A method for improving the specific energy of zinc-silver reserve batteries by floating charging

Abstract

The application provides a floating charging method for improving specific energy of a zinc-silver storage battery, and the steps of the method comprise: obtaining the number of zinc-silver single batteries of each battery group and the single cutoff voltage value and the single floating charging voltage value of each battery group according to a target load voltage lower limit value, a floating charging voltage value and a zinc-silver single battery load voltage value range, and performing charging and discharging on the single batteries of each battery group respectively, so as to screen out the optimal cutoff voltage value and the optimal floating charging voltage value of the single batteries, obtain the number of zinc-silver single batteries of a corresponding battery group, assemble the battery group P according to the number of zinc-silver single batteries, perform charging and discharging on the battery group P, and compare the specific energy values before and after the charging and discharging of the battery group P; the zinc-silver single batteries are charged and discharged, the number of single batteries of the battery group is reasonably designed, the weight of the battery group is reduced, and the specific energy of the zinc-silver storage battery group is improved.

Description

Technical Field

[0001] This invention relates to the field of charge and discharge performance research of zinc-silver reserve batteries, and particularly to a float charging method for improving the specific energy of zinc-silver reserve batteries. Background Technology

[0002] Zinc-silver backup batteries, characterized by high energy density, safety, reliability, and long storage life, are frequently used in aerospace equipment. Currently, zinc-silver backup battery packs are assembled by connecting multiple primary single cells in series for direct use. A common approach is to connect 20 primary zinc-silver single cells in series to form a battery pack, with an energy density of less than 40 Wh / kg. Following this design approach, achieving a higher energy density requires increasing the number of zinc-silver single cells connected in series. However, increasing the number of cells increases the overall weight of the battery pack, which no longer meets the requirements of aerospace and other fields that demand high energy density and low weight in zinc-silver backup batteries.

[0003] To improve the specific energy of battery packs, Chinese patent CN102544533A discloses an electrolyte storage method for electrically activated zinc-silver backup battery packs, such as its... Figure 1 As shown, the square housing (1) has a liquid inlet connector (3) and a gas generator connector (8). Inside the liquid inlet connector (3) and the gas generator connector (8) are a No. I sealing membrane (4), a No. II sealing membrane (5), and a clamping ring (6), respectively. The square housing (1) has a cuboid structure. A clamping nut (7) is provided at the end of the gas generator connector (8). The liquid reservoir of the present invention has a cuboid structure. After docking with the battery stack, although it can make the maximum use of the space above the battery stack in the battery pack and improve the specific energy of the battery, the structure of the invention is complex. The sealing performance of the sealing membrane affects the storage of electrolyte, which limits the application scenarios and does not reduce the weight of the battery pack itself. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a float charging method for improving the specific energy of zinc-silver reserve batteries.

[0005] The present invention is achieved through the following technical solutions.

[0006] A float charging method for improving the specific energy of a zinc-silver reserve battery, wherein the zinc-silver reserve battery is a battery pack composed of multiple individual cells connected in series, characterized by the following steps:

[0007] Step 1: Calculate the number n of zinc-silver cells in each battery pack under the target load voltage lower limit and the zinc-silver cell load voltage range;

[0008] Step 2: Calculate the cutoff voltage and float charge voltage of the zinc-silver cells for each battery pack under the target load voltage lower limit and the target float charge voltage value respectively;

[0009] Step 3: Using the calculated cutoff voltage and float charge voltage of each zinc-silver cell in each battery pack, charge and discharge the zinc-silver cells respectively, and collect the discharge capacity of each zinc-silver cell.

[0010] Step 4: Calculate the total discharge capacity of each zinc-silver cell after charging and discharging based on the individual cell discharge capacity. Select the zinc-silver cell with the largest total discharge capacity and determine the optimal cutoff voltage and optimal float charge voltage. Based on this, determine the number of zinc-silver cells in the corresponding battery pack.

[0011] Step 5: Assemble battery pack P according to the corresponding number of zinc and silver cells in the battery pack, and charge and discharge battery pack P to compare the specific energy of battery pack P before and after charging and discharging.

[0012] In step one, the calculation steps for the number n of zinc-silver individual cells in each battery pack are as follows:

[0013] (1) Assuming the target lower limit of the load voltage is V1, and the load voltage range of the zinc-silver single cell is 1.2V to 1.6V, the load voltage of the zinc-silver single cells in each battery pack must satisfy the following relationship:

[0014]

[0015] (2) Solve for the value of n when it is an integer according to formula (1), and let the solved n be n1, n2, ..., n a That is, the battery pack can consist of n1, n2, ..., n a It consists of only zinc-silver single-cell batteries.

[0016] In step two, the calculation steps for the cutoff voltage and float charge voltage of the zinc-silver single cell are as follows:

[0017] If the target float charging voltage is V2, then the cutoff voltage V of the zinc-silver individual cells in each battery pack is... 截 and float charging voltage value V 浮 for:

[0018]

[0019]

[0020] In the formula, n = n1, n2, ..., n a n1, n2, ..., n a This refers to the number of zinc-silver individual cells in the battery pack.

[0021] In step three, the specific charging and discharging steps for the zinc-silver cells in each battery pack are as follows: Let the charging and discharging cells of each battery pack be cell A and cell B. The specific charging and discharging steps for cell A and cell B are as follows:

[0022] (a) Using a battery discharge test system, cells A and B were discharged to different degrees under a constant current I:

[0023] (1) Single cell A is discharged at a constant current I until the cutoff voltage V. 截 The discharge capacity value of the collected single cell A is C. A ;

[0024] (2) Single cell B is discharged at a constant current I until the collected discharge capacity value C is reached. B C A Discharge stops when two-thirds of the charge has been discharged;

[0025] (ii) After discharge, cells A and B are charged with a float charging voltage V respectively. 浮 Perform constant voltage float charging for t hours;

[0026] (III) Using a battery discharge test system, discharge the charged cells A and B at a constant current I until the cutoff voltage V. 截 The discharge capacity value of the collected single cell A is C. A The discharge capacity value of the collected single cell B is C. B '.

[0027] In step four, the selection steps for the optimal cutoff voltage and optimal float charge voltage used in the zinc-silver single cell are as follows:

[0028] (1) Calculate the total discharge capacity of cells A and B in each battery pack:

[0029] C A放总 =C A +C' A (4)

[0030] C B放总 =C B +C' B (5)

[0031] In the formula: C A放总 C represents the total discharge capacity of cell A. B放总 This represents the total discharge capacity of cell B.

[0032] (2) Compare the total discharge capacity of cells A and B after each battery pack is charged and discharged. The cell with the largest total discharge capacity is the optimal cut-off voltage and optimal float charge voltage of the zinc-silver cell.

[0033] In step five, the charging and discharging steps of battery pack P are as follows:

[0034] (1) Use a battery discharge test system to discharge battery pack P at a constant current I to the target lower limit of the load voltage V1, and collect the discharge capacity value C. p ;

[0035] (2) The discharged battery pack P is subjected to constant voltage float charging for t hours at the target float charging voltage value V2.

[0036] (3) Using a battery discharge test system, discharge the charged battery pack P at a constant current I to the target lower limit of the load voltage V1, and collect the discharge capacity value C. p '.

[0037] In step five, the formula for calculating the specific energy (BSE) of battery pack P is:

[0038]

[0039] In the formula: V is the plateau voltage value. Due to the characteristics of zinc-silver batteries, there is a voltage plateau during discharge, that is, a stable and continuous voltage value exists for a period of time during discharge. This range is the plateau voltage. When the active material is almost exhausted, the voltage will gradually drop from the plateau to the cutoff voltage. C is the discharge capacity of the battery pack, C = C P +C P '; W represents the weight of the battery pack.

[0040] The t = 3;

[0041] The current value of the constant current I is 15A.

[0042] The beneficial effects of this invention are as follows: Based on the load voltage and float charge voltage of the battery pack, the number of zinc-silver cells in each battery pack is determined. The cutoff voltage and float charge voltage of each cell in each battery pack are then calculated. Two cells in each battery pack are charged and discharged separately to select the optimal number of zinc-silver cells for each pack. The battery pack is then charged and discharged, and the specific energy values ​​after discharge and after charging and discharging are compared. Compared to the traditional method of using zinc-silver cells connected in series for a single discharge, the zinc-silver reserve battery pack of this invention not only increases the total discharge capacity of the battery pack but also improves its specific energy. Attached Figure Description

[0043] Figure 1 This is a flowchart illustrating the method described in this invention;

[0044] Figure 2 The graph shows the current and voltage changes during the charging process of cell E in Example 1.

[0045] Figure 3This is a graph showing the current and voltage changes during the charging process of a single cell F in Example 1;

[0046] Figure 4 This is a graph showing the current and voltage changes during the charging process of a single cell G in Example 1;

[0047] Figure 5 The graph shows the current and voltage changes during the charging process of the single cell H in Example 1. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] The technical solution of the present invention is further described below, but the scope of protection is not limited to what is described.

[0050] Combination Figure 1 A float charging method for improving the specific energy of a zinc-silver reserve battery, wherein the zinc-silver reserve battery is a battery pack composed of multiple individual cells connected in series, characterized by the following steps:

[0051] Step 1: Calculate the number n of zinc-silver cells in each battery pack under the target load voltage lower limit and the zinc-silver cell load voltage range;

[0052] Step 2: Calculate the cutoff voltage and float charge voltage of the zinc-silver cells for each battery pack under the target load voltage lower limit and the target float charge voltage value respectively;

[0053] Step 3: Using the calculated cutoff voltage and float charge voltage of each zinc-silver cell in each battery pack, charge and discharge the zinc-silver cells respectively, and collect the discharge capacity value of each zinc-silver cell.

[0054] Step 4: Calculate the total discharge capacity of each zinc-silver cell after charging and discharging based on the individual cell discharge capacity value. Select the zinc-silver cell with the largest total discharge capacity value and the optimal cutoff voltage and optimal float charge voltage value. Based on this, determine the number of zinc-silver cells in the corresponding battery pack.

[0055] Step 5: Assemble battery pack P according to the corresponding number of zinc and silver cells in the battery pack, and charge and discharge battery pack P to compare the specific energy of battery pack P before and after charging and discharging.

[0056] Technical effect: By charging and discharging battery pack P, the specific energy value of battery pack P when discharged to the cutoff voltage value and after charging and discharging can be calculated.

[0057] In step one, the calculation steps for the number n of zinc-silver individual cells in each battery pack are as follows:

[0058] (1) Assuming the target lower limit of the load voltage is V1, and the load voltage range of the zinc-silver single cell is 1.2V to 1.6V, the load voltage of the zinc-silver single cells in each battery pack must satisfy the following relationship:

[0059]

[0060] (2) Solve for the value of n when it is an integer according to formula (1), and let the solved n be n1, n2, ..., n a That is, the battery pack can consist of n1, n2, ..., n a It consists of only zinc-silver single-cell batteries;

[0061] Technical effect: Based on the known load voltage value and the load voltage range of the zinc-silver single cell, the battery pack consists of n1, n2, ..., or na zinc-silver cells.

[0062] In step two, the calculation steps for the cutoff voltage and float charge voltage of the zinc-silver single cell are as follows:

[0063] If the target float charging voltage is V2, then the cutoff voltage V of the zinc-silver individual cells in each battery pack is... 截 and float charging voltage value V 浮 for:

[0064]

[0065]

[0066] In the formula, n = n1, n2, ..., n a n1, n2, ..., n a The number of zinc-silver individual cells in the battery pack;

[0067] Technical effect: Based on the battery packs composed of different numbers of zinc-silver individual cells obtained in step one, and combined with the known float charge voltage values, the cutoff voltage and float charge voltage values ​​of the zinc-silver individual cells in each battery pack can be obtained.

[0068] In step three, the specific charging and discharging steps for the zinc-silver cells in each battery pack are as follows: Let the charging and discharging cells of each battery pack be cell A and cell B. The specific charging and discharging steps for cell A and cell B are as follows:

[0069] (a) Using a battery discharge test system, cells A and B were discharged to different degrees under a constant current I:

[0070] (1) Single cell A is discharged at a constant current I until the cutoff voltage V. 截 The discharge capacity value of the collected single cell A is C. A ;

[0071] (2) Single cell B is discharged at a constant current I until the collected discharge capacity value C is reached. B C A Discharge stops when two-thirds of the charge has been discharged;

[0072] (ii) After discharge, cells A and B are charged with a float charging voltage V respectively. 浮 Perform constant voltage float charging for t hours;

[0073] (III) Using a battery discharge test system, discharge the charged cells A and B at a constant current I until the cutoff voltage V. 截 The discharge capacity value of the collected single cell A is C. A The discharge capacity value of the collected single cell B is C. B ';

[0074] Technical effect: By charging and discharging individual cells A and B of the zinc-silver cells in each battery pack, the discharge capacity values ​​of individual cells A and B of the zinc-silver cells in each battery pack can be collected during the discharge process.

[0075] In step four, the selection steps for the optimal cutoff voltage and optimal float charge voltage used in the zinc-silver single cell are as follows:

[0076] (1) Calculate the total discharge capacity of cells A and B in each battery pack:

[0077] C A放总 =C A +C' A (4)

[0078] C B放总 =CB+C' B (5)

[0079] In the formula: C A放总 C represents the total discharge capacity of cell A. B放总 This represents the total discharge capacity of cell B.

[0080] (2) Compare the total discharge capacity values ​​of cells A and B after charging and discharging in each battery pack. The cell with the largest total discharge capacity value is the optimal cutoff voltage value and optimal float charge voltage value of the zinc-silver cell.

[0081] Technical effect: By comparing the total discharge capacity of individual cells, the optimal cutoff voltage and optimal float charge voltage of the zinc-silver cell can be selected.

[0082] In step five, the charging and discharging steps of battery pack P are as follows:

[0083] (1) Use a battery discharge test system to discharge battery pack P at a constant current I to the target load voltage value V1, and collect the discharge capacity value C. p ;

[0084] (2) The discharged battery pack P is subjected to constant voltage float charging for t hours at the target float charging voltage value V2.

[0085] (3) Using a battery discharge test system, discharge the charged battery pack P at a constant current I to the target load voltage value V1, and collect the discharge capacity value C. p '.

[0086] In step five, the formula for calculating the specific energy (BSE) of battery pack P is:

[0087]

[0088] In the formula: V is the plateau voltage value. Due to the characteristics of zinc-silver batteries, there is a voltage plateau during discharge, that is, a stable and continuous voltage value exists for a period of time during discharge. This range is the plateau voltage. When the active material is almost exhausted, the voltage will gradually drop from the plateau to the cutoff voltage. C is the discharge capacity of the battery pack, C = C P +C P '; W represents the weight of the battery pack.

[0089] The t = 3;

[0090] The current value of the constant current I is 15A.

[0091] The target lower limit of the load voltage refers to the minimum value within the range of the load voltage when the load voltage has a range.

[0092] Example 1:

[0093] Assume the known lower limit of the load voltage of the battery pack is 22.0V, the float charge voltage is 29.0V, the load voltage range of the zinc-silver individual cells is 1.2V to 1.6V, and the battery pack is composed of n zinc-silver individual cells connected in series.

[0094] According to formula (1), we know Solving for n, we get n = 14, 15, 16, 17, 18;

[0095] Take n = 16, 18;

[0096] The battery discharge test system is model DHS8262;

[0097] 1. When n=16, the cutoff voltage V of the zinc-silver individual cells in battery pack L1. L1截 and float charging voltage value V L1浮 for:

[0098]

[0099]

[0100] When n=18, the cutoff voltage V of the zinc-silver individual cells in battery pack L2 is... L2截 and float charging voltage value V L2浮 for:

[0101]

[0102]

[0103] 2. Charge and discharge individual cells E and F of battery pack L1, and individual cells G and H of battery pack L2:

[0104] (1) A battery discharge test system was used to discharge cell E at a constant current of 15A until the cutoff voltage of 1.375V, and the discharge capacity value C was collected. E1 It is 8.78 Ah;

[0105] (2) The battery discharge test system was used to discharge the single cell F at a constant current of 15A until the collected discharge capacity value C was obtained. F1 The discharge capacity value C of a single cell (E) E1 Two-thirds, that is, the collected discharge capacity value C F1 It is 5.85Ah;

[0106] (3) The battery discharge test system was used to discharge the single cell G at a constant current of 15A until the cutoff voltage value of 1.22V, and the discharge capacity value C was collected. G2 It is 9.34 Ah;

[0107] (4) The battery discharge test system was used to discharge the single cell H at a constant current of 15A until the collected discharge capacity value C was obtained. H2 The discharge capacity value C of a single cell G G2 Two-thirds, that is, the collected discharge capacity value C H2 It is 6.23Ah.

[0108] 3. Perform float charging on cells E, F, G, and H after discharge:

[0109] (1) After discharge, the cell E is float-charged at a single-cell float charging voltage of 1.81V for 3 hours, such as Figure 2The figure shows the changes in current and voltage over time during the charging process of cell E. Over 3 hours, the charging current gradually decreases from 3.361A to 0.205A, while the voltage of cell E gradually increases to 1.796V. At this point, the area of ​​the current-time curve is approximately 10414.81A·s, which is equivalent to 2.893Ah of charging.

[0110] (2) After discharge, the cell F is float-charged at a single-cell float charging voltage of 1.81V for 3 hours, such as Figure 3 The figure shows the changes in current and voltage over time during the charging process of a single cell F. Within 3 hours, the charging current gradually decreases from 1.896A to 0.183A, while the voltage of the single cell F gradually increases to 1.792V. At this point, the area calculated by integrating the current-time curve is approximately 6155.63A·s, which is equivalent to charging for 1.709Ah.

[0111] (3) After discharge, the cell G is float-charged at a single-cell float charging voltage of 1.61V for 3 hours, such as Figure 4 The figure shows the changes in current and voltage over time during the charging process of a single cell G. Within 3 hours, the charging current gradually decreased from 0.495A to 0.042A, and the voltage of the single cell G remained basically stable at 1.616V. At this time, according to the current-time curve, the area calculated by integration is approximately 1209.41A·s, which is equivalent to charging for 0.336Ah.

[0112] (4) After discharge, the single cell H is float-charged at a single cell float charging voltage of 1.61V for 3 hours, such as Figure 5 The figure shows the changes in current and voltage over time during the charging process of cell H. Within 3 hours, the charging current gradually decreased from 0.302A to 0.017A, and the voltage of cell H remained basically stable at 1.614V. At this time, according to the integral calculation of the current-time curve, the area is approximately 703.70A·s, which is equivalent to charging for 0.195Ah.

[0113] As can be seen from (1) to (4), the charging capacity of single cell E is the highest.

[0114] 4. Discharge the charged cells E, F, G, and H respectively:

[0115] (1) Using a battery discharge test system, the charged cells E and F were discharged at a constant current of 15A until the cutoff voltage of 1.375V. The discharge capacity value C of cell E was collected. E1 The discharge capacity of a single cell F is 3.76 Ah, C. F1 'It is 2.13Ah;

[0116] (2) Using a battery discharge test system, the charged cells G and H were discharged at a constant current of 15A until the cutoff voltage of 1.22V. The discharge capacity value C of cell G was collected. G2 The discharge capacity value C of single cell H is 0.94Ah. H2 It is 2.57Ah.

[0117] 5. Calculate the total discharge capacity of cells E, F, G, and H:

[0118] (1) Total discharge capacity value C of cell E E for:

[0119] C E =C E1 +C′ E1 =8.78 + 3.76 = 12.54 Ah

[0120] (2) Total discharge capacity value C of single cell F F for:

[0121] C F =C F1 +C′ F1 =5.85 + 2.13 = 7.98 Ah

[0122] (2) Total discharge capacity value C of single cell G G for:

[0123] C G =C G2 +C′ G2 =9.34 + 0.94 = 10.28 Ah

[0124] (3) Total discharge capacity value C of single cell H H for:

[0125] C H =C H2 +C′ H2 =6.23 + 2.57 = 8.8 Ah

[0126] 6. Comparing the total discharge capacity values ​​of cells E, F, G, and H, the calculation results in step 5 show that cell E has the largest total discharge capacity value. Therefore, when a cell is discharged to the cutoff voltage, then float-charged at a constant voltage, and then discharged to the cutoff voltage again, it will have the largest single-cell discharge capacity value. Moreover, the number of zinc-silver cells in the battery pack is 16.

[0127] Example 2:

[0128] 1. For the battery pack L consisting of 16 zinc-silver individual cells connected in series... 组 Perform charging and discharging:

[0129] (1) The battery pack L was tested using a battery discharge test system. 组 The battery pack L was discharged at a constant current of 15A until the cutoff voltage of 22V was reached. 组 Discharge capacity C 组 20.74Ah

[0130] (2) After the battery pack L is discharged 组 Charged at a constant voltage of 29V for 3 hours;

[0131] (3) The battery pack L was tested using a battery discharge test system. 组 The battery pack L was discharged at a constant current of 15A until the cutoff voltage of 22V was reached. 组 Discharge capacity C 组 'It is 5.66Ah;

[0132] 2. Platform voltage value V 台 =24.79V, 16 zinc-silver batteries weigh W=6.4kg

[0133] According to the specific energy formula:

[0134] Battery pack L 组 Specific energy (BSE) at discharge to cutoff voltage L组 for:

[0135]

[0136] Battery pack L 组 Specific energy (BSE) after charging and discharging L组 'for:

[0137]

[0138] This demonstrates that by matching the float charging voltage with the number of individual cells, the number of individual cells in the battery pack was rationally designed, thereby improving the specific energy of the battery pack.

Claims

1. A float charging method for improving the specific energy of a zinc-silver reserve battery, wherein the zinc-silver reserve battery is a battery pack composed of multiple zinc-silver individual cells connected in series, characterized in that... The steps of this method are as follows: Step 1: Calculate the number n of zinc-silver cells in each battery pack under the target load voltage lower limit and the zinc-silver cell load voltage range; Step 2: Calculate the cutoff voltage and float charge voltage of the zinc-silver cells for each battery pack under the target load voltage lower limit and the target float charge voltage value respectively; Step 3: Using the calculated cutoff voltage and float charge voltage of each zinc-silver cell in each battery pack, charge and discharge the zinc-silver cells respectively, and collect the discharge capacity value of each zinc-silver cell. Step 4: Calculate the total discharge capacity of each zinc-silver cell after charging and discharging based on the individual cell discharge capacity value. Select the zinc-silver cell with the largest total discharge capacity value and the optimal cutoff voltage and optimal float charge voltage value. Based on this, determine the number of zinc-silver cells in the corresponding battery pack. Step 5: Assemble battery pack P according to the corresponding number of zinc and silver cells in the battery pack, and charge and discharge battery pack P to compare the specific energy of battery pack P before and after charging and discharging.

2. The float charging method for improving the specific energy of a zinc-silver reserve battery as described in claim 1, characterized in that: In step one, the calculation steps for the number n of zinc-silver individual cells in each battery pack are as follows: (1) Assuming the target lower limit of the load voltage is V1, and the load voltage range of the zinc-silver single cell is 1.2V~1.6V, the load voltage of the zinc-silver single cell in each battery pack must satisfy the following relationship: （1）； (2) Solve for the value of n when it is an integer according to formula (1), and let the solved n be n1, n2, ..., n a， That is, the battery pack can consist of n1, n2, ..., n a It consists of only zinc-silver single-cell batteries.

3. The float charging method for improving the specific energy of a zinc-silver reserve battery as described in claim 2, characterized in that: In step two, the calculation steps for the cutoff voltage and float charge voltage of the zinc-silver single cell are as follows: If the target float charging voltage is V2, then the cutoff voltage V of the zinc-silver individual cells in each battery pack is... 截 and float charging voltage value V 浮 for: （2） （3） In the formula, n = n1, n2, ..., n a， n1, n2, ..., n a This refers to the number of zinc-silver individual cells in the battery pack.

4. The float charging method for improving the specific energy of a zinc-silver reserve battery as described in claim 3, characterized in that: In step three, the specific charging and discharging steps for the zinc-silver cells in each battery pack are as follows: Let the charging and discharging cells of each battery pack be cell A and cell B. The specific charging and discharging steps for cell A and cell B are as follows: (a) Using a battery discharge test system, cells A and B were discharged to different degrees at a constant current I: (1) Single cell A is discharged at a constant current I until the cutoff voltage V. 截 The discharge capacity value of the collected single cell A is C. A ; (2) Single cell B is discharged at a constant current I until the collected discharge capacity value C is obtained. B C A Discharge stops when two-thirds of the charge has been discharged; (ii) After discharge, cells A and B are charged with a float charging voltage of V. 浮 Perform constant voltage float charging for t hours; (iii) Using a battery discharge test system, discharge the charged cells A and B at a constant current I until the cutoff voltage V. 截 The discharge capacity value of the collected single cell A is C. A ’ The discharge capacity value of the collected single cell B is C. B ’ .

5. The float charging method for improving the specific energy of a zinc-silver reserve battery as described in claim 1, characterized in that: In step four, the selection steps for the optimal cutoff voltage and optimal float charge voltage used in the zinc-silver single cell are as follows: (1) Calculate the total discharge capacity of cells A and B in each battery pack: （4） （5） In the formula: C A放总 C represents the total discharge capacity of cell A. B放总 This represents the total discharge capacity of cell B. (2) Compare the total discharge capacity of cells A and B after each battery pack is charged and discharged. The cell with the largest total discharge capacity is the optimal cut-off voltage and optimal float charge voltage of the zinc-silver cell.

6. The float charging method for improving the specific energy of a zinc-silver reserve battery as described in claim 1, characterized in that: In step five, the charging and discharging steps are as follows: (a) Using a battery discharge test system, discharge battery pack P at a constant current I to the target load voltage lower limit V1, and collect the discharge capacity value C. p ; (ii) The discharged battery pack P is subjected to constant voltage float charging for t hours at the target float charging voltage value V2; (iii) Using a battery discharge test system, discharge the charged battery pack P at a constant current I to the target load voltage lower limit V1, and collect the discharge capacity value C. p ’ .

7. The float charging method for improving the specific energy of a zinc-silver reserve battery as described in claim 6, characterized in that: In step five, the formula for calculating the specific energy (BSE) of battery pack P is: （6） In the formula: V is the plateau voltage value. Because of the characteristic of zinc-silver batteries, there is a voltage plateau during discharge, meaning a stable and continuous voltage value exists for a period of time during discharge. This range is the plateau voltage. The voltage will gradually decrease from the plateau to the cutoff voltage when the active material is almost depleted; C is the discharge capacity of the battery pack, C = C0. P +C P '; W represents the weight of the battery pack.

8. A float charging method for improving the specific energy of a zinc-silver reserve battery as described in claim 4 or 6, characterized in that: The value of t is 3.

9. A float charging method for improving the specific energy of a zinc-silver reserve battery as described in claim 4 or 6, characterized in that: The current value of the constant current I is 15A.

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