A method for optimizing the SEI film structure composition of secondary batteries and its application

Abstract

This invention provides a method for optimizing the SEI film structure of a secondary battery and its application. The method includes the following steps: the battery is placed in a physical field for formation; the physical field includes an alternating electric field and / or a magnetic field; the direction of the physical field makes an angle of 0 to 90° with the direction along the line connecting the center of the positive electrode and the center of the negative electrode. In the battery formation process, this invention applies an external physical field, thereby changing the movement trajectory of solvent molecules and anions around the metal ions in the battery, adjusting the interface solvation structure, optimizing the SEI film composition and structure, and achieving uniform deposition and stripping on the electrode surface, thereby improving the battery's coulombic efficiency, cycle performance, and service life.

Description

Technical Field

[0001] This invention belongs to the field of battery technology and relates to a method for optimizing the SEI film structure composition of secondary batteries, and more particularly to a method for optimizing the SEI film structure composition of secondary batteries and its application. Background Technology

[0002] With the development and widespread adoption of electric vehicles, smart grids, and large-scale energy storage stations, higher demands are being placed on the energy density, power density, and safety performance of secondary batteries. Compared to traditional lead-acid and nickel-metal hydride batteries, secondary batteries using alkali metals such as lithium, sodium, and magnesium as negative electrodes are highly favored due to their higher theoretical specific capacity and wider charge-discharge electrochemical windows. However, the instability of the SEI (Solid Electrolyte Interphase) film hinders the application of secondary batteries.

[0003] The electrolyte interphase (SEI) film is the boundary between the electrode and the electrolyte, a thin film formed on the negative electrode surface due to side reactions of the electrolyte during charging and discharging. While the formation of the SEI film prolongs the transport path of metal ions, a stable and dense SEI film possesses high ionic conductivity and low electronic conductivity, serving as a passivation layer to inhibit further electrolyte decomposition. However, spontaneously formed SEI films on the electrode surface are porous and have high impedance, making them susceptible to the influence of interface volume and morphology during charging and discharging. Furthermore, uneven deposition and stripping of metal ions often lead to dendrites and pits on the electrode surface, causing SEI film rupture, continuous consumption of electrolyte and metal, and a decrease in battery energy density.

[0004] To address the problems of SEI membrane rupture, instability, and slow ion transport, existing technologies disclose improvement methods including: (1) changing the composition of the electrolyte or adding additives to the electrolyte. Since the ion diffusion mechanisms of different SEI components are different, many existing technologies currently change the solvation structure of metal ions in the electrolyte by introducing additives, thereby generating SEI with specific components having high ionic conductivity in situ; for example, adding nitrates to the electrolyte to promote NO 3-(2) Construct artificial SEI and build a smooth SEI film with high ion conductivity and good mechanical properties by physical coating. For example, fix a layer of perfluorinated ion exchange membrane on the surface of metal electrode and realize single ion conduction through the jumping and collision transport mechanism of lithium ions in metal fluoride. Control the transport capacity of the interface layer by controlling the coating thickness. (3) Utilize non-in-situ reaction to directly generate a dense SEI film with high mechanical properties on the surface. Direct interface reaction can provide an interface environment with good electrochemical performance and enhance the integration and adhesion of SEI with electrode. For example, introduce gases that can react with metal (N2, F2 and sulfur vapor, etc.) into the electrode surface, dry nitrogen pretreatment or fluorination treatment to generate metal nitride and metal fluoride, thereby improving the performance of SEI film.

[0005] CN 110289448A discloses a lithium metal anode with an artificially constructed SEI film and its preparation method. The preparation method includes: dissolving a lithium salt in a first solvent to obtain a lithium salt solution; dissolving an organic additive in a second solvent to obtain an additive solution; mixing the lithium salt solution and the additive solution, stirring until the viscosity is higher than 1000 centipoise to obtain a viscous liquid; coating the liquid onto the surface of a lithium battery anode current collector; and then drying to remove the first and second solvents, thereby obtaining a lithium metal anode with an artificially constructed SEI film. The SEI film obtained by the disclosed preparation method exhibits poor high-temperature cycling performance and poor storage thermal stability.

[0006] The methods described above often involve complex reaction steps and harsh reaction conditions. Furthermore, most of these methods are designed for specific systems and lack universality, and their cycle performance and lifespan are limited at high current densities.

[0007] Based on the above research, it is necessary to start from the reaction mechanism of the interface and construct a method to optimize the SEI film of secondary batteries. This method should be universal and can optimize the structure and composition of the SEI film, thereby generating an SEI film with excellent performance and improving the charge-discharge performance, coulombic efficiency and cycle performance of secondary batteries. Summary of the Invention

[0008] The purpose of this invention is to provide a method for optimizing the SEI membrane structure of secondary batteries and its application. In order to solve the problems of existing SEI membranes cracking during charging and discharging and low metal ion conductivity, which easily cause irreversible capacity loss and shorten battery life under high current density, this invention generates an SEI membrane with excellent performance by externally controlling the solvation structure of metal ions in the electrolyte, thereby improving the charge and discharge performance, coulombic efficiency, rate performance, cycle performance and service life of metal secondary batteries.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a method for optimizing the SEI film structure composition of a secondary battery, the method comprising the following steps:

[0011] The battery is formed under a physical field;

[0012] The physical fields include alternating electric fields and / or magnetic fields;

[0013] The angle between the direction of the physical field and the direction along the line connecting the center of the positive electrode and the center of the negative electrode is 0 to 90°. For example, it can be 0°, 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80° or 90°, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0014] In the SEI film formation process, the present invention places the battery in an external physical field and uses the electric field force generated by the alternating electric field and / or the Lorentz force generated by the magnetic field to change the movement trajectory of solvent molecules and anions around the metal ions, adjust the interface solvation structure, optimize the SEI film composition and structure, and achieve uniform deposition and peeling on the electrode surface, thereby improving the battery coulombic efficiency, cycle performance and service life.

[0015] The battery described in this invention is a metal secondary battery, which is assembled from electrode plates and a separator. The positive and negative electrodes are separated by the separator, and then an electrolyte is injected to ensure that the electrolyte can fully wet the electrode plates and the separator, and to ensure that the battery is sealed.

[0016] The physical field described in this invention is added throughout the entire battery formation process.

[0017] The included angle described in this invention is the small angle formed by the intersection of two lines.

[0018] Preferably, the electric field strength of the alternating current field is 1 to 50 V / cm, for example, it can be 1 V / cm, 5 V / cm, 10 V / cm, 15 V / cm, 20 V / cm, 25 V / cm, 30 V / cm, 35 V / cm, 40 V / cm, 45 V / cm or 50 V / cm, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0019] Preferably, the frequency of the alternating electric field is 20 to 200 Hz, for example, it can be 20 Hz, 40 Hz, 60 Hz, 80 Hz, 100 Hz, 120 Hz, 140 Hz, 160 Hz, 180 Hz or 200 Hz, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0020] The electric field strength and frequency described in this invention are within a reasonable range, which enables the SEI film to have high ion conductivity, significantly improves the overall performance of the battery, and suppresses the generation of dendrites and pits on the electrode surface during charging and discharging.

[0021] Preferably, the alternating electric field includes two parallel plates, which are connected to an alternating power source.

[0022] Preferably, the parallel plates are metallic conductors.

[0023] The area of ​​the parallel plates described in this invention is larger than the area of ​​the battery cells, and the distance between the parallel plates is larger than the size of the battery, ensuring that the battery as a whole is placed in a physical field.

[0024] Preferably, the area of ​​one of the parallel plates is 1 to 10 times the area of ​​one electrode sheet, for example, it can be 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 times, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0025] Preferably, the magnetic induction intensity of the magnetic field is 0.1 to 2000 mT, for example, it can be 0.1 mT, 1 mT, 10 mT, 100 mT, 500 mT, 1000 mT, 1500 mT or 2000 mT, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0026] Preferably, the magnetic field comprises a single magnetic pole or two opposite magnetic poles.

[0027] The alternating current electric field described in this invention exhibits a regular change in direction. The electric field's direction, magnitude, and time are cosine or sine functions achieved by adding an external alternating current power source. The magnetic field's direction is changed by adding an external permanent magnet or a magnetic field generator. The addition of this physical field causes periodic movement of solvent molecules and anions around the metal ions in the electrolyte, promoting the formation of new solvation structures at the interface. These structures can induce interfacial side reactions to generate more LiF, Li2S, and other substances, thereby forming an SEI film with high ionic conductivity and stronger mechanical properties at the interface.

[0028] Preferably, the formation is performed using constant current charging and discharging or constant potential reduction.

[0029] The voltage range for constant current charging and discharging, and the voltage range for constant potential reduction, described in this invention are all potential ranges from the open circuit potential of the battery to the reduction potential of the battery metal.

[0030] Preferably, the current generated is 0.01 to 1C, for example, it can be 0.01C, 0.05C, 0.1C, 0.2C, 0.3C, 0.4C, 0.5C, 0.6C, 0.7C, 0.8C, 0.9C or 1C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0031] Preferably, the current density of the formation is 5 μA / cm. 2 ~20mA / cm 2 For example, it could be 5mA / cm 2 10mA / cm 2 15mA / cm 2 Or 20mA / cm 2 However, this does not limit the listed values; other unlisted values ​​within the range are also applicable.

[0032] As a preferred embodiment of the method described in this invention, the method includes the following steps:

[0033] The battery is formed in a physical field, the direction of which is at an angle of 0 to 90° with the direction of the line connecting the center of the positive electrode and the center of the negative electrode.

[0034] The physical field includes an alternating electric field and / or a magnetic field, wherein the electric field strength of the alternating electric field is 1 to 50 V / cm and the frequency is 20 to 200 Hz;

[0035] The alternating electric field includes two parallel plates, which are connected to an alternating power source. The parallel plates are metallic conductors.

[0036] The magnetic field includes a single magnetic pole or two opposite magnetic poles, with a magnetic induction intensity of 0.1 to 2000 mT;

[0037] The formation is performed using constant current charge-discharge or constant potential reduction, with a current of 0.01–1C and a current density of 5 μA / cm². 2 ~20mA / cm 2 .

[0038] Preferably, the operating temperature of the battery after formation is -5 to 75°C, for example, it can be -5°C, 0°C, 5°C, 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C or 75°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0039] In a second aspect, the present invention provides a battery obtained by the formation method described in the first aspect.

[0040] Thirdly, the present invention provides an electronic device comprising a battery as described in the second aspect.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] This invention optimizes the composition and structure of the SEI film by placing the battery in an external physical field and utilizing the electric force generated by the alternating electric field or the Lorentz force generated by the magnetic field. This enables uniform deposition and peeling on the electrode surface, thereby improving the battery's coulombic efficiency, cycle performance, and lifespan. It also solves the problems of existing SEI films such as cracking during charging and discharging, low metal ion conductivity, irreversible capacity loss under high current density, and shortened battery life. Attached Figure Description

[0043] Figure 1 This is a schematic diagram showing the relative positions of the parallel plates and the battery as described in Example 1;

[0044] Figure 2 This is a graph showing the coulombic efficiency of the batteries provided in Example 1 and Comparative Example 1 as a function of the number of cycles.

[0045] Figure 3 This is a graph showing the voltage versus capacity of the batteries provided in Example 1 and Comparative Example 1 during the 70th cycle;

[0046] Figure 4 These are graphs showing the change of Aurbach coulomb efficiency test potential over time for the batteries provided in Example 1 and Comparative Example 1.

[0047] Figure 5 These are graphs showing the change in battery potential versus specific capacity provided in Example 1 and Comparative Example 1.

[0048] Figure 6 These are the electrochemical impedance spectra of the batteries provided in Example 1 and Comparative Example 1;

[0049] Figure 7 This is a lithium deposition morphology image of the copper foil surface of the battery provided in Example 1;

[0050] Figure 8 This is a morphology diagram of lithium deposition on the copper foil surface of the battery provided in Comparative Example 1;

[0051] Wherein, 1-parallel plates, 2-cell battery. Detailed Implementation

[0052] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0053] The following embodiments and comparative examples of the present invention describe Li||Cu coin cells of 2032 specification. The battery assembly process includes: using copper foil as the positive electrode and lithium metal as the negative electrode, separating the copper foil and lithium metal with a separator (Celgard 2400), injecting 60 μL of 1M-LiTFSI-DOL / DME (v:v, 1:1) electrolyte, and stamping it on a coin cell sealing machine to obtain a Li||Cu coin cell of 2032 specification.

[0054] The above description of the battery is for the purpose of more fully illustrating the technical solution of the present invention and should not be regarded as a specific limitation of the present invention.

[0055] Example 1

[0056] This embodiment provides a method for optimizing the SEI film structure composition of a secondary battery, the formation method comprising the following steps:

[0057] Battery 2 according to Figure 1 The battery is placed in an alternating current field, the direction of which is 90° with the direction of the line connecting the center of the positive electrode and the center of the negative electrode, and is formed to obtain the formed battery.

[0058] The electric field strength of the alternating current field is 2.5V / cm, and the frequency is 80Hz.

[0059] The alternating electric field consists of two parallel plates 1 spaced 20mm apart. The parallel plates 1 are copper sheets pre-wrapped with insulating glue and connected to the AC power supply.

[0060] The formation temperature was 25°C, and the formation method was 25 μA / cm². 2 A constant current density, within a voltage range of 0.1 to 1.3V, is maintained for 10 charge-discharge cycles.

[0061] In this embodiment, an external AC electric field is applied to the entire formation process, and the entire battery is placed in the AC electric field.

[0062] The coulombic efficiency of the battery obtained after formation in this embodiment as a function of cycle number is shown in the figure below, at an operating temperature of 25°C. Figure 2 As shown in the figure, the voltage changes with capacity at the 70th cycle is as follows. Figure 3 As shown in the figure, the Aurbach coulomb efficiency test potential changes over time. Figure 4 As shown in the figure, the change in potential with specific capacitance is as follows: Figure 5 As shown, the electrochemical impedance spectroscopy is as follows: Figure 6 As shown in the figure, the lithium deposition morphology on the copper foil surface is as follows: Figure 7 As shown;

[0063] The battery obtained in this embodiment has an interface resistance of 84Ω and an SEI film conductivity of 1.19×10⁻⁶ at an operating temperature of 25°C. -7 With an S / cm ratio, an interfacial resistance of 417Ω at an operating temperature of 10℃, and an SEI film conductivity of 0.24×10⁻⁶, the SEI film exhibits a high conductivity. -7 S / cm.

[0064] Example 2

[0065] This embodiment provides a method for optimizing the SEI film structure composition of a secondary battery, the formation method comprising the following steps:

[0066] The battery is placed in an alternating current electric field, the direction of which makes an angle of 90° with the direction of the line connecting the center of the positive electrode and the center of the negative electrode, and is formed to obtain the formed battery.

[0067] The electric field strength of the alternating current field is 1.5V / cm, and the frequency is 80Hz.

[0068] The alternating electric field consists of two parallel plates spaced 20 mm apart. The parallel plates are copper sheets pre-wrapped with insulating glue and connected to the AC power supply.

[0069] The formation temperature was 25°C, and the formation method was 25 μA / cm². 2 With a constant current density, within a voltage range of 0.1 to 1.3V, after 10 charge-discharge cycles, the operating temperature of the battery after formation is 25℃.

[0070] In this embodiment, an external AC electric field is applied to the entire formation process, and the entire battery is placed in the AC electric field.

[0071] Example 3

[0072] This embodiment provides a method for optimizing the SEI film structure composition of a secondary battery, the formation method comprising the following steps:

[0073] The battery is placed in an alternating current electric field, the direction of which makes an angle of 90° with the direction of the line connecting the center of the positive electrode and the center of the negative electrode, and is formed to obtain the formed battery.

[0074] The electric field strength of the alternating current field is 2.5V / cm, and the frequency is 100Hz.

[0075] The alternating electric field consists of two parallel plates spaced 20 mm apart. The parallel plates are copper sheets pre-wrapped with insulating glue and connected to the AC power supply.

[0076] The formation temperature was 25°C, and the formation method was 25 μA / cm². 2With a constant current density, within a voltage range of 0.1 to 1.3V, after 10 charge-discharge cycles, the operating temperature of the battery after formation is 25℃.

[0077] In this embodiment, an external AC electric field is applied to the entire formation process, and the entire battery is placed in the AC electric field.

[0078] Example 4

[0079] This embodiment provides a method for optimizing the SEI film structure of a secondary battery. The method is the same as in Embodiment 1, except that the electric field strength of the AC electric field is 0.75V / cm.

[0080] Example 5

[0081] This embodiment provides a method for optimizing the SEI film structure of a secondary battery. The method is the same as in Embodiment 1, except that the electric field strength of the AC electric field is 60V / cm.

[0082] Example 6

[0083] This embodiment provides a method for optimizing the SEI film structure of a secondary battery. The method is the same as that in Embodiment 1, except that the frequency of the alternating electric field is 40Hz.

[0084] Example 7

[0085] This embodiment provides a method for optimizing the SEI film structure of a secondary battery. The method is the same as that in Embodiment 1, except that the frequency of the alternating electric field is 120Hz.

[0086] Example 8

[0087] This embodiment provides a method for optimizing the SEI film structure of a secondary battery. Except for the fact that the direction of the alternating electric field is at a 45° angle with the direction of the line connecting the center of the positive electrode and the center of the negative electrode, the method is the same as in Embodiment 1.

[0088] Example 9

[0089] This embodiment provides a method for optimizing the SEI film structure of a secondary battery. The method is the same as in Embodiment 1, except that the angle between the direction of the alternating electric field and the direction along the line connecting the center of the positive electrode and the center of the negative electrode is 0°, that is, the direction of the alternating electric field is parallel to the line connecting the positive electrode and the negative electrode.

[0090] Example 10

[0091] This embodiment provides a method for optimizing the SEI film structure of a secondary battery. Except for the formation in a magnetic field with a magnetic induction intensity of 185mT, the method is the same as in Embodiment 1.

[0092] Comparative Example 1

[0093] This comparative example provides a formation method, which is the same as that in Example 1 except that no alternating electric field is added;

[0094] The coulombic efficiency of the battery obtained after formation in this comparative example varies with the number of cycles at an operating temperature of 25℃. Figure 2 As shown in the figure, the voltage changes with capacity at the 70th cycle is as follows. Figure 3 As shown in the figure, the Aurbach coulomb efficiency test potential changes over time. Figure 4 As shown in the figure, the change in potential with specific capacitance is as follows: Figure 5 As shown, the electrochemical impedance spectroscopy is as follows: Figure 6 As shown in the figure, the lithium deposition morphology on the copper foil surface is as follows: Figure 8 As shown;

[0095] The battery obtained in this comparative example has an interfacial resistance of 142 Ω and an SEI film conductivity of 0.70 × 10⁻⁶ at an operating temperature of 25 °C. -7 At an operating temperature of 10℃, the interfacial resistance is 473Ω (S / cm), and the conductivity of the SEI film is 0.21×10⁻⁶. -7 S / cm.

[0096] Performance testing:

[0097] The batteries obtained after formation in the above embodiments and comparative examples were subjected to performance testing.

[0098] Coulomb efficiency: at 0.5 mA cm -2 The current density deposited on the copper foil is 0.5 mAh cm⁻¹. -2 Lithium metal, then at 0.5 mA cm -2 The current density was stripped down to 0.9V, and the test was repeated.

[0099] Overpotential test: at 0.5 mAcm -2 Lithium deposition at current density up to 5 mAh cm⁻¹ -2 And stripped to 0.9V; then at 0.5mA cm -2 Deposition rate of lithium up to 5 mAh cm⁻¹ -2 As a lithium storage layer; further, with 0.5mAh cm -2 The capacity was repeatedly deposited and stripped 10 times, and finally 0.5 mA cm -2 The rate of stripping was reduced to 0.9V.

[0100] Electrochemical impedance spectroscopy (EIS) was used to analyze the interface impedance of the battery. The initial potential of the test was set to the open circuit potential after ten constant current charge and discharge cycles, and the frequency range of the test was 0.1 to 100 kHz.

[0101] Sedimentary morphology test: at 0.5 mA cm -2 At a rate that allows for the deposition of 5 mAh cm⁻¹ on copper foil. -2 The lithium metal was deposited; the deposited battery was disassembled, the copper foil was removed, and the deposition morphology was observed using a scanning electron microscope.

[0102] The test results are shown in Table 1:

[0103] Table 1

[0104]

[0105]

[0106] The following points can be observed from Table 1:

[0107] (1) As can be seen from Examples 1 to 7, the electric field strength or frequency of the AC electric field described in Examples 1 to 7 have changed to different degrees, and the overall performance of the battery after formation is improved compared with Comparative Example 1. It can be seen that the electric field strength and frequency described in this invention are within a reasonable range, which can enable the formed SEI film to have a high ion conductivity, significantly improve the overall performance of the battery, and suppress the generation of dendrites and pits on the electrode surface during charging and discharging.

[0108] (2) As can be seen from Examples 1 and 8-9, the angle between the direction of the AC electric field in Examples 8-9 and the direction of the line connecting the center of the positive electrode and the center of the negative electrode gradually decreases, and its overall performance is slightly lower than that in Example 1. It can be seen that the present invention makes the direction of the physical field have a certain angle with the electrode, so that the solvent molecules and anions around the metal ions in the electrolyte move periodically, thereby promoting the formation of a new solvation structure at the interface, and then forming an SEI film with high ionic conductivity and stronger mechanical properties at the interface.

[0109] (3) As can be seen from Examples 1 and 10, Example 10 uses a magnetic field as an external physical field. Compared with the alternating electric field, the overall performance of the battery after formation is worse than that of Example 1, but better than that of Comparative Example 1. It can be seen that the electric field force generated by the alternating electric field as an external physical field can promote the movement of charged particles and make the performance of the obtained SEI film more optimized.

[0110] (4) As can be seen from Example 1 and Comparative Example 1, no physical field was added during the formation stage of Comparative Example 1, and its performance was significantly reduced compared to Example 1. Figure 2It can be seen that Comparative Example 1 has a coulombic efficiency similar to Example 1 before 50 cycles, but after 50 cycles, the coulombic efficiency gradually decreases significantly, while Example 1 still maintains a higher coulombic efficiency. In the 70th cycle, the overpotential of Example 1 is 31mV, far lower than the 68mV overpotential of Comparative Example 1, indicating that after multiple cycles, Example 1 still maintains a lower internal resistance, while the overpotential of Comparative Example 1 increases with the number of cycles, gradually failing. Combined with... Figure 6 It can be seen that the interface impedance of Example 1 is 84Ω, which is much smaller than the interface impedance of Comparative Example 1 (142Ω). This indicates that under the influence of an external field, the interface resistance of the battery formed in Example 1 is greatly reduced, and the transport rate of lithium ions in the SEI film is significantly improved. Figure 7 and Figure 8 It can be seen that the battery deposition morphology after formation in Example 1 is mainly bulk lithium, while the deposition morphology of Comparative Example 1 is mainly a dendritic structure with a high aspect ratio. This indicates that the addition of an externally generated SEI film during the formation process can induce lithium to deposit in a bulk morphology, avoiding the formation of dendrites and thus extending the battery's lifespan. Furthermore, at different operating temperatures, the electrochemical performance of the battery provided in Example 1 is better than that of Comparative Example 1.

[0111] In summary, this invention provides a method for composing a secondary battery SEI film structure and its application. The method includes adding a physical field during the battery formation stage to change the movement trajectory of solvent molecules and anions around the battery metal ions, adjusting the interfacial solvation structure, optimizing the SEI film composition and structure, and achieving uniform deposition and stripping on the electrode surface, thereby improving the battery coulombic efficiency, cycle performance, and service life.

[0112] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method of optimizing a secondary battery SEI film structure composition, characterized by, The method includes the following steps: The battery is formed under a physical field; The physical field is an alternating electric field; The angle between the direction of the physical field and the direction along the line connecting the center of the positive electrode and the center of the negative electrode is 0~90°; The electric field strength of the alternating current field is 1~50V / cm; the frequency of the alternating current field is 20~200Hz.

2. The method of claim 1, wherein, The alternating electric field includes two parallel plates, which are connected to an alternating power source.

3. The method of claim 2, wherein, The parallel plates are metallic conductors.

4. The method of claim 1, wherein, The formation process employs constant current charge-discharge or constant potential reduction.

5. The method according to claim 1, characterized in that, The current generated is 0.01~1C.

6. The method according to claim 1, characterized in that, The current density of the said formation is 5 μA / cm 2 20 mA / cm 2 .

7. The method according to claim 1, characterized in that, The method includes the following steps: The alternating electric field includes two parallel plates, which are connected to an alternating power source. The parallel plates are metallic conductors. The formation is performed by constant current charge-discharge or constant potential reduction, the current is 0.01-1C, and the current density is 5 μA / cm 2 ~20 mA / cm 2 .

8. A battery, characterized in that, The battery is obtained by the method described in any one of claims 1 to 7.

9. An electronic device, characterized in that, The electronic device includes the battery as described in claim 8.

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