Lithium battery and heating method thereof

Abstract

The invention provides a lithium battery and a heating method thereof, the lithium battery comprises an electrode, the electrode comprises an electrode current collector and an electrode material arranged on the electrode current collector, the electrode material comprises a first material and / or a second material, the conductivity of the first material is greater than 10 < 4 > S / m, and the relative permeability of the second material is greater than 10. The invention provides a lithium battery and a heating method thereof. The temperature rise of the lithium battery in the use process in a low-temperature environment can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of lithium batteries, and in particular to a lithium battery and a heating method thereof. Background Art

[0002] Lithium batteries have attracted widespread attention due to their high energy density and excellent performance. Under low temperature conditions, the viscosity of the electrolyte increases, resulting in a significant decrease in the diffusion rate of lithium ions in the electrolyte, thereby affecting the reaction rate between the electrode material and the electrolyte. Low temperature will increase the solid electrolyte interface (SEI) film impedance and electron migration impedance at the electrode interface, and will also reduce the reactivity of the active material, reducing the available capacity of the battery. Under low temperature conditions, the insertion / deinsertion rate of lithium ions slows down, resulting in the precipitation of lithium metal on the negative electrode surface during charging, forming lithium dendrites, further affecting charging efficiency and safety. At the same time, low temperature may cause the performance of the electrolyte and electrode materials to deteriorate, accelerating the aging of lithium batteries. Frequent low-temperature cycles may cause irreversible losses during the insertion / deinsertion of negative electrode lithium ions, resulting in capacity decay.

[0003] Based on this, it is necessary to provide a more effective and reliable technical solution to achieve rapid heating of the battery in a low temperature environment to avoid the problems caused by using the battery in a low temperature environment. Summary of the invention

[0004] The present application provides a lithium battery and a heating method thereof, which can realize rapid heating of the lithium battery in a low temperature environment.

[0005] One aspect of the present application provides a lithium battery, comprising: an electrode, wherein the electrode comprises an electrode current collector and an electrode material disposed on the electrode current collector, wherein the electrode material comprises a first material and / or a second material, wherein the electrical conductivity of the first material is greater than 10 4 S / m, and the relative magnetic permeability of the second material is greater than 10.

[0006] In some embodiments of the present application, the first material includes single-walled carbon tubes, graphene, conductive carbon black, carbon nanotubes, silver nanowires, and high conductivity alloy powder containing copper and aluminum; the second material includes iron powder, cobalt powder, nickel powder, iron carbide, manganese carbide, cobalt carbide, and high magnetic permeability alloy powder containing iron, cobalt, and nickel.

[0007] Another aspect of the present application further provides a method for heating a lithium battery as described above, comprising: forming an electromagnetic eddy current in the lithium battery, and heating the lithium battery by the electromagnetic eddy current.

[0008] In some embodiments of the present application, the method for forming electromagnetic eddy current in the lithium battery includes: applying an alternating current to the lithium battery to generate an alternating magnetic field inside the lithium battery, wherein the alternating magnetic field forms an electromagnetic eddy current inside the lithium battery, wherein the peak current of the alternating current is I a , the frequency of the alternating current is f c , the time for which the current is applied is t.

[0009] In some embodiments of the present application, when an alternating current is applied to the lithium battery, a biased direct current is also superimposed, and the current value of the biased direct current is I c .

[0010] In some embodiments of the present application, the I c is the current for charging or discharging the lithium battery, the I a is the current for heating the lithium battery.

[0011] In some embodiments of the present application, controlling the I c and the I a Different working strategies are implemented on the lithium battery.

[0012] In some embodiments of the present application, controlling the I a =0 and I c >0, only the lithium battery is charged; control the I a >0 and I c = 0, only the lithium battery is heated; control the I a >0 and I c >0, the lithium battery is charged and heated at the same time; the I a >

[0013] 0 and I c When <0, the lithium battery is discharged and heated simultaneously.

[0014] In some embodiments of the present application, the I c 10% to 100% of the maximum charge or discharge current of the lithium battery.

[0015] In some embodiments of the present application, the f c 50Hz to 100MHz.

[0016] The present application provides a lithium battery and a heating method thereof. The electrodes of the lithium battery are made of materials with high electrical conductivity and high magnetic permeability. Such materials will produce electromagnetic eddy current effects under the action of high-frequency alternating current, thereby increasing the temperature rise of the battery. Combined with the heating method of the present application, the temperature rise of the lithium battery during charging or discharging in a low-temperature environment can be increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The following figures describe in detail the exemplary embodiments disclosed in this application. The same reference numerals represent similar structures in several views of the drawings. Those skilled in the art will understand that these embodiments are non-limiting, exemplary embodiments, and the drawings are only for the purpose of illustration and description, and are not intended to limit the scope of this application. Other embodiments may also accomplish the inventive intent in this application. It should be understood that the drawings are not drawn to scale.

[0018] in:

[0019] Figure 1 A flowchart of a heating method according to some embodiments of the present application;

[0020] Figure 2 This is a battery temperature variation diagram of Comparative Example 1 in this application;

[0021] Figure 3 This is a battery temperature variation diagram of Example 1 in this application;

[0022] Figure 4 This is a battery temperature variation diagram of Example 2 in this application. DETAILED DESCRIPTION

[0023] The following description provides specific application scenarios and requirements of the present application, with the purpose of enabling those skilled in the art to make and use the content in the present application. It will be apparent to those skilled in the art that various local modifications to the disclosed embodiments are apparent, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present application. Therefore, the present application is not limited to the embodiments shown, but to the widest scope consistent with the claims.

[0024] The technical solution of the present invention is described in detail below in conjunction with the embodiments and drawings.

[0025] In the field of battery heating research, researchers start from the internal composition structure of the battery, and develop new electrode materials, electrolytes or additives to enhance the temperature rise phenomenon during the charging and discharging process of the battery in a low-temperature environment. In addition, researchers heat the battery to increase the temperature of the battery in a low-temperature environment, thereby increasing the ion diffusion rate and improving the battery performance. Recently, researchers have made a lot of efforts in the innovative design of battery materials and system thermal management. Existing preheating technologies are mainly divided into two methods: external heating and internal heating. External heating usually heats the battery through an independent heating element, and the heat is transferred to the outside of the battery cell by conduction or convection. In this field, many researchers have systematically analyzed and compared different battery thermal management technologies (such as air cooling, liquid cooling, phase change materials, and heat pipes). However, in addition to complex system design and increased weight, these external heating methods also face significant heat loss, cost and space occupancy problems. In contrast, internal heating technology has the advantages of higher efficiency, shorter preheating time, simpler structure and more uniform temperature distribution.

[0026] In order to increase the battery temperature and improve the battery performance in a low temperature environment, we proposed a high-frequency AC heating method, which applies a DC bias superimposed AC (frequency of 50Hz to 100MHz) alternating current to the battery for charging or discharging, which will have a heating effect at the same time. On the one hand, this method can achieve rapid heating of the battery in a low temperature environment to avoid the problems caused by using the battery in a low temperature environment. At the same time, the present application changes the material of the lithium battery, and the electrode of the lithium battery adopts a material with high electrical conductivity and high magnetic permeability. This material will produce an electromagnetic eddy current effect under the action of high-frequency alternating current, further increasing the temperature rise of the battery.

[0027] The embodiment of the present application provides a lithium battery, comprising: an electrode, wherein the electrode comprises an electrode current collector and an electrode material disposed on the electrode current collector, wherein the electrode material comprises a first material and / or a second material, wherein the electrical conductivity of the first material is greater than 10 4 S / m, the relative magnetic permeability of the second material is greater than 10. The electrode can be a positive electrode or a negative electrode, and the present application does not limit this. In other words, the technical solution of the present application can improve the positive electrode material, can also improve the negative electrode material, and can also improve both the positive electrode and the negative electrode materials.

[0028] In some embodiments of the present application, the first material includes single-walled carbon tubes, graphene, conductive carbon black, carbon nanotubes, silver nanowires, high conductivity alloy powder containing copper and aluminum, etc., and the second material includes iron powder, cobalt powder, nickel powder, iron carbide, manganese carbide, cobalt carbide, and high magnetic permeability alloy powder containing iron, cobalt, and nickel, etc.

[0029] In some embodiments of the present application, when the electrode is a positive electrode, the positive electrode material further includes conventional positive electrode materials such as nickel, cobalt, and manganese; when the electrode is a negative electrode, the negative electrode material further includes conventional negative electrode materials such as graphite and conductive agents. The technical solution of the present application is to add the first material and / or the second material having high electrical conductivity and high magnetic permeability in addition to conventional electrode materials.

[0030] In some embodiments of the present application, other structures of the lithium battery except the electrodes, such as electrolyte, diaphragm, etc. are conventional structures and will not be described in detail in the present application.

[0031] The present application also provides a method for heating the lithium battery provided in the above embodiment of the present application, referring to Figure 1 As shown, the method comprises: step S1: applying an alternating current to the lithium battery to generate an alternating magnetic field inside the lithium battery, wherein the alternating magnetic field forms an electromagnetic eddy current inside the lithium battery, and the lithium battery is heated by the electromagnetic eddy current, wherein the peak current of the alternating current is I a (A), the frequency of the alternating current is f c (Hz), and the time for applying current is t(s). The principle that high magnetic permeability materials and high electrical conductivity materials can increase temperature rise is that they enhance the electromagnetic eddy current effect and thermal effect. High magnetic permeability materials increase the magnetic induction intensity inside the material by focusing and enhancing the magnetic field, thereby accelerating the generation of electromagnetic eddy currents under the alternating magnetic field. High electrical conductivity materials increase the density of electromagnetic eddy currents by improving electrical conductivity, further enhancing the electromagnetic eddy current heating effect. The power generated by the electromagnetic eddy current thermal effect is proportional to the square of the electrical conductivity and the rate of change of the magnetic field. Therefore, the combination of high magnetic permeability and high electrical conductivity materials can work synergistically to significantly increase the thermal power per unit volume and improve the temperature rise efficiency.

[0032] In some embodiments of the present application, when an alternating current is applied to the lithium battery, a biased direct current is also superimposed, and the current value of the biased direct current is I c (A), the total current I applied to the lithium battery B =I c +I a sin(2πf c t). The total current consists of the DC component I c and AC component I a sin(2πf c t) is composed of c is the constant current, I a sin(2πf c t) is an alternating current that changes sinusoidally with time. According to Ampere's law, a constant current will produce a constant magnetic field, and a changing current will produce a changing magnetic field. For the DC component I c , an alternating magnetic field B will be generated 0; For AC component I a sin(2πf c t), an alternating magnetic field B will be generated a sin(2πf c t). The alternating magnetic field generated inside the lithium battery can be expressed as B=B 0 +B a sin(2πf c t), where B 0 The DC component I c The constant magnetic field generated, B a sin(2πf c t) is composed of the AC component and I a sin(2πf c t) produces an alternating magnetic field.

[0033] In some embodiments of the present application, the I c It is 10% to 100% of the maximum charge or discharge current of the battery, for example, 20%, 30%, 40%, 50%, 60%, 70%, 80% or 90%. The maximum charge or discharge current of the lithium battery refers to the maximum current value that the lithium battery can safely accept. This parameter is usually provided by the lithium battery manufacturer to ensure rapid charging or discharging without damaging the life or performance of the lithium battery. Exceeding this current may cause the lithium battery to overheat and the internal chemical reaction to become unstable, thereby affecting the safety and life of the lithium battery. The maximum charge or discharge current of an ordinary lithium-ion battery is generally 1C to 3C, and the maximum charge or discharge current of a high-power lithium-ion battery is generally 5C to 8C.

[0034] In some embodiments of the present application, the I c is the current for charging or discharging the lithium battery, the I a is the current for heating the lithium battery.

[0035] In some embodiments of the present application, controlling the I c and the I a Different working strategies are implemented on the lithium battery.

[0036] In some embodiments of the present application, controlling the I a =0 and I c >0, it is possible to charge only the lithium battery; control the I a >0 and I c = 0, it is possible to heat only the lithium battery; control the I a >0 and I c >0, the lithium battery can be charged and heated at the same time; control the I a >0 and Ic When I c and the I a The value of can control the charging or discharging efficiency and heating efficiency of the lithium battery. c and the I a The larger the size of , the greater the charging or discharging efficiency and the heating efficiency.

[0037] In some embodiments of the present application, the f c 50Hz to 100MHz.

[0038] In summary, the above is the basic concept of the technical solution of this application. First, this application uses the method of simultaneously applying a bias DC current and superimposing an AC current to charge or discharge a lithium battery, which can increase the battery temperature at low temperatures. Furthermore, by selecting appropriate DC current and AC current sizes, the charging or discharging effect can be further optimized. Furthermore, by improving the electrode material of the lithium battery, the battery temperature rise effect can be further improved on the original basis.

[0039] Below, in order to more clearly illustrate the technical effects of the present application, the present application sets up different embodiments and comparative examples. Among them, the comparative example is that the conventional soft-pack battery is charged or discharged by direct current. The embodiment is the heating method of the present application and the lithium battery of the present application, among which the parameters such as current size or current frequency and the electrode additive materials are different in different embodiments.

[0040] Comparative Example 1

[0041] A conventional lithium battery is charged with direct current. The current value of the direct current is 1A. The relevant parameters (charging time (s), temperature (℃)) during the charging process are recorded and Figure 2 exhibit.

[0042] Examples 1 and 2

[0043] At the same time, a biased DC current is applied to charge the lithium battery by superimposing an AC current. Among them, the DC current value, AC current peak value, AC frequency and electrode material in different embodiments are different. In the embodiment of the present application, the electrode includes both a positive electrode and a negative electrode, that is, the positive electrode material and the negative electrode material are improved at the same time. For detailed data, see Table 1. The relevant parameters (charging time (s), temperature (℃)) during the charging process are recorded, respectively. Figure 3 and Figure 4 exhibit.

[0044] It should be noted that the present application sets up several test batteries, and each comparative example and embodiment uses a brand new, separate test battery with exactly the same specifications (that is, a new battery of the same specifications is selected for each charging to avoid the impact of the battery being overcharged on subsequent tests).

[0045] Table 1 below shows the test results of different comparative examples and embodiments.

[0046]

[0047]

[0048] Refer to Table 1 and Figure 2 , Figure 3 It can be found that compared with DC charging, the DC superimposed high-frequency AC charging heating method can increase the battery temperature more and reach the maximum temperature faster. This further shows that high-frequency AC will significantly promote the temperature rise of the battery.

[0049] Refer to Table 1 and Figure 2 , Figure 4 It can be found that compared with conventional electrode materials, adding high magnetic permeability and high electrical conductivity materials will make the battery heating more obvious, and the heating temperature is also higher than that of conventional materials.

[0050] Refer to Table 1 and Figure 3 , Figure 4 It can be found that compared with conventional electrode materials, adding high magnetic permeability and high electrical conductivity materials will make the battery heat more obviously, and the heating temperature is also higher than that of conventional materials. This also shows that high magnetic permeability and high electrical conductivity materials will produce electromagnetic eddy current effect under the action of high-frequency alternating current, further increasing the temperature rise of the battery. This type of material plays a significant role in promoting the temperature rise of the battery.

[0051] The present application provides a lithium battery heating method, which can improve the temperature rise of the lithium battery during charging or discharging in a low temperature environment.

[0052] In summary, after reading the contents of this application, those skilled in the art will appreciate that the aforementioned application contents may be presented only in an exemplary manner and may not be restrictive. Although not explicitly stated herein, those skilled in the art will appreciate that this application is intended to encompass various reasonable changes, improvements and modifications to the embodiments. These changes, improvements and modifications are within the spirit and scope of the exemplary embodiments of this application.

[0053] It should be understood that the term "and / or" used in this embodiment includes any or all combinations of one or more of the associated listed items. It should be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to another element, or there can also be intermediate elements.

[0054] It should also be understood that the terms "comprising", "containing", "including" or "comprising", when used in this application document, indicate the presence of the recorded features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or groups thereof.

[0055] It should also be understood that although the terms first, second, third, etc. can be used to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. Therefore, without departing from the teachings of the present application, the first element in some embodiments can be referred to as the second element in other embodiments. The same reference numerals or the same reference signs represent the same elements throughout the specification.

[0056] In addition, the present specification describes exemplary embodiments by reference to idealized exemplary cross-sectional views and / or plan views and / or stereograms. Therefore, differences from the illustrated shapes due to, for example, manufacturing techniques and / or tolerances are foreseeable. Therefore, the exemplary embodiments should not be interpreted as being limited to the shapes of the regions shown herein, but should include deviations in shapes caused by, for example, manufacturing. Therefore, the regions shown in the figures are schematic in nature, and their shapes are not intended to illustrate the actual shapes of the regions of the device nor to limit the scope of the exemplary embodiments.

Claims

1. A lithium battery, characterized in that: include: The electrode comprises an electrode current collector and an electrode material disposed on the electrode current collector, wherein the electrode material comprises a first material and / or a second material, and the electrical conductivity of the first material is greater than 10 4 S / m, and the relative magnetic permeability of the second material is greater than 10.

2. The lithium battery according to claim 1, characterized in that The first material includes single-walled carbon tubes, graphene, conductive carbon black, carbon nanotubes, silver nanowires, and high-conductivity alloy powder containing copper and aluminum; the second material includes iron powder, cobalt powder, nickel powder, iron carbide, manganese carbide, cobalt carbide, and high-magnetic permeability alloy powder containing iron, cobalt, and nickel.

3. A method for heating a lithium battery according to any one of claims 1 to 2, characterized in that: include: An electromagnetic eddy current is formed in the lithium battery, and the lithium battery is heated by the electromagnetic eddy current.

4. The heating method according to claim 3, characterized in that: The method for forming electromagnetic eddy current in the lithium battery comprises: applying an alternating current to the lithium battery to generate an alternating magnetic field inside the lithium battery, wherein the alternating magnetic field forms an electromagnetic eddy current inside the lithium battery, wherein the current peak value of the alternating current is I a , the frequency of the alternating current is f c , the time for which the current is applied is t.

5. The heating method according to claim 4, characterized in that: When an alternating current is applied to the lithium battery, a biased direct current is also superimposed, and the current value of the biased direct current is I c .

6. The heating method according to claim 5, characterized in that: I c is the current for charging or discharging the lithium battery, the I a is the current for heating the lithium battery.

7. The heating method according to claim 6, characterized in that: Control the I c and the I a Different working strategies are implemented on the lithium battery.

8. The heating method according to claim 7, characterized in that: Control the I a =0 and I c >0, only the lithium battery is charged; control the I a =0 and I c <0, only discharge the lithium battery; control the I a >0 and I c = 0, only the lithium battery is heated; control the I a >0 and I c >0, the lithium battery is charged and heated at the same time; the I a > 0 and I c When <0, the lithium battery is discharged and heated simultaneously.

9. The heating method according to claim 5, characterized in that: I c 10% to 100% of the maximum charge or discharge current of the lithium battery.

10. The heating method according to claim 4, characterized in that: The f c 50Hz to 100MHz.

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