Zinc-silver reserve battery monomer with high loading voltage and long working time and preparation method thereof

Abstract

The invention provides a zinc-silver reserve battery monomer with high loading voltage and long working time and a preparation method thereof, and the preparation method comprises the following steps: separating a silver positive plate from a zinc negative plate by using a diaphragm, and assembling the separated silver positive plate and zinc negative plate with a chloride-containing formation electrolyte to form a formation battery; pre-charging the formed battery to a positive theoretical capacity; pre-discharging the pre-charged formation battery, wherein the discharge capacity is 25%-30% of the theoretical capacity of the positive electrode; and disassembling the pre-discharged formed battery, and assembling the zinc-silver reserve battery monomer by using the disassembled silver positive plate and zinc negative plate. The prepared zinc-silver reserve battery monomer is simple in structure and convenient to prepare, a current-limiting resistor, a time resistor and the like do not need to be added when a battery pack is assembled, the mass and the size of the battery pack are not increased, and the reliability of the battery pack can be ensured; and high loading voltage and long discharge time can be effectively kept no matter whether the battery is discharged after activation for a period of time or discharged after wet standing for a long period of time.

Description

Technical Field

[0001] The invention relates to the technical field of zinc-silver reserve batteries, in particular to a zinc-silver reserve battery monomer with high loading voltage and long working time and a preparation method thereof. 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, reliability, and good safety. Zinc-silver reserve batteries are generally composed of battery pack shells, sockets, gas generators, liquid reservoirs, combined plate groups, electric heaters and other components. The positive and negative electrodes inside the zinc-silver reserve battery are completely isolated. When the battery pack is in use, the 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] Due to its characteristics, the loading voltage at the moment of activation of zinc-silver storage batteries is generally low, especially after dry storage, the loading voltage at the moment of activation will drop significantly. This is caused by the combined effects of electrode polarization, the passivation film on the electrode surface, and the high-impedance monovalent silver oxide generated by the decomposition of the positive electrode surface after dry storage on the internal resistance of the zinc-silver storage battery. After a long period of dry storage, the internal resistance of the zinc-silver storage battery is large when activated, and the loading voltage at the moment of activation will be reduced.

[0004] As the requirements of weapons and equipment for the voltage and weight of zinc-silver reserve batteries continue to increase, higher requirements are placed on the loading voltage and working time of zinc-silver reserve batteries. However, the currently known method of increasing the initial voltage of the zinc-silver reserve battery pack when supplying power to the user end is: a current limiting resistor and a time relay are connected in series inside the battery pack, and when the zinc-silver reserve battery monomer is activated, the battery monomer is discharged to burn out the current limiting resistor, so that the zinc-silver reserve battery is pre-activated before supplying power to the user end, so that the zinc-silver reserve battery is increased to a specified voltage before supplying power to the user end.

[0005] However, this method has the following two problems:

[0006] (1) This method connects two components, a current limiting resistor and a time relay, in series in the zinc-silver reserve battery pack, which increases the weight and volume of the battery pack and reduces the reliability of the battery pack.

[0007] (2) In some usage scenarios, the zinc-silver reserve battery needs to be activated and wet-shelved for a period of time before the user end is started to use electricity. During the wet-shelf period, the reaction of electrode oxidation or decomposition to generate high-impedance substances continues to occur. When the battery supplies power to the user end, the initial voltage it can supply has decreased again. However, the current limiting resistor and time relay in the activated zinc-silver reserve battery pack have failed and the battery cannot be pre-activated again, which results in the zinc-silver reserve battery that has been wet-shelved for a period of time being unable to meet the initial voltage requirements required by the user end. Summary of the invention

[0008] The object of the present invention is to provide a zinc-silver reserve battery monomer with high loading voltage and long working time and a preparation method thereof, so as to solve the problems in the background technology.

[0009] The technical solution of the present invention includes: a method for preparing a zinc-silver reserve battery monomer with high loading voltage and long working time, which includes the steps of:

[0010] The silver positive electrode plate and the zinc negative electrode plate are separated by a separator and assembled into a formation battery with a formation electrolyte containing chloride;

[0011] Pre-charge the formation battery to the positive electrode theoretical capacity;

[0012] Pre-discharge the pre-charged formation battery, with the discharge capacity being 25% to 30% of the positive electrode theoretical capacity;

[0013] The pre-discharged formation battery is disassembled, and the disassembled silver positive plate and zinc negative plate are used to assemble the zinc-silver reserve battery monomer.

[0014] Preferably, the silver positive electrode plate contains silver with a particle size of 0.1 μm to 10 μm.

[0015] Preferably, the zinc negative electrode plate contains zinc and zinc oxide, wherein the mass proportion of zinc is 20% to 50%, and the particle size of zinc is 0.1 μm to 10 μm.

[0016] Preferably, the current density of pre-charge and pre-discharge is 1 mA / cm 2 ~10mA / cm 2 The pre-charge time is 5h~10h, and the pre-discharge time is 10min~1h.

[0017] Preferably, the chloride comprises at least one of sodium chloride and potassium chloride.

[0018] Preferably, the chloride content in the formation electrolyte is 10 g / L to 50 g / L.

[0019] Preferably, the formation electrolyte is an inorganic alkaline solution with a concentration of 30% to 50%.

[0020] Preferably, the formation electrolyte is a potassium hydroxide solution.

[0021] Preferably, after disassembling the pre-discharged formation battery, the silver positive plate and the zinc negative plate are washed with distilled water until they are alkali-free, the washed silver positive plate is dried at 30-70°C, the washed zinc negative plate is dried at 100-300°C, and then assembled into a zinc-silver reserve battery cell.

[0022] The technical solution of the present invention also includes: a zinc-silver reserve battery monomer with high loading voltage and long working time, which is prepared by the preparation method as described above.

[0023] The invention has the following beneficial effects: the zinc-silver reserve battery monomer prepared by the invention has a simple structure and is easy to prepare; there is no need to add a current limiting resistor and a time resistor when assembling the battery pack, the mass and volume of the battery pack will not be increased, and the reliability of the battery pack can be guaranteed; and whether it is discharged after an activation period or discharged after a long period of wet storage, a high loading voltage and a long discharge time can be effectively maintained, and the discharge utilization rate of the battery is higher than 65%. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The zinc-silver reserve battery monomer prepared by the prior art and the zinc-silver reserve battery monomer prepared by the embodiment of the present invention are loaded and discharged at a current of 25A after being activated for 60s and wet-shelf for 8h;

[0025] Figure 2 The zinc-silver reserve battery monomer prepared by the prior art and the zinc-silver reserve battery monomer prepared by the embodiment of the present invention are activated for 60 seconds and wet-shelf for 8 hours, and then loaded with discharge curves at discharge currents of 25A and 30A (including 200ms pulses of 42A and 54A once each). DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with embodiments and drawings:

[0027] 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.

[0028] Unless otherwise defined, the raw materials, reagents, etc. in the following examples can be purchased from the market or prepared according to reported methods.

[0029] The present invention provides a method for preparing a zinc-silver reserve battery monomer with high loading voltage and long working time and a battery monomer prepared by the method. The preparation method comprises the following steps:

[0030] (1) separating the silver positive electrode plate and the zinc negative electrode plate by a separator and assembling them into a formation cell with a chloride-containing formation electrolyte;

[0031] Among them, the silver positive electrode plate can be prepared with silver with a particle size of 0.1μm to 10μm, and the zinc negative electrode plate can use a mixture of zinc and zinc oxide, in which the mass proportion of zinc is 20% to 50% and the particle size of zinc is 0.1μm to 10μm, so as to ensure that the positive and negative electrodes have high capacity and electrochemical activity.

[0032] In this embodiment, zinc is prepared by electrolysis, and silver is prepared by thermal decomposition of silver acetate. The silver prepared by this method has a purity higher than 95% and can be used to prepare silver positive plates.

[0033] The diaphragm is made of one or more of a porous polymer membrane, filter paper, glass paper and a spunlace non-woven fabric diaphragm, which is bent in a serpentine shape. The silver positive electrode plate and the zinc negative electrode plate are alternately arranged on both sides of the diaphragm to ensure the mutual independence of the silver positive electrode plate and the zinc negative electrode plate to prevent the two from short-circuiting.

[0034] The formation electrolyte may be an inorganic alkali solution, preferably a potassium hydroxide solution, and its concentration is controlled at 30% to 50%.

[0035] The chloride can be sodium chloride, potassium chloride or a mixture of the two, and its concentration in the formation electrolyte is controlled at 10g / L to 50g / L.

[0036] (2) pre-charging the formation battery to the theoretical capacity of the positive electrode;

[0037] In this step, the silver in the silver positive plate is fully converted into silver oxide and silver peroxide. If a conventional zinc-silver reserve battery cell is to be prepared, the battery component can be assembled and dry-stored for standby use after this step. The positive electrode active ingredients of normal discharge after activation are silver oxide and silver peroxide, the negative electrode active ingredient is zinc, and the electrolyte is potassium hydroxide solution.

[0038] When the battery pack is discharged, the current must overcome the internal resistance of the battery pack when passing through the battery pack. The smaller the internal resistance of the battery pack, the smaller the voltage drop caused, and the higher the discharge voltage of the battery pack. Ohmic resistance includes the sum of the resistance of each component of the battery pack (electrodes, electrolyte, etc.) and the contact resistance (electrical connector). By comparison, it can be seen that the specific resistance of silver oxide is about 1×10 8 Ω·cm, the specific resistance of silver peroxide is about 10Ω·cm, and the specific resistance of zinc is about 5.2×10 -6Ω·cm, the specific resistance of the electrolyte is about 1.6Ω·cm (usually the electrical connector adopts a current redundant design, and its ohmic resistance can be ignored). The specific resistance of silver oxide is much higher than that of other substances, and its content becomes the main influencing factor of the internal resistance of the zinc-silver reserve battery at the moment of loading.

[0039] Since the decomposition of silver peroxide into high-impedance silver oxide is unavoidable during the storage of the zinc-silver reserve battery, this embodiment reduces the total content of silver oxide in the silver positive plate when the zinc-silver reserve battery is activated by reducing the content of silver oxide in the silver positive plate before assembling the zinc-silver reserve battery, thereby reducing the internal resistance of the zinc-silver reserve battery during activation and increasing the loading voltage. The specific method used is step (3).

[0040] (3) pre-discharging the pre-charged formation battery, with the discharge capacity being 25% to 30% of the theoretical capacity of the positive electrode;

[0041] During the pre-discharge process, silver oxide is reduced to silver, the content of silver oxide decreases, and the specific resistance of silver is about 1.6×10 -6 Ω·cm, 10 lower than the specific resistance of silver oxide 14 times, the reduction in silver oxide content greatly increases the conductivity of the silver positive plate, reduces the internal resistance of the battery, and increases the battery's loading voltage.

[0042] Since the silver oxide content in the silver positive plate is reduced before the zinc-silver reserve battery is assembled, even if the silver oxide still decomposes into some silver oxide during the battery storage period (whether dry storage or wet storage), the user's demand for loading voltage can still be met.

[0043] Part of the battery energy will be lost during the pre-discharge process, which will lead to a decrease in the capacity of the zinc-silver reserve battery and a shortened discharge time. However, the chloride added to the formation electrolyte can form a stable complex with silver peroxide during the pre-charge process, reducing the operating voltage of the battery and making the silver positive plate more stable in the electrolyte, reducing the loss of silver peroxide caused by dissolution in the electrolyte during the discharge process, so the total discharge time of the zinc-silver reserve battery is longer.

[0044] In the above steps, the current density of pre-charge and pre-discharge is 1mA / cm 2 ~10mA / cm 2 The two can be equal or unequal; the pre-charge time is controlled at 5h~10h, and the pre-discharge time is controlled at 10min~1h to avoid diaphragm failure and short circuit of positive and negative electrodes.

[0045] (4) Finally, the pre-discharged formation battery is disassembled, and the disassembled silver positive electrode plate and zinc negative electrode plate are used to assemble a zinc-silver reserve battery cell.

[0046] This step is the same as the assembly method of ordinary zinc-silver reserve battery cells. The silver positive plate and zinc negative plate after pre-discharge are separated by a diaphragm, and assembled together with ordinary electrolyte ("ordinary" is used to distinguish it from the formation electrolyte, that is, the electrolyte in this step does not contain chloride), electrode columns and other necessary components.

[0047] It is worth noting that after disassembling the pre-discharged formation battery, the silver positive plate and the zinc negative plate are washed with distilled water until they are alkali-free, the washed silver positive plate is dried at 30-70°C, and the washed zinc negative plate is dried at 100-300°C, and then assembled into zinc-silver reserve battery cells.

[0048] Compared with the prior art, the zinc-silver reserve battery monomer prepared by the present invention has a simple structure and is easy to prepare. There is no need to add current limiting resistors and time resistors when assembling the battery pack, which will not increase the mass and volume of the battery pack and can ensure the reliability of the battery pack. Moreover, whether it is discharged after an activation period or discharged after a long period of wet storage, it can effectively maintain a high loading voltage and a long discharge time, and the discharge utilization rate of the battery is higher than 65%.

[0049] Example:

[0050] Preparation of silver positive plate: Place (30-70) mm × (20-60) mm silver conductive mesh and 1g-10g of silver acetate thermal decomposition silver powder (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.

[0051] Preparation of zinc negative plate: Place (30-70) mm × (20-60) mm silver conductive mesh and 1g-10g of a mixture of electrolytic zinc powder and zinc oxide powder (electrolytic zinc powder accounts for 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), 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 zinc negative plate with the mold core, and demold and take out the zinc negative plate.

[0052] Assembling a formation battery: separating the silver positive electrode plate and the zinc negative electrode plate by a diaphragm, and assembling the formation battery with a formation electrolyte, wherein the formation electrolyte is a potassium hydroxide solution with a concentration of 30% to 50%, to which 10g / L to 50g / L sodium chloride or potassium chloride is added.

[0053] Pre-charge: 1mA / cm 2 ~10mA / cm 2The current density will charge the voltage of the battery to no less than 2.05V (the voltage value corresponding to the theoretical capacity of the positive electrode).

[0054] Pre-discharge: 1mA / cm 2 ~10mA / cm 2 The discharge capacity is 25% to 30% of the theoretical capacity of the positive electrode.

[0055] Assembling zinc-silver reserve battery cells: dismantling the pre-discharged formation battery, washing the silver positive plate and the zinc negative plate with distilled water until they are alkali-free (colorless after adding phenolphthalein reagent), drying the washed silver positive plate at 30-70°C, and drying the washed zinc negative plate at 100-300°C; taking 3-12 dried silver positive plates and 3-12 dried zinc negative plates (the difference between the two numbers is ≤1), bending the diaphragm into a serpentine shape, alternately placing the silver positive plate and the zinc negative plate on both sides of the diaphragm to ensure that the positive and negative electrodes do not overlap, and finally pressing electrode columns on the positive and negative electrode leads for conduction.

[0056] Reference Figure 1 The zinc-silver reserve battery monomer prepared by the prior art (no pre-discharge, no chloride added to the formation electrolyte) and the zinc-silver reserve battery monomer prepared by this embodiment are loaded and discharged at a current of 25A for 0s to 0.6s after being activated for 60s and wet-shelf for 8h. It can be seen from the figure that the zinc-silver reserve battery monomer prepared by this embodiment has a higher loading voltage. Figure 2 The zinc-silver reserve battery monomer prepared by the prior art (no pre-discharge, no chloride added to the formation electrolyte) and the zinc-silver reserve battery monomer prepared in this embodiment are loaded with discharge curves at discharge currents of 25A and 30A (including 200ms pulses of 42A and 54A once each) after being activated for 60s and wet-shelf for 8h. It can be seen from the figure that the zinc-silver reserve battery monomer prepared in this embodiment has a longer working time.

[0057] 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 preparing a zinc-silver reserve battery monomer with high loading voltage and long working time, characterized in that: Includes steps: The silver positive electrode plate and the zinc negative electrode plate are separated by a separator and assembled into a formation battery with a formation electrolyte containing chloride; Pre-charge the formation battery to the positive electrode theoretical capacity; Pre-discharge the pre-charged formation battery, with the discharge capacity being 25% to 30% of the theoretical capacity of the positive electrode; The pre-discharged formation battery is disassembled, and the disassembled silver positive plate and zinc negative plate are used to assemble the zinc-silver reserve battery monomer.

2. The method for preparing a zinc-silver reserve battery monomer with high loading voltage and long working time according to claim 1, characterized in that: The silver positive electrode plate contains silver with a particle size of 0.1 μm to 10 μm.

3. The method for preparing a zinc-silver reserve battery monomer with high loading voltage and long working time according to claim 1, characterized in that: The zinc negative electrode plate contains zinc and zinc oxide, wherein the mass proportion of zinc is 20% to 50%, and the particle size of zinc is 0.1 μm to 10 μm.

4. The method for preparing a zinc-silver reserve battery monomer with high loading voltage and long working time according to claim 1, characterized in that: The current density of pre-charge and pre-discharge is 1mA / cm 2 ~10mA / cm 2 The pre-charge time is 5h~10h, and the pre-discharge time is 10min~1h.

5. The method for preparing a zinc-silver reserve battery monomer with high loading voltage and long working time according to any one of claims 1 to 4, characterized in that: The chloride includes at least one of sodium chloride and potassium chloride.

6. The method for preparing a zinc-silver reserve battery monomer with high loading voltage and long working time according to claim 5, characterized in that: The chloride content in the formation electrolyte is 10 g / L to 50 g / L.

7. The method for preparing a zinc-silver reserve battery monomer with high loading voltage and long working time according to any one of claims 1-4 and 6, characterized in that: The formation electrolyte is an inorganic alkali solution with a concentration of 30% to 50%.

8. The method for preparing a zinc-silver reserve battery monomer with high loading voltage and long working time according to claim 7, characterized in that: The formation electrolyte is a potassium hydroxide solution.

9. The method for preparing a zinc-silver reserve battery monomer with high loading voltage and long working time according to claim 7, characterized in that: After disassembling the pre-discharged formation battery, wash the silver positive plate and the zinc negative plate with distilled water until they are alkali-free, dry the washed silver positive plate at 30-70°C, and dry the washed zinc negative plate at 100-300°C, and then assemble them into zinc-silver reserve battery cells.

10. A zinc-silver reserve battery cell with high loading voltage and long working time, characterized in that: The method is prepared by any one of claims 1 to 9.

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