Formation method of zinc-silver reserve battery pole plate

Abstract

The invention provides a formation method of a zinc-silver reserve battery pole plate. The formation method comprises the following steps: S1, assembling a formed battery; s2, connecting a plurality of formed batteries in series, and performing constant-current charging until the theoretical capacity of the formed batteries is reached; and S3, connecting the plurality of formed batteries obtained in the step S2 in parallel, and charging by utilizing alternating voltage until the charging current density is less than or equal to a theoretical minimum value. According to the method, the positive plate and the negative plate of the zinc-silver reserve battery are formed, the positive plate and the negative plate are subjected to constant-current charging to the theoretical capacity and then are subjected to alternating voltage charging until the charging current density is smaller than or equal to the theoretical minimum value, and the positive plate and the negative plate can be prevented from being overcharged by controlling the voltage peak value of the alternating voltage not to exceed the voltage value corresponding to the theoretical capacity; zinc dendritic crystals caused by overhigh voltage of the formed battery are avoided, the formation efficiency is ensured, and the energy loss of the negative electrode is reduced; and moreover, the positive electrode and the negative electrode are prevented from being overcharged, the electrolytic water reaction during overcharging can be avoided, frequent observation and supplement operation on the residual amount of the formation electrolyte are avoided, and the operation difficulty of the formation process is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of zinc-silver reserve batteries, in particular to a formation method of a zinc-silver reserve battery polar plate. Background Art

[0002] Zinc-silver reserve batteries are widely used in various fields due to their high specific energy, high specific power, large current discharge, stable discharge voltage, high voltage accuracy, wet shelf discharge, good reliability and safety. Zinc-silver reserve batteries are generally composed of battery pack casing, socket, gas generator, liquid reservoir, combined plate group, electric heater and other components. Among them, the positive and negative electrodes inside the zinc-silver reserve battery are completely isolated. When the battery pack is used, an external activation power supply is connected to ignite the gas generator to generate sufficient pressure, and the separately stored electrolyte is injected into the combined plate group within the specified time to activate it to establish an electromotive force and output voltage to the outside through the socket.

[0003] Before assembling the zinc-silver reserve battery, the battery plates need to be formed, that is, the battery plates are assembled into formed batteries and the formed batteries are charged. In order to improve the formation efficiency, the common practice in the industry is to connect multiple formed batteries in series and charge them with constant current. Due to the differences in formed batteries, the full charging time of each formed battery is usually different. If the charging time is calculated using 100% capacity, some formed batteries cannot be fully charged. Therefore, it is often necessary to extend the charging time to 115% to 125% of the theoretical time to ensure that all formed batteries are fully charged. But this will cause new problems:

[0004] (1) Some formation batteries that have been fully charged within the theoretical time will have an overcharge problem. During the overcharge process, the voltage of the formation battery is relatively high, generally exceeding 2.30V, and even reaching 2.40V or above (the theoretical voltage corresponding to 100% capacity is generally 2.10V~2.15V). When overcharged, a large number of zinc dendrites will be generated in the formation battery. The zinc dendrites may pierce the diaphragm of the formation battery. Since zinc dendrites are conductive, piercing the diaphragm will cause a micro-short circuit in the formation battery, reducing the formation efficiency. Moreover, after the formation is completed, the zinc dendrites will be cleaned when the plates are cleaned. When the plates are assembled into a zinc-silver reserve battery, the capacity will be lost.

[0005] (2) The late stage of overcharging is mainly the electrolysis of water reaction, which consumes a large amount of water in the electrolyte, resulting in an increase in electrolyte concentration, a decrease in the electrolyte level or even complete consumption. Therefore, it is necessary to observe the electrolyte level in the formation cell at any time in the late stage of formation and replenish the electrolyte in time, which greatly increases the difficulty of the formation process. Summary of the invention

[0006] The object of the present invention is to provide a method for forming a zinc-silver reserve battery plate to solve the problems in the background technology.

[0007] The technical solution of the present invention includes: a method for forming a zinc-silver reserve battery plate, which includes:

[0008] S1, assembling and forming batteries;

[0009] S2, connect several formation batteries in series and charge them at a constant current to the theoretical capacity of the formation batteries;

[0010] S3, connecting the plurality of formed batteries obtained in step S2 in parallel, and charging them with an alternating voltage until the charging current density is less than or equal to the theoretical minimum value.

[0011] Preferably, in step S2, when constant current charging is performed to the theoretical capacity of the formation battery, the voltage of the formation battery is 2.10V to 2.15V.

[0012] Preferably, in step S2, the current density of constant current charging is 1 mA / cm 2 ~10mA / cm 2 .

[0013] Preferably, in step S3, the peak voltage of the alternating voltage is 2.20V, and the valley voltage is 2.10V.

[0014] Preferably, in step S3, the theoretical minimum value is 0.05 mA / cm 2 .

[0015] Preferably, the formation battery assembled in step S1 comprises: a silver positive electrode plate, a zinc negative electrode plate, a separator and a formation electrolyte, and the formation electrolyte is a potassium hydroxide solution with a concentration of 30% to 50%.

[0016] Preferably, the silver positive electrode plate comprises a silver conductive mesh and silver powder; the silver powder has a purity of 95% to 100% and is prepared by thermal decomposition of silver acetate.

[0017] Preferably, the zinc negative electrode plate comprises a silver conductive mesh, zinc powder and zinc oxide powder; the zinc powder is prepared by electrolysis, and the mass ratio of the zinc powder to the zinc oxide powder is 1:1 to 1:4.

[0018] Preferably, the several formation batteries obtained in step S3 are disassembled, the silver positive electrode plates and the zinc negative electrode plates are washed with distilled water until they are alkali-free, and then dried.

[0019] Preferably, the drying temperature of the silver positive electrode plate is 30-70° C., and the drying time is 2 h to 4 h; the drying temperature of the zinc negative electrode plate is 100-300° C., and the drying time is 1 h to 2 h.

[0020] The invention has the beneficial effects that the positive and negative plates of the zinc-silver reserve battery are firstly charged with a constant current to a theoretical capacity, and then charged with an alternating voltage to a charging current density less than or equal to a theoretical minimum value, and by controlling the voltage peak of the alternating voltage not to exceed the voltage value corresponding to the theoretical capacity, overcharging of the positive and negative plates can be avoided, and the generation of zinc dendrites caused by excessively high voltage of the formation battery can be avoided, so that the formation efficiency is guaranteed and the energy loss of the negative electrode is reduced, and the battery capacity of the finally assembled zinc-silver reserve battery is guaranteed to be qualified; and overcharging of the positive and negative electrodes can be avoided, and the occurrence of electrolytic water reaction during overcharging can be avoided, so that frequent observation and replenishment of the remaining amount of the formation electrolyte can be avoided, and the operation difficulty of the formation process can be reduced. DETAILED DESCRIPTION

[0021] The present invention will be further described below in conjunction with embodiments:

[0022] Unless otherwise defined, all professional terms used hereinafter have the same meaning as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and comparative examples, and are not intended to limit the scope of protection of the present invention. It should be particularly noted that there may be multiple names for the same organic structure, as long as the structure is within the scope of this patent, it belongs to the protection object of this patent.

[0023] Unless otherwise defined, the raw materials, reagents, etc. in the following examples can be purchased from the market or prepared according to reported methods.

[0024] The embodiment of the present invention provides a method for forming a zinc-silver reserve battery plate, comprising the following steps:

[0025] S1, assembling the battery;

[0026] S2, connect several formation batteries in series and charge them at a constant current to the theoretical capacity of the formation batteries;

[0027] S3, connecting the plurality of formation batteries obtained in step S2 in parallel, and charging them using an alternating voltage until the charging current density is less than or equal to the theoretical minimum value;

[0028] S4, disassembling the several formation batteries obtained in step S3, washing the silver positive electrode plate and the zinc negative electrode plate with distilled water until they are alkali-free, and drying them to prepare for assembling the zinc-silver reserve battery.

[0029] By adopting the above technical scheme, the positive and negative plates of the zinc-silver reserve battery are formed, firstly they are charged with constant current to the theoretical capacity, and then they are charged with alternating voltage to a charging current density ≤ the theoretical minimum value. By controlling the voltage peak of the alternating voltage not to exceed the voltage value corresponding to the theoretical capacity, overcharging of the positive and negative plates can be avoided, and the generation of zinc dendrites caused by excessively high voltage of the formation battery can be avoided, so that the formation efficiency is guaranteed and the energy loss of the negative electrode is reduced, so that the battery capacity of the finally assembled zinc-silver reserve battery is guaranteed to be qualified; and by avoiding overcharging of the positive and negative electrodes, the occurrence of water electrolysis reaction during overcharging can be avoided, and frequent observation and replenishment of the remaining amount of the formation electrolyte can be avoided, so as to reduce the difficulty of the formation process.

[0030] In step S1, the assembled formation battery includes: a silver positive electrode plate, a zinc negative electrode plate, a separator and a formation electrolyte, wherein: the silver positive electrode plate includes a silver conductive mesh and silver powder, and the silver powder is combined with the silver conductive mesh to form a silver positive electrode plate by a compression molding method; the silver powder has a purity of 95% to 100%, and is prepared by a silver acetate thermal decomposition method, and the silver powder prepared by the silver acetate thermal decomposition method has a small particle size and high electrochemical activity; the zinc negative electrode plate includes a silver conductive mesh, zinc powder and zinc oxide powder; the zinc powder and zinc oxide powder are combined with the silver conductive mesh to form a zinc negative electrode plate by a compression molding method, and the zinc powder is prepared by an electrolysis method, and the mass ratio of the zinc powder to the zinc oxide powder is 1:1 to 1:4; the formation electrolyte is a potassium hydroxide solution with a concentration of 30% to 50%.

[0031] In step S2, the constant current charging current density is 1mA / cm 2 ~10mA / cm 2 When charged to the theoretical capacity of the formation battery, the voltage of the formation battery is 2.10V~2.15V.

[0032] In step S3, the voltage peak value of the alternating voltage is 2.20V, and the voltage valley value is 2.10V. The advantage of using alternating voltage is that when the charging voltage is higher than the theoretical voltage of 100% capacity, the electrode is in a charging state, and when the charging voltage is lower than the theoretical voltage of 100% capacity, the electrode is in a discharging state. When charging with alternating voltage, the battery is actually in a state of alternating charge and discharge. If DC charging is used, an oxidation reaction occurs near the conductive mesh, and the generated silver peroxide is near the conductive mesh, which is difficult to diffuse deep into the electrode active material particles. When charging with alternating voltage, since the battery is in a state of alternating charge and discharge, there is negative discharge in each voltage change cycle, which is conducive to the diffusion of ions into the deep of the active material, so the charging efficiency is higher and the battery discharge time is longer.

[0033] In step S3, the alternating voltage is used to charge the formation battery until the charging current density is less than the theoretical minimum value, indicating that the resistance in the parallel circuit increases to the theoretical maximum, indicating that each formation is fully charged. In a preferred embodiment, the theoretical minimum value is 0.05 mA / cm 2 .

[0034] In step S4, in order to prevent high temperature from damaging the positive and negative plates, the drying temperature of the silver positive plate is controlled at 30-70°C, the drying time is controlled at 2h-4h, and the drying temperature of the zinc negative plate is controlled at 100-300°C, the drying time is controlled at 1h-2h.

[0035] The following are specific embodiments of the present invention.

[0036] Example 1

[0037] S1, assembling the battery;

[0038] Place (30-70) mm × (20-60) mm silver conductive mesh and 1g-10g silver acetate thermal decomposition silver powder (silver powder purity is 95%-100%) into the plate pressing mold, place the plate pressing mold in the press, and press it into shape at a certain pressure (5MPa-15MPa), and the holding time (5s-15s) should not be less than 1s. Take out the plate pressing mold, open the mold cover, push out the silver positive plate from the mold core, and demold and take out the silver positive plate;

[0039] Place (30-70) mm × (20-60) mm silver conductive mesh and 1g-10g of a mixture of electrolytic zinc powder and zinc oxide powder (the mass proportion of electrolytic zinc powder is 20%-50%) into the plate pressing mold, place the plate pressing mold in a press, and press it into shape at a certain pressure (5MPa-15MPa). The holding time (5s-15s) should not be less than 1s. Take out the plate pressing mold, open the mold cover, push out the zinc negative plate with the mold core, and demold and take out the zinc negative plate;

[0040] The silver positive electrode plate and the zinc negative electrode plate are separated by a diaphragm and assembled with a formation electrolyte to form a formation battery. The formation electrolyte is a potassium hydroxide solution with a concentration of 30% to 50%.

[0041] S2, connect several formation batteries in series and charge them at a constant current to the theoretical capacity of the formation batteries;

[0042] The constant current charging current density is 1mA / cm 2 ~10mA / cm 2 When charged to the theoretical capacity of the formation battery, the voltage of the formation battery is 2.10V~2.15V.

[0043] S3, connecting the plurality of formation batteries obtained in step S2 in parallel, and charging them using an alternating voltage until the charging current density is less than or equal to the theoretical minimum value;

[0044] The peak voltage of the alternating voltage is 2.20V, and the valley voltage is 2.10V;

[0045] The theoretical minimum value is 0.05mA / cm 2 .

[0046] S4. Disassemble the several formation batteries obtained in step S3, wash the silver positive electrode plates and the zinc negative electrode plates with distilled water until they are free of alkali (colorless after adding phenolphthalein reagent), dry the washed silver positive electrode plates at 30°C to 70°C for 2h to 4h, and dry the washed zinc negative electrode plates at 100°C to 300°C for 1h to 2h, in preparation for assembling zinc-silver reserve batteries.

[0047] The above are preferred embodiments of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for forming a zinc-silver reserve battery plate, characterized in that: Includes steps: S1, assembling and forming batteries; S2, connect several formation batteries in series and charge them at a constant current to the theoretical capacity of the formation batteries; S3, connecting the plurality of formed batteries obtained in step S2 in parallel, and charging them with an alternating voltage until the charging current density is less than or equal to the theoretical minimum value.

2. The method for forming a zinc-silver reserve battery plate according to claim 1, characterized in that: In step S2, when the constant current is charged to the theoretical capacity of the formation battery, the voltage of the formation battery is 2.10V to 2.15V.

3. The formation method of the zinc-silver reserve battery plate according to claim 1 or 2, characterized in that: In step S2, the current density of constant current charging is 1 mA / cm 2 ~10mA / cm 2 .

4. The method for forming a zinc-silver reserve battery plate according to claim 3, characterized in that: In step S3, the peak value of the alternating voltage is 2.20V, and the valley value of the voltage is 2.10V.

5. The method for forming a zinc-silver reserve battery plate according to any one of claims 1-2 and 4, characterized in that: In step S3, the theoretical minimum value is 0.05 mA / cm 2 .

6. The method for forming a zinc-silver reserve battery plate according to claim 5, characterized in that: The formation battery assembled in step S1 includes: a silver positive electrode plate, a zinc negative electrode plate, a separator and a formation electrolyte, wherein the formation electrolyte is a potassium hydroxide solution with a concentration of 30% to 50%.

7. The method for forming a zinc-silver reserve battery plate according to claim 6, characterized in that: The silver positive plate comprises a silver conductive mesh and silver powder; the silver powder has a purity of 95% to 100% and is prepared by thermal decomposition of silver acetate.

8. The method for forming a zinc-silver reserve battery plate according to claim 6, characterized in that: The zinc negative electrode plate includes a silver conductive mesh, zinc powder and zinc oxide powder; the zinc powder is prepared by electrolysis, and the mass ratio of the zinc powder to the zinc oxide powder is 1:1 to 1:

4.

9. The method for forming a zinc-silver reserve battery plate according to claim 7 or 8, characterized in that: The several cells obtained in step S3 are disassembled, and the silver positive electrode plates and the zinc negative electrode plates are washed with distilled water until they are free of alkali, and then dried.

10. The method for forming a zinc-silver reserve battery plate according to claim 9, characterized in that: The drying temperature of the silver positive plate is 30-70°C, and the drying time is 2h-4h; the drying temperature of the zinc negative plate is 100-300°C, and the drying time is 1h-2h.