Activation method of lithium ion battery

Abstract

The invention provides an activation method of a lithium ion battery. According to the embodiment of the invention, the activation method comprises the following steps: placing the lithium ion battery in a pressurization tool, dividing voltage interval segments of battery phase change according to a differential capacity curve of battery charging, and giving external voltage values corresponding to the segments of different voltage interval segments to the lithium ion battery through the pressurization tool, therefore, the lithium ion battery is subjected to charge-discharge activation. According to the activation method provided by the embodiment of the invention, the ohmic impedance can be reduced, the stress caused by material phase change is relieved, the resistance of lithium intercalation and deintercalation of positive and negative electrode materials is reduced, and the lithium ion battery performance is improved.

Description

Technical Field

[0001] The present application relates to the technical field of lithium-ion batteries, and in particular, to a method for activating lithium-ion batteries, and more particularly, to lithium-ion batteries and electronic devices. Background Art

[0002] Silicon negative electrode has been applied in high specific energy lithium-ion batteries by virtue of its advantages such as high specific capacity and low cost. However, it expands and generates stress during the charging and discharging process, which causes the battery to experience significant volume expansion during the charging and discharging process, especially during the initial activation process, and causes the electrode sheet to wrinkle. This problem is more significant in all-solid-state batteries using pure silicon negative electrode materials for the negative electrode. Since the aluminum-plastic film of soft-pack batteries is relatively thin, the constraint force on the internal electrode sheet is poor. Therefore, external pressurization is usually used in the production and testing process to reduce the internal resistance between the electrode sheets, constrain the expansion of the battery, and reduce the wrinkles of the negative electrode sheet, thereby improving the battery performance. The current common method is to place the soft-pack battery in a metal fixture, set the initial pressure, fix the fixture with bolts, and charge and discharge the battery. Due to the phase change of the positive and negative electrode materials during the process of lithium removal or lithium insertion, the volume of the material changes significantly, especially the expansion of the negative electrode brings obvious stress. The above-mentioned activation method using a metal fixture cannot release the stress caused by the phase change of the material, which hinders the lithium removal and insertion of the material and degrades the battery performance. In addition, the expansion of the electrode during the activation process increases the electrode porosity, and the electrolyte further enters the electrode pores, which is beneficial to improving the electrode uniformity and battery life. The fixed metal clamp inhibits the expansion of the battery and is not conducive to the infiltration of the electrolyte.

[0003] Therefore, it is urgent to develop new lithium-ion battery activation methods to improve battery performance. Summary of the invention

[0004] In one aspect of the present application, the present invention proposes a method for activating a lithium-ion battery. According to an embodiment of the present application, the activation method includes: placing the lithium-ion battery in a pressurized fixture, dividing the voltage interval of the battery phase change into segments according to the differential capacity curve of the battery charging, and applying the external pressure value corresponding to each segment of the different voltage intervals of the lithium-ion battery through the pressurized fixture, so as to charge and discharge the lithium-ion battery. The activation method according to the embodiment of the present application can reduce ohmic impedance, relieve the stress caused by material phase change, reduce the resistance to lithium deintercalation of positive and negative electrode materials, and improve the performance of lithium-ion batteries.

[0005] In a second aspect of the present application, the present application provides a lithium-ion battery. According to an embodiment of the present application, the lithium-ion battery is obtained by activation treatment using the activation method described in the first aspect of the present application.

[0006] In a third aspect of the present application, the present invention provides an electronic device. According to an embodiment of the present invention, the electronic device includes the lithium-ion battery described in the second aspect of the present application.

[0007] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0009] Figure 1 It is a schematic diagram of a method flow according to an embodiment of the present application. DETAILED DESCRIPTION

[0010] The embodiments of the present application are described in detail below. Examples of the embodiments are shown in the drawings, but unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of actually identical structures may be omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0011] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by technicians in the technical field to which this application belongs; the terms used in this application are only for the purpose of describing specific embodiments and are not intended to limit this application; unless otherwise specified, the numerical values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (for example, they can be tested according to the methods given in the embodiments of this application).

[0012] The terms "including" and "having" in the specification and claims of the present application and any modifications thereof are open expressions, that is, including the contents specified in the present application but not excluding other contents.

[0013] In the description of the present application, it should be understood that the terms "width", "thickness", etc. indicate orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0014] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. "First feature" and "second feature" may include one or more of the features.

[0015] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0016] In the description of the present application, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being “above”, “above”, and “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “below”, “below”, and “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0017] In the description of the present application, “plurality” means two or more.

[0018] In the description of the present application, "A and / or B" may include the case of A alone, the case of B alone, or any of the cases of A and B, where A and B are only used for examples and may be any technical feature connected by "and / or" in the present application.

[0019] If not otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0020] Silicon negative electrodes have been used in high-energy lithium-ion batteries due to their advantages such as high specific capacity and low cost. However, they expand and generate stress during the charging and discharging process, causing the battery to experience significant volume expansion during the charging and discharging process, especially during the initial activation process, and causing the electrode sheets to wrinkle. This problem is more significant in all-solid-state batteries that use pure silicon negative electrode materials for the negative electrode. Since the aluminum-plastic film of soft-pack batteries is thin, the restraint force on the internal electrode sheets is poor. Therefore, in the process of producing and testing activated batteries, external pressurization is usually used to reduce the internal resistance between the electrodes, restrain the expansion of the battery, and reduce the wrinkles of the negative electrode sheets, thereby improving battery performance. The current common method is to place the soft-pack battery in a metal fixture, set the initial pressure, fix the fixture with bolts, and charge and discharge the battery. However, due to the phase change of positive and negative electrode materials during the process of lithium removal or lithium insertion, the volume of the materials changes significantly, especially the expansion of the negative electrode brings obvious stress. The fixed metal plate pressurization cannot release the stress caused by the phase change of the material, which hinders the lithium removal and insertion of the material. In addition, the expansion of the electrode during the activation process can promote the infiltration of the electrolyte, which is beneficial to improve the electrode uniformity and battery life. At present, there are production equipment that can realize the servo motor to control the constant external pressure during the battery activation process and perform segmented pressurization. However, the setting of the external pressure value also has a significant impact on the battery's pole piece contact, impedance value and other performance. Therefore, the determination of the pressure value is also very critical in the activation process.

[0021] Based on this, in one aspect of the present application, the present invention proposes an activation method, see specifically Figure 1 . According to an embodiment of the present application, the activation method includes: placing the lithium-ion battery in a pressurized fixture, dividing the voltage interval of the battery phase change into segments according to the differential capacity curve of the battery charging, and applying the external pressure value corresponding to each segment of the different voltage intervals of the lithium-ion battery through the pressurized fixture, so as to activate the lithium-ion battery for charge and discharge. The activation method according to the embodiment of the present application can reduce ohmic impedance, relieve the stress caused by material phase change, reduce the resistance to lithium deintercalation of positive and negative electrode materials, and improve the electrical performance of lithium-ion batteries, especially the capacity retention rate after 100 cycles and the liquid retention of the battery.

[0022] In some embodiments, the external pressure value corresponding to each segment of the lithium-ion battery in different voltage intervals is determined by measuring ohmic impedance through AC impedance spectroscopy.

[0023] In some embodiments, the voltage interval of the differential capacity curve is 5 to 50 mV, for example, it can be 5 mV, 10 mV, 15 mV, 20 mV, 25 mV, 30 mV, 35 mV, 40 mV, 45 mV, 50 mV or a range of 10 to 50 mV, 15 to 50 mV therebetween.

[0024] In some embodiments, the voltage interval of the differential capacity curve is 10-30 mV.

[0025] In some embodiments, the external pressure ranges from 0.1 MPa to 10 MPa, for example, it can be 0.1 MPa, 1 MPa, 2 MPa, 3 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa, or 10 MPa.

[0026] In some embodiments, the external pressure ranges from 1 MPa to 10 MPa.

[0027] In some embodiments, the AC impedance spectrum test frequency range is 1 Hz to 100 kHz, for example, it can be 1 Hz, 5 Hz, 10 Hz, 20 Hz, 30 Hz, 40 Hz, 50 Hz, 60 Hz, 70 Hz, 80 Hz, 90 Hz, 100 Hz or a range of 5 Hz to 100 kHz therebetween, and the voltage amplitude is 2 to 10 mV, for example, it can be 2 mV, 3 mV, 4 mV, 5 mV, 6 mV, 7 mV, 8 mV, 9 mV, 10 mV or a range of 3 to 10 mV, 4 to 10 mV therebetween.

[0028] In some embodiments, the activation method includes the following steps: fully charging the lithium-ion battery after injection, and differentiating the charged capacity (Q)-voltage (V) curve to make a dQ / dV~V graph, and dividing the peak potentials of the dQ / dV~V curve into n voltage intervals, namely V1, V2...Vn, 0~V1, V1~V2, V2~...Vn, etc., placing the lithium-ion battery in a pressurizing tool, charging it to the starting voltage of the above voltage interval, applying different pressures, and after the pressure stabilizes, testing the ohmic internal resistance of the battery through an AC impedance spectrum to determine the pressure Px of each voltage interval, and when the battery voltage rises to the lower voltage limit of the interval, the pressurizing tool automatically adjusts the pressure to the pressure Px of the current interval until the entire activation charging process is completed.

[0029] In a second aspect of the present application, the present application provides a lithium-ion battery. According to an embodiment of the present application, the lithium-ion battery is obtained by activation treatment by the activation method described in the first aspect of the present application. According to the lithium-ion battery of the embodiment of the present application, the battery performance is improved.

[0030] In a third aspect of the present application, the present invention provides an electronic device. According to an embodiment of the present invention, the electronic device comprises the lithium-ion battery according to the second aspect of the present application. The performance of the electronic device according to the embodiment of the present application is improved.

[0031] The scheme of the present invention will be explained below in conjunction with the embodiments. It will be appreciated by those skilled in the art that the following embodiments are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. Where specific techniques or conditions are not indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used are not indicated by the manufacturer and are all conventional products that can be obtained commercially.

[0032] Embodiment 1:

[0033] (1) The positive electrode material used in this embodiment is high nickel ternary, and the negative electrode material is graphite. The pressurization is performed in a segmented manner. For details, see Table 1.

[0034] (2) A lithium-ion battery after injection is charged to a target voltage according to an activation process, the capacity-voltage curve is differentiated to obtain a dQ / dV-V curve, and the activation process is divided into four voltage intervals according to four peak potentials.

[0035] (3) A battery after injection was charged at a constant current of 0.02C for 5 h and at a constant current of 0.1C for 5 h. The capacity-voltage curve of the charging process was differentiated with the voltage interval set to 10 mV. A dQ / dV-V graph was plotted and four peak voltages were obtained, namely V1=1.94 V, V2=2.41 V, V3=3.4 V, and V4=3.67 V.

[0036] (4) Place a battery after liquid injection in a constant pressure fixture, and connect the tabs to the electrochemical workstation and the charge and discharge channel. Set the pressure to 0.1MPa, the voltage amplitude of the electrochemical workstation to 5mV, and the frequency range to 1Hz~100kHz. After the pressure stabilizes, test the AC impedance spectrum and record the value R of the horizontal axis when the vertical axis is 0. O , increase the external pressure by 0.1MPa until R O If the drop is less than 5%, set the pressure value to the initial pressure value of 0.5Mpa.

[0037] (5) Test the optimal pressure value in different intervals according to the above voltage. The external pressure is set to 0.5Mpa before charging. When the voltage reaches 1.94V, the charging is suspended. According to the above method, P1=0.4MPa is obtained, and the external pressure is adjusted to the next interval; the charging is continued to 2.41V, the charging is suspended, and P2=0.3MPa is obtained according to the above method, and the external pressure is adjusted to the next interval; the charging is continued to 3.4V, the charging is suspended, and P3=0.2MPa is obtained according to the above method, and the external pressure is adjusted to the next interval; the charging is continued to 3.67V, the charging is suspended, and P4=0.1MPa is obtained according to the above method, and the external pressure is adjusted to the next interval, until the charging activation process is completed.

[0038] (6) Setting the battery activation procedure according to the voltage range and pressure obtained by the above method, charging the batteries of the same batch, canceling the pause step in the above steps, and completing the battery activation process at one time.

[0039] (7) The activated battery is aged at room temperature for 24 hours, vacuum sealed, the air bag is cut, and the liquid retention of the battery is recorded.

[0040] (8) The packaged battery is charged at a constant current and constant voltage of 0.2C to the upper limit voltage, with a cut-off current of 0.05C, and discharged at 0.33C to the lower limit voltage, and the capacity is recorded to complete the capacity division process.

[0041] (9) Disassemble the battery after capacity division and confirm the status of the negative electrode.

[0042] Embodiment 2:

[0043] The experimental process of this embodiment is basically the same as that of embodiment 1, except that the negative electrode material is silicon carbon, and the battery is charged at a constant current of 0.02C for 5 hours and at a constant current of 0.1C for 5 hours. The external pressure before charging is set to 0.5Mpa. When the voltage reaches 1.95V, the charging is suspended, and P1=0.5MPa is obtained according to the above method, and adjusted to the external pressure of the next interval; the charging is continued to 2.4V, and the charging is suspended, and P2=0.4MPa is obtained according to the above method, and adjusted to the external pressure of the next interval; the charging is continued to 3.4V, and the charging is suspended, and P3=0.3MPa is obtained according to the above method, and adjusted to the external pressure of the next interval; the charging is continued to 3.58V, and the charging is suspended, and P4=0.2MPa is obtained according to the above method, and adjusted to the external pressure of the next interval, until the charging activation process is completed. The battery activation program is set according to the voltage interval and pressure obtained by the above method, and the batteries of the same batch are charged, and the suspension step in the above steps is cancelled, and the battery activation process is completed at one time. The other processes are the same as those in embodiment 1.

[0044] Embodiment 3:

[0045] The experimental process of this embodiment is basically the same as that of embodiment 1, except that the positive electrode material is lithium-rich manganese-based, the negative electrode material is silicon carbon, and the battery is charged at a constant current of 0.02C for 5 hours and at a constant current of 0.1C for 5 hours. The external pressure before charging is set to 0.5Mpa. When the voltage reaches 1.97V, the charging is suspended. According to the above method, P1=0.5MPa is obtained, and the external pressure of the next interval is adjusted; the charging is continued to 2.45V, the charging is suspended, and P2=0.4MPa is obtained according to the above method, and the external pressure of the next interval is adjusted; the charging is continued to 3.41V, the charging is suspended, and P3=0.3MPa is obtained according to the above method, and the external pressure of the next interval is adjusted; the charging is continued to 3.55V, the charging is suspended, and P4=0.2MPa is obtained according to the above method, and the external pressure of the next interval is adjusted until the charging activation process is completed. The battery activation program is set according to the voltage interval and pressure obtained by the above method, and the batteries of the same batch are charged. The suspension step in the above steps is cancelled, and the battery activation process is completed at one time. The other processes are the same as those in embodiment 1.

[0046] Embodiment 4:

[0047] The experimental process of this embodiment is basically the same as that of embodiment 1, except that the positive electrode material is lithium cobalt oxide, the negative electrode material is silicon carbon, and the battery is charged at a constant current of 0.02C for 5 hours and at a constant current of 0.1C for 5 hours. The external pressure before charging is set to 0.5Mpa. When the voltage reaches 1.95V, the charging is suspended. According to the above method, P1=0.4MPa is obtained, and the external pressure of the next interval is adjusted; the charging is continued to 2.41V, the charging is suspended, and P2=0.4MPa is obtained according to the above method, and the external pressure of the next interval is adjusted; the charging is continued to 3.42V, the charging is suspended, and P3=0.3MPa is obtained according to the above method, and the external pressure of the next interval is adjusted; the charging is continued to 3.57V, the charging is suspended, and P4=0.2MPa is obtained according to the above method, and the external pressure of the next interval is adjusted until the charging activation process is completed. The battery activation program is set according to the voltage interval and pressure obtained by the above method, and the batteries of the same batch are charged. The suspension step in the above steps is cancelled, and the battery activation process is completed at one time. The other processes are the same as those in embodiment 1.

[0048] Embodiment 5:

[0049] The experimental process of this embodiment is basically the same as that of embodiment 1, except that the positive electrode material is lithium iron phosphate, the negative electrode material is silicon carbon, and the battery is charged at a constant current of 0.02C for 5 hours and at a constant current of 0.1C for 5 hours. The external pressure before charging is set to 0.5Mpa. When the voltage reaches 1.93V, charging is suspended. According to the above method, P1=0.4MPa is obtained, and the external pressure of the next interval is adjusted; charging is continued to 2.33V, charging is suspended, and P2=0.4MPa is obtained according to the above method, and the external pressure of the next interval is adjusted; charging is continued to 3.1V, charging is suspended, and P3=0.3MPa is obtained according to the above method, and the external pressure of the next interval is adjusted until the charging activation process is completed. The battery activation program is set according to the voltage interval and pressure obtained by the above method, and the batteries of the same batch are charged. The pause step in the above steps is cancelled, and the battery activation process is completed at one time. The other processes are the same as those in embodiment 1.

[0050] Embodiment 6:

[0051] The experimental process of this embodiment is basically the same as that of embodiment 1, except that the positive electrode material is lithium-manganese-rich, and the other processes are the same as those of embodiment 1.

[0052] Embodiment 7:

[0053] The experimental process of this embodiment is basically the same as that of embodiment 1, except that the positive electrode material is lithium cobalt oxide, and the other processes are the same as those of embodiment 1.

[0054] Embodiment 8:

[0055] The experimental process of this embodiment is basically the same as that of embodiment 1, except that the positive electrode material is lithium iron phosphate, and the other processes are the same as those of embodiment 1.

[0056] Comparative Example 1:

[0057] The experimental process of this comparative example is basically the same as that of Example 1, except that the battery has no external pressure and is not pressurized. The other processes are the same as those of Example 1.

[0058] Comparative Example 2:

[0059] The experimental process of this comparative example is basically the same as that of Example 2, except that the battery has no external pressure and is not pressurized. The other processes are the same as those of Example 2.

[0060] Comparative Example 3:

[0061] The experimental process of this comparative example is basically the same as that of Example 3, except that the battery has no external pressure and is not pressurized. The other processes are the same as those of Example 3.

[0062] Comparative Example 4:

[0063] The experimental process of this comparative example is basically the same as that of Example 4, except that the battery has no external pressure and is not pressurized. The other processes are the same as those of Example 4.

[0064] Comparative Example 5:

[0065] The experimental process of this comparative example is basically the same as that of Example 5, except that the battery has no external pressure and is not pressurized. The other processes are the same as those of Example 1.

[0066] Comparative Example 6:

[0067] The experimental process of this comparative example is basically the same as that of Example 1, except that the battery is placed in a metal fixture, an initial pressure of 0.5 MPa is applied, 0.02C constant current charging is performed for 5 h, and 0.1C constant current charging is performed for 5 h. The other processes are the same as those of Example 1.

[0068] Comparative Example 7:

[0069] The experimental process of this comparative example is basically the same as that of Example 2, except that the battery is placed in a metal fixture, an initial pressure of 0.5 MPa is applied, 0.02C constant current charging is performed for 5 h, and 0.1C constant current charging is performed for 5 h. The other processes are the same as those of Example 2.

[0070] Comparative Example 8:

[0071] The experimental process of this comparative example is basically the same as that of Example 3, except that the battery is placed in a metal fixture, an initial pressure of 0.5 MPa is applied, 0.02C constant current charging is performed for 5 h, and 0.1C constant current charging is performed for 5 h. The other processes are the same as those of Example 3.

[0072] Comparative Example 9:

[0073] The experimental process of this comparative example is basically the same as that of Example 4, except that the battery is placed in a metal fixture, an initial pressure of 0.5 MPa is applied, 0.02C constant current charging is performed for 5 h, and 0.1C constant current charging is performed for 5 h. The other processes are the same as those of Example 4.

[0074] Comparative Example 10:

[0075] The experimental process of this comparative example is basically the same as that of Example 5, except that the battery is placed in a metal fixture, an initial pressure of 0.5 MPa is applied, and the battery is charged at a constant current of 0.02C for 5 hours and at a constant current of 0.1C for 5 hours. The other processes are the same as those of Example 5.

[0076] Table 1: Material system, voltage range and activation pressurization method of comparative examples and examples

[0077]

[0078]

[0079]

[0080] Comparison between Example 1 and Comparative Example 1 shows that the capacity retention rate of the battery prepared by staged pressurization after 100 cycles is higher than that of the battery prepared by no pressurization.

[0081] Comparison between Example 2 and Comparative Example 2, Example 3 and Comparative Example 3, Example 4 and Comparative Example 4, and Example 5 and Comparative Example 5 shows that the battery prepared by segmented pressurization has higher capacity retention rate and fewer wrinkles after 100 cycles than the battery prepared by no pressurization.

[0082] Comparison between Example 1 and Comparative Example 6 shows that the battery prepared by the stepwise pressurization has a higher liquid retention and a higher capacity retention rate after 100 cycles than the battery prepared by the metal clamp fixing the initial pressure.

[0083] Comparison between Example 2 and Comparative Example 7, Example 3 and Comparative Example 8, Example 4 and Comparative Example 9, and Example 5 and Comparative Example 10 shows that the battery prepared by the staged pressurization has higher liquid retention, higher capacity retention rate after 100 cycles, and fewer wrinkles than the battery prepared by the metal clamp fixing the initial pressure.

[0084] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0085] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for activating a lithium ion battery, characterized in that: include: The lithium-ion battery is placed in a pressurizing fixture, and the voltage interval of the battery phase change is divided into segments according to the differential capacity curve of battery charging. The pressurizing fixture is used to apply external pressure values ​​corresponding to each segment of the lithium-ion battery in different voltage intervals, so as to charge and discharge and activate the lithium-ion battery.

2. The activation method according to claim 1, characterized in that The external pressure value corresponding to each segment of the lithium-ion battery with different voltage intervals is determined by measuring the ohmic impedance through AC impedance spectroscopy.

3. The activation method according to claim 1, characterized in that The voltage interval of the differential capacity curve is 5 to 50 mV.

4. The activation method according to claim 1, characterized in that The voltage interval of the differential capacity curve is 10 to 30 mV.

5. The activation method according to claim 1, characterized in that The external pressure ranges from 0.1 MPa to 10 MPa.

6. The activation method according to claim 1, characterized in that: The external pressure ranges from 1 MPa to 10 MPa.

7. The activation method according to claim 2, characterized in that: The AC impedance spectrum test frequency range is 1 Hz to 100 kHz, and the voltage amplitude is 2 to 10 mV.

8. The activation method according to any one of claims 1 to 7, characterized in that: The following steps are involved: The lithium-ion battery after liquid injection is fully charged, and the charging capacity (Q)-voltage (V) curve is differentiated to make a dQ / dV~V graph. According to the peak potential marks of the dQ / dV~V curve, V1, V2...Vn are respectively marked, and it is divided into n voltage intervals such as 0~V1, V1~V2, V2~...Vn. The lithium-ion battery is placed in a pressurizing tool and charged to the starting voltage of the above voltage interval. Different pressures are applied. After the pressure is stable, the ohmic internal resistance of the battery is tested by AC impedance spectroscopy to determine the pressure Px of each voltage interval. When the battery voltage rises to the lower voltage limit of the interval, the pressurizing tool automatically adjusts the pressure to the pressure Px of the current interval until the entire activation charging process is completed.

9. A lithium ion battery, characterized in that: Obtained by activation treatment by the activation method according to any one of claims 1 to 8.

10. An electronic device, characterized in that: include: The lithium ion battery according to claim 9.

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