Formation method of nickel-hydrogen battery and nickel-hydrogen battery formed by the method

Abstract

The application provides a formation method of a nickel-hydrogen battery and a nickel-hydrogen battery formed by the method. The formation method of the nickel-hydrogen battery comprises the following steps: performing normal-temperature activation treatment on a nickel-hydrogen battery primary product to obtain a first-stage nickel-hydrogen battery; performing first heating activation treatment on the first-stage nickel-hydrogen battery to obtain a second-stage nickel-hydrogen battery; performing charging formation on the second-stage nickel-hydrogen battery to obtain a third-stage nickel-hydrogen battery; and performing second heating aging treatment on the third-stage nickel-hydrogen battery to obtain the nickel-hydrogen battery. The pre-charging and 3-4 charging and discharging formation processes are reduced, the charging formation is directly performed after the normal-temperature activation and the heating activation, the charging and discharging is not required to be repeatedly performed for multiple times, and then the heating aging is performed. Compared with the prior art, the formation method of the nickel-hydrogen battery in the application greatly reduces the equipment investment and the power consumption, simplifies the production process, reduces the production period, and improves the production efficiency under the condition that the normal formation effect of the nickel-hydrogen battery is achieved.

Description

Technical Field

[0001] This application belongs to the field of nickel-metal hydride battery technology, and more specifically, relates to a method for forming nickel-metal hydride batteries and a nickel-metal hydride battery formed using this method. Background Technology

[0002] Nickel-metal hydride (NiMH) batteries are high-performance rechargeable batteries, classified into high-voltage and low-voltage types. The positive electrode active material is Ni(OH)₂ (called the NiO electrode), the negative electrode active material is a metal hydride, also known as a hydrogen storage alloy (the electrode is called the hydrogen storage electrode), and the electrolyte is a potassium hydroxide solution.

[0003] To improve electrode conductivity, CoO is typically added to the electrodes of nickel-metal hydride batteries. Formation mainly involves oxidizing the CoO in the electrodes to CoOOH, forming a conductive network of CoOOH, reducing the battery's ohmic internal resistance, improving the electrode conductivity, and thus enhancing the battery's electrochemical performance.

[0004] Formation, including external cell formation and internal cell formation, is a crucial step in the production of lead-acid, cadmium / nickel, and nickel-metal hydride batteries. The traditional nickel-metal hydride battery formation process includes: room temperature activation – pre-charging – high-temperature activation – 3-4 charge-discharge cycles – capacity testing – high-temperature aging. However, omitting pre-charging, without a suitable activation process to fully oxidize the CoO in the electrodes to CoOOH, leads to poor battery conductivity, resulting in low voltage and excessive self-discharge. The capacity testing step is used to sort batteries to ensure they meet design requirements, ensuring more rational battery pairing. Without this step, batteries from the same batch may have varying capacities. Furthermore, due to manufacturing processes or material factors, nickel-metal hydride batteries require pre-charging, multiple charge-discharge activation cycles, and then capacity sorting using capacity testing equipment. This results in high equipment investment, long production cycles, and high power consumption, severely impacting the production efficiency of nickel-metal hydride batteries. Summary of the Invention

[0005] Based on this, one objective of this application is to provide a formation method for nickel-metal hydride batteries to solve the technical problems existing in the prior art, which require multiple charge-discharge activations and then capacity sorting using capacity grading equipment. This results in large equipment investment, long production cycles, and high power consumption, which seriously affect the production efficiency of nickel-metal hydride batteries.

[0006] Another object of this application is to provide a nickel-metal hydride battery formed using the above-described nickel-metal hydride battery formation method.

[0007] To achieve the above objectives, the technical solution adopted in this application is as follows:

[0008] A method for forming a nickel-metal hydride battery includes the following steps:

[0009] The initial nickel-metal hydride battery product was activated at room temperature to obtain a first-stage nickel-metal hydride battery.

[0010] The first-stage nickel-metal hydride battery is subjected to a first heating activation treatment to obtain a second-stage nickel-metal hydride battery.

[0011] The second-stage nickel-metal hydride battery is charged and formed to obtain the third-stage nickel-metal hydride battery.

[0012] The third-stage nickel-metal hydride battery is subjected to a second heating and aging treatment to obtain a nickel-metal hydride battery.

[0013] Optionally, the initial nickel-metal hydride battery product is activated at room temperature for 24-72 hours; and / or,

[0014] The normal temperature is 20℃-30℃.

[0015] Optionally, the first heating activation treatment of the first-stage nickel-metal hydride battery is performed for 12-24 hours; and / or,

[0016] The temperature for the first heating activation treatment is 40℃-50℃.

[0017] Optionally, the number of charging cycles is 2-3.

[0018] Optionally, the charging and formation process is performed twice, including the following steps:

[0019] The second-stage nickel-metal hydride battery is charged for the first time at 0.3-0.4C until the total charge reaches 70%-80% of the capacity of the second-stage nickel-metal hydride battery, thus obtaining a second-stage nickel-metal hydride battery after one charge.

[0020] The second-stage nickel-metal hydride battery is charged a second time at 0.15-0.2C until the total charge reaches 100%-120% of the capacity of the second-stage nickel-metal hydride battery, thus obtaining the third-stage nickel-metal hydride battery.

[0021] Optionally, the charging and formation process is performed three times, including the following steps:

[0022] The second-stage nickel-metal hydride battery is charged for the first time at 0.3-0.4C to obtain a second-stage nickel-metal hydride battery that has been charged once.

[0023] A first-charged second-stage nickel-metal hydride battery is charged a second time at 0.15-0.2C to obtain a second-charged second-stage nickel-metal hydride battery.

[0024] The second-stage nickel-metal hydride battery is charged a third time at 0.1C to obtain a third-stage nickel-metal hydride battery.

[0025] Optionally, the total charge of the first charge reaches 70%-80% of the capacity of the second-stage nickel-metal hydride battery;

[0026] The total charge during the second charge reaches 100%-120% of the capacity of the second-stage nickel-metal hydride battery;

[0027] The total charge of the third charge reaches 140%-160% of the capacity of the second-stage nickel-metal hydride battery.

[0028] Optionally, the temperature of the second heat aging treatment is 40℃-50℃; and / or,

[0029] The aging process takes 90-100 hours.

[0030] Optionally, the initial capacity of the nickel-metal hydride battery product is less than or equal to 800mAh.

[0031] And, a nickel-metal hydride battery, formed using any of the nickel-metal hydride battery formation methods described above.

[0032] 1. The nickel-metal hydride battery formation method provided in this application reduces the pre-charging and 3-4 charge-discharge formation processes. After room temperature activation and high temperature activation, it can be directly charged and formed without repeated charge-discharge cycles, followed by high temperature aging. Compared with the prior art, the nickel-metal hydride battery formation method of this application significantly reduces equipment investment and power consumption, simplifies production processes, reduces production cycles, and improves production efficiency while achieving the normal formation effect of nickel-metal hydride batteries.

[0033] 2. The nickel-metal hydride battery provided in this application is formed using the above-mentioned nickel-metal hydride battery formation method. The nickel-metal hydride battery is fully activated, its capacity is normal, and its electrical performance is stable. Detailed Implementation

[0034] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following embodiments are provided to further illustrate this application in detail. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0035] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0036] definition

[0037] Nickel-metal hydride batteries are batteries made with nickel oxide as the positive electrode, hydrogen storage alloy as the negative electrode, and alkaline solution (mainly potassium hydroxide) as the electrolyte.

[0038] Hydrogen storage alloys are generally hydrogen storage materials formed by lanthanide elements and nickel.

[0039] The charging and discharging reaction of a nickel-metal hydride battery can be considered as hydrogen ion (H+) ... + The electron moves back and forth between the positive and negative electrodes, storing electrical energy as chemical energy during charging and converting chemical energy into electrical energy during discharging.

[0040] After a batch of batteries is manufactured, although they may be the same size, their capacities may vary. Capacity testing refers to obtaining data from each test point through computer management, thereby detecting data such as battery capacity and internal resistance, and determining the battery's quality grade.

[0041] A method for forming a nickel-metal hydride battery according to an embodiment of this application includes the following steps:

[0042] S10: The initial nickel-metal hydride battery product is activated at room temperature to obtain a first-stage nickel-metal hydride battery.

[0043] The nickel-metal hydride battery initial product in this application refers to the product after the nickel-metal hydride battery blank has been assembled and properly sealed.

[0044] Optionally, the ambient temperature is 20℃-30℃.

[0045] Optionally, the initial nickel-metal hydride battery product may be activated at room temperature for 24-72 hours.

[0046] S20: The first-stage nickel-metal hydride battery is subjected to a first heating activation treatment to obtain a second-stage nickel-metal hydride battery.

[0047] As a crucial component of nickel-metal hydride (NiMH) batteries, the electrolyte directly affects the battery's capacity, internal resistance, cycle life, and internal pressure. Electrochemical reactions can only occur between the positive and negative electrodes of a NiMH battery within the electrolyte. If the electrodes are not completely immersed in the electrolyte, the electrochemical reaction will be incomplete, or certain parts of the electrodes will fail to undergo the reaction. This results in the NiMH battery failing to meet design requirements, increasing internal resistance, and shortening cycle life.

[0048] The room temperature activation treatment and the first heating activation treatment can fully diffuse the electrolyte on the positive electrode, negative electrode and the separator, and the positive electrode, negative electrode and the separator are completely immersed in the electrolyte.

[0049] First, the electrolyte diffuses naturally at room temperature, and then it is activated by heating. The first heating activation treatment can reduce the surface tension of the electrolyte, promote the uniform distribution of the electrolyte, and facilitate the uniform electrochemical reaction, thus initially ensuring the performance of the nickel-metal hydride battery, such as capacity, internal resistance, cycle life, and internal pressure.

[0050] The temperature and time of the first heating activation treatment also affect the battery performance. If the first heating temperature is too low, for example, below 40°C, the reaction rate is too slow, affecting production efficiency. If the first heating temperature is too high, for example, above 50°C, it may cause a short circuit in the nickel-metal hydride battery, excessive expansion of the electrode, and affect the performance of the nickel-metal hydride battery.

[0051] According to the experiment, the temperature of the first heating can be selected as 40℃-50℃, and the time of the first heating activation treatment can be selected as 12h-24h.

[0052] S30: Charge and form a second-stage nickel-metal hydride battery to obtain a third-stage nickel-metal hydride battery.

[0053] The nickel oxide cathode (active material is Ni(OH)2) has added CoO (cobalt oxide). During the charging formation process, because the oxidation potential of Co(OH)2 is lower than that of Ni(OH)2, CoO is oxidized to form CoOOH before Ni(OH)2 is converted to NiOOH. This reduces the contact resistance between particles and greatly improves the conductivity between particles and the matrix, thereby improving the conductivity of the cathode, reducing the internal resistance and charging voltage of the nickel-metal hydride battery, and improving the charging efficiency and discharge capacity.

[0054] Optionally, the charging process is repeated 2-3 times to fully oxidize CoO into stable β-CoOOH.

[0055] In some embodiments, the charging formation is performed twice, including the following steps:

[0056] The second-stage nickel-metal hydride battery is charged for the first time at 0.3-0.4C until the total charge reaches 70%-80% of the capacity of the second-stage nickel-metal hydride battery, thus obtaining a second-stage nickel-metal hydride battery after one charge.

[0057] The second-stage nickel-metal hydride battery is charged a second time at 0.15-0.2C until the total charge reaches 100%-120% of the capacity of the second-stage nickel-metal hydride battery, thus obtaining the third-stage nickel-metal hydride battery.

[0058] In some embodiments, the charging formation is performed three times, including the following steps:

[0059] The second-stage nickel-metal hydride battery is charged for the first time at 0.3-0.4C to obtain a second-stage nickel-metal hydride battery that has been charged once.

[0060] A first-charged second-stage nickel-metal hydride battery is charged a second time at 0.15-0.2C to obtain a second-charged second-stage nickel-metal hydride battery.

[0061] The second-stage nickel-metal hydride battery is charged a third time at 0.1C to obtain a third-stage nickel-metal hydride battery.

[0062] In the embodiments of this application, the charging formation current gradually decreases from large to small. The first charge oxidizes most of CoO into CoOOH, and then the second charge is performed, or the second and third charges oxidize CoO into stable β-CoOOH to the greatest extent.

[0063] Optionally, the total charge of the first charge reaches 70%-80% of the capacity of the second-stage nickel-metal hydride battery;

[0064] The total charge during the second charge reaches 100%-120% of the capacity of the second-stage nickel-metal hydride battery;

[0065] The total charge of the third charge reaches 140%-160% of the capacity of the second-stage nickel-metal hydride battery.

[0066] The first, second, and third charges, using the aforementioned total charge amount, effectively activated the nickel-metal hydride battery while avoiding overcharging that could waste energy, cause battery swelling, or lead to leakage.

[0067] S40: The third-stage nickel-metal hydride battery undergoes a second heating and aging process to obtain a nickel-metal hydride battery.

[0068] Optionally, the temperature of the second heating aging treatment is 40℃-50℃.

[0069] The aging process takes 90-100 hours.

[0070] For medium and low capacity nickel-metal hydride batteries, such as those with a capacity of 800mAh or less, since they are suitable for a single application scenario and do not have high requirements for capacity deviation, the existing formation methods require multiple activations, pre-charging, multiple charge-discharge cycles, and final capacity testing, which will consume a lot of resources and time and affect delivery time.

[0071] Nickel-metal hydride batteries with a capacity of 800mAh or less include, but are not limited to, NI-MH 2 / 3AA 600mAh, NI-MHAAA300-600mAh, and NI-MH AA300-800mAh.

[0072] The nickel-metal hydride battery formation method provided in this application reduces the pre-charging and 3-4 charge-discharge formation steps. After room temperature activation and high temperature activation, it can be directly charged and formed without repeated charge-discharge cycles and high temperature aging, thus achieving a good activation effect and stable performance of the nickel-metal hydride battery.

[0073] Compared with the prior art, the nickel-metal hydride battery formation method of the present application embodiment significantly reduces equipment investment and power consumption, simplifies production processes, reduces production cycles, and improves production efficiency while achieving the normal formation effect of nickel-metal hydride batteries.

[0074] This application also provides a nickel-metal hydride battery, which is formed using the above-described nickel-metal hydride battery formation method. The nickel-metal hydride battery is fully activated, its capacity is normal, and its electrical performance is stable.

[0075] The following examples illustrate this point.

[0076] Example 1

[0077] The nickel-metal hydride battery to be formed in this embodiment, i.e., the initial product of the nickel-metal hydride battery, is a NI-MH 2 / 3AA 600mAh battery.

[0078] The formation method of the nickel-metal hydride battery in this embodiment includes the following steps:

[0079] S1: Place the NI-MH 2 / 3AA 600mAh battery in an environment of 25±5℃ and activate it at room temperature for 24-72h to obtain the first-stage nickel-metal hydride battery.

[0080] S2: Place the first-stage nickel-metal hydride battery in an environment of 45±5℃ and activate it for 12-24h to obtain the second-stage nickel-metal hydride battery.

[0081] S3: Place the second-stage nickel-metal hydride battery in the formation equipment and charge it for the first time at 0.4C (240mA) for 105 minutes, with a total charge of 70%-80% of the capacity, to obtain a second-stage nickel-metal hydride battery after one charge.

[0082] S4: Charge the first-charged second-stage nickel-metal hydride battery at 0.2C (120mA) for 120 minutes, with a total charge of 100%-120% of the capacity, to obtain a second-charged second-stage nickel-metal hydride battery.

[0083] S5: Charge the second-stage nickel-metal hydride battery at 0.1C (60mA) for 240 minutes, with a total charge of 140%-160% of the capacity, to obtain the third-stage nickel-metal hydride battery.

[0084] S6: The third-stage nickel-metal hydride battery was aged in an environment of 45±5℃ for 96 hours to obtain the nickel-metal hydride battery.

[0085] The nickel-metal hydride batteries obtained in Example 1 were tested for nominal capacity, and the capacity ranged from 610 to 630 mAh.

[0086] Example 2

[0087] The nickel-metal hydride battery to be formed in this embodiment, i.e., the initial product of the nickel-metal hydride battery, is a NI-MH 2 / 3AA 600mAh battery.

[0088] The formation method of the nickel-metal hydride battery in this embodiment includes the following steps:

[0089] S1: Place the NI-MH 2 / 3AA 600mAh battery in an environment of 25±5℃ and activate it at room temperature for 24-72h to obtain the first-stage nickel-metal hydride battery.

[0090] S2: Place the first-stage nickel-metal hydride battery in an environment of 45±5℃ and activate it for 12-24h to obtain the second-stage nickel-metal hydride battery.

[0091] S3: Place the second-stage nickel-metal hydride battery in the formation equipment and charge it for the first time at 0.3C (180mA) for 140 minutes, with a total charge of 70%-80% of the capacity, to obtain a second-stage nickel-metal hydride battery after one charge.

[0092] S4: Charge the first-charged second-stage nickel-metal hydride battery at 0.15C (120mA) for 160 minutes, with a total charge of 100%-120% of the capacity, to obtain a second-charged second-stage nickel-metal hydride battery.

[0093] S5: Charge the second-stage nickel-metal hydride battery at 0.1C (60mA) for 240 minutes, with a total charge of 140%-160% of the capacity, to obtain the third-stage nickel-metal hydride battery.

[0094] S6: The third-stage nickel-metal hydride battery was aged in an environment of 45±5℃ for 96 hours to obtain the nickel-metal hydride battery.

[0095] The nickel-metal hydride batteries obtained in Example 2 were tested for nominal capacity, and the capacity ranged from 615 to 635 mAh.

[0096] Example 3

[0097] The nickel-metal hydride battery to be formed in this embodiment, i.e., the initial product of the nickel-metal hydride battery, is a NI-MH 2 / 3AA 600mAh battery.

[0098] The formation method of the nickel-metal hydride battery in this embodiment includes the following steps:

[0099] S1: Place the NI-MH 2 / 3AA 600mAh battery in an environment of 25±5℃ and activate it at room temperature for 24-72h to obtain the first-stage nickel-metal hydride battery.

[0100] S2: Place the first-stage nickel-metal hydride battery in an environment of 45±5℃ and activate it for 12-24h to obtain the second-stage nickel-metal hydride battery.

[0101] S3: Place the second-stage nickel-metal hydride battery in the formation equipment and charge it for the first time at 0.5C (180mA) for 90 minutes, with a total charge of 70%-80% of the capacity, to obtain a second-stage nickel-metal hydride battery after one charge.

[0102] S4: Charge the first-charged second-stage nickel-metal hydride battery at 0.3C (120mA) for 80 minutes, with a total charge of 100%-120% of the capacity, to obtain a second-charged second-stage nickel-metal hydride battery.

[0103] S5: Charge the second-stage nickel-metal hydride battery at 0.2C (60mA) for 120 minutes, with a total charge of 140%-160% of the capacity, to obtain the third-stage nickel-metal hydride battery.

[0104] S6: The third-stage nickel-metal hydride battery was aged in an environment of 45±5℃ for 96 hours to obtain the nickel-metal hydride battery.

[0105] The nickel-metal hydride batteries obtained in Example 3 were tested for nominal capacity, and the capacity ranged from 605 to 625 mAh.

[0106] Comparative Example 1

[0107] S1: Place the NI-MH 2 / 3AA 600mAh battery in an environment of 25±5℃ and activate it at room temperature for 24-72h to obtain the first-stage nickel-metal hydride battery.

[0108] S2: Place the first-stage nickel-metal hydride battery in an environment of 25±5℃ and charge it for the first time at 0.1C (600mA) for 90 minutes to obtain the second-stage nickel-metal hydride battery.

[0109] S3: Place the second-stage nickel-metal hydride battery in an environment of 45±5℃ and activate it for 12-24 hours to obtain the third-stage nickel-metal hydride battery.

[0110] S4: Place the third-stage nickel-metal hydride battery in the formation equipment, charge it for 60 minutes at 0.4C (240mA) for the second time, then charge it for 240 minutes at 0.1C (60mA), and discharge it to 1.0V at 0.5C (300mA) for the first formation.

[0111] S5: Charge for 90 minutes at 0.4C (240mA) for the third time, then charge for 240 minutes at 0.1C (60mA), and discharge to 1.0V at 0.5C (300mA) for the second formation.

[0112] S6: Charge for the fourth time at 0.4C (240mA) for 120 minutes, then charge at 0.1C (60mA) for 240 minutes, discharge at 0.5C (300mA) to 1.0V, and perform the third formation to obtain the fourth-stage nickel-metal hydride battery.

[0113] S7: Charge the fourth-stage nickel-metal hydride battery at 0.5C (300mA) for 144 minutes, let it rest for 30 minutes, discharge it to 1.0V at 0.5C (300mA), and then sort it by capacity. Batteries with the correct capacity are replenished with 60-80% at 0.5C to obtain the fifth-stage nickel-metal hydride battery.

[0114] S6: The fifth-stage nickel-metal hydride battery was aged in an environment of 45±5℃ for 96 hours to obtain the nickel-metal hydride battery.

[0115] The nickel-metal hydride batteries obtained from the comparative example were tested for nominal capacity, and the capacity ranged from 610 to 635 mAh.

[0116] Performance testing

[0117] The nickel-metal hydride batteries of Examples 1 to 3 and Comparative Example 1 were subjected to performance tests such as capacity, open-circuit AC internal resistance, charge retention capability, and low-voltage rate.

[0118] Detection methods

[0119] Nominal capacity testing method: In an environment of 20±5℃, charge at 0.1C (60mA) for 16 hours, let stand for 1 hour, discharge at 0.2C (120mA) to 1.0V, and record the discharge capacity. 1000 nickel-metal hydride batteries are randomly selected for each test.

[0120] Method for testing open-circuit AC internal resistance: Charge the battery at standard 0.1C (60mA) for 16 hours, let it stand for 1-4 days, and then test it using a BK600 internal resistance tester. 1000 NiMH batteries are randomly selected for each test.

[0121] Method for testing charge retention capacity: After testing the nominal capacity (C0), the battery is charged to standard capacity and left to stand for 28 days at 20±5℃. Then, it is discharged to 1.0V at 0.2C, and the remaining capacity (C1) is recorded. The charge retention rate is calculated by dividing C1 by C0. Ten nickel-metal hydride batteries are randomly selected for testing in each case.

[0122] Low voltage test method: After the battery is charged to standard, store it in an environment of 20±5℃ for 28 days, and measure the open circuit voltage. If the voltage is lower than 1.31V, the battery is considered to have low voltage.

[0123] The test results are shown in Table 1.

[0124] Table 1

[0125] Nominal capacity / mAh Internal resistance / mΩ Charge retention capability low pressure ratio Example 1 610-630 21-25 83％-85％ 0.10％ Example 2 615-635 22-25 81％-83％ 0.10％ Example 3 605-625 22-26 82％-84％ 0.10％ Comparative Example 1 610-635 22-25 83％-85％ 0.10％

[0126] In summary, by strictly controlling the quality of the positive and negative electrodes during the manufacturing process of nickel-metal hydride (NiMH) batteries and assembling them normally, they can be produced through a simplified formation process. When the three-step charging reaches 140%-160% charge, the NiMH battery can be fully activated and its capacity can be fully utilized, greatly reducing formation time and energy consumption.

[0127] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for forming a nickel-metal hydride battery, characterized in that: Includes the following steps: The initial nickel-metal hydride battery product was activated at room temperature to obtain a first-stage nickel-metal hydride battery. The first-stage nickel-metal hydride battery is subjected to a first heating activation treatment to obtain a second-stage nickel-metal hydride battery. The second-stage nickel-metal hydride battery is charged and formed to obtain the third-stage nickel-metal hydride battery; The third-stage nickel-metal hydride battery is subjected to a second heating aging treatment to obtain a nickel-metal hydride battery. When the charging and transformation are performed twice, the following steps are included: The second-stage nickel-metal hydride battery is charged for the first time at 0.3-0.4C until the total charge reaches 70%-80% of the capacity of the second-stage nickel-metal hydride battery, thus obtaining a second-stage nickel-metal hydride battery after one charge. The first-charged second-stage nickel-metal hydride battery is charged a second time at 0.15-0.2C until the total charge reaches 100%-120% of the capacity of the second-stage nickel-metal hydride battery, thus obtaining a third-stage nickel-metal hydride battery. or, When the charging and transformation is performed 3 times, the following steps are included: The second-stage nickel-metal hydride battery is first charged at 0.3-0.4C to obtain a first-charge second-stage nickel-metal hydride battery; the total charge of the first charge reaches 70%-80% of the capacity of the second-stage nickel-metal hydride battery. The first-charged second-stage nickel-metal hydride battery is charged a second time at 0.15-0.2C to obtain a second-charged second-stage nickel-metal hydride battery; the total charge of the second charge reaches 100%-120% of the capacity of the second-stage nickel-metal hydride battery. The second-stage nickel-metal hydride battery is charged a third time at 0.1C to obtain a third-stage nickel-metal hydride battery; the total charge of the third charge reaches 140%-160% of the capacity of the second-stage nickel-metal hydride battery.

2. The formation method of a nickel-metal hydride battery as described in claim 1, characterized in that: The activation time for the initial nickel-metal hydride battery product at room temperature is 24h-72h; and / or, The ambient temperature is 20℃-30℃.

3. The formation method of a nickel-metal hydride battery as described in claim 1, characterized in that: The time for the first heating activation treatment of the first-stage nickel-metal hydride battery is 12h-24h; and / or, The temperature of the first heating is 40℃-50℃.

4. The formation method of a nickel-metal hydride battery as described in claim 1, characterized in that: The charging and transformation process is performed 2-3 times.

5. The formation method of a nickel-metal hydride battery as described in claim 4, characterized in that: The temperature of the second heat aging treatment is 40℃-50℃; and / or, The second heating and aging treatment takes 90-100 hours.

6. The formation method of a nickel-metal hydride battery as described in claim 1, characterized in that: The initial capacity of the nickel-metal hydride battery is less than or equal to 800mAh.

7. A nickel-metal hydride battery, characterized in that: The nickel-metal hydride battery is formed using the formation method described in any one of claims 1 to 6.