Water-soluble lead-acid battery charging and discharging method and battery

Abstract

The invention belongs to the technical field of electrochemical energy storage, and particularly relates to a water-soluble lead-acid battery charging and discharging method and a battery. The charging and discharging method provided by the invention comprises the following steps: during charging, adjusting an electrode to a first height of electrolyte; during discharging, adjusting the electrode to a second height of the electrolyte; the first height is lower than the second height. By utilizing the acid floating and lead sinking effects caused by solute density difference in the charge-discharge cycle of the lead-acid battery electrolyte, an electrode is positioned at the bottom of the electrolyte which is beneficial to lead ion supplement and acid liquor removal in the charging process, the electrode polarization can be reduced, and the negative electrode lead dendritic crystal growth can be inhibited; in the discharging process, the electrode is located at the top of the electrolyte beneficial to acid liquid supplement and lead ion removal, electrode polarization can be reduced, the electrode is fully discharged, and active substances falling off from the positive electrode can be settled to the surface of the negative electrode to be reduced and regenerated.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage technology, and particularly relates to a method for charging and discharging a water-soluble lead-acid battery and the battery itself. Background Technology

[0002] Water-soluble lead-acid batteries are a type of electrochemical energy storage technology that uses water-soluble lead salts as redox active materials. Their main characteristic is that during charging, divalent lead ions in the electrolyte are reduced to lead at the negative electrode and oxidized to lead dioxide at the positive electrode, depositing as conductive solids on the surfaces of both electrodes. During discharge, they dissolve back into lead ions. This continuous deposition and dissolution of the active material during charging and discharging avoids the capacity decay caused by structural damage during charging and discharging, as is common in lithium-ion and lead-acid batteries. This simplifies the electrode manufacturing process and results in a high areal capacity.

[0003] Water-soluble lead-acid batteries mainly suffer from two problems: ① Lead dendrite growth at the negative electrode during charging, causing short circuits; ② Active material detaches from the positive electrode during discharging, failing to dissolve and leading to a continuous decrease in lead ion concentration in the electrolyte and battery capacity decay. For problem ①, lead dendrite growth can be suppressed by optimizing the electrolyte composition (e.g., selecting a suitable acid, adding dendrite inhibitors) and stirring the electrolyte. For problem ②, redox couples such as iron and vanadium can be added as lead dissolving agents, and the electrolyte can be stirred to promote the dissolution of detached active material. However, the shuttle discharge of the lead dissolving agent between the positive and negative electrodes can cause self-discharge, thereby reducing current efficiency. In view of this, Chinese patent CN120389126A discloses a water-soluble lead-acid static battery in which the active material detached from the positive electrode can settle to the surface of the negative electrode and be reduced, eliminating the need for stirring equipment. The shuttle discharge of the lead dissolving agent can be slowed down by avoiding the use of lead dissolving agents or keeping the electrolyte static.

[0004] However, during the discharge process of this water-soluble lead-acid static battery, the diffusion and exchange of hydrogen and lead ions between the upper and lower layers of the electrolyte is slow, and when the current density is too high (positive maximum greater than 20 mA / cm²), the exchange becomes even more difficult. 2 Water-soluble lead-acid batteries are prone to intensified polarization and incomplete discharge due to the accumulation of discharge products. In addition, water-soluble lead-acid batteries have a self-discharge problem after charging: the electrode potential of lead dioxide at the positive electrode is higher than that of oxygen, which easily leads to oxygen evolution side reaction and consumption of active materials; if the electrolyte contains lead solvent, self-discharge will be accelerated. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, this invention provides a method for charging and discharging a water-soluble lead-acid battery and a battery that can fully utilize the concentration stratification effect of the solute under the action of density difference, reduce electrode polarization during the charging and discharging process, and improve charging and discharging efficiency.

[0006] To achieve the above objectives, the technical solution provided by the present invention is as follows: In a first aspect, the present invention provides a method for charging and discharging a water-soluble lead-acid battery, comprising: during charging, adjusting the electrode to a first height of the electrolyte; during discharging, adjusting the electrode to a second height of the electrolyte; wherein the first height is lower than the second height.

[0007] Optionally, the first height is the bottom height of the electrolyte along the vertical direction, and the second height is the top height of the electrolyte along the vertical direction.

[0008] Optionally, the electrode includes a positive electrode and a negative electrode, with the negative electrode disposed below the positive electrode or extending below the positive electrode; during charging, the electrode is adjusted to the bottom of the electrolyte; during discharging, the electrode height is adjusted to the top of the electrolyte.

[0009] Optionally, adjusting the electrode to the first height of the electrolyte includes: keeping the positions of the electrolyte and the container holding the electrolyte unchanged while lowering the electrode height; or, keeping the electrode position unchanged while raising the height of the electrolyte and the container holding the electrolyte; or, keeping the relative positions between the electrode and the container holding the electrolyte unchanged while rotating the battery in the direction that lowers the height of the electrode in the electrolyte.

[0010] The adjustment of the electrode to the second height of the electrolyte includes: keeping the positions of the electrolyte and the container holding the electrolyte unchanged, raising the electrode height; or, keeping the electrode position unchanged, lowering the height of the electrolyte and the container holding the electrolyte; or, keeping the relative positions between the electrode and the container holding the electrolyte unchanged, rotating the battery in the direction that raises the height of the electrode in the electrolyte.

[0011] Optionally, the rotating battery includes: rotating the battery about any horizontal axis.

[0012] Optionally, when the battery stops charging or discharging, adjust one or more of the electrodes to be outside the electrolyte.

[0013] Optionally, when lead residue appears on the negative electrode of the battery, the negative electrode area can be moved outside the electrolyte to accelerate the oxidation of lead by air.

[0014] Secondly, this application also provides a water-soluble lead-acid battery for implementing the water-soluble lead-acid battery charging and discharging method described in the first aspect, comprising a battery cell, the battery cell comprising an electrode, an electrolyte and a container for holding the electrolyte, the electrode being disposed in the electrolyte, and the height of the electrode in the electrolyte being adjustable.

[0015] Optionally, it also includes a lifting drive component, one end of which is fixed and the other end is connected to an electrode.

[0016] Optionally, it also includes an outer shell and a sliding drive, wherein the electrode is fixed to the outer shell, the container holding the electrolyte is slidably connected to the outer shell, and the sliding drive is used to drive the container holding the electrolyte to slide along the outer shell.

[0017] Optionally, the sliding drive includes a retractable chamber disposed on the outer shell. The retractable chamber is arranged below the container holding the electrolyte, with the bottom of the electrolyte serving as the interface between the container and the retractable chamber. The retractable chamber is provided with a filler inlet and / or outlet, which are used to fill or discharge filler into the retractable chamber to extend or shorten the retractable chamber.

[0018] Optionally, the filler is one of a liquid, a solid, or a gas.

[0019] Optionally, the container holding the electrolyte includes a flexible telescopic container, the electrolyte is placed in the flexible telescopic container, the electrode is connected to the top wall of the flexible telescopic container, and the flexible telescopic container is provided with an inflation port and an exhaust port.

[0020] Optionally, the battery cell is also provided with an exhaust valve, which is used to balance the internal and external air pressure.

[0021] Optionally, the battery cells are connected in series and / or in parallel.

[0022] Optionally, the electrolyte includes a water-soluble lead salt, an acid, and water.

[0023] Optionally, the electrolyte may also include a lead-dissolving agent.

[0024] Optionally, the soluble lead salt includes one or more of lead fluoroborate, lead methanesulfonate, lead trifluoromethanesulfonate, lead perchlorate, and lead fluorosilicate.

[0025] Optionally, the acid is one or more of fluoroboric acid, methanesulfonic acid, trifluoromethanesulfonic acid, perchloric acid, and fluorosilicic acid.

[0026] Optionally, the lead dissolving agent includes water-soluble iron(III), iron(II), vanadium(V), vanadium(IV), and vanadium(III) salts.

[0027] Compared with the prior art, the present invention has at least the following beneficial effects:

[0028] This invention fully utilizes the "acid floats and lead sinks" effect caused by the solute density difference in the lead-acid battery electrolyte during charge-discharge cycles. During charging, the electrode is positioned at the bottom of the electrolyte, which is conducive to lead ion replenishment and acid removal, thereby reducing electrode polarization and inhibiting the growth of lead dendrites on the negative electrode. During discharging, the electrode is positioned at the top of the electrolyte, which is conducive to acid replenishment and lead ion removal, thereby reducing electrode polarization, allowing the electrode to discharge fully, and enabling the active material detached from the positive electrode to settle to the surface of the negative electrode for reduction and regeneration.

[0029] The water-soluble lead-acid battery and charging / discharging method provided by this invention can charge and discharge at higher current densities, resulting in greater power.

[0030] The water-soluble lead-acid battery provided by this invention can disconnect the circuit from the inside, blocking the self-discharge when the battery is idle, thereby preserving power for a long time. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of a water-soluble lead-acid battery in the charging and discharging states according to an embodiment of the present invention, wherein a represents the charging state; b represents the discharging state; and c represents the disconnected state. Figure 2 This is a schematic diagram illustrating the charging and discharging state of a highly water-soluble lead-acid battery using a sliding drive mechanism, where a represents the charging state, b represents the discharging state, and c represents the disconnected state. Figure 3 This is a schematic diagram of the structure of a lead-acid battery with highly water-soluble electrodes in the electrolyte, where the retractable chamber is used to adjust the charge and discharge states. a represents the charging state; b represents the discharging state; and c represents the disconnected state. Figure 4 This is a schematic diagram showing how to adjust the electrode height in the electrolyte by rotating the battery, where a represents the charging state; b represents the discharging state; and c represents the disconnected state. Figure 5 This is a schematic diagram of a water-soluble lead-acid battery pack in a rotating state. Figure 6 The results of the charge-discharge test are for Comparative Example 1 of this invention; Figure 7 This is the charge-discharge test result of Comparative Example 2 of the present invention; Figure 8 The results are the charge / discharge test results of Embodiment 1 of the present invention; Figure 9 The results are the charge / discharge test results of Embodiment 2 of the present invention; Figure 10 This is a schematic diagram of the charging and discharging states of the water-soluble lead-acid battery in Embodiment 2 of the present invention, where a represents the charging state and b represents the discharging state. In the diagram: 1. Electrode; 2. Electrolyte; 3. Container; 4. Vent valve; 5. Outer shell; 6. Retractable chamber; 7. Battery cell. Detailed Implementation

[0032] The present invention will now be described in further detail with reference to the accompanying drawings:

[0033] Unless otherwise specified, the experimental methods used in the embodiments of this invention are all conventional methods.

[0034] All reagents and materials used in this example can be purchased routinely.

[0035] In Comparative Examples 1-2 and Examples 1-2, the electrolyte 2 was an aqueous solution of 1.5 M Pb(BF4)2 + 1 M HBF4 + 0.01 M Fe(BF4)2.

[0036] The present invention provides a water-soluble lead-acid battery, comprising a battery cell 7, wherein the battery cell 7 includes an electrode 1, an electrolyte 2 and a container 3 for holding the electrolyte, the electrode 1 is disposed in the electrolyte 2 and the height of the electrode 1 in the electrolyte 2 is adjustable, and the electrode 1 includes a positive electrode and a negative electrode.

[0037] In some embodiments of the present invention, a lifting drive component is also included, one end of which is fixed and the other end is connected to electrode 1.

[0038] like Figure 1 As shown, by keeping the container 3 containing the electrolyte and the electrolyte 2 at constant heights, the lifting drive (not shown in the figure) drives the electrode 1 to rise or fall, thus raising or lowering the electrode 1 within the electrolyte 2. The lifting drive can be any device capable of raising or lowering the electrode 1, such as a lifting platform, telescopic rod, etc.

[0039] In some embodiments of the present invention, a housing 5 and a sliding drive are also included. The electrode 1 is fixed to the housing 5, and the container 3 containing the electrolyte is slidably connected to the housing 5. The sliding drive is used to drive the container 3 containing the electrolyte to slide along the housing 5.

[0040] like Figure 2 As shown, the structure is piston-type. A sliding drive component slides along the slide rails of the outer casing 5, allowing the container 3 holding the electrolyte to rise and fall, thereby raising or lowering the electrode 1 within the electrolyte 2. The sliding drive component can be a piston rod, a telescopic component, etc.

[0041] Optionally, the sliding drive includes a retractable chamber 6 disposed on the outer shell 5. The retractable chamber 6 is arranged at the bottom of the container 3 containing the electrolyte. The bottom of the electrolyte 2 is the interface between the container 3 and the retractable chamber. The retractable chamber 6 is provided with a filler inlet and / or outlet. The inlet and outlet are used to fill or discharge filler into the retractable chamber 6 to extend or shorten the retractable chamber 6.

[0042] The filler is one of a liquid, a solid, or a gas.

[0043] like Figure 3 As shown, by injecting filler into the expandable chamber 6 through the inlet, the volume of the expandable chamber 6 increases, thereby raising the height of the electrolyte 2 and reducing the height of the electrode 1 in the electrolyte 2; conversely, when the filler is discharged, the height of the electrolyte 2 can be reduced.

[0044] In some embodiments of the present invention, the container 3 holding the electrolyte includes a flexible telescopic container, the electrolyte 2 is disposed in the flexible telescopic container, the electrode 1 is connected to the top wall of the flexible telescopic container, the flexible telescopic container is provided with an inflation port and an exhaust port, the height of the electrode 1 in the electrolyte 2 can be reduced by longitudinal compression or exhaust, and the height of the electrode 1 in the electrolyte 2 can be increased by longitudinal stretching or inflation.

[0045] The battery cell 7 is also equipped with an exhaust valve 4, which is used to balance the internal and external air pressure.

[0046] The adjustment of the electrode 1 to the first height of the electrolyte 2 includes: keeping the positions of the electrolyte 2 and the container 3 holding the electrolyte unchanged, and lowering the height of the electrode 1; or, keeping the position of the electrode 1 unchanged, and raising the height of the electrolyte 2 and the container 3 holding the electrolyte; or, keeping the relative position between the electrode 1 and the container 3 holding the electrolyte unchanged, and rotating the battery in the direction that lowers the height of the electrode 1 in the electrolyte 2. Figure 4 and Figure 10 As shown;

[0047] The adjustment of the electrode 1 to the second height of the electrolyte 2 includes: keeping the positions of the electrolyte 2 and the container 3 holding the electrolyte unchanged, and raising the height of the electrode 1; or, keeping the position of the electrode 1 unchanged, and lowering the height of the electrolyte 2 and the container 3 holding the electrolyte; or, keeping the relative position between the electrode 1 and the container 3 holding the electrolyte unchanged, and rotating the battery in the direction that raises the height of the electrode 1 in the electrolyte 2.

[0048] When the battery stops charging or discharging, adjust one of the electrodes to be outside the electrolyte.

[0049] When adjusting the height of electrode 1 in electrolyte 2 by rotating the battery, simply rotate the battery around any horizontal axis.

[0050] Example 1

[0051] Production Figure 1 As shown in Figure a, 50 mL of electrolyte 2 is placed in a container with a base area of ​​25 cm². 2In the cylindrical container 3, the negative electrode is a 3 cm × 3 cm copper sheet, and the positive electrode is a 2 cm × 2 cm single-sided conductive plastic plate (one side of which is covered with insulating tape), with the conductive side facing down. During charging, the negative electrode is placed at the bottom of the container 3, and the positive electrode is located 0.6 cm above the negative electrode. The charging current is 320 mA, the cutoff voltage is 2.6 V, and the charging time is 4 h. During discharging, the positive electrode is moved to near the liquid surface (0.1 cm below the liquid surface), and the negative electrode is placed 0.6 cm below the positive electrode. The discharging current is 160 mA, the cutoff voltage is 0 V, and the discharging time is 8 h. The charge-discharge cycle is repeated 5 times.

[0052] Comparative Example 1

[0053] The difference between this comparative example and Example 1 is that the positions of the positive and negative electrodes in the electrolyte 2 are not moved during the discharge process.

[0054] The test results for Comparative Example 1 are shown below. Figure 6 The average charging voltage was 2.164 V, the average discharging voltage was 1.559 V, the current efficiency was 79.2%, and the energy efficiency was 57.0%. As can be seen from the figure, the battery could not fully discharge due to the inability to replenish and remove reactants and products in the later stages of discharge, resulting in low current efficiency. Furthermore, because the battery could not fully discharge in each cycle, the lead ion concentration in electrolyte 2 continuously decreased, and the voltage increased with each cycle at the end of charging, exacerbating the oxygen evolution side reaction and leading to rapid capacity decay.

[0055] The test results for Example 1 are shown below. Figure 8 The average charging voltage is 2.190 V, the average discharging voltage is 1.534 V, the current efficiency is 93.8%, and the energy efficiency is 65.7%.

[0056] The current efficiency of Example 1 is significantly higher than that of Comparative Example 1. This is because the mass transfer efficiency is higher when electrode 1 is located at the liquid surface during discharge, resulting in more complete discharge and thus higher energy efficiency. The test results show that the 5-cycle charge-discharge patterns of Example 1 are similar, indicating that the battery capacity did not change significantly, and its cycle stability is better than that of Comparative Example 1. The voltage efficiency of Example 1 is slightly lower than that of Comparative Example 1 because Comparative Example 1 did not discharge sufficiently, leaving a large amount of porous lead oxide on the positive electrode surface. This lead oxide has a lower voltage plateau at the beginning of charging, while Example 1, due to more complete discharge and less residual lead oxide, has a shorter duration of the low voltage plateau at the beginning of charging, resulting in a higher average charging voltage. During discharge, the lead ion concentration in Comparative Example 1 decreases gradually while the hydrogen ion concentration increases gradually, leading to a higher battery discharge voltage. Although Comparative Example 1 has a slightly higher voltage efficiency, its energy efficiency and cycle stability are significantly lower than those of Example 1 due to its lower current efficiency.

[0057] Example 2

[0058] Production Figure 10 For the water-soluble lead-acid battery shown in Figure a, take a plastic box with internal dimensions of 5 cm × 5 cm × 5 cm as container 3; take a copper strip with dimensions of 7 cm × 5 cm, bend it into an L-shape, with the horizontal part measuring 4 cm × 5 cm and tightly attached to the bottom of container 3, and the vertical part measuring 3 cm × 5 cm and tightly attached to the left inner wall of the container, connect it with a wire and lead it out of container 3 as the negative electrode of the battery; take a conductive plastic plate with dimensions of 1 cm × 4 cm, connect one side to a copper current collector and cover it with epoxy resin for insulation, and the other side is a conductive surface, place it face down in container 3, 1 cm above the negative electrode, with the right side of the positive electrode 1 cm away from the right inner wall and 0.5 cm away from the front and rear inner walls, and lead the current collector out of container 3 as the positive electrode; cover container 3 with a cap with an exhaust valve 4, and seal the edge of the cap with epoxy resin, open the exhaust valve 4, inject 88 mL of electrolyte 2 into container 3, close the valve, and the battery is completed.

[0059] During charging, the battery remains Figure 10 As shown in state a, the charging current is 320 mA, the duration is 4 h, and the cutoff voltage is 2.5 V; during the discharge process, the battery is rotated 90° along the horizontal axis. Figure 10 As shown in b, the discharge current is 160 mA, the duration is 8 h, the cutoff voltage is 0 V, and the cycle is 3 times.

[0060] Comparative Example 2

[0061] The difference between this comparative example and Example 2 is that the battery always maintains [a certain state] during the charging and discharging process. Figure 10 The state shown in figure a indicates that the battery does not rotate during charging and discharging.

[0062] The test results for Comparative Example 2 are shown below. Figure 7 Due to the accumulation of lead ions and the consumption of hydrogen ions at the bottom of electrolyte 2, electrode 1 at the bottom of container 3 cannot discharge fully, and the current efficiency of the second cycle is less than 42.0%. The third cycle is terminated because it cannot charge and discharge normally.

[0063] The test results of Example 2 are shown below. Figure 9 The average current efficiency reached 94.9%, voltage efficiency 71.0%, and energy efficiency 67.3% after 3 rotations. This demonstrates that by adjusting the height of the battery by rotating it around a horizontal axis, electrode 1 is positioned at the bottom of the electrolyte 2 during charging and near the surface during discharging, effectively improving the battery's charging and discharging efficiency.

[0064] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and optimizations can be made based on the content of this specification. The embodiments selected and specifically described in this specification are intended to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and apply the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for charging and discharging a water-soluble lead-acid battery, characterized in that, include: During charging, adjust the electrodes to the first height of the electrolyte; During discharge, the electrode is adjusted to the second height of the electrolyte; the first height is lower than the second height.

2. The method for charging and discharging a water-soluble lead-acid battery according to claim 1, characterized in that, The first height is the bottom height of the electrolyte along the vertical direction, and the second height is the top height of the electrolyte along the vertical direction.

3. The method for charging and discharging a water-soluble lead-acid battery according to claim 2, characterized in that, The electrode includes a positive electrode and a negative electrode. The negative electrode is located below the positive electrode, or the negative electrode extends below the positive electrode. During charging, the electrode is adjusted to the bottom of the electrolyte. During discharging, the electrode height is adjusted to the top of the electrolyte.

4. The method for charging and discharging a water-soluble lead-acid battery according to claim 1, characterized in that, The adjustment of the electrode to the first height of the electrolyte includes: keeping the positions of the electrolyte and the container holding the electrolyte unchanged, and lowering the electrode height; or, keeping the electrode position unchanged, and raising the height of the electrolyte and the container holding the electrolyte; or, keeping the relative position between the electrode and the container holding the electrolyte unchanged, and rotating the battery in the direction that lowers the height of the electrode in the electrolyte. The adjustment of the electrode to the second height of the electrolyte includes: keeping the positions of the electrolyte and the container holding the electrolyte unchanged, raising the electrode height; or, keeping the electrode position unchanged, lowering the height of the electrolyte and the container holding the electrolyte; or, keeping the relative positions between the electrode and the container holding the electrolyte unchanged, rotating the battery in the direction that raises the height of the electrode in the electrolyte.

5. The method for charging and discharging a water-soluble lead-acid battery according to claim 4, characterized in that, The rotating battery includes: the battery rotating about any horizontal axis.

6. The method for charging and discharging a water-soluble lead-acid battery according to claim 1, characterized in that, When the battery stops charging or discharging, adjust one of the electrodes to be outside the electrolyte.

7. A water-soluble lead-acid battery, characterized in that, A method for charging and discharging a water-soluble lead-acid battery according to any one of claims 1-6 includes a battery cell, the battery cell including an electrode, an electrolyte and a container for holding the electrolyte, the electrode being disposed in the electrolyte, and the height of the electrode in the electrolyte being adjustable.

8. The water-soluble lead-acid battery according to claim 7, characterized in that, It also includes a lifting drive, one end of which is fixed and the other end is connected to the electrode; and / or, it also includes a housing and a sliding drive, the electrode is fixed to the housing, the container holding the electrolyte is slidably connected to the housing, and the sliding drive is used to drive the container holding the electrolyte to slide along the housing.

9. The water-soluble lead-acid battery according to claim 8, characterized in that, The sliding drive includes a retractable chamber disposed on the outer shell, the retractable chamber being arranged below the container holding the electrolyte, and the retractable chamber being provided with a filler inlet and / or outlet, the inlet and outlet being used to fill or discharge filler into the retractable chamber to extend or shorten the retractable chamber.

10. The water-soluble lead-acid battery according to claim 7, characterized in that, The container for holding the electrolyte includes a flexible telescopic container, in which the electrolyte is placed, and the electrodes are connected to the top wall of the flexible telescopic container. The flexible telescopic container is provided with an inflation port and an exhaust port.

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