A method for recovering the capacity of a water-soluble lead-acid battery

Abstract

This invention discloses a method for capacity recovery of water-soluble lead-acid batteries in the field of electrochemical energy storage technology. It aims to solve the problem of capacity decay caused by the oxygen evolution side reaction during the charging and discharging process of water-soluble lead-acid batteries, where the evolved oxygen is difficult to reduce, leading to lead ions in the battery electrolyte being reduced to lead but unable to dissolve, thus causing capacity decay. The method includes: using a regenerated electrode as the cathode and the positive and / or negative electrode of the water-soluble lead-acid battery as the anode, oxidizing and dissolving residual lead into lead ions, thereby restoring battery capacity. This invention is simple to operate, consumes only water and electricity, is low in cost, has high capacity recovery efficiency, and can be adapted to various structures of water-soluble lead-acid batteries, such as gravity-fed and flow-fed batteries.

Description

Technical Field

[0001] This invention relates to the field of electrochemical energy storage technology, and in particular to a method for restoring the capacity of a water-soluble lead-acid battery. Background Technology

[0002] Water-soluble lead-acid batteries are a type of rechargeable battery that uses water-soluble lead salts as redox active materials. During charging, lead ions in the electrolyte react with water and are deposited at the positive and negative electrodes as lead dioxide and lead, respectively. Hydrogen ions from water dissociation replace lead ions, increasing the acidity of the electrolyte. During discharging, lead dioxide and lead dissolve into lead ions, while hydrogen ions are consumed, decreasing the acidity of the electrolyte. The corresponding electrode reaction equations are as follows.

[0003] positive electrode: ,

[0004] negative electrode: ,

[0005] Overall reaction: ;

[0006] In this equation, the reaction direction to the right represents charging, and to the left represents discharging. Water-soluble lead-acid batteries have many advantages, such as simple structure, low cost of electrodes and electrolytes, non-flammable electrolyte, and easy recycling, and they have broad prospects in the field of energy storage.

[0007] However, conventional water-soluble lead-acid batteries experience rapid capacity decay during charge and discharge. The reasons for this capacity decay are: ① the positive electrode active material, after detaching during discharge, cannot participate in the discharge dissolution process; and ② the oxygen released from the positive electrode during charge and discharge is difficult to participate in the discharge reaction, leading to the deposition of lead ions in the electrolyte that cannot be redissolved, thus causing a decrease in the lead ion concentration in the electrolyte.

[0008] Regarding question ①, existing water-soluble lead-acid battery technology has significantly slowed down battery capacity decay by improving electrolyte composition and battery structure, allowing the detached positive electrode active material to dissolve during discharge. Regarding question ②, due to the loss of the positive electrode oxidant in the form of oxygen evolution, the battery exhibits excess lead at the negative electrode. The oxygen evolution side reaction process is as follows...

[0009] Overall reaction: ;

[0010] According to the reaction formula, the oxygen evolution reaction (OER) causes battery capacity decay because lead ions and water are decomposed into oxygen (escape), lead, and hydrogen ions. Existing technologies typically use oxidants (such as oxygen or hydrogen peroxide) to dissolve excess lead at the negative electrode and consume excess hydrogen ions in the electrolyte. Oxygen dissolution of lead is essentially the reverse of the OER; a complete reaction can restore the electrolyte composition to its initial state. However, its efficiency is low due to the rate of the oxygen reduction reaction. Hydrogen peroxide has high lead dissolution efficiency, but the reagent cost is high, and hydrogen peroxide solutions contain a large amount of water, easily diluting the electrolyte. Using other oxidants to dissolve lead may introduce impurities. Summary of the Invention

[0011] The purpose of this invention is to overcome the battery capacity decay problem caused by oxygen evolution side reaction in existing water-soluble lead-acid battery technology, and to provide a method for restoring the capacity of water-soluble lead-acid batteries.

[0012] To solve the above-mentioned technical problems, the present invention is implemented using the following technical solution:

[0013] The present invention provides a method for restoring the capacity of a water-soluble lead-acid battery, comprising: connecting a regenerating electrode to the electrolyte of the water-soluble lead-acid battery, using the positive electrode and / or negative electrode of the water-soluble lead-acid battery as the anode, and using the regenerating electrode as the cathode, to restore the capacity of the water-soluble lead-acid battery.

[0014] Optionally, the regenerated electrode includes a current collector and a regenerated electrode electrolyte; the regenerated electrode electrolyte includes one or more of a battery electrolyte and an acid solution; the current collector is disposed in the regenerated electrode electrolyte.

[0015] Optionally, the regeneration electrode includes a diaphragm for separating and connecting different electrolytes; the diaphragm is one or more of an ion exchange membrane and a porous membrane.

[0016] Optionally, the positive electrode and / or negative electrode of the water-soluble lead-acid battery are connected to the positive terminal of the power supply, and the regenerating electrode is connected to the negative terminal of the power supply. After the power is turned on, hydrogen gas and / or lead are released on the surface of the current collector of the regenerating electrode, and lead dioxide is released from the positive electrode of the water-soluble lead-acid battery or the lead on the negative electrode is dissolved. The negative electrode is connected to the positive terminal of the power supply by circuit connection or by lead dissolving agent in the battery electrolyte.

[0017] Optionally, the regenerated electrode includes a lead dioxide electrode; the lead dioxide electrode is connected to the negative electrode of the water-soluble lead-acid battery via a circuit connection and / or a lead-dissolving agent in the battery electrolyte, so that the lead dioxide in the regenerated electrode is reduced and the lead on the negative electrode of the water-soluble lead-acid battery is dissolved.

[0018] Optionally, the lead dioxide electrode is prepared by the following steps: immersing a regenerated electrode comprising a current collector, a regenerated electrode electrolyte, and a separator into the battery electrolyte and connecting it to the negative terminal of a power supply; immersing an inert current collector into the battery electrolyte and connecting it to the positive terminal of a power supply; the lead dioxide deposited on the inert current collector after energization is the lead dioxide electrode.

[0019] Optionally, the lead on the current collector is transferred to the battery electrolyte for anodic oxidation dissolution.

[0020] Optionally, it also includes replenishing the water lost due to electrolysis in the regenerated electrode electrolyte and battery electrolyte.

[0021] Optionally, it also includes battery capacity measurement; the battery capacity measurement includes measuring the amount of residual lead on the negative electrode after the water-soluble lead-acid battery is fully discharged, and one or more of the following indicators of the battery electrolyte: lead ion concentration, hydrogen ion concentration, electrode potential, density, refractive index, and absorbance.

[0022] Optionally, the amount of charge to be transferred by the regenerated electrode and / or the positive electrode and / or the negative electrode can be determined based on the capacity of the water-soluble lead-acid battery and the current efficiency of the regenerated electrode and / or the positive electrode and / or the negative electrode.

[0023] Compared with the prior art, the beneficial effects achieved by the present invention are: it can efficiently reverse the battery capacity decay caused by oxygen evolution at the positive electrode and restore the battery capacity online; the capacity recovery method is simple to operate, consumes only water and electricity, does not introduce impurities, is low in cost, has high capacity recovery efficiency, and is suitable for water-soluble lead-acid batteries with various structures such as gravity type and flow type. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a method for restoring the capacity of a water-soluble lead-acid battery according to an embodiment of the present invention, wherein a represents the case where the negative electrode is connected to the positive terminal of the power supply, and b represents the case where the positive electrode is connected to the positive terminal of the power supply.

[0025] Figure 2 A schematic diagram illustrating the restoration of the capacity of a flow-type water-soluble lead-acid battery using a regenerative electrode comprising a lead dioxide electrode, according to an embodiment of the present invention.

[0026] Figure 3 This is a schematic diagram of a lead dioxide electrode electrolytic preparation method according to an embodiment of the present invention;

[0027] Figure 4 This is a schematic diagram of a method for restoring the capacity of a water-soluble lead-acid battery according to an embodiment of the present invention;

[0028] In the diagram: 1-positive electrode; 2-negative electrode; 3-battery electrolyte; 4-regenerating electrode; 41-current collector; 42-regenerating electrode electrolyte; 43-diaphragm; 44-lead dioxide electrode; 5-circulating pump; 6-graphite felt. Detailed Implementation

[0029] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical solution of the present invention, rather than limitations thereof. In the absence of conflict, the embodiments of the present invention and the technical features in the embodiments can be combined with each other.

[0030] It should be noted that the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0031] This invention proposes a method for restoring the capacity of a water-soluble lead-acid battery, comprising: connecting a regenerating electrode 4 to the electrolyte 3 of the water-soluble lead-acid battery, using the positive electrode 1 and / or negative electrode 2 of the water-soluble lead-acid battery as the anode, and the regenerating electrode 4 as the cathode, to restore the capacity of the water-soluble lead-acid battery.

[0032] A water-soluble lead-acid battery includes a positive electrode 1, a negative electrode 2, and a battery electrolyte 3. The battery electrolyte 3 includes a water-soluble lead salt, an acid, and water. The water-soluble lead salt is one or more of lead fluoroborate, lead methanesulfonate, lead trifluoromethanesulfonate, lead perchlorate, and lead fluorosilicate. The acid is one or more of fluoroboric acid, methanesulfonic acid, trifluoromethanesulfonic acid, perchloric acid, and fluorosilicic acid. A lead-dissolving agent may also be added to the battery electrolyte 3. The lead-dissolving agent includes one or more of water-soluble iron (III) salt, iron (II) salt, vanadium (V) salt, vanadium (IV) salt, and vanadium (III) salt.

[0033] The regenerating electrode 4 includes a current collector 41, a regenerating electrode electrolyte 42, and a separator 43. The regenerating electrode electrolyte 42 includes one or more of battery electrolyte and acid solution. The current collector 41 is one or more of copper, conductive plastic, and graphite felt, and the current collector 41 is disposed in the regenerating electrode electrolyte 42. The separator 43 is used to separate and connect different electrolytes, such as the regenerating electrode electrolyte 42 and the battery electrolyte 3. The separator 43 is one or more of ion exchange membrane and porous membrane. The regenerating electrode 4 also includes a lead dioxide electrode 44, which can be used alone as a regenerating electrode.

[0034] like Figure 1As shown, the regeneration electrode 4 is connected to the negative terminal of the power supply and to the battery electrolyte 3. The positive electrode 1 and / or negative electrode 2 are connected to the positive terminal of the power supply. After power is applied, the lead or lead ions in the water-soluble lead-acid battery are oxidized to lead ions or lead dioxide, that is, the lead on the negative electrode 2 dissolves or lead dioxide is precipitated on the positive electrode 1. The hydrogen ions in the battery electrolyte 3 pass through the separator 43 into the regeneration electrode 4, are reduced to hydrogen gas on the surface of the current collector 41, and escape. The overall reaction formula is as follows.

[0035] The negative electrode is connected to the positive terminal of the power supply. ,

[0036] The positive electrode is connected to the positive terminal of the power supply. ,

[0037] Lead dioxide is deposited at the positive electrode 1, and after the concentration of hydrogen ions in the battery electrolyte 3 increases, the remaining lead on the positive electrode 1 and the negative electrode 2 discharges, as shown in the following reaction equation.

[0038] Lead dioxide and lead discharge: ;

[0039] The discharge reaction formula is superimposed on the "positive electrode connected to the positive terminal of the power supply" reaction formula. After simplification, the resulting reaction formula is the same as "negative electrode connected to the positive terminal of the power supply". Therefore, connecting either positive electrode 1 or negative electrode 2 to the positive terminal of the power supply can ultimately achieve the effect of restoring battery capacity.

[0040] If the positive electrode 1 and the negative electrode 2 are connected to the positive terminal of the power supply at the same time, for example, in a flow battery using a bipolar plate with the positive and negative electrodes on both sides, the bipolar plate may be connected to the positive terminal of the power supply at the same time. In this case, the residual lead on the negative electrode 1 will be oxidized to lead ions first due to the lower electrode potential.

[0041] The oxygen evolution reaction leads to the loss of oxidant in the battery, causing an imbalance in the ratio of oxidant to reductant. The hydrogen evolution reaction at the regenerating electrode 4, however, causes excess reductant in the battery to be released as hydrogen gas, thus restoring the battery to balance and capacity. This process consumes only water and electrical energy, making capacity recovery cost-effective and efficient. When water in the battery electrolyte 3 and the regenerating electrode electrolyte 42 is lost due to electrolysis, or when acid and water in the electrolyte are lost through evaporation or carryover, the corresponding acid and water can be added.

[0042] Ideally, the separator 43 allows hydrogen ions to pass through while completely blocking lead ions from entering the regeneration electrode 4, exhibiting selective hydrogen ion permeability. However, some commercially available separators 43 fail to achieve this ideal selective permeability. Therefore, a small amount of lead ions still permeate through the separator 43 from the battery electrolyte 3 into the regeneration electrode electrolyte 42, depositing as lead on the surface of the current collector 41. This results in lead ion loss from the battery electrolyte 3 and a loss of current efficiency. The current efficiency of the regeneration electrode 4 (including the current collector 41, the regeneration electrode electrolyte 42, and the separator 43) is the ratio of the amount of hydrogen gas produced to the amount of energy passing through the regeneration electrode 4. For water-soluble lead-acid batteries, the current efficiency of the positive electrode 1 and the current efficiency of the negative electrode 2 are respectively the amount of oxidized lead ions and the ratio of the amount of oxidized lead to the amount of energy passing through the positive electrode 1 and the negative electrode 2. The lead deposited on the current collector 41 can be transferred to the battery electrolyte 3 and dissolved as a water-soluble lead salt through anodic oxidation (the principle is the same). Figure 1 This prevents the loss of lead ions from the battery electrolyte 3.

[0043] For flow-type water-soluble lead-acid batteries, the small gap between the bipolar plates in the stack, the difficulty in disassembling the stack (some stacks use a welding process that makes disassembly impossible), and the high electrolyte resistance between the stack and the electrolyte tank make it difficult to directly connect the battery electrodes to the regeneration electrode via a circuit and restore capacity. The lead dioxide electrode 44 can be used as the regeneration electrode, and the negative electrode 2 and the lead dioxide electrode 44 can be connected through the lead-dissolving agent in the battery electrolyte 3, such as... Figure 2 As shown. Taking iron (II) salt lead dissolving agent as an example, the lead dioxide electrode 44 is placed into the storage tank of the flow battery. The iron (II) in the battery electrolyte 3 is oxidized to iron (III) by the regenerating electrode and transported to the negative electrode 2 of the battery via the circulation pump 5. The lead on the negative electrode 2 is oxidized to lead ions, while the lead dissolving agent is reduced to iron (II) and returned to the storage tank along with the battery electrolyte 3 to continue the next redox cycle. In this process, the lead dissolving agent in the battery electrolyte 3 only acts as a carrier for electron transfer between lead and lead dioxide and is not consumed itself, so it can be recycled. This capacity recovery method, which uses the lead dioxide electrode as the regenerating electrode and utilizes the lead dissolving agent in the battery electrolyte to connect the regenerating electrode and the negative electrode of the battery, can adapt to water-soluble lead-acid batteries with complex structures and has good adaptability.

[0044] Using an exogenous lead dioxide electrode as a regenerated electrode is equivalent to adding extra lead and oxygen elements to the water-soluble lead-acid battery system, which will cause the lead content of the battery to be higher than the initial level. To avoid this, the lead ions in the water-soluble lead-acid battery whose capacity needs to be restored can be used directly as the lead source to prepare the lead dioxide electrode 44, such as... Figure 3As shown. The specific steps are as follows: The current collector 41, the regenerated electrode electrolyte 42, and the separator 43 form a regenerated electrode, which is immersed in the battery electrolyte 3 whose capacity needs to be restored, and connected to the negative terminal of the power supply; the inert current collector is immersed in the battery electrolyte 3 whose capacity needs to be restored, and connected to the positive terminal of the power supply; the lead dioxide deposited on the inert current collector after power is applied is the lead dioxide electrode 44. The lead and oxygen elements of the lead dioxide electrode prepared in this way come from the battery itself whose capacity needs to be restored, and are endogenous, so it will not cause an increase in the lead content of the battery. Alternatively, if the lead ion concentration in the battery electrolyte 3 is too high due to the use of an exogenous lead dioxide electrode, a pair of current collectors are inserted into the battery electrolyte 3 and connected to the positive and negative terminals of the power supply. Lead is deposited on the current collector connected to the negative terminal of the power supply, and then the lead is removed from the battery electrolyte 3, which can reduce the lead content in the battery; the lead dioxide deposited on the current collector connected to the positive terminal of the power supply can remain in the battery and play the role of a regenerated electrode.

[0045] Battery capacity measurement includes measuring the amount of residual lead on the negative electrode 2 after the water-soluble lead-acid battery is fully discharged, and one or more of the following indicators of the battery electrolyte: lead ion concentration, hydrogen ion concentration, density, electrode potential, refractive index, and absorbance; and determining the amount of charge to be transferred by the regenerated electrode 4 and / or the positive electrode 1 and / or the negative electrode 2 based on the capacity of the water-soluble lead-acid battery and the current efficiency of the regenerated electrode 4 and / or the positive electrode 1 and / or the negative electrode 2.

[0046] Comparative Example 1

[0047] The comparative examples of this invention are used to verify that the capacity decay of water-soluble lead-acid batteries is caused by the oxygen evolution side reaction during the charge and discharge process. The specific steps are as follows:

[0048] Gravity-driven water-soluble lead-acid battery assembly: Internal bottom area 25 cm² 2 50 mL of a solution containing 1.5 M Pb(BF4)2 + 1 M HBF4 + 0.01 M Fe(BF4)2 was added to a cylindrical container with a height of 5 cm to serve as the battery electrolyte. 2 A copper sheet (1.4470 g) was held in place by an L-shaped electrode clamp and immersed in the bottom of the container as the negative electrode of the battery; 2.4 cm 2 A single-sided conductive plastic plate is held in place with the conductive side facing down, 0.6 cm above the negative electrode, serving as the positive electrode 1 of the battery.

[0049] Charge / discharge conditions: charging current 320 mA, charging cut-off voltage 2.3 V; during discharge, adjust positive electrode 1 to 0.1 cm below the liquid surface and negative electrode 2 to 0.6 cm below positive electrode 1, discharge current 160 mA, discharge cut-off voltage 0 V, after discharge, return the positive and negative electrodes to their original positions; repeat the above steps 5 times, i.e., 5 charge / discharge cycles. After 5 charge / discharge cycles, short-circuit the positive and negative electrodes and stir for 24 hours.

[0050] Because no maximum charging time was set, the lead ion concentration in the solution was low at the end of charging, resulting in the precipitation of a large number of bubbles at the positive electrode 1. Bubble precipitation was also observed during the discharge process. After constant current charging and discharging, and following a thorough short-circuit discharge, the lead oxide on the positive electrode 1 completely dissolved, while silvery-white metallic lead remained undissolved on the copper sheet of the negative electrode 2. The copper sheet was removed, washed, dried, and weighed; its mass was 2.0195 g. This comparative example verifies the phenomenon of excess lead at the negative electrode of the battery caused by the oxygen evolution side reaction, which leads to battery capacity decay.

[0051] Example 1

[0052] This embodiment is used for verification. Figure 1 The effectiveness of the capacity recovery method for water-soluble lead-acid batteries shown in diagram a is demonstrated by the following specific steps.

[0053] Preparation of battery electrolyte 3: Prepare 50 mL of 1.05 M Pb(BF4)2 + 1.9 M HBF4 solution and place it in a container with a bottom area of ​​25 cm². 2 In a cylindrical container, the state of the battery electrolyte with an initial concentration of 1.5 M Pb(BF4)2 + 1 M HBF4 after a 30% capacity decay was simulated.

[0054] Fabrication of negative electrode 2: A 3 cm × 3 cm copper sheet is held in an L-shaped electrode clamp, and an excess of lead (2400 mAh) is deposited on the copper sheet. After being removed, washed, dried, and weighed, the total mass of the electrode clamp and the electrode is 17.5450 g. The electrode is then immersed in the battery electrolyte 3 mentioned above to simulate the state of residual lead in the negative electrode of a water-soluble lead-acid battery.

[0055] Fabrication of regeneration electrode 4: Take a plastic tube with an inner diameter of 2.6 cm, use an ion exchange membrane as a diaphragm 43 to seal one end of the plastic tube, and the ion exchange region is a circle with a diameter of 1.4 cm; add 25 mL of 4 M HBF4 solution to the plastic tube as the electrolyte 42 for the regeneration electrode, insert a 1 cm × 10 cm copper sheet into the solution as the current collector 41, the copper sheet has a mass of 0.8850 g; plug the tube opening with a cotton ball to reduce the escape of acid mist.

[0056] like Figure 1As shown in Figure a, the ion exchange membrane 43 of the regeneration electrode 4 is immersed in the battery electrolyte 3, the copper sheet 41 is connected to the negative terminal of the power supply, and the battery negative electrode 2 is connected to the positive terminal of the power supply. The current is set to 100 mA and the upper limit of the voltage is 10 V. After 12 h of power supply, bubbles are observed to precipitate on the surface of the copper sheet 41 in the regeneration electrode 4, and the silvery-white metal on the battery negative electrode 2 dissolves.

[0057] The copper sheet 41 in the regeneration electrode 4 was removed. No solid deposits were found on its surface. After washing and drying, it was weighed and found to be 0.8836 g. The copper sheet 41 did not gain weight, indicating that the ion exchange membrane 43 has good selective permeability, allowing hydrogen ions to pass through while blocking lead ions, thus preventing lead deposition and improving the current efficiency of the regeneration electrode 4. The slight decrease in the mass of the copper sheet 41 is likely due to acid adhering to it from the bursting of hydrogen bubbles, which then oxidized and dissolved a small amount of copper under the influence of air. If the membrane 43 has poor selective permeability and metallic lead has deposited on the copper sheet 41, the lead can be scraped off and transferred to the battery electrolyte, or the copper sheet 41 can be transferred together with the lead sheet to the electrolyte for anode dissolution.

[0058] Remove the negative electrode 2 of the battery, wash and dry it, and weigh it; its mass is 12.8548 g. After transferring 1200 mAh of charge through the external circuit, the negative electrode 2 should theoretically lose 4.6386 g of mass. However, the actual measured mass loss was 4.6902 g, which is 1.11% higher than the theoretical value, meaning the anodic current efficiency is greater than 100%. The possible reason is that a small amount of anode sludge was generated during the lead dissolution process and was lost during rinsing. The error is within the experimentally acceptable range.

[0059] Weigh 5.00 mL of the battery electrolyte prepared by electrolysis. The mass is 7.6675 g, and the density is 1.55 g / cm³. 3 A 1.5 M Pb(BF4)2 + 1 M HBF4 solution was prepared, and the mass of 5.00 mL of the freshly prepared solution was measured to be 7.5437 g.

[0060] The density of the electrolyte 3 prepared by electrolysis was 1.64% higher than that of the freshly prepared solution. This may be due to the evaporation of water and fluoroboric acid in the electrolyte during the test, and the error is within the allowable range of the experiment.

[0061] This embodiment demonstrates that the water-soluble lead-acid battery capacity recovery method provided by the present invention can oxidize the lead connected to the positive electrode of the power supply into lead ions, while the excess hydrogen ions in the electrolyte are reduced to hydrogen gas at the regeneration electrode connected to the negative electrode of the power supply, thereby restoring the battery capacity. This process is highly efficient and inexpensive.

[0062] Example 2

[0063] This embodiment is used for verification. Figure 1The effectiveness of the capacity recovery method for water-soluble lead-acid batteries shown in b is demonstrated by the following specific steps.

[0064] Preparation of battery electrolyte 3: Prepare 50 mL of 1.05 M Pb(BF4)2 + 1.9 M HBF4 solution and place it in a container with a bottom area of ​​25 cm². 2 The cylindrical container simulates the battery electrolyte after capacity decay.

[0065] Fabrication of negative electrode 2: A 3 cm × 3 cm copper sheet with a mass of 0.7900 g was clamped in an L-shaped electrode clamp. A lead charge of 1200 mAh was deposited on the copper sheet. After removing, washing and drying, it was set aside to simulate the state of residual lead in the negative electrode of a water-soluble lead-acid battery.

[0066] Preparation of positive electrode 1: Clamp a 2 cm × 3 cm conductive plastic plate with an electrode clamp and immerse it in the above-mentioned battery electrolyte to simulate the positive electrode of the battery after discharge.

[0067] Fabrication of regenerated electrode 4: Same as in Example 1, the mass of copper sheet current collector 41 is 0.8739 g.

[0068] like Figure 1 As shown in b, the regenerated electrode 4 was immersed in the battery electrolyte 3, the copper sheet 41 was connected to the negative terminal of the power supply, and the positive electrode 1 was connected to the positive terminal of the power supply. The current was set to 100 mA and the upper limit of the voltage was 10 V. After 13.2 h of energization, bubbles were observed to precipitate on the surface of the copper sheet 41 in the regenerated electrode 4, and black solids were deposited on the positive electrode 1 and thickened. After the energization was completed, the regenerated electrode 4 was removed from the battery electrolyte 3, and the copper sheet 41 was removed, washed, dried, and weighed. The mass was 0.8708 g, and there was no silvery-white solid on the surface. The negative electrode 2 was placed in the battery electrolyte 3, located below the positive electrode 1, to form a gravity-type water-soluble lead-acid battery. It was fully discharged with a current of 160 mA (cutoff voltage 0.8 V). After the constant current discharge was completed, the solids on the positive electrode 1 were pulverized and detached, while a small amount of silvery-white metal remained on the negative electrode 2. Add 0.5 mL of a lead-dissolving solution consisting of 1 M Fe(BF4)2 + 2 M HBF4 to the battery electrolyte 3, and stir magnetically for 12 h. The silvery-white solid on the negative electrode 2 is completely dissolved, and a small amount of black solid remains at the bottom of the battery. The battery electrolyte 3 is light blue. The copper current collector of the negative electrode 2 is removed, washed, dried, and weighed. The mass is 0.6589 g.

[0069] After the lead dioxide in the positive electrode 1 is discharged in excess and fully, the copper sheet (current collector) of the negative electrode 2 will dissolve slightly. However, since copper is less reactive than lead, it will preferentially deposit on the negative electrode 2 during subsequent charging. The dissolution of the current collector of the negative electrode 2 can be prevented by replacing it with an inert current collector (such as conductive plastic) or controlling the discharge amount. The excess lead oxide produced by the positive electrode 1 will be reduced and dissolved by the remaining lead during subsequent charging and discharging.

[0070] This embodiment shows that the method provided by the present invention can pre-deposit lead dioxide on the positive electrode and then use lead dioxide to oxidize the residual lead on the negative electrode, thus achieving the same effect of battery capacity recovery.

[0071] Example 3

[0072] Considering the complex structure of some water-soluble lead-acid batteries, such as flow batteries, it is difficult to incorporate the regenerative electrode shown in Example 1 into the battery system. Furthermore, noting the potential advantages of Example 2's capacity recovery method, which utilizes pre-fabricated lead dioxide to oxidize excess lead on the negative electrode, this embodiment utilizes a lead-dissolving agent in the battery electrolyte to connect the lead dioxide electrode and excess lead, thereby restoring battery capacity. The specific steps are as follows.

[0073] Preparation of battery electrolyte 3: Prepare 100 mL of 0.5 M Pb(BF4)2 + 3 M HBF4 + 0.05 M Fe(BF4)2 solution for later use, wherein Fe(BF4)2 is the iron(II) salt lead dissolving agent used in this example.

[0074] Assembly of a flow-type battery cell: A liquid tank with a flow channel size of 3.3 cm × 3.3 cm × 0.8 cm is placed between two 7 cm × 7 cm conductive plastic plates. The liquid tank has an inlet and an outlet. The liquid tank and the conductive plastic plates are sealed with a 1 mm thick rubber sheet. The two conductive plastic plates are clamped together on both sides. The battery electrolyte is then introduced to form a flow-type water-soluble lead-acid battery cell.

[0075] Preparation of regenerated electrode 4: A lead dioxide electrode with a charge of 1200 mAh was deposited on a 2 cm × 3 cm conductive plastic plate (leaving a 2 cm × 1 cm bare plastic plate) to obtain lead dioxide electrode 44, which is the regenerated electrode 4 of this embodiment.

[0076] like Figure 2As shown, a 50 mL centrifuge tube was used as a storage tank, into which the regeneration electrode 4 was placed, and 50 mL of battery electrolyte 3 was added. 14.5532 g of lead sheet was added to the flow cell to simulate an excess of lead in the stack. A peristaltic pump was used as a circulation pump 5 to deliver the battery electrolyte 3 at a flow rate of 10 mL / min, allowing the electrolyte 3 to circulate between the storage tank and the flow cell. After 24 hours, no significant change in the size of the regeneration electrode was observed in the storage tank. The liquid in the flow cell was drained and the cell was disassembled. The lead sheet was removed, washed, dried, and weighed; its mass was 13.1119 g, meaning that 1.4413 g of lead dissolved in 24 hours, indicating low efficiency.

[0077] To improve lead dissolution efficiency, the exposed conductive plastic plate of regenerated electrode 4 was fixed together with a 2 cm × 5 cm × 0.3 cm graphite felt, placed in a centrifuge tube, and 50 mL of battery electrolyte 3 was added. 11.1024 g of lead sheet was added to the aforementioned flow cell, and the electrolyte was pumped using a peristaltic pump at a flow rate of 10 mL / min. After 12 h, the lead dioxide immersed in the solution was mostly dissolved (a small amount of undissolved portion remained at the bottom of the storage tank, with a small amount of black solid detached from regenerated electrode 4). The liquid in the flow cell was drained and the cell disassembled. The lead sheet was removed, washed, dried, and weighed; its mass was 8.3512 g, meaning 2.7512 g of lead dissolved in 12 h. Because the connection between the regenerated electrode and the graphite felt increased the reaction area of ​​the lead-dissolving agent, the lead dissolution efficiency was significantly improved.

[0078] In this embodiment, the electrolyte in the feed pipe of the flow cell is cut off by the peristaltic pump, and the end of the discharge pipe is suspended above the electrolyte in the storage tank. Therefore, the cell is disconnected from the electrolyte in the storage tank, and the regeneration electrode is not connected to the electrode circuit of the cell. The regeneration electrode 4 can oxidize the lead inside the cell (and the stack) simply by delivering the lead dissolving agent, demonstrating the high adaptability of the present invention to various complex battery structures.

[0079] Example 4

[0080] In conjunction with Examples 1 and 3, a capacity recovery method can also be adopted, in which the regenerating electrode 4 is connected to the negative terminal of the power supply, and the negative electrode 2 is connected to the positive terminal of the power supply through the lead-dissolving agent in the battery electrolyte 3. The specific steps are as follows:

[0081] Preparation of battery electrolyte 3: Same as in Example 3, except that ferrous salt is added as a lead solvent.

[0082] Flow cell assembly: Same as in Example 3, except that metallic lead is provided in the cell to simulate the lead remaining on the negative electrode 2.

[0083] Fabrication of regenerated electrode 4: Same as in Example 1.

[0084] like Figure 4 As shown, graphite felt 6 is placed in battery electrolyte 3 and connected to the positive terminal of the power supply, while regeneration electrode 4 is placed in battery electrolyte 3 and connected to the negative terminal of the power supply. After the power is turned on, ferrous ions in battery electrolyte 3 are oxidized to ferric ions on the surface of graphite felt 6, and excess hydrogen ions enter regeneration electrode 4 and are reduced to hydrogen gas; the ferric ions generated by oxidation reach the surface of negative electrode 2 via peristaltic pump (i.e., circulation pump 5), oxidizing lead to lead ions, while the ferric ions are reduced to ferrous ions and return to the surface of graphite felt 6 to be oxidized to ferric ions. This cycle repeats until all the lead remaining on negative electrode 2 is oxidized and dissolved. The overall reaction formula is the same as in Example 1.

[0085] In this embodiment, the negative electrode 2 is connected to the positive electrode of the power supply through a lead-soluble agent in the battery electrolyte 3. The lead-soluble agent in the electrolyte acts as a carrier for electron transfer between the negative electrode 2 and the positive electrode of the power supply, while the graphite felt 6 serves as an extension of the positive electrode of the power supply in the battery electrolyte 3 and is also the site where the lead-soluble agent releases electrons.

[0086] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A method for restoring the capacity of a water-soluble lead-acid battery, characterized in that, include: The regenerated electrode (4) is connected to the electrolyte (3) of the water-soluble lead-acid battery, with the positive electrode (1) and / or negative electrode (2) of the water-soluble lead-acid battery as the anode and the regenerated electrode (4) as the cathode, to restore the capacity of the water-soluble lead-acid battery. The regenerating electrode (4) includes a current collector (41), a regenerating electrode electrolyte (42), and a separator (43); the regenerating electrode electrolyte (42) includes one or more of a battery electrolyte (3) and an acid solution; the current collector (41) is disposed in the regenerating electrode electrolyte (42); the separator (43) is used to separate and connect different electrolytes; the separator (43) is one or more of an ion exchange membrane and a porous membrane; The positive electrode (1) and / or negative electrode (2) of the water-soluble lead-acid battery are connected to the positive terminal of the power supply, and the regeneration electrode (4) is connected to the negative terminal of the power supply. After the power supply is turned on, hydrogen gas and / or lead are released on the surface of the current collector (41) of the regeneration electrode (4), and lead dioxide is released on the positive electrode (1) of the water-soluble lead-acid battery or the lead on the negative electrode (2) is dissolved. The negative electrode (2) is connected to the positive terminal of the power supply by circuit connection or lead dissolving agent in the battery electrolyte (3). or, The regenerating electrode (4) includes a lead dioxide electrode (44); the lead dioxide electrode (44) is connected to the negative electrode (2) of the water-soluble lead-acid battery through a circuit connection and / or a lead dissolving agent in the battery electrolyte (3), so that the lead dioxide in the regenerating electrode (4) is reduced and the lead on the negative electrode (2) of the water-soluble lead-acid battery is dissolved.

2. The method for restoring the capacity of a water-soluble lead-acid battery according to claim 1, characterized in that, The lead dioxide electrode (44) is prepared by the following steps: the regenerated electrode (4) containing the current collector (41), the regenerated electrode electrolyte (42) and the separator (43) is immersed in the battery electrolyte (3) and connected to the negative terminal of the power supply; the inert current collector is immersed in the battery electrolyte (3) and connected to the positive terminal of the power supply; the lead dioxide deposited on the inert current collector after power is applied is the lead dioxide electrode (44).

3. The method for restoring the capacity of a water-soluble lead-acid battery according to claim 1, characterized in that, The lead on the current collector (41) is transferred to the battery electrolyte (3) as an anodic oxidation dissolution.

4. The method for restoring the capacity of a water-soluble lead-acid battery according to claim 1, characterized in that, It also includes replenishing the water lost due to electrolysis in the regenerated electrode electrolyte (42) and battery electrolyte (3).

5. The method for restoring the capacity of a water-soluble lead-acid battery according to claim 1, characterized in that, It also includes battery capacity measurement; the battery capacity measurement includes measuring the amount of residual lead on the negative electrode (2) after the water-soluble lead-acid battery is fully discharged, and one or more of the following indicators of the battery electrolyte (3): lead ion concentration, hydrogen ion concentration, electrode potential, density, refractive index and absorbance.

6. The method for restoring the capacity of a water-soluble lead-acid battery according to claim 1, characterized in that, Based on the capacity of the water-soluble lead-acid battery and the current efficiency of the regenerating electrode (4) and / or the positive electrode (1) and / or the negative electrode (2), determine the amount of charge to be transferred by the regenerating electrode (4) and / or the positive electrode (1) and / or the negative electrode (2).

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