Method for testing activity of silver powder for battery

Abstract

The invention relates to a method for testing the activity of silver powder for a zinc-silver battery, and belongs to the field of silver powder activity tests.According to the testing method, silver powder to be tested is adopted for preparing a positive plate, the capacity of the positive plate is tested with the help of an auxiliary electrode, a reference electrode and charging and discharging equipment, and the tested capacity is compared with the theoretical capacity of the silver powder; and calculating the silver powder activity utilization rate. The activity of the silver powder is an important index for measuring the electrical property of the silver powder, and is an important basis for screening the silver powder for the zinc-silver battery. According to the test method, the activity of the silver powder can be tested only by manufacturing the positive plate and adopting a simple test groove, and a zinc-silver battery does not need to be manufactured; the method is simple and easy to implement, low in material consumption, low in cost and short in manufacturing and testing period, the electrical performance of the silver powder can be rapidly judged, accurate data support is provided for screening silver powder raw materials in batch production of zinc-silver batteries, and the development period of the zinc-silver batteries is shortened.

Description

Technical Field

[0001] This invention belongs to the field of silver powder activity testing, and specifically relates to a method for testing the activity of silver powder for batteries. Background Technology

[0002] Due to cost considerations, zinc-silver batteries are designed with an excess negative electrode, therefore their electrical performance is determined by the positive electrode active material—silver powder. To avoid production defects caused by poor silver powder performance, the electrical performance of the silver powder needs to be tested before mass production to select silver powder that meets the performance requirements.

[0003] In the past, the electrical performance testing of silver powder mainly involved preparing individual cells and then judging the performance of silver powder by charging and discharging tests on the individual cells. This method involves many steps, a long cycle, requires a large amount of silver material, and the test results are easily affected by many factors such as the preparation process of the individual cells, the negative electrode material, and the structural components, which may lead to certain deviations in the measured silver powder activity.

[0004] To meet the mass production needs of zinc-silver batteries, there is an urgent need for an efficient, accurate, and low-cost method for testing the performance of silver powder.

[0005] Typically, testing the electrical performance of silver powder, the positive electrode material used in zinc-silver batteries, requires the fabrication of individual cells. The performance of the silver powder is then determined through charge-discharge tests on these individual cells. This method involves a series of steps, including electrode framework preparation (silver mesh + silver strip), positive electrode preparation (silver powder spread onto the electrode framework), negative electrode preparation (negative electrode active material prepared and then spread onto the electrode framework), formation and cleaning of the positive and negative electrodes, individual cell assembly, and individual cell testing. The entire cycle takes approximately three weeks, and the formation process occupies production line access. The fabrication of individual cells consumes a significant amount of silver material, and the test results are easily affected by various factors such as the individual cell fabrication process, negative electrode material, and structural components, leading to potential fluctuations and deviations in the measured silver powder activity. Summary of the Invention

[0006] The purpose of this invention is to provide a method for testing the activity of silver powder in batteries. This method is short in cycle, simple to operate, economical and practical, has few interfering factors in the testing process, and has high accuracy in test results. It can provide accurate data support for the screening of silver powder in the mass production of zinc-silver batteries.

[0007] The above-mentioned objectives of the present invention are mainly achieved through the following technical solutions: A method for testing the activity of silver powder for batteries includes the following steps: (1) Weigh out multiple groups of silver powder of equal mass; (2) Spread the silver powder obtained in step (1) onto the electrode skeleton to obtain the electrode; (3) Group the electrode sheets obtained in step (2), each group includes 3 electrode sheets, one of which is a positive electrode and two of which are negative electrodes, as auxiliary electrodes, and pack them into the slots in the order of negative electrode, positive electrode and negative electrode. (4) Place the reference electrode between the positive and negative electrode plates after the tank is filled in step (3), add electrolyte and connect the wires, and perform multiple charge and discharge cycle tests. The average discharge capacity is the actual capacity. The ratio of the actual capacity to the theoretical capacity of the silver powder is the activity utilization rate of the silver powder.

[0008] In step (1), nine groups of silver powder of equal mass are weighed for the first test, and three groups of silver powder of equal mass are weighed for subsequent batch tests.

[0009] In step (2), the aspect ratio of the electrode skeleton is 5:3 to 10:7, and the thickness of the prepared electrode is 0.6 to 0.8 mm.

[0010] In step (2), the electrode density is 4.3~4.7 g / cm³. 3 The electrode sheets are sintered at 490~510℃ for 10~15 minutes.

[0011] In step (4), the reference electrode is a zinc rod with a length longer than the electrode sheet, and the surface of the zinc rod is wrapped with a silver-magnesium salt film or covered with a perforated plastic sleeve.

[0012] In step (4), the electrolyte is a potassium hydroxide solution with a mass concentration of 30-35%, and the liquid level extends 4-6 mm beyond the upper edge of the electrode. The solution is soaked at 20-30°C for 1-1.5 hours before testing.

[0013] In step (4), the charge-discharge cycle test consists of three charge-discharge cycles, and the test environment temperature is 22~28℃. In step (4), after the auxiliary electrode is tested, it is cleaned, dried and reduced, and then used as an auxiliary electrode in subsequent tests.

[0014] Compared with the prior art, the present invention has at least the following beneficial effects: The silver powder activity testing method of this invention is simple and easy to operate, and has low cost; the electrode fabrication and testing process has a short cycle, and the test can be completed within one day, with rapid results; at the same time, this method can effectively avoid interference from many processes and negative electrode materials during the manufacturing of finished batteries, and the test results are accurate and reliable. Attached Figure Description

[0015] Figure 1 This is a flowchart of the silver powder activity testing process of the present invention; Figure 2 This is a schematic diagram of the dedicated electrode test groove structure of the present invention; Figure 3This is a schematic diagram of the electrode installation of the present invention; Figure 4 This is a schematic diagram of the silver powder test wiring for the present invention. Detailed Implementation

[0016] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments: like Figure 1 As shown, the present invention provides a method for testing the activity of silver powder, comprising the following steps: (1) Weigh the silver powder sample; for the first test, weigh 9 portions of silver powder of the same weight for later use; for subsequent batch tests, weigh 3 portions.

[0017] (2) Positive electrode sheet preparation: The aspect ratio of the electrode frame used for electrode sheet preparation is generally controlled within the range of 5:3 to 10:7. Using appropriate positive electrode sheet preparation fixtures, the weighed silver powder is evenly spread on the electrode frame. A press is then used to press the sheet, with the thickness controlled within the range of 0.70±0.1 mm. The electrode density of the prepared electrode sheet is controlled within 4.5±0.2 g / cm³. 3 Within the specified range, the electrode sheets are sintered in a muffle furnace at 500±10℃ for 10~15min and then set aside for use. (3) Grouping and mounting of electrode sheets; such as Figure 2 As shown, three electrodes form a group. The electrode for the silver powder to be tested is the positive electrode, and the other two electrodes are the negative electrodes, serving as auxiliary electrodes. The auxiliary electrodes can be cleaned, dried, and restored after the test, and can be reused as auxiliary electrodes in subsequent tests. The mounting is done by sequentially mounting one auxiliary electrode, one test electrode, and one auxiliary electrode into the corresponding slot of the dedicated electrode test slot.

[0018] (4) Place the reference electrode; such as Figure 3 As shown, prepare a zinc rod with a length slightly longer than the electrode as a reference electrode. Wrap the surface of the zinc rod with a silver-magnesium salt film or put it on a perforated plastic sleeve, and insert it into the special test slot between the positive and negative electrodes.

[0019] (5) Add electrolyte and soak: Add 30-35% potassium hydroxide solution to the battery test cell, with the liquid level about 4-6 mm above the upper edge of the electrode. Soak in an environment of 25±5℃ for 1-1.5 hours before subsequent tests can be carried out.

[0020] (6) Wiring; such as Figure 4 As shown, prepare the corresponding equipment, instruments and wires, etc. Connect the electrode to be tested, the charging and discharging equipment and the voltmeter with wires. The three sets of test electrodes can be connected in series or tested using three independent circuits.

[0021] (7) Activity Test. The test electrode is subjected to three charge-discharge cycles. The average discharge capacity of the three cycles is taken as the actual capacity. The percentage of the actual capacity to the theoretical capacity of the silver powder is the activity utilization rate of the silver powder. The ambient temperature during this step should be controlled within the range of 25±3℃.

[0022] Example 1 Step S1: Sampling. Take samples from the active silver powder to be tested. For the first batch of tests, weigh out 9 portions of silver powder, each weighing 14g, and set aside. For subsequent batches of tests, weigh out 3 portions.

[0023] Step S2: Spread the positive electrode sheet. The electrode frame size is 56mm×77mm. With the help of the spreading tool, the weighed silver powder is evenly spread on the electrode frame. The press pressure is adjusted to 6.0±0.2MPa. The electrode thickness can be controlled within 0.70±0.1mm. Sinter in a muffle furnace at 500±10℃ for 10min.

[0024] Step S3: Group and pack the electrodes into slots. Three electrodes form a group. The electrode containing the silver powder to be tested is placed in the middle as the positive electrode, and the other two electrodes are negative electrodes, serving as auxiliary electrodes. The auxiliary electrodes can be cleaned, dried, and restored after testing, and can be reused as auxiliary electrodes in subsequent tests. The slotting process involves sequentially packing one auxiliary electrode, one test electrode, and one auxiliary electrode into a dedicated electrode testing slot. Auxiliary electrodes are placed in positions 1 and 3 of the test slot, and the electrode to be tested is placed in position 2. See details... Figure 2 .

[0025] Step S4: Place the reference electrode. Prepare a zinc rod 80mm long, 0.5mm wide, and 0.3mm thick. Wrap the surface of the zinc rod with a silver-magnesium salt film or cover it with a perforated plastic sleeve. Insert it into the dedicated test cell between the positive and negative electrode plates. See details below. Figure 3 .

[0026] Step S5: Add electrolyte and soak. Add 30% potassium hydroxide solution to the battery test cell, with the liquid level about 5mm above the upper edge of the electrode. Soak in an environment of 25±3℃ for 1 to 1.5 hours before proceeding with subsequent tests.

[0027] Step S6: According to Figure 4 For wiring, connect the electrode to be tested, the charging and discharging equipment, and the voltmeter with wires. The three sets of test electrodes can be connected in series or tested using three independent circuits.

[0028] Step S7: Charge-discharge test. Perform 3 charge-discharge cycles on the test electrode. The charge-discharge regime can be referred to Table 1. The average discharge capacity of the three cycles is taken as the actual capacity. The ratio of the actual capacity to the theoretical capacity (7Ah) of 14g of silver powder is the activity utilization rate of the silver powder. Activity utilization rate = actual capacity / 7Ah × 100%.

[0029] Table 1 Electrode Charge / Discharge Schedule

[0030] The above description is only the best specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the protection scope of the present invention.

[0031] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A method for testing the activity of silver powder for batteries, characterized in that: Includes the following steps: (1) Weigh out multiple groups of silver powder of equal mass; (2) Spread the silver powder obtained in step (1) onto the electrode skeleton to obtain the electrode; (3) Group the electrode sheets obtained in step (2), each group includes 3 electrode sheets, one of which is a positive electrode and two of which are negative electrodes, as auxiliary electrodes, and pack them into the slots in the order of negative electrode, positive electrode and negative electrode. (4) Place the reference electrode between the positive and negative electrode plates after the tank is filled in step (3), add electrolyte and connect the wires, and perform multiple charge and discharge cycle tests. The average discharge capacity is the actual capacity. The ratio of the actual capacity to the theoretical capacity of the silver powder is the activity utilization rate of the silver powder.

2. The method for testing the activity of silver powder for batteries according to claim 1, characterized in that: In step (1), nine groups of silver powder of equal mass are weighed for the first test, and three groups of silver powder of equal mass are weighed for subsequent batch tests.

3. The method for testing the activity of silver powder for batteries according to claim 1, characterized in that: In step (2), the aspect ratio of the electrode skeleton is 5:3 to 10:7, and the thickness of the prepared electrode is 0.6 to 0.8 mm.

4. The method for testing the activity of silver powder for batteries according to claim 1, characterized in that: In step (2), the electrode density is 4.3~4.7 g / cm³. 3 The electrode sheets are sintered at 490~510℃ for 10~15 minutes.

5. The method for testing the activity of silver powder for batteries according to claim 1, characterized in that: In step (4), the reference electrode is a zinc rod with a length 2-4 mm longer than the electrode plate, and the surface of the zinc rod is wrapped with a silver-magnesium salt film or covered with a perforated plastic sleeve.

6. The method for testing the activity of silver powder for batteries according to claim 1, characterized in that: In step (4), the electrolyte is a potassium hydroxide solution with a mass concentration of 30-35%, and the liquid level extends 4-6 mm beyond the upper edge of the electrode. The solution is soaked at 20-30°C for 1-1.5 hours before testing.

7. The method for testing the activity of silver powder for batteries according to claim 1, characterized in that: In step (4), the charge-discharge cycle test consists of three charge-discharge cycles, and the test environment temperature is 22~28℃.

8. The method for testing the activity of silver powder for batteries according to claim 1, characterized in that: In step (4), after the auxiliary electrode is tested, it is cleaned, dried and reduced, and then used as an auxiliary electrode in subsequent tests.

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