Water-soluble plumbic acid static storage battery

Abstract

The invention relates to a water-soluble plumbic acid static storage battery. The battery comprises a battery monomer, the battery monomer comprises an electrode plate, a static electrolyte and a container, the electrode plate is inserted in the electrolyte, the electrolyte comprises water-soluble lead salt, acid and water, and the battery monomer further comprises a lead dissolving agent or a structure extending the bottom end of a negative plate to the position below a positive plate. The lead dissolving agent can provide at least one water-soluble redox couple R oxidation and R reduction, and the redox couple electrode potential meets E theta (Pb < 2 + > / Pb) lt; e [theta] (R oxidation / R reduction) [lt]; e theta (PbO2 / Pb2 +). No diaphragm exists, the electrolyte is in a static state, facilities such as a circulating pump are not needed, lead ions are allowed to migrate under the concentration gradient effect, and meanwhile self-discharge caused by convection shuttling of the lead dissolving agent is greatly reduced. In the charging process, lead and lead dioxide can be flatly deposited on the surface of an electrode and can be completely dissolved in the discharging process, the cycling stability is good, and the components can be kept stable for a long time.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochemical energy storage, and particularly relates to a water-soluble lead-acid static battery. Background Art

[0002] Since the advent of lead-acid batteries, they have been used for over a hundred years. Due to their safety, economy, and reliability, they are still widely used today. However, the production and recycling processes of lead electrodes have problems of heavy metal pollution, and the battery usually has a cycle life of only several hundred cycles. Pletcher et al. proposed a water-soluble lead-acid flow battery, which uses nickel sheets and carbon plastic plates as electrodes, lead methyl sulfonate and methyl sulfonic acid as active substances and supporting electrolytes. During charging, lead methyl sulfonate is deposited as lead metal and lead dioxide at the negative and positive electrodes respectively, and dissolves and regenerates during discharging. Compared with traditional lead-acid batteries, its production and recycling processes are simpler, less polluting, and the utilization rate of lead is higher; compared with conventional flow batteries, it does not require a diaphragm and can adopt a single-flow structure, greatly reducing the cost, so it has great development prospects. However, for the disclosed water-soluble lead-acid flow battery, due to the problems of oxygen evolution side reaction at the positive electrode and pulverization and shedding of the positive active substance at the end of discharging, the lead metal at the negative electrode cannot be completely dissolved. After several cycles, the concentration of lead ions in the electrolyte continuously decreases, resulting in capacity attenuation.

[0003] Patent CN110190312B discloses an electrolyte for a lead flow battery, which uses iron nitrate or hexafluoroferrate complex or iron chloride as a catalyst to promote the re-dissolution of the shed lead and lead dioxide into lead ions, thereby improving the cycle stability of the electrolyte. However, on the one hand, this solution does not mention whether a diaphragm or other isolation facilities are provided between the positive and negative electrodes. Without a diaphragm and when the iron concentration in the electrolyte reaches the level capable of effectively dissolving solid lead (lead, lead dioxide), iron ions / ferrous ions shuttle back and forth between the positive and negative electrodes during the electrolyte flow process, which is bound to cause self-discharge and thus reduce the current efficiency; if a diaphragm is used, it will increase the cost of the flow battery and is also prone to problems where it is difficult to dissolve the lead dendrites after shedding. On the other hand, the electrolyte of this solution also contains fluoride ions, cobalt ions, nitrate ions, and chloride ions. The presence of impurity ions will have a negative impact on the charge and discharge process: fluoride ions are prone to form free hydrofluoric acid molecules in a strong acidic solution, nitrate ions and chloride ions may participate in redox reactions, and are not conducive to the electrodeposition of lead at the negative electrode. Although this battery solves the problem of lead dioxide dissolution to a certain extent, it causes problems such as self-discharge, and impurity ions will affect the battery performance. Summary of the Invention

[0004] Aiming at the above problems existing in the prior art, the present invention provides a water-soluble lead-acid static battery, which can avoid the self-discharge problem caused by the electrolyte flow.

[0005] To achieve the above object, the technical solution provided by the present invention is as follows:

[0006] In a first aspect, the present application provides a water-soluble lead-acid static battery, including battery cells. Each battery cell includes electrode plates, an electrolyte in a static state, and a container for holding the electrolyte. The electrode plates are inserted into the electrolyte. The electrolyte composition includes a water-soluble lead salt, an acid, a lead solvent, and water. The lead solvent can provide at least one pair of water-soluble redox couples R 氧化 and R 还原 . The electrode potential of the redox couple satisfies E θ (Pb 2+ / Pb) < E θ (R 氧化 / R 还原 ) < E θ (PbO2 / Pb 2+ ).

[0007] In a second aspect, the present application provides a water-soluble lead-acid static battery, including battery cells. Each battery cell includes electrode plates, an electrolyte in a static state, and a container for holding the electrolyte. The electrode plates are inserted into the electrolyte. The electrolyte composition includes a water-soluble lead salt, an acid, and water,

[0008] The battery is a stack composed of a group of battery cells or at least two groups of battery cells connected in series; when the battery is a stack composed of battery cells connected in series, the electrolytes between different battery cells are isolated from each other;

[0009] In a battery cell, the electrode plates include a positive electrode plate and a negative electrode plate. The bottom end of the negative electrode plate extends below the positive electrode plate and / or the bottom end of the negative electrode plate is connected to the bottom end of the positive electrode plate through an isolation guiding plate; the isolation guiding plate is used to guide the active substances shed from the positive electrode plate to the negative electrode plate of the same battery cell under the action of gravity.

[0010] Optionally, the battery is a stack composed of a group of battery cells or at least two groups of battery cells connected in series; when the battery is a stack composed of battery cells connected in series, the electrolytes between different battery cells are isolated from each other.

[0011] Optionally, when the battery is a stack composed of battery cells connected in series, the electrode plates on both sides are used as the positive electrode and the negative electrode respectively, and bipolar plates are used for the electrode plates between the positive electrode and the negative electrode to isolate the electrolytes between different battery cells.

[0012] Optionally, in the battery cell, the electrode plate includes a positive electrode plate and a negative electrode plate. The bottom end of the negative electrode plate extends below the positive electrode plate and / or the bottom end of the negative electrode plate is connected to the bottom end of the positive electrode plate through an isolation guiding plate. The isolation guiding plate is used to guide the active material shed from the positive electrode plate to the negative electrode plate of the same battery cell under the action of gravity. This design is also applicable to the battery stack obtained by connecting battery cells in series. In the battery stack, the electrode plate with a lower potential among the adjacent two electrode plates serves as the negative electrode plate, and the electrode plate with a higher potential serves as the positive electrode plate.

[0013] The advantage of extending the bottom end of the negative electrode plate below the positive electrode plate and / or connecting the bottom end of the negative electrode plate to the bottom end of the positive electrode plate through an isolation guiding plate is that the lead dioxide shed during the positive electrode discharge process can reach the negative electrode by gravity sedimentation, which is beneficial to the reaction of the active material falling off the electrode into the electrolyte, eliminating the stirring or oscillation process and simplifying the operation steps and the required additional equipment.

[0014] Optionally, when the battery is a battery stack composed of battery cells connected in series, the positive electrode plate isolates the electrolyte between different battery cells or the isolation guiding plate and the positive electrode plate jointly act to isolate the electrolyte between different battery cells.

[0015] Optionally, the included angle between the isolation guiding plate and the horizontal direction is ≥45°.

[0016] Optionally, the shortest distance between the positive electrode plate and the negative electrode plate is 0.1 - 20 cm.

[0017] Optionally, the negative electrode is used as the container for holding the electrolyte, and the positive electrode is immersed in the electrolyte in the container.

[0018] Optionally, the electrolyte is connected to the air.

[0019] Optionally, the lead solvent includes one or more of water-soluble iron salts, ferrous salts, vanadium (V) salts, vanadium (IV) salts, and vanadium (III) salts.

[0020] In the lead-acid static battery of the present application, water-soluble lead salts participate in the main battery reaction, and the acid serves as a supporting electrolyte and a conductive agent. The reaction formula is as follows:

[0021] Positive electrode: (1)

[0022] Negative electrode: (2)

[0023] For equations (1) and (2), the right direction is for charging and the left direction is for discharging;

[0024] Since a small amount of lead dioxide will fall off from the electrode during the positive electrode discharge process and cannot be discharged and dissolved, the lead solvent can play a catalytic role in discharging. The reaction formula is as follows:

[0025] Dissolving lead dioxide:

[0026] (3)

[0027] (4)

[0028] (5)

[0029] Dissolved lead:

[0030] (6)

[0031] (7)

[0032] (8)

[0033] Because the positive electrode will also undergo oxygen evolution side reaction during the charging and discharging process:

[0034] (9)

[0035] This reaction will result in the lead not being completely dissolved. When the electrolyte is connected to the outside air or the air sealed inside the battery, the lead dissolving agent reacts with the oxygen in the air to generate a high-valent lead dissolving agent. The reaction formula is as follows:

[0036] (10)

[0037] (11)

[0038] (12)

[0039] The generated high-valent lead dissolving agent participates in the reaction of dissolving the lead element in the above formula (6) to formula (8), which can accelerate the oxygen absorption and dissolution of the residual lead element in the negative electrode.

[0040] In this application, no external force is required to be applied to the electrolyte. The electrolyte remains static and is exposed to an oxygen-containing environment. Lead ions migrate mainly by the concentration gradient between the electrode and the electrolyte, while the lead dissolving agent diffuses slowly due to the static state of the electrolyte and the absence of a concentration gradient, thus reducing self-discharge. The residual lead at the negative electrode promotes Fe 3+ The generated can also fully react and dissolve.

[0041] Optionally, the lead dissolving agent is one or more of methanesulfonate and fluoroborate.

[0042] Optionally, the electrode plate is made of one or more of conductive plastic, graphite, graphite felt, copper, nickel, and stainless steel.

[0043] Optionally, the water-soluble lead salt is one or more of lead methyl sulfonate and lead fluoborate; the acid is one or more of methyl sulfonic acid and fluoboric acid.

[0044] Optionally, the electrolyte solution comprises components with the following concentrations: in mol / L, lead ions 0.05 - 3, hydrogen ions 0.001 - 8, iron element 0 - 0.2, vanadium element 0 - 0.2, methyl sulfonate ions 0 - 8, fluoborate ions 0 - 8. The concentrations of the methyl sulfonate ions and the fluoborate ions are not both 0 at the same time, and the concentrations of the iron element and the vanadium element are not both 0 at the same time.

[0045] Optionally, the electrolyte solution comprises components with the following concentrations: in mol / L, lead ions 1.5 - 2, hydrogen ions 0.5 - 1, iron element 0 - 0.2, vanadium element 0 - 0.2, methyl sulfonate ions 0 - 4, fluoborate ions 0 - 4. The concentrations of the methyl sulfonate ions and the fluoborate ions are not both 0 at the same time, and the concentrations of the iron element and the vanadium element are not both 0 at the same time.

[0046] Optionally, it further comprises a lead dendrite inhibitor, which is one or more of methyl sulfate salts, methyl sulfonates, and fluoborates of alkyltrimethylammonium, and the alkyl is a straight chain with 12 - 22 carbon atoms.

[0047] During charging, lead dendrites are likely to be generated at the negative electrode, especially in the methyl sulfonic acid system. The dendrites grow rapidly and are likely to contact the positive electrode, leading to a short circuit. They are likely to fall off during discharging. Therefore, a dendrite inhibitor is needed. Additives commonly used in lead electroplating, such as emulsifier op - 10, can effectively inhibit dendrite growth, but it is easily oxidized and decomposed by lead dioxide at the positive electrode. Alkyltrimethylammonium salts have good chemical stability and can withstand the strong oxidizing property of lead dioxide without decomposition in a strong acidic environment, and can inhibit the growth of lead dendrites.

[0048] Optionally, the lead dendrite inhibitor is methyl sulfate salt of alkyltrimethylammonium.

[0049] Optionally, the concentration of the lead dendrite inhibitor in the electrolyte solution is 0 - 0.1 mol / L.

[0050] Optionally, the concentration of the lead dendrite inhibitor in the electrolyte solution is 0 - 0.02 mol / L.

[0051] Compared with the prior art, the present application has at least the following beneficial effects:

[0052] In the present invention, there is no diaphragm, and the electrolyte is in a static state, eliminating the need for facilities such as a circulation pump. It allows lead ions to migrate under the action of a concentration gradient, while significantly reducing the self-discharge caused by the convective shuttling of the lead solvent (oxidized state / reduced state). During the charging process, lead and lead dioxide can be evenly deposited on the electrode surface, and can be completely dissolved during the discharging process, with good cycle stability, stable components over a long period, and low cost; moreover, the electrolyte does not contain harmful impurity ions.

[0053] In the present invention, an innovative lead-acid static stack is designed, with the electrolytes between different battery monomers isolated from each other, avoiding the short circuit caused by part of the current moving along the electrolyte between the electrode plates during the charging process and the self-discharge caused by the potential difference of the active substances between the electrolytes connected on both sides of the bipolar plate after charging stops.

[0054] In the present invention, the bottom end of the negative electrode plate is lower than that of the positive electrode plate, and the bottom end of the negative electrode plate extends below the positive electrode plate and / or the bottom end of the negative electrode plate is connected to the bottom end of the positive electrode plate through an isolation guiding plate; the active substances shed from the positive electrode plate can directly settle under the action of gravity or settle along the isolation guiding plate to the surface of the negative electrode plate to be reduced. The electrolyte can be used for a long time under completely static conditions while maintaining stable composition, and the battery has high efficiency. Description of the Drawings

[0055] Figure 1 is a schematic structural diagram of a traditional flow battery series stack in the prior art;

[0056] Figure 2 is a static battery structure with parallel electrode plates in the present invention, where a is a battery monomer and b is a stack;

[0057] Figure 3 is a structural diagram of the improved electrode plate arrangement in the present invention, where a and b are battery monomers and c is a stack;

[0058] Figure 4 is the charge-discharge curve of Example 4 of the present invention;

[0059] Figure 5 is the charge-discharge curve of Example 5 of the present invention;

[0060] Figure 6 is the charge-discharge curve of Example 6 of the present invention;

[0061] Figure 7 is the battery state diagram (a) and the charge-discharge curve (b) of the battery after charge and discharge in Example 7 of the present invention;

[0062] 1. Isolation guiding plate. Detailed Embodiments

[0063] The following further describes the present invention in detail with reference to the drawings:

[0064] The experimental methods used in the embodiments of the present invention are all conventional methods unless otherwise specified.

[0065] The reagent materials used in this example can be purchased conventionally.

[0066] In the present invention, the electrode plates of the battery monomer or the battery stack can be arranged in parallel, as Figure 2 shown.

[0067] In order to facilitate the active material shed from the positive electrode plate to sink to the negative electrode plate under the action of gravity, the electrode plates in the battery monomer can be arranged such that the bottom end of the negative electrode plate extends below the positive electrode plate (as Figure 3 a), or the negative electrode is used as a container for holding the electrolyte, and the positive electrode is immersed in the electrolyte in the container (as Figure 3 b), or the negative electrode plate extends towards the positive electrode plate and the bottom end of the negative electrode plate is connected to the bottom end of the positive electrode plate through the isolation guide plate 1 (as Figure 3 c). The side of the isolation guide plate 1 connected to the positive electrode plate is higher than the side connected to the negative electrode plate, so that the lead dioxide shed from the positive electrode plate can sink to the negative electrode plate under the action of gravity.

[0068] In Examples 1 - 5 and Comparative Example 1, the width of the single-sided conductive plastic plate (the other side is insulated with tape) is 1 cm.

[0069] Comparative Example 1

[0070] 40 mL of water-soluble lead-acid electrolyte is placed in a quartz cup. The electrolyte contains 1.5 mol / L lead borofluoride, 1 mol / L fluoboric acid, and 0.01 mol / L ferrous methyl sulfonate. Both the positive and negative electrodes are single-sided conductive plastic plates. The positive and negative electrodes are inserted into the electrolyte 1 cm deep (i.e., the effective area is 1 cm 2 ), the spacing is 2.5 cm, and the structure is as Figure 2 shown in a. It is stirred with a magnetic stirrer at a speed of 300 rpm; charged and discharged at a constant current of 20 mA, the upper voltage limit is 2.5 V, the lower voltage limit is 0 V, the charging duration is 4 h, and it is cycled 3 times, taking 21.983 h, and the average current efficiency is only 83.2%.

[0071] Continue to add ferrous methyl sulfonate to 0.05 mol / L and keep stirring; charged and discharged at a constant current of 20 mA, the upper voltage limit is 2.5 V, the lower voltage limit is 0 V, and it is cycled 1 time, taking 5.642 h, and the current efficiency is only 41.1%. It shows that as the iron concentration increases, the current efficiency drops severely.

[0072] Example 1

[0073] 40 mL of water-soluble lead-acid electrolyte is placed in a quartz cup. The electrolyte contains 1.5 mol / L lead borofluoride, 1 mol / L fluoboric acid, and 0.01 mol / L ferrous methyl sulfonate. Both the positive and negative electrodes are single-sided conductive plastic plates, inserted 1 cm deep into the electrolyte (i.e., the effective area is 1 cm 2 ), with a spacing of 2.5 cm. The structure is as shown in Figure 2 Figure a, and the solution remains stationary. Constant current charge and discharge are carried out at 20 mA, with a voltage upper limit of 2.5 V and a lower limit of 0 V. The charging duration is 4 h, and it is cycled 5 times, taking 38.733 h in total, with an average current efficiency of 93.7%.

[0074] Compared with Comparative Example 1, the current efficiency in Example 1 is higher, indicating that keeping the solution stationary during the charge and discharge process can effectively prevent self-discharge caused by the convective diffusion of the lead solvent. After the charge and discharge are completed, there is a small amount of lead dioxide solid at the bottom of the positive electrode. The electrode is stirred with a magnetic stirrer at a speed of 300 rpm for 8 h, and the lead and lead dioxide on the electrode are completely dissolved, and there is no solid lead residue at the bottom of the container, indicating that the water-soluble lead-acid static battery can maintain good stability.

[0075] Ferrous methyl sulfonate is continuously added to 0.05 mol / L. After the electrolyte is stirred evenly, it remains stationary. Constant current charge and discharge are carried out at 20 mA, with a voltage upper limit of 2.5 V and a lower limit of 0 V. The charging duration is 4 h, and it is cycled 5 times, taking 36.455 h in total, with a current efficiency of 82.3%, which is lower than the current density when the iron content is 0.01 mol / L, indicating that an increase in the content of the lead solvent will accelerate self-discharge, but it is significantly higher than that in Comparative Example 1, indicating that in the case of no diaphragm and flowing electrolyte, iron ions / ferrous ions shuttle back and forth between the positive and negative electrodes, resulting in serious self-discharge. Therefore, the traditional diaphragm-free water-soluble lead-acid flow battery is not suitable for electrolytes containing lead solvents.

[0076] After the charge and discharge are completed, there is a little lead dioxide at the bottom of the positive electrode. The electrode is stirred with a magnetic stirrer at a speed of 300 rpm for 10 min, and the lead dioxide at the bottom of the container is completely dissolved. After stirring for another 8 h, most of the lead is dissolved, indicating that an increase in the content of the lead solvent will accelerate the dissolution of lead dioxide, but it has no significant effect on the oxygen absorption dissolution of lead.

[0077] Example 2

[0078] 40 mL of water-soluble lead-acid electrolyte is placed in a quartz cup. The electrolyte contains 1.5 mol / L lead borofluoride, 1 mol / L fluoboric acid, and 0.05 mol / L ferrous methyl sulfonate. The positive electrode is a single-sided conductive plastic plate, inserted 1 cm deep into the electrolyte (i.e., the effective area is 1 cm 2 ), the negative electrode is a nickel sheet, clamped with an L-shaped electrode clip. The negative electrode is arranged horizontally and is located about 1 cm directly below the positive electrode. The structure is as shown in Figure 3As shown in a (the vertical direction here is the insulating part of the electrode clamp), the solution remains stationary; constant current charge and discharge at 20 mA, upper voltage limit 2.5 V, lower voltage limit 0 V, charging duration 4 h, cycle 5 times, time used 35.701 h, current efficiency 78.5%.

[0079] After the charge and discharge, there is no lead dioxide residue on the surface of the negative electrode under the positive electrode, indicating that the lead dioxide is rapidly dissolved as soon as it settles on the surface of the negative electrode; after standing still in an open container for 24 h, most of the lead on the surface of the negative electrode absorbs oxygen and dissolves, indicating that a static storage battery, especially a structure where the negative electrode extends under the positive electrode, can allow the electrolyte to be used for a long time under completely static conditions while maintaining the stability of the composition.

[0080] Example 3

[0081] 40 mL of water-soluble lead-acid electrolyte is placed in a quartz cup. The electrolyte contains 1.5 mol / L lead methyl sulfonate, 1 mol / L methyl sulfonic acid, 0.05 mol / L ferrous methyl sulfonate, and 0.01 mol / L hexadecyltrimethylammonium methyl sulfate; the positive electrode is a single-sided conductive plastic plate, inserted 1 cm deep into the electrolyte (i.e., the effective area is 1 cm 2 ), the negative electrode is a nickel sheet, clamped by an L-shaped electrode clamp, the negative electrode is set horizontally and is located about 1 cm directly below the positive electrode. The structure is as Figure 3 shown in a (the vertical direction here is the insulating part of the electrode clamp), the solution remains stationary; constant current charge and discharge at 20 mA, upper voltage limit 2.5 V, lower voltage limit 0 V, charging duration 4 h, cycle 5 times, time used 35.412 h, current efficiency 77.1%, and no obvious dendrite growth or shedding is observed at the edge of the electrode (high current density area).

[0082] Example 4

[0083] 15 mL of water-soluble lead-acid electrolyte is placed in a nickel container. The electrolyte contains 1.5 mol / L lead fluoroborate, 1 mol / L fluoroboric acid, and 0.02 mol / L ferrous fluoroborate; the positive electrode is a single-sided conductive plastic plate, inserted 1 cm deep into the electrolyte (i.e., the effective area is 1 cm 2 ), the structure is as Figure 3 shown in b, the solution remains stationary; constant current charge and discharge at 20 mA, upper voltage limit 2.5 V, lower voltage limit 0 V, charging duration 4 h, cycle 5 times, time used 37.844 h, current efficiency 89.2%, and the charge and discharge curve is shown in Figure 4 .

[0084] During the test, there is no lead dioxide solid at the bottom of the container, and the charge and discharge voltage tends to be stable starting from the 5th cycle; the container is in an open state and there is almost no lead residue.

[0085] Example 5

[0086] 15 mL of water-soluble lead-acid electrolyte is placed in a nickel container. The electrolyte contains 1.5 mol / L lead fluoborate, 1 mol / L fluoboric acid, and 0.01 mol / L VO(BF4)2. The positive electrode is a single-sided conductive plastic plate inserted 1 cm deep into the electrolyte (i.e., the effective area is 1 cm 2 ), and the structure is as shown in Figure 3 b. The solution remains static. A constant current of 20 mA is used for charge and discharge, with a voltage upper limit of 2.5 V and a lower limit of 1 V. The charging duration is 2 h, and it is cycled 5 times. The current efficiency is 91.6%. The charge-discharge curve is shown in Figure 5 .

[0087] During the test, there is no lead dioxide solid at the bottom of the container.

[0088] Example 6

[0089] The plastic box is separated into compartments by 3 pieces of 5 cm × 10 cm conductive plastic bipolar plates (the electrolytes in different compartments cannot flow into each other). The conductive plastic bipolar plates are placed in parallel, and the distance between adjacent conductive plates is 2 cm, resulting in a static battery stack of 2 monomers in series. 50 mL of electrolyte is poured into each battery monomer compartment. The electrolyte contains 1.5 mol / L lead fluoborate, 1 mol / L fluoboric acid, and 0.01 mol / L ferrous fluoborate. The effective area of each monomer bipolar plate is approximately 14 cm 2 , and the electrolyte in the compartment remains static. The electrodes at both ends and the middle bipolar plate are arranged in parallel; a constant current of 200 mA is used for charging for 3.1 h, with a voltage upper limit of 5 V, and then discharged to 2 V. One cycle takes 5.817 h, and the current efficiency is 87.6%. The test results are shown in Figure 6 .

[0090] Example 7

[0091] 50 mL of water-soluble lead-acid electrolyte is placed in a quartz cup. The electrolyte contains 1.5 mol / L lead fluoborate and 1 mol / L fluoboric acid. A copper strip with a width of 4.5 cm is taken, folded into an L shape, and the horizontal part is trimmed so that the horizontal part can be placed in the quartz cup and fit the bottom of the cup. The upper end of the vertical part of the L-shaped copper strip is clamped, and the L-shaped copper strip is used as the negative electrode. A 2 cm × 2 cm conductive plastic plate is taken, and one side is pasted with insulating tape. The single-sided conductive plastic plate is clamped with an L-shaped electrode clamp (the clamped part area is 0.25 cm 2 ). The conductive side of the plastic plate is horizontal and facing downwards. It is immersed in the electrolyte and is 0.8 cm above the horizontal part of the copper strip, serving as the battery positive electrode. By rotating the electrode clamp, the horizontal position of the conductive plastic plate is adjusted so that its horizontal projection completely falls on the horizontal part of the copper strip, ensuring that all the lead dioxide during subsequent discharge settles on the surface of the negative electrode. After assembly, it isFigure 3 A structure as shown in a.

[0092] To simulate the scenario of high-rate charging in actual applications (for example, during the peak power generation period of a photovoltaic power station, the battery needs to have a sufficiently large charging power to store as much electrical energy as possible), the charging current of the battery in this embodiment is 320 mA (i.e., the positive electrode current density is 80 mA / cm 2 ), the duration is 4 h (i.e., the positive electrode surface capacity is 320 mAh / cm 2 ), the upper voltage limit is 2.5 V, the discharge current is 80 mA, the maximum duration is 16 h, the lower voltage limit is 0 V, and it is cycled 3 times.

[0093] During the charging process, no obvious lead dendrites appeared on the negative electrode; during the discharging process, a small amount of lead dioxide fell off from the positive electrode and settled on the surface of the negative electrode, but was reduced during subsequent discharging or charging processes, and no lead dioxide solid remained on the surface of the negative electrode after the end of the next charging cycle, as shown in Figure 7 a. The charge-discharge curves are shown in Figure 7 b. It can be seen from the figure that even when charging at a high current density, the voltage still remains at a relatively low level. The average charging voltage for 3 cycles is 2.180 V, and the discharging voltage is relatively high. The average discharging voltage for 3 cycles is 1.580 V, and the voltage efficiency is 72.5%; the average current efficiency for 3 cycles is 92.1%, and the energy efficiency is 66.8%.

[0094] Examples 2 - 5 and Example 7 fully illustrate that regardless of whether the electrolyte contains a lead solvent, adopting a battery structure in which the bottom end of the negative electrode extends below the positive electrode and / or the bottom end of the negative electrode is connected to the bottom end of the positive electrode through an isolation guiding plate can enable the active substances falling off from the positive electrode to participate in the charge-discharge cycle again, keeping the electrolyte composition stable, and there is no significant growth of lead dendrites on the negative electrode, indicating that the battery with this structural feature has good lead dissolution effect, does not require a stirring facility, can simplify auxiliary equipment and reduce self-discharge.

[0095] In Examples 1 and 6, for the battery structure without the bottom end of the negative electrode extending below the positive electrode, in the battery containing the lead solvent of the present application, the active substances falling off from the positive electrode directly settle at the bottom of the container after discharging, and the lead oxides can be dissolved after stirring after discharging. Experiments found that when the lead solvent in Example 1 is 0, even with stirring, not all the lead oxides can be dissolved, and the active substances falling off from the positive electrode will cause the battery capacity to decay due to being unable to participate in the charge-discharge cycle.

[0096] In terms of battery structure, traditional flow battery stacks usually adopt the assembly method of monomer series connection. This method is simple and convenient, can make full use of bipolar plates, and has low requirements for the conductivity of bipolar plates. However, between the monomers of traditional series-connected stacks, the electrolytes are connected. The inventor found that the conventional stack design has serious technical defects for water-soluble lead-acid flow batteries. To illustrate this problem more clearly, Figure 1 The structure of a traditional series-connected stack (2 monomers in series) is given, including stacks with and without diaphragms. During charging, most of the current starts from the left end plate, passes through the middle bipolar plate, and reaches the right end plate (i.e., the effective current I1). There is also a considerable part of the current starting from the left end plate and flowing along the electrolyte pipeline to the right end plate (i.e., I2), causing a short circuit; after charging stops, there is a potential difference between the active substances on both sides of the middle bipolar plate, and the electrolytes on both sides are connected through the pipeline, forming a closed loop (I3), causing self-discharge. For all-liquid flow batteries, such as all-vanadium flow batteries and iron-chromium flow batteries, since there is no deposition of active substances involved and the amount of active substances stored in the stack is very small, the influence caused by currents I2 and I3 is limited (usually only reducing the current efficiency and energy efficiency), and thus it is difficult to detect. However, for water-soluble lead-acid flow batteries, all the positive and negative active substances are deposited on the bipolar plates. The short circuit during charging will cause differences in the surface capacity of different bipolar plates. After charging stops, there is serious self-discharge on the bipolar plates except for the left and right end plates, resulting in serious surface capacity decline and energy loss. For this problem, although an independent liquid flow pump can be equipped for each battery monomer to solve it, it will greatly increase the volume and complexity of the stack and significantly increase the cost. In addition, facilities such as electrolyte pipelines and liquid storage tanks greatly increase the complexity of the energy storage system, reduce the energy density of the flow battery, increase the cost, and lose portability. Therefore, in this application, the electrolytes between different battery monomers are isolated from each other, avoiding the short circuit caused by part of the current moving between the plates along the electrolyte during the charging process and the self-discharge caused by the potential difference of the active substances between the electrolytes connected on both sides of the bipolar plate after charging stops.

[0097] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all details in detail, nor limit the invention to the specific embodiments described. Obviously, many modifications and optimizations can be made according to the content of this specification. These embodiments selected and specifically described in this specification are for better explaining the principle and practical application of the present invention, so that those skilled in the art in the technical field can better understand and apply the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A water-soluble lead-acid static battery, characterized in that, Comprising a battery cell, the battery cell includes electrode plates, an electrolyte in a static state, and a container for containing the electrolyte. The electrode plates are inserted into the electrolyte. The electrolyte composition includes a water-soluble lead salt, an acid, a lead solvent, and water. The lead solvent can provide at least one pair of water-soluble redox couples R 氧化 and R 还原 , and the electrode potential of the redox couple satisfies E θ (Pb 2+ / Pb) < E θ (R 氧化 / R 还原 ) < E θ (PbO2 / Pb 2+ ).

2. A water-soluble lead-acid static battery, characterized in that, It includes battery cells, and each battery cell includes electrode plates, an electrolyte in a static state, and a container for containing the electrolyte. The electrode plates are inserted into the electrolyte, and the electrolyte composition includes a water-soluble lead salt, an acid, and water. The battery is a stack composed of a group of battery cells or at least two groups of battery cells connected in series; when the battery is a stack composed of battery cells connected in series, the electrolytes between different battery cells are isolated from each other. In a battery cell, the electrode plates include a positive electrode plate and a negative electrode plate. The bottom end of the negative electrode plate extends below the positive electrode plate and / or the bottom end of the negative electrode plate is connected to the bottom end of the positive electrode plate through an isolation guide plate. The isolation guide plate is used to guide the active substances shed from the positive electrode plate to the negative electrode plate of the same battery cell under the action of gravity.

3. The water-soluble lead-acid static storage battery according to claim 1, characterized in that, The battery is a stack composed of a group of battery cells or at least two groups of battery cells connected in series; when the battery is a stack composed of battery cells connected in series, the electrolytes between different battery cells are isolated from each other.

4. The water-soluble lead-acid static battery according to claim 2 or 3, characterized in that, When the battery is a stack composed of battery cells connected in series, the electrode plates on both sides are used as the positive electrode and the negative electrode respectively, and bipolar plates are used for the electrode plates between the positive electrode and the negative electrode to isolate the electrolytes between different battery cells.

5. The water-soluble lead-acid static storage battery according to claim 3, characterized in that, In a battery cell, the electrode plates include a positive electrode plate and a negative electrode plate. The bottom end of the negative electrode plate extends below the positive electrode plate and / or the bottom end of the negative electrode plate is connected to the bottom end of the positive electrode plate through an isolation guide plate. The isolation guide plate is used to guide the active substances shed from the positive electrode plate to the negative electrode plate of the same battery cell under the action of gravity.

6. The water-soluble lead-acid static storage battery according to claim 2 or 5, characterized in that, The negative electrode is used as the container for containing the electrolyte, and the positive electrode is immersed in the electrolyte in the container.

7. The water-soluble lead-acid static storage battery according to claim 1 or 2, characterized in that, The electrolyte is in communication with the air.

8. The water-soluble lead-acid static battery according to claim 1, wherein, The lead solvent includes one or more of water-soluble iron salts, ferrous salts, vanadium (V) salts, vanadium (IV) salts, and vanadium (III) salts.

9. The water-soluble lead-acid static storage battery according to claim 1, wherein The lead solvent is one or more of methyl sulfonates and fluoroborates.

10. The water-soluble lead-acid static storage battery according to claim 1 or 2, characterized in that, The electrolyte includes the following components in the following concentrations: the water-soluble lead salt is one or more of lead methyl sulfonate and lead fluoroborate; the acid is one or more of methyl sulfonic acid and fluoroboric acid.

11. The water-soluble lead-acid static battery according to claim 1, wherein, The electrolyte includes the following components in the following concentrations: in mol / L, lead ions are 0.05 - 3, hydrogen ions are 0.001 - 8, iron element is 0 - 0.2, vanadium element is 0 - 0.2, methyl sulfonate ions are 0 - 8, fluoroborate ions are 0 - 8. The concentrations of methyl sulfonate ions and fluoroborate ions are not both 0 at the same time, and the concentrations of iron element and vanadium element are not both 0 at the same time.

12. The water-soluble lead-acid static storage battery according to claim 1, wherein, It further includes a lead dendrite inhibitor, and the lead dendrite inhibitor is one or more of methyl sulfate salts, methyl sulfonates, and fluoroborates of alkyltrimethylammonium, and the alkyl is a straight chain with 12 - 22 carbon atoms.

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