pack and its individual cells are measured and examined at t. CC终 The voltage value at a given moment.

[0109] In step d above, when the lead-acid battery pack is charged at a constant voltage of 14.8V for 10 minutes (t... CV10min (Time), measuring and examining the lead-acid battery pack and its individual cells at t CV10min The voltage value at a given moment.

[0110] In step d above, when the cumulative charging time of constant current charging in step c and constant voltage charging in step d reaches 3.5 hours (t... CV终 (Time), measuring and examining the lead-acid battery pack and its individual cells at t CV终 The voltage value at a given moment.

[0111] Table 1 shows the voltage values ​​of the battery pack and its individual cells at each of the above measurement and observation times. ΔV represents the absolute value of the difference between the maximum and minimum voltage values ​​of each individual cell at each measurement and observation time. A smaller absolute value indicates a lower degree of inconsistency in the battery pack, while a larger absolute value indicates a higher degree of inconsistency. STDEVP in Table 1 represents the overall standard deviation of the voltage values ​​of each individual cell at each measurement and observation time. A smaller STDEVP value indicates a lower degree of inconsistency in the battery pack, while a larger STDEVP value indicates a higher degree of inconsistency.

[0112] Table 1 shows the voltage values ​​(V) of the battery pack and its individual cells at each measurement and observation time.

[0113]

[0114]

[0115] Note: t DC终 ΔV = t at time t DC终 The maximum value of all single cell voltages at time t DC终 The minimum voltage of all single cells at time t = 1.962V - 1.288V = 0.674V; the calculation of ΔV at other times is similar.

[0116] t DC终 STDEVP at time t DC终 The overall standard deviation at time t = sqrt(((V1-V_average)) 2 +(V2-Vflat) 2 +......(V6-V flat)2 sqrt((V1-V2)2+(V2-V3)2+(V3-V4)2+(V4-V5)2+(V5-V6)2) / 6), wherein Vmean represents the average value of the voltages V1, V2, V3, V4, V5 and V6 of the No. 1 to No. 6 single cells at the moment, sqrt represents square root; the STDEVP at other moments is similar. DC终 sqrt((V1-V2)2+(V2-V3)2+(V3-V4)2+(V4-V5)2+(V5-V6)2) / 6), wherein Vmean represents the average value of the voltages V1, V2, V3, V4, V5 and V6 of the No. 1 to No. 6 single cells at the moment, sqrt represents square root; the STDEVP at other moments is similar.

[0117] It should be noted that when measuring the voltage values shown in Table 1, the positive electrode measurement end of the voltage measuring instrument is connected to the positive electrode of the lead-acid storage battery or single cell, and the negative electrode measurement end of the voltage measuring instrument is connected to the negative electrode of the lead-acid storage battery or single cell; the physical connection mode of the voltage measuring instrument to the battery or single cell is the same as above when referring to voltage values.

[0118] In addition, after step b, the discharge capacity of the lead-acid storage battery before the method for repairing and improving the inconsistency of the lead-acid storage battery is implemented is measured to be 9.473 Ah (2h rate, 28°C), and after the charging of step a and the discharging of step b, the charge-discharge coulomb efficiency (charge-discharge coulomb efficiency = discharge capacity / charge capacity) is measured to be 82.2%.

[0119] Then, the method for repairing and improving the inconsistency of the lead-acid storage battery is implemented, specifically as follows:

[0120] Step A: discharge the lead-acid storage battery at a constant current of 10 A (0.5C rate) to reduce the battery voltage from a positive value to 0 V;

[0121] Step B: reverse-polarity charge the lead-acid storage battery at a current of 10 A (0.5C rate) to reduce the battery voltage from 0 V to n x (-1.75 ± 0.1) V = -(10.5 ± 0.6) V, and then continue reverse-polarity charging to reduce the battery voltage to less than -(10.5 ± 0.6) V, such as -12.3 V, and finally the reverse-polarity charging amount reaches 46.73 Ah; in this step, the maximum temperature of the single cell shell surface of the battery is controlled to be in the range of 60-70°C (the temperature of the battery shell surface represents the temperature of the battery); in this step, the heat that raises the temperature of the battery is mainly generated from the inside to the outside of the battery during reverse-polarity charging.

[0122] Note: reverse-polarity charging refers to charging the lead-acid storage battery with the original positive electrode as the negative electrode and the original negative electrode as the positive electrode; for example, -(10.5 ± 0.6) V and -12.3 V are negative values measured by connecting the positive electrode of the voltage measuring instrument to the original positive electrode of the lead-acid storage battery and connecting the negative electrode of the voltage measuring instrument to the original negative electrode of the lead-acid storage battery;

[0123] Table 2 shows the voltage values of each cell and the inconsistency of the battery pack when the battery pack voltage is decreased from (10.5 ± 0.6) V to (-10.5 ± 0.6) V and below (-10.5 ± 0.6) V in steps A and B. As can be seen, the consistency of the battery pack deteriorates in the voltage region from (10.5 ± 0.6) V to (-10.5 ± 0.6) V during overdischarge and reverse polarity charging, but the degree of inconsistency of the battery pack starts to improve significantly in the state of reverse polarity charging after decreasing to (-10.5 ± 0.6) V (i.e., n x (-1.75 ± 0.1) V).

[0124] Table 2 shows the voltage values of each cell and the inconsistency of the battery pack when the battery pack voltage is decreased from (10.5 ± 0.6) V to (-10.5 ± 0.6) V and below (-10.5 ± 0.6) V in steps A and B. As can be seen, the consistency of the battery pack deteriorates in the voltage region from (10.5 ± 0.6) V to (-10.5 ± 0.6) V during overdischarge and reverse polarity charging, but the degree of inconsistency of the battery pack starts to improve significantly in the state of reverse polarity charging after decreasing to (-10.5 ± 0.6) V (i.e., n x (-1.75 ± 0.1) V).

[0125]

[0126]

[0127] t 10.5V is the time when the battery pack voltage is 10.5 V. The others are similar.

[0128] Step C: The lead-acid battery pack is discharged in reverse polarity with a current of 10 A (0.5C rate) to increase the voltage of the battery pack from a negative value to 0 V.

[0129] Note: Reverse polarity discharge means that the original positive electrode of the lead-acid battery pack (the positive electrode before reverse polarity charging of the battery pack) is used as the negative electrode, and the original negative electrode (the negative electrode before reverse polarity charging of the battery pack) is used as the positive electrode for discharging.

[0130] Step D: The lead-acid battery pack is charged in forward polarity (i.e., forward charging) with a current of 10 A (0.5C rate) to increase the voltage of the battery pack from 0 V to n x (1.75 ± 0.1) V = 10.5 ± 0.6 V (which belongs to a positive voltage).

[0131] Table 3 shows the voltage values of each cell and the inconsistency of the battery pack when the battery pack voltage is increased from -12.6 V to n x (1.75 ± 0.1) V and above n x (1.75 ± 0.1) V in steps C and D. As can be seen, the voltage of the battery pack deteriorates in the region from n x (-1.75 ± 0.1) V to n x (1.75 ± 0.1) V during reverse polarity discharge and forward polarity charging, but the degree of inconsistency of the battery pack starts to improve significantly in the state of forward polarity charging after increasing to (10.5 ± 0.6) V (i.e., n x (1.75 ± 0.1) V).

[0132] Table 3 shows the voltage values of each cell and the inconsistency of the battery pack when the battery pack voltage is increased from -12.6 V to n x (1.75 ± 0.1) V and above n x (1.75 ± 0.1) V in steps C and D. As can be seen, the voltage of the battery pack deteriorates in the region from n x (-1.75 ± 0.1) V to n x (1.75 ± 0.1) V during reverse polarity discharge and forward polarity charging, but the degree of inconsistency of the battery pack starts to improve significantly in the state of forward polarity charging after increasing to (10.5 ± 0.6) V (i.e., n x (1.75 ± 0.1) V).

[0133]

[0134]

[0135] t -12.688V t = -12.688V

[0136] To continue the analysis of the battery pack's inconsistency and capacity, the following steps E, F, G and H were performed.

[0137] Step E: The battery pack was charged at 10A constant current to 14.8V, then charged at 14.8V constant voltage until the current was less than 5A, then overcharged at 5A constant current for 3hrs, then rested for 1h, then discharged at 10A to 10.5V, and the battery pack was rested for 10min; the discharge capacity was measured to be 20.389Ah (2h rate, 36°C).

[0138] Table 4 is the measured voltage value (V) of the battery pack and each single cell at each measurement time in Step E

[0139]

[0140] Step F: The battery pack was charged at 10A constant current to 14.8V, then charged at 14.8V constant voltage until the current was less than 5A, then overcharged at 5A constant current for 6hrs, then rested for 1h, then discharged at 10A to 10.5V, and the battery pack was rested for 10min; the discharge capacity was measured to be 22.01Ah (2h rate, 34.5°C)

[0141] Table 5 is the measured voltage value (V) of the battery pack and each single cell at each measurement time in Step F

[0142]

[0143] Step G: The battery pack was charged at 10A constant current to 14.8V, then charged at 14.8V constant voltage until the cumulative charging time of constant current and constant voltage reached 3.5h, then stopped charging, then rested for 1h, then discharged at 10A to 10.5V, and the battery pack was rested for 10min; the discharge capacity was measured to be 20.90Ah (2h rate, 30°C), and the coulombic efficiency of charge and discharge was 92.1%

[0144] Table 6 is the measured voltage value (V) of the battery pack and each single cell at each measurement time in Step G

[0145]

[0146] From the comparison of the consistency of the battery pack at each time in Tables 1-6, it can be seen that the consistency of the battery pack of the present embodiment is obviously improved after the implementation of steps A-G. Meanwhile, from the comparison of the relevant data before the implementation of step A and the relevant data after the implementation of step G in terms of the capacity of the battery pack and the charge-discharge efficiency, it can be seen that the discharge capacity and the charge-discharge efficiency of the battery pack are increased from 9.473 Ah and 82.2% before the implementation of step A to 20.9 Ah and 92.1%, respectively.

[0147] Note: 14.8V has exceeded the gas evolution potential in the electrochemical reaction system of the present battery pack.

[0148] The above description is only the preferred embodiment of the present application, but the protection scope of the present application is not limited to this. Any change or replacement within the technical range disclosed by the present application can be easily thought by those skilled in the art, and should be covered in the protection scope of the present application.

Claims

1. A method of improving the consistency of a lead acid battery pack, characterized by, The lead-acid battery pack comprises two or more single cells connected in series or / and parallel, and the method comprises the following steps: Step 1: discharging the lead-acid battery pack so that the voltage of the lead-acid battery pack decreases from a positive voltage to 0V; Step 2: reverse-polarity charging the lead-acid battery pack; Step 3: reverse-polarity discharging the lead-acid battery pack so that the voltage of the lead-acid battery pack increases from a negative voltage to 0V; Step 4: normal-polarity charging the lead-acid battery pack to a threshold voltage; Before, during and after the implementation, the electrolyte of each single cell in the lead-acid battery pack is in excess; the excess amount of the electrolyte of each single cell in the battery pack is controlled to be in a range where the minimum amount of the excess amount divided by the maximum amount is greater than or equal to 50%, and the excess amount is the mass or volume; the maximum difference between the liquid levels of the electrolyte of each single cell is less than the distance from the average value of the liquid levels of the electrolyte of each single cell to the top of the electrode or active material; the liquid amount of the excess electrolyte is not less than 5% of the original electrolyte liquid amount of the battery; In step 2 and / or 4, the lead-acid battery pack is heated so that the temperature of the battery pack or the electrolyte in the single cell is higher than the room temperature or the upper limit temperature of the temperature control range during the conventional use or repair of the lead-acid battery; the heating of the lead-acid battery pack comprises the following steps: firstly, using the heat generated from the inside to the outside of the single cell during reverse-polarity charging and normal-polarity charging to heat the lead-acid battery pack so that the temperature of the lead-acid battery pack or the electrolyte increases, and the heat generated from the inside to the outside of the single cell includes the heat generated by the chemical reaction, electrochemical reaction and current passing through the internal resistance of the battery during reverse-polarity charging; when the heat generated from the inside to the outside of the single cell during reverse-polarity charging and normal-polarity charging is insufficient to make the temperature of the lead-acid battery pack or the electrolyte reach a predetermined value or range, an external heating source is used to heat the lead-acid battery pack so that the temperature of the lead-acid battery pack or the electrolyte increases; After step 4, the lead-acid battery pack is overcharged at least once before liquid removal; After step 4, the lead-acid battery pack is subjected to at least one more charging and discharging cycle before liquid removal, and the depth of the charging and discharging cycle is more than 30%.

2. The method of improving consistency of lead acid battery packs of claim 1, wherein, Before, during and after steps 1, 2, 3 and 4, the liquid level or amount and concentration of the electrolyte of the battery are adjusted through liquid supplementing and / or liquid removing operations; The liquid supplementing operation for each single cell in the lead-acid battery pack comprises the following steps: Obtaining the liquid level or amount of the electrolyte in each single cell; Determining whether the liquid level or amount of the electrolyte in each single cell is lower than a threshold value, and if yes, supplementing liquid into the single cell with the electrolyte liquid level lower than the threshold value, and if no, no liquid supplementing is needed; The liquid removing operation for each single cell in the lead-acid battery pack comprises the following steps: Obtaining the liquid level or amount of the electrolyte in each single cell; Determining whether the liquid level or amount of the electrolyte in each single cell is higher than a threshold value, and if yes, removing liquid from the single cell with the electrolyte liquid level or amount higher than the threshold value, and if no, no liquid removing is needed; The liquid is water or a liquid containing water.

3. The method of improving consistency of lead acid battery packs of claim 2, wherein, The liquid supplementing and / or liquid removing operation further comprises the following steps: before, during and after the liquid supplementing and / or liquid removing operation, The lead-acid battery is subjected to air extraction.

4. The method of improving consistency of lead acid battery packs of claim 1, wherein, In step 2, the lead-acid battery is subjected to reverse polarity charging, so that the voltage of the lead-acid battery is decreased from 0V to ≤n×(-1.75±0.1)V; And / or, in step 4, the lead-acid battery is subjected to forward polarity charging, so that the voltage of the lead-acid battery is increased from 0V to n×(1.75±0.1)V or above; n is the number of single cells connected in series in the lead-acid battery, and n is 1 when the single cells in the lead-acid battery are connected in parallel.

5. The method of improving consistency of lead acid battery packs of claim 1, wherein, In step 2, the single cells are subjected to gas evolution reaction during reverse polarity charging.

6. The method of improving consistency of lead-acid battery packs of claim 1, wherein, Before, during or after the implementation of steps 1, 2, 3 and 4, the following steps are further included: The battery tank or the liquid injection port of each single cell is communicated with a container; Or, the space containing the electrolyte of the single cell is opened.

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