Electrodes, cells, battery packs, and methods for manufacturing battery packs

Abstract

This application discloses an electrode, a battery cell, a battery pack, and a method for preparing the battery pack, belonging to the field of battery technology. The electrode is composed of a first electrode material and a second electrode material, wherein the resistivity of the first electrode material is greater than the resistivity of the second electrode material.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to an electrode, a battery cell, a battery pack, and a method for preparing the battery pack. Background Technology

[0002] In low-temperature environments, battery packs experience significant capacity degradation due to factors such as increased electrolyte viscosity, decreased conductivity, and slowed ion diffusion. For example, in environments below -10°C, battery pack capacity degradation exceeds 40%, and charging efficiency is less than 50%, severely restricting the application of battery packs in cold regions. Therefore, reducing the rate of battery capacity degradation in low-temperature environments is an urgent problem to be solved. Summary of the Invention

[0003] In view of the above-mentioned problem of how to reduce the battery capacity decay rate of battery packs in low-temperature environments, this application is proposed to provide an electrode, a cell, a battery pack, and a method for manufacturing a battery pack that solves the above-mentioned problem, which can reduce the battery capacity decay rate of battery packs in low-temperature environments.

[0004] In a first aspect, this application provides an electrode, the constituent materials of which include a first electrode material and a second electrode material, wherein the resistivity of the first electrode material is greater than the resistivity of the second electrode material.

[0005] In one embodiment, the electrode is composed of a mixture of the first electrode material and the second electrode material, wherein the first electrode material accounts for 16%-84% of the mixture, and the second electrode material accounts for 16%-84% of the mixture.

[0006] In one embodiment, the electrode includes a first sub-electrode and a second sub-electrode, the first sub-electrode being composed of the first electrode material, the second sub-electrode being composed of the second electrode material, and the second sub-electrode being provided on at least one side of the first sub-electrode.

[0007] In one embodiment, the first electrode material is a first graphite, and the second electrode material is a second graphite. The first graphite and the second graphite differ in at least one of their target characteristics, including: particle size, specific surface area, and tapped or compacted density. Alternatively, the first electrode material may be graphite, and the second electrode material may be hard carbon.

[0008] Secondly, this application provides a battery cell comprising a positive electrode and a negative electrode, wherein at least one of the positive electrode and the negative electrode is an electrode as described in any one of the first aspects.

[0009] In one embodiment, when the electrode includes a first sub-electrode and a second sub-electrode, the cell includes at least two sub-cells, at least one of the sub-cells includes the first sub-electrode, at least one of the sub-cells includes the second sub-electrode, the sub-cell including the first sub-electrode and the sub-cell including the second sub-electrode are different sub-cells, and the first sub-electrode and the second sub-electrode included in the sub-cell constitute the positive electrode and / or negative electrode of the cell.

[0010] In one embodiment, the sub-cells including the first sub-electrode and the sub-cells including the second sub-electrode are alternately distributed; or, The first sub-electrode is located at the apex of the positive electrode and / or the negative electrode.

[0011] In one embodiment, when the positive electrode is an electrode as described in any one of the second aspects, the negative electrode comprises a mixture of lithium and sodium materials, wherein the sodium material accounts for 1-30% of the composition.

[0012] Thirdly, this application provides a battery pack comprising a plurality of cells as described in any of the second aspects.

[0013] Fourthly, this application provides a method for preparing a battery pack, comprising: At least one of the positive and negative electrodes of the battery cell is prepared using a first electrode material and a second electrode material, wherein the resistivity of the first electrode material is greater than the resistivity of the second electrode material. A battery cell is prepared using the positive electrode and the negative electrode; A battery pack is prepared using the aforementioned battery cell.

[0014] In one embodiment, the method further includes: The safe range of values ​​for the electrical characteristics of the electrical signal pulses connected to the battery pack is detected, wherein the electrical characteristics include the amplitude and frequency of the electrical signal pulses; An electrical signal pulse whose electrical characteristics satisfy the safety value range is selected, and the selected electrical signal pulse is connected to the battery pack. The first electrode material and the second electrode material in the battery pack generate heat after the electrical signal pulse is connected, and the heat generated by the first electrode material is greater than the heat generated by the second electrode material.

[0015] In one embodiment, the safe range of values ​​for the electrical characteristics of the detected electrical signal pulses connected to the battery pack includes: When the state of charge of the battery pack falls within any of the target state of charge ranges, the electrical characteristics of the electrical signal pulse are adjusted, and the health status of the cells in the battery pack after the electrical characteristics are adjusted is obtained. Based on the adjusted electrical characteristics and the health status of the cells in the battery pack after the electrical characteristics were adjusted, the safe range of electrical characteristics of the electrical signal pulse under the target state of charge range is determined.

[0016] In one embodiment, when the battery cell comprises at least two sub-cells, the safe range of values ​​for the electrical characteristics of the detected electrical signal pulses connected to the battery pack includes: Determine the internal resistance and temperature of each sub-cell in the battery pack; Based on the internal resistance and temperature of each of the sub-cells, the electrical characteristics of the electrical signal pulses of the sub-cells are adjusted, and the health status of the sub-cells after the electrical characteristics are adjusted is obtained. Based on the adjusted electrical characteristics and the health status of the cells in the battery pack after the adjustment of the electrical characteristics, the safe range of electrical characteristics of the electrical signal pulses connected to the sub-cells is determined. The safe range of electrical characteristics of the electrical signal pulses of the battery pack includes the safe range of electrical characteristics of the electrical signal pulses of each sub-cell.

[0017] In one embodiment, the preparation of the negative electrode of the battery cell using a first electrode material and a second electrode material includes: Based on the target characteristics of multiple electrode materials, the material characteristics of each electrode material are determined; wherein, the target characteristics include at least one of particle size, specific surface area, tapped density and compacted density, and the material characteristics include at least one of rate capability, energy and resistivity; Based on the material characteristics of each electrode material, the first electrode material and the second electrode material are selected from the plurality of electrode materials; The negative electrode is prepared using the first electrode material and the second electrode material.

[0018] Fifthly, this application provides an electronic device, including: a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, and the processor executing the computer instructions to perform the method as described in the first aspect.

[0019] In a sixth aspect, this application provides a computer-readable storage medium storing computer instructions for causing the computer to perform the method described in the first aspect.

[0020] The technical solutions provided in this application embodiment have at least the following technical effects or advantages: This application provides an embodiment of an electrode, a battery cell, a battery pack, and a method for preparing the battery pack. The electrode is composed of a first electrode material and a second electrode material. Since the resistivity of the first electrode material is greater than that of the second electrode material, under the same electrical signal pulse conditions, the heat generated by the first electrode material is greater than that generated by the second electrode material. By preparing the electrode using the first electrode material and then assembling the electrode into a battery pack, the self-heating of the battery cell is achieved, increasing the heat generated by the entire battery cell. As a result, after the battery cell is assembled into a battery pack, the battery capacity decay rate of the battery pack under low-temperature conditions can be reduced.

[0021] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0022] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This is a schematic diagram of an electrode provided in an embodiment of this application; Figure 2 This is another schematic diagram of the electrode provided in the embodiments of this application; Figure 3 This is another schematic diagram of the electrode provided in the embodiment of this application; Figure 4(a) is a schematic diagram of one arrangement of the first sub-electrode and the second sub-electrode of this application; Figure 4(b) is a schematic diagram of another arrangement of the first and second sub-electrodes of this application; Figure 5(a) is a schematic diagram of one arrangement of the first sub-electrode of this application; Figure 5(b) is a schematic diagram of another arrangement of the first sub-electrode of this application; Figure 6 This is a schematic diagram of the battery cell structure of this application; Figure 7 This is a flowchart of the method for preparing the battery pack of this application; Figure 8 This is a schematic diagram illustrating one possible scenario for material-level mixing; Figure 9 This is a schematic diagram illustrating one possible scenario for cell-level hybridization. Figure 10 This is a schematic diagram of the electronic device. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings. It should be understood that the embodiments of this disclosure and the specific features in the embodiments are detailed descriptions of the technical solutions of this application, rather than limitations on the technical solutions of this application. Unless otherwise specified, the embodiments of this application and the technical features in the embodiments can be combined with each other.

[0024] Reference Figure 1 This application provides an electrode 3, the constituent materials of which include a first electrode material 311 and a second electrode material 321, wherein the resistivity of the first electrode material 311 is greater than the resistivity of the second electrode material 321.

[0025] In this application, the constituent materials of electrode 3 include a first electrode material 311 and a second electrode material 321. Since the resistivity of the first electrode material 311 is greater than that of the second electrode material 321, under the same electrical signal pulse conditions, the heat generated by the first electrode material 311 is greater than that generated by the second electrode material 321. After electrode 3 is prepared by the first electrode material 311 and then the electrode 3 is used to form cell 2, the self-heating of cell 2 is realized, which increases the heat generated by the entire cell 2. Thus, after the cell is prepared into a battery pack, the battery capacity decay rate of the battery pack under low temperature environment can be reduced.

[0026] It can be seen that electrode 3 can be made by mixing the first electrode material 311 and the second electrode material 321 at the material level, or it can be made by mixing the first electrode material 311 and the second electrode material 321 into individual cells at the cell level.

[0027] If the electrode is prepared by material-level mixing, in one embodiment of this application, the constituent materials of the electrode 3 include a mixture of a first electrode material 311 and a second electrode material 321, wherein the proportion of the first electrode material 311 in the mixture is 16%-84%, and the proportion of the second electrode material 321 in the mixture is 16%-84%.

[0028] The specific proportion of the first electrode material 311 in the mixed material can be any one of 20%, 30%, 55%, 70%, etc. The specific proportion of the second electrode material 321 in the mixed material can be any one of 80%, 70%, 45%, 30%, etc.

[0029] In one embodiment, if the first electrode material 311 and the second electrode material 321 are sodium ion material and lithium ion material respectively, then the lithium ion material and the sodium ion material can be mixed in any proportion.

[0030] Reference Figure 2 If the electrode is produced by cell-level mixing, in one embodiment of this application, the electrode 3 includes a first sub-electrode 31 and a second sub-electrode 32. The first sub-electrode 31 is composed of the first electrode material 311, and the second sub-electrode 32 is composed of the second electrode material 321. The second sub-electrode 32 is provided on at least one side of the first sub-electrode 31.

[0031] In this embodiment, a second sub-electrode 32 is provided on at least one side of the first sub-electrode 31. The first sub-electrode 31 is made of a first electrode material 311, and the second sub-electrode 32 is made of a second electrode material 321. The resistivity of the first electrode material 311 is greater than that of the second electrode material 321. Therefore, under the same electrical signal pulse conditions, the heat generated by the first sub-electrode 31 is greater than that generated by the second sub-electrode 32. Since the second sub-electrode 32 is provided on at least one side of the first sub-electrode 31, the first sub-electrode 31 can transfer heat to the second sub-electrode 323. It can be seen that the heat generated by the first sub-electrode 31 increases the heat generated by the entire electrode 3.

[0032] In one embodiment, the electrode 3 can be either a positive electrode 4 or a negative electrode 5. If the electrode 3 refers to the positive electrode 4, then either the first electrode material 311 or the second electrode material 321 may be any one of the following: ternary materials, lithium iron phosphate, lithium manganese iron phosphate, Prussian blue, sodium vanadium phosphate, oxide sodium ions, polyanionic sodium ions, Prussian blue sodium ions, and organic sodium ions.

[0033] If electrode 3 refers to negative electrode 5, then any one of the first electrode material 311 and the second electrode material 321 may be: natural graphite, artificial graphite, hard carbon material, silicon-containing material, silicon-carbon material, alloy, oxide, and any one of metallic lithium.

[0034] In this embodiment, for cell-level hybridization, a sub-cell with high internal resistance or excellent low-temperature performance is preferred as the heating sub-cell; generally, after the first sub-electrode is made of lithium iron phosphate material and the second sub-electrode is made of ternary material, the sub-cell including the first sub-electrode is used as the heating cell; after the first sub-electrode is made of sodium ion material and the second sub-electrode is made of lithium ion material, the sub-cell including the first sub-electrode is used as the heating cell.

[0035] For material-level mixing, electrode materials with high resistivity or excellent low-temperature performance are preferred for mixing. After mixing to form an electrode, the entire cell including the electrode is used as a heating cell.

[0036] In one embodiment, if electrode 3 is negative electrode 5, then the first electrode material 311 is first graphite and the second electrode material 321 is second graphite. The first graphite and the second graphite have at least one different target feature, including: particle size, specific surface area, and tapped or compacted density. Alternatively, the first electrode material 311 may be graphite, and the second electrode material 321 may be hard carbon.

[0037] In this embodiment, since the first graphite and the second graphite have different target characteristics, including particle size, specific surface area, and tap or compaction density, the material characteristics of the first graphite and the second graphite are different, such as the ratio and / or energy. Ultimately, this is to achieve the preparation of the negative electrode 5 by mixing high-ratio graphite and high-energy graphite, or to prepare the negative electrode 5 by mixing high-energy graphite and hard carbon.

[0038] Reference Figure 6 This application also provides a battery cell 2, which includes a positive electrode 4 and a negative electrode 5, wherein at least one of the positive electrode 4 and the negative electrode 5 is an electrode 3 as described in any of the above embodiments.

[0039] Reference Figure 3 In one embodiment, when the electrode 3 includes a first sub-electrode 31 and a second sub-electrode 32, the battery cell 2 includes at least two sub-cells 21, at least one of the sub-cells includes the first sub-electrode 31, at least one of the sub-cells 21 includes the second sub-electrode 32, the sub-cell 21 including the first sub-electrode 31 and the sub-cell 21 including the second sub-electrode 32 are different sub-cells 21, the first sub-electrode 31 included in the sub-cell 21 and the second sub-electrode 32 included in the sub-cell 21 constitute the positive electrode 4 and / or negative electrode 5 of the battery cell 2.

[0040] In this embodiment, the number of sub-cells 21 in the cell 2 can be two. One sub-cell 21 includes a first sub-electrode 31, and the other sub-cell 21 includes a second sub-electrode 32. The first sub-electrode 31 and the second sub-electrode 32 constitute the electrode 3 in the cell 2. The number of sub-cells 21 in cell 2 can be two or more. One or more sub-cells 21 include a first sub-electrode 31, and one or more sub-cells 21 include a second sub-electrode 32. One or more first sub-electrodes 31 and one or more second sub-electrodes 32 constitute the electrode 3 in cell 2. In this embodiment, the sub-cell 21 including the first sub-electrode 31 and the sub-cell 21 including the second sub-electrode 323 are different sub-cells 21. That is, a sub-cell 21 can only include the first sub-electrode 31 or the second sub-electrode 32, and cannot include the first sub-electrode 31 and the second sub-electrode 32 at the same time.

[0041] For the positive electrode 4 and negative electrode 5 of the battery cell 2, one possibility is that the positive electrode 4 is made of a mixture of two electrode materials. Specifically, the positive electrode 4 of the battery cell 2 includes a mixture of a first electrode material 311 and a second electrode material 321, and the negative electrode 5 of the battery cell 2 is a single electrode material. It is also possible that the positive electrode 4 of the cell 2 is composed of the first sub-electrode 31 and the second sub-electrode 32 included in the sub-cell 21, and the negative electrode 5 of the cell 2 is a single electrode material. Another possibility is that the negative electrode 5 is made of a mixture of two electrode materials. Specifically, the negative electrode 5 of the battery cell 2 includes a mixture of the first electrode material 311 and the second electrode material 321, while the positive electrode 4 of the battery cell 2 is a single electrode material. It is also possible that the negative electrode 5 of the cell 2 is composed of the first sub-electrode 31 and the second sub-electrode 32 included in the sub-cell 21, and the positive electrode 4 of the cell 2 is a single electrode material. Another possibility is that both the positive electrode 4 and the negative electrode 5 are made by mixing two different electrode materials, specifically: The positive electrode 4 of the battery cell 2 includes a mixture of a first electrode material 311 and a second electrode material 321, and the negative electrode 5 of the battery cell 2 includes a mixture of a first electrode material 311 and a second electrode material 321. The positive electrode 4 of the battery cell 2 includes a mixture of a first electrode material 311 and a second electrode material 321, and the negative electrode 5 of the battery cell 2 is composed of a first sub-electrode 31 and a second sub-electrode 32 included in the sub-cell 21.

[0042] It is also possible that the positive electrode 4 of the battery cell 2 is composed of the first sub-electrode 31 and the second sub-electrode 32 included in the sub-cell 21, and the negative electrode 5 of the battery cell 2 is composed of the first sub-electrode 31 and the second sub-electrode 32 included in the sub-cell 21.

[0043] The positive electrode 4 of the cell 2 is composed of a first sub-electrode 31 and a second sub-electrode 32 included in the sub-cell 21, and the negative electrode 5 of the cell 2 is a mixture of a first electrode material 311 and a second electrode material 321.

[0044] It should be noted that although the first electrode material 311 and the second electrode material 321 constituting the positive electrode 4 and the first electrode material 311 and the second electrode material 321 constituting the negative electrode 5 have the same name and designation, they are actually different electrode materials. For details, please refer to the relevant descriptions of the electrode materials used in the positive electrode and the electrode materials used in the negative electrode in the above embodiments, which will not be repeated here.

[0045] In one embodiment, for the case of material-level mixing, the materials can be arranged sequentially and grouped in a conventional manner.

[0046] In one embodiment, for the case of cell-level hybridization, the sub-cell 21 including the first sub-electrode 31 is selected as the heating cell, and then arranged in the following manner, specifically: The sub-cells 21 of the first sub-electrode 31 and the sub-cells 21 including the second sub-electrode 32 are alternately distributed; or, the first sub-electrode 31 is located at the apex of the positive electrode 4 and / or the negative electrode 5.

[0047] In this embodiment, the heat generated by the sub-cell 21 of the first sub-electrode 31 is greater than that of the sub-cell 21 of the second sub-electrode 32. By alternating the distribution of the sub-cell 21 including the first sub-electrode 31 and the sub-cell 21 including the second sub-electrode 32, the sub-cell 21 of the first sub-electrode 31 can transfer heat to the sub-cell 21 of the second sub-electrode 32, thereby increasing the heat generated by the cell 2.

[0048] The sub-cell 21 including the first sub-electrode 31 is referred to as A, and the sub-cell 21 including the second sub-electrode 32 is referred to as B. The alternating distribution of A and B can be in the form of "ABAB" alternation as shown in Figure 4(a), or in the form of one A and n B alternation as shown in Figure 4(b), where n is an integer greater than 1.

[0049] If the number of first sub-electrodes 31 is less than the preset number, then when electrode 3 is the positive electrode 4, the first sub-electrode 31 is located at the vertex of the positive electrode 4; when electrode 3 is the negative electrode 5, the first sub-electrode 31 is located at the vertex of the negative electrode 5; the preset number is preset manually, for example, it can be set to 4 or 8.

[0050] As shown in Figure 5(a), the positive electrode 4 and / or the negative electrode 5 can be cubic in shape, and the first sub-electrode 31 is located at the 8 vertices of the cube; As shown in Figure 5(b), the positive electrode 4 and / or the negative electrode 5 can be cylindrical in shape, and the first sub-electrode 31 is located at the four vertices of the cylinder as shown in the figure.

[0051] In this embodiment, if the electrodes 3 are made of the same conductivity material, the heat generated when current passes through the apex of the positive electrode 4 and / or the negative electrode 5 is higher than that in other areas of the positive electrode 4 and / or the negative electrode 5. Therefore, placing the first sub-electrode 31 at the apex of the positive electrode 4 and / or the negative electrode 5 allows the first sub-electrode 31 to generate more heat, thus achieving optimal heat preservation and heating effects for the entire battery pack 1. Simultaneously, when the first sub-electrode 31 is placed at the apex of the positive electrode 4 and / or the negative electrode 5, due to geometric advantages, heat is evenly transferred in all directions through radiation, conduction, and thermal convection, allowing the second sub-electrode 32 in the positive electrode 4 and / or the negative electrode 5 to be uniformly heated. Furthermore, since the sub-cell 21 of the first sub-electrode 31 can transfer heat to the sub-cell 21 of the second sub-electrode 32, the heat generated by the cell 2 is increased, thereby achieving self-heating of the cell 2.

[0052] In one embodiment, when the positive electrode 4 is the electrode 3 described in the above embodiment, the negative electrode 5 is composed of a mixture of lithium and sodium materials, and the sodium material accounts for 1-30% of the composition.

[0053] In this embodiment, lithium material and sodium material are mixed to form negative electrode 5, and when the proportion of sodium material is 1-30%, negative electrode 5 can be directly regarded as lithium-ion negative electrode 5.

[0054] Specifically, the sodium component can be any one of 10%, 20%, or 30%.

[0055] In one embodiment, when the positive electrode 4 is the electrode 3 described in the above embodiment, the electrode 3 material containing lithium ions is not mixed with the battery material containing sodium ions at the material level.

[0056] Reference Figure 6 This application also provides a battery pack 1, which includes a plurality of battery cells 2 as described in any of the above embodiments.

[0057] Reference Figure 7 This application also provides a method for preparing a battery pack, which can be specifically executed by a preparation device, and includes the following steps: Step 101: Prepare at least one of the positive and negative electrodes of the battery cell using a first electrode material and a second electrode material, wherein the resistivity of the first electrode material is greater than the resistivity of the second electrode material. In this embodiment, the positive electrode of the battery cell can be prepared using a first electrode material and a second electrode material, while the negative electrode of the battery cell is a single electrode material; alternatively, the negative electrode of the battery cell can be prepared using both the first and second electrode materials, while the positive electrode of the battery cell is a single electrode material; or the negative electrode of the battery cell can be prepared using both the first and second electrode materials. It should be noted that the electrode material used to prepare the positive electrode (either the first or second electrode material) and the electrode material used to prepare the negative electrode (either the first or second electrode material) are different electrode materials.

[0058] It should be noted that the battery pack preparation method is used to prepare the above-mentioned battery pack, and at least one of the positive electrode and negative electrode prepared in step 101 is the electrode described in the above embodiment.

[0059] Step S102: A battery cell is prepared using a positive electrode and a negative electrode; Step S103: Prepare a battery pack using battery cells.

[0060] In this embodiment, multiple cells can be connected in parallel and / or in series to form a battery pack.

[0061] In this embodiment, the resistivity of the first electrode material is greater than that of the second electrode material. Therefore, under the same electrical signal pulse conditions, the heat generated by the first electrode material is greater than that generated by the second electrode material. At least one of the positive and negative electrodes of the battery cell is prepared by the first electrode material, and the battery cell is then composed of the positive and negative electrodes. This achieves self-heating of the battery cell and increases the heat generated by the entire battery cell. As a result, after the battery cell is made into a battery pack, the battery capacity decay rate of the battery pack in low-temperature environments can be reduced.

[0062] In this application, a three-electrode method is also required to determine the safety boundaries of the cell's current or voltage and pulse frequency. Specifically: In one embodiment, after the battery pack is prepared using the battery cell, the method further includes: The safe range of electrical characteristics of the electrical signal pulse connected to the battery pack is detected, the electrical characteristics including the amplitude and frequency of the electrical signal pulse; an electrical signal pulse whose electrical characteristics meet the safe range is selected, and the selected electrical signal pulse is connected to the battery pack. The first electrode material and the second electrode material in the battery pack generate heat after the electrical signal pulse is connected, and the heat generated by the first electrode material is greater than the heat generated by the second electrode material.

[0063] In this embodiment, the electrical signal pulse includes a voltage pulse or a current pulse. The electrical characteristics of the electrical signal pulse include the amplitude and frequency of the electrical signal pulse. If it is a voltage pulse, it specifically includes the amplitude and frequency of the voltage pulse. The amplitude of the voltage pulse represents the voltage value. If it is a current pulse, it specifically includes the amplitude and frequency of the current pulse. The amplitude of the current pulse represents the current value.

[0064] The safe range of values ​​for electrical characteristics includes the range of values ​​for the amplitude of electrical signal pulses and the range of values ​​for their frequency.

[0065] If the electrical characteristics of the electrical signal pulse connected to the battery pack are within the safe range of electrical characteristics, it means that it will not damage the battery, such as the absence of side reactions such as solid electrolyte interphase (SEI) decomposition and lithium plating.

[0066] Therefore, an electrical signal pulse whose electrical characteristics meet the safety range is selected and connected to the battery pack. As a result, the first electrode material and the second electrode material in each cell of the battery pack generate heat after the electrical signal pulse is connected. Since the resistivity of the first electrode material is greater than that of the second electrode material, the heat generated by the first electrode material is greater than that generated by the second electrode material.

[0067] In the above embodiments, the safe range of electrical characteristics for detecting electrical signal pulses connected to the battery pack can be achieved through the following possible implementations: In one implementation, when the state of charge of the battery pack belongs to any one of the target state of charge ranges, the electrical characteristics of the electrical signal pulse are adjusted, and the health status of the cells in the battery pack after the electrical characteristics are adjusted is obtained; based on the adjusted electrical characteristics and the health status of the cells in the battery pack after the electrical characteristics are adjusted, a safe range of values ​​for the electrical characteristics of the electrical signal pulse under the target state of charge range is determined.

[0068] Multiple State of Charge (SOC) ranges can be preset manually, such as 0 < SOC < 20% and 50% < SOC < 80%.

[0069] Adjusting the electrical characteristics of the electrical signal pulse includes: adjusting the pulse frequency of the electrical signal pulse or adjusting the amplitude of the current pulse; Obtaining the health status of the cells in the battery pack after the electrical characteristics are adjusted specifically refers to detecting whether side reactions such as SEI decomposition and lithium plating occur in the cells after the electrical characteristics are adjusted. If no side reactions occur, the health status is considered qualified; otherwise, the health status is considered unqualified.

[0070] The critical value of the electrical characteristic is determined when the health status changes from qualified to unqualified. Based on the initial electrical characteristic before adjustment and the critical electrical characteristic, the safe value range of the electrical characteristic is determined as the safe value range of the electrical characteristic under the target state of charge range. The safe value range of the electrical characteristic is different under different state of charge range conditions.

[0071] For example, by increasing the pulse frequency of the electrical signal pulse by 1 Hz each time to adjust it from 0 Hz to 20 Hz, if the cell's health status is qualified when the pulse frequency of the electrical signal pulse is 10 Hz, and the cell's health status becomes unqualified when it is 11 Hz, then the safe range of the electrical signal pulse frequency is 0 Hz to 10 Hz.

[0072] For example, the amplitude of the current pulse is increased by 0.1C each time to adjust from 0C to 10C. If the cell's health status is qualified when the amplitude of the current pulse is 0.5C, and the cell's health status becomes unqualified when the amplitude of the current pulse is 0.6C, then the safe range of the current pulse amplitude is 0Hz to 0.5C.

[0073] In one scenario: when the state of charge of the battery pack meets the condition 0 < SOC < 20%, the pulse frequency of the current pulse can be greater than 10Hz, and the current amplitude can be less than 0.2C. When the state of charge of the battery pack meets the condition of 50% < SOC < 80%, the pulse frequency of the current pulse can be in the range of < 5Hz, and the current amplitude can be in the range of > 0.5C.

[0074] In another implementation, for cell-level hybridization, the individual sub-cells within the cell can be differentiated, specifically: When the battery cell includes at least two sub-cells, the safe range of values ​​for detecting the electrical characteristics of the electrical signal pulses connected to the battery pack includes: determining the internal resistance and temperature of each sub-cell in the battery pack; adjusting the electrical characteristics of the electrical signal pulses of each sub-cell based on the internal resistance and temperature of each sub-cell, and obtaining the health status of the sub-cell after the adjustment of the electrical characteristics; determining the safe range of values ​​for the electrical characteristics of the electrical signal pulses connected to the sub-cell based on the adjusted electrical characteristics and the health status of the cells in the battery pack after the adjustment of the electrical characteristics, wherein the safe range of values ​​for the electrical characteristics of the electrical signal pulses of the battery pack includes the safe range of values ​​for the electrical characteristics of the electrical signal pulses of each sub-cell.

[0075] Based on the real-time internal resistance and temperature of each sub-cell, the amplitude of the voltage pulse is dynamically adjusted, and the health status of the sub-cell after electrical characteristic adjustment is obtained; Obtaining the health status of the sub-cell after electrical characteristic adjustment specifically refers to detecting whether side reactions such as SEI decomposition and lithium plating occur in the sub-cell after voltage pulse amplitude adjustment. If no side reactions occur, the health status is considered qualified; otherwise, the health status is considered unqualified.

[0076] The critical value of the voltage pulse amplitude when the health status changes from qualified to unqualified is determined. Based on the initial voltage pulse amplitude before adjustment and the critical voltage pulse amplitude, the safe range of voltage pulse amplitude for that sub-cell is determined. It should be noted that the safe range of voltage pulse amplitude differs for different sub-cells.

[0077] In this embodiment, the upper limit of the voltage pulse amplitude of the sub-cell made of ternary material can be increased from 4.2V to 4.25V, and the lower limit of the voltage pulse amplitude of the sub-cell made of lithium iron phosphate material can be reduced from 2.5V to 2.0V. The lower or upper limit of the amplitude is allowed to deviate within ±50mV.

[0078] In this embodiment, by exploring the range of pulse frequency, current pulse amplitude, and voltage pulse amplitude, the electrical signal pulses connected to the battery pack can be selected according to these safe ranges, thus avoiding health damage to the battery pack and preventing side reactions such as SEI film decomposition and lithium plating.

[0079] In one embodiment, the electrolyte compatibility and chemical compatibility of different electrode materials need to be considered. Electrolyte compatibility refers to the compatibility of different electrode materials with electrolytes of the same concentration, while chemical compatibility refers to the absence of chemical reactions between different electrode materials. In one embodiment, the voltage compatibility of different electrode materials also needs to be considered, that is, the safe range of voltage pulse amplitudes of a sub-cell made of one electrode material overlaps with that of a sub-cell made of another electrode material.

[0080] In one embodiment, the preparation of the negative electrode of the battery cell using a first electrode material and a second electrode material includes: Based on the target characteristics of multiple electrode materials, the material characteristics of each electrode material are determined; wherein, the target characteristics include at least one of particle size, specific surface area, tapped density, and compacted density, and the material characteristics include at least one of rate capability, energy, and resistivity; based on the material characteristics of each electrode material, the first electrode material and the second electrode material are selected from the multiple electrode materials; the negative electrode is prepared using the first electrode material and the second electrode material.

[0081] The target characteristics of the electrode material, as described above, determine the rate capability, energy, and resistivity of the electrode material. When preparing the negative electrode for a battery cell, based on the material characteristics of each electrode material, high-rate graphite and high-energy graphite are selected from multiple electrode materials to prepare the negative electrode; alternatively, a negative electrode is prepared by mixing high-energy graphite with hard carbon. Rate is used to measure the discharge rate after the electrode materials are made into a battery cell.

[0082] In this embodiment, high-ratio graphite refers to graphite with a ratio higher than a preset ratio threshold, which can be preset manually. High-energy graphite refers to graphite with an energy higher than a preset energy threshold, which can also be preset manually.

[0083] In this embodiment, based on the resistivity of each electrode material, the first electrode material and the second electrode material with different resistivity are selected from a plurality of electrode materials.

[0084] In this embodiment, when selecting the first electrode material and the second electrode material to prepare the negative electrode, it is also necessary to adjust the component ratio of the first electrode material and the second electrode material based on the capacity matching requirements of the positive electrode and / or the cell rate requirement. Specifically: If the capacity of the positive electrode is X Ah, the capacity of the negative electrode is: X * 1.05 - 1.1.

[0085] As can be seen, this application can prepare negative electrodes based on high-rate graphite and / or high-energy graphite, thereby improving the battery capacity after the electrodes are made into batteries. In one embodiment, this application may also conduct differentiated control of each sub-cell based on the safe value range of the electrical characteristics of the electrical signal pulses corresponding to each sub-cell to carry out heating tests of the whole package, evaluate the temperature rise rate of each sub-cell, and disassemble and analyze the sub-cells at different cycle stages to confirm that there are no safety risks and the impact of pulse heating on cycle life.

[0086] Reference Figure 8 The diagram below illustrates material-level mixing. The possible electrode configurations for this application are as follows: Example 1: (1) The positive electrode is prepared by mixing lithium iron phosphate material and 8-series ternary material in a ratio of 7:3, and then the positive electrode is used to prepare the battery cell. Subsequently, a safety boundary assessment test is carried out. Ternary materials produce cells with low internal resistance, and compared to cells made of lithium iron phosphate, they can output a higher voltage during discharge (corresponding to the high voltage platform in the figure) and have a relatively shorter lifespan. Conversely, cells made of lithium iron phosphate have high internal resistance, can output a lower voltage during discharge (corresponding to the low voltage platform in the figure), and have a relatively long lifespan.

[0087] (2) The tested and analyzed cells are assembled and grouped in the battery box to obtain a battery pack; (3) The battery pack was then placed at -20°C and pulse heating was carried out before the battery pack temperature rise rate test and capacity test were performed.

[0088] When the battery pack is at a low SOC, for example, when the battery pack's state of charge meets the condition 0 < SOC < 20%, an electrical signal pulse is applied, and the lithium iron phosphate material is used as the heating component.

[0089] Comparative Example 1 (Existing Solution) (1) The battery cell is made of lithium iron phosphate material; (2) The cells are assembled into groups in the battery box to obtain a battery pack; (3) The battery pack was then placed at -20°C to conduct battery capacity, fast charging and cycle life tests.

[0090] Example 2 (1) The ternary material and the 6-series lithium manganese iron phosphate material were mixed in a ratio of 3:7 to prepare the positive electrode, and then the positive electrode was used to prepare the battery cell. Subsequently, the safety boundary was investigated and tested. (2) The tested and analyzed cells are assembled and grouped in the battery box to obtain a battery pack; (3) The battery pack was then placed at -20°C and pulse heating was carried out before the battery pack temperature rise rate test and capacity test were performed.

[0091] Comparative Example 2 (Existing Solution) (1) The battery cell is made of lithium iron phosphate material; (2) The cells are assembled into groups in the battery box to obtain a battery pack; (3) The battery pack was then placed at -30°C to conduct battery capacity, fast charging and cycle life tests.

[0092] During the heating process, taking lithium iron phosphate and ternary materials as examples, when the ambient temperature is -20℃, the charge transfer impedance of lithium iron phosphate material is about 1.8 times that of ternary material. If the same pulse current is used, the heat generated by ternary material after being made into a cell will be much greater than that of lithium iron phosphate material after being made into a cell. If material components or cells with high internal resistance are used as the heat source, rapid heating of the battery pack can be achieved, which can significantly improve the user experience of the battery pack in low-temperature environments.

[0093] Meanwhile, in the traditional pulse self-heating technology, a battery cell with a mixture of two materials is prepared by using both the first electrode material and the second electrode material, instead of the traditional battery cell containing only a single material. This retains the second electrode material with low resistivity, which can also reduce the impact on the battery cell's lifespan.

[0094] It is evident that selecting high internal resistance materials or electrode materials with excellent low-temperature performance as the primary or sole heat source, and using low internal resistance materials or electrode materials with relatively poor low-temperature performance as auxiliary temperature control materials or not as heat sources, helps to maximize the heating rate of the battery pack and minimize energy consumption.

[0095] Meanwhile, the proposed solution is low-cost and highly feasible.

[0096] Reference Figure 9 The diagram shows a cell-level hybrid structure. Cell A has low internal resistance and does not act as a heat source, thus not affecting battery life. Cell B has high internal resistance and acts as a single heat source. Cell B is selected because it has a longer lifespan. Cells A and B are the aforementioned sub-cells, which are then mixed to form the cells in this application.

[0097] Reference Figure 10 The present invention also provides an electronic device, which may include a processor 1002 and a memory 1001, wherein the processor 1002 and the memory 1001 can communicate with each other through a bus or other means.

[0098] The processor 1002 may be a central processing unit (CPU), or an application specific integrated circuit (ASIC), or one or more integrated circuits that can be configured to implement the embodiments of this application, or it may be other general-purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or other chips, or combinations of the above types of chips.

[0099] Memory 1001 may include mass storage for data or instructions. For example, and not limitingly, memory may include a hard disk drive (HDD), floppy disk drive, flash memory, optical disk, magneto-optical disk, magnetic tape, or Universal Serial Bus (USB) drive, or a combination of two or more of these. Where suitable, memory may include removable or non-removable (or fixed) media. Where suitable, memory may be internal or external to an electronic device. In a particular embodiment, memory may be non-volatile solid-state memory.

[0100] In one instance, memory 1002 may be read-only memory (ROM). In one instance, the ROM may be a mask-programmed ROM, a programmable ROM (PROM), an erasable PROM (EPROM), an electrically erasable PROM (EEPROM), an electrically rewritable ROM (EAROM), or flash memory, or a combination of two or more of these.

[0101] The processor 1001 reads and executes computer program instructions stored in the memory to implement any of the battery pack preparation methods in the above embodiments.

[0102] In one example, the electronic device may further include a communication interface and a bus. The processor, memory, and communication interface are connected via the bus to communicate with each other. The communication interface is primarily used to enable communication between the various modules, devices, units, and / or equipment in the embodiments of this application. Where appropriate, the bus may include one or more buses.

[0103] Furthermore, in conjunction with the battery pack fabrication methods described in the above embodiments, this invention can be implemented using a computer-readable storage medium. This computer-readable storage medium stores computer program instructions; when these computer program instructions are executed by a processor, they implement any of the battery pack fabrication methods described in the above embodiments.

[0104] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the methods described above. The storage medium can be read-only memory (ROM), random access memory (RAM), flash memory, hard disk drive (HDD), or solid-state drive (SSD), etc.; the storage medium can also include combinations of the above types of memory.

[0105] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0106] Similarly, it should be understood that, in order to simplify this disclosure and aid in understanding one or more of the various aspects of the invention, in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof. However, this method of disclosure should not be construed as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as reflected in the following claims, inventive aspects lie in fewer than all features of a single foregoing disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into this detailed description, wherein each claim itself is a separate embodiment of the invention.

[0107] It should be noted that the above embodiments are illustrative of the invention and not restrictive, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses should not be construed as limiting the claims. The word "comprising" does not exclude the presence of components or steps not listed in the claims. The word "a" or "an" preceding a component does not exclude the presence of a plurality of such components. The invention can be implemented by means of hardware comprising several different components and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third, etc., does not indicate any order. These words can be interpreted as names.

Claims

1. An electrode, characterized in that, The electrode is composed of a first electrode material and a second electrode material, wherein the resistivity of the first electrode material is greater than that of the second electrode material.

2. The electrode according to claim 1, characterized in that, The electrode is composed of a mixture of the first electrode material and the second electrode material, wherein the first electrode material accounts for 16%-84% of the mixture and the second electrode material accounts for 16%-84% of the mixture.

3. The electrode according to claim 1, characterized in that, The electrode includes a first sub-electrode and a second sub-electrode. The first sub-electrode is made of the same material as the first electrode, and the second sub-electrode is made of the same material as the second electrode. The second sub-electrode is provided on at least one side of the first sub-electrode.

4. The electrode according to any one of claims 1-3, characterized in that, The first electrode material is first graphite, and the second electrode material is second graphite. The first graphite and the second graphite have at least one different target feature, including: particle size, specific surface area, and tapped or compacted density. Alternatively, the first electrode material may be graphite, and the second electrode material may be hard carbon.

5. A battery cell, characterized in that, The battery cell includes a positive electrode and a negative electrode, at least one of the positive electrode and the negative electrode being an electrode as described in any one of claims 1-4.

6. The battery cell according to claim 5, characterized in that, When the electrode includes a first sub-electrode and a second sub-electrode, the cell includes at least two sub-cells, at least one of the sub-cells includes the first sub-electrode, at least one of the sub-cells includes the second sub-electrode, the sub-cell including the first sub-electrode and the sub-cell including the second sub-electrode are different sub-cells, and the first sub-electrode and the second sub-electrode included in the sub-cell constitute the positive electrode and / or negative electrode of the cell.

7. The battery cell according to claim 6, characterized in that, The sub-cells including the first sub-electrode and the sub-cells including the second sub-electrode are alternately distributed; or, The first sub-electrode is located at the apex of the positive electrode and / or the negative electrode.

8. The battery cell according to claim 5, characterized in that, When the positive electrode is the electrode as described in any one of claims 1-4, the negative electrode comprises a mixture of lithium and sodium materials, and the sodium material accounts for 1-30% of the composition.

9. A battery pack, characterized in that, The battery pack includes a plurality of cells as described in any one of claims 5-8.

10. A method for preparing a battery pack, characterized in that, include: At least one of the positive and negative electrodes of the battery cell is prepared using a first electrode material and a second electrode material, wherein the resistivity of the first electrode material is greater than the resistivity of the second electrode material. A battery cell is prepared using the positive electrode and the negative electrode; A battery pack is prepared using the aforementioned battery cell.

11. The method according to claim 10, characterized in that, The method further includes: The safe range of values ​​for the electrical characteristics of the electrical signal pulses connected to the battery pack is detected, wherein the electrical characteristics include the amplitude and frequency of the electrical signal pulses; An electrical signal pulse whose electrical characteristics satisfy the safety value range is selected, and the selected electrical signal pulse is connected to the battery pack. The first electrode material and the second electrode material in the battery pack generate heat after the electrical signal pulse is connected, and the heat generated by the first electrode material is greater than the heat generated by the second electrode material.

12. The method according to claim 11, characterized in that, The safe range of values ​​for the electrical characteristics of the electrical signal pulses detected by the battery pack includes: When the state of charge of the battery pack falls within any of the target state of charge ranges, the electrical characteristics of the electrical signal pulse are adjusted, and the health status of the cells in the battery pack after the electrical characteristics are adjusted is obtained. Based on the adjusted electrical characteristics and the health status of the cells in the battery pack after the electrical characteristics were adjusted, the safe range of electrical characteristics of the electrical signal pulse under the target state of charge range is determined.

13. The method according to claim 11, characterized in that, When the battery cell comprises at least two sub-cells, the safe range of values ​​for the electrical characteristics of the detected electrical signal pulses connected to the battery pack includes: Determine the internal resistance and temperature of each sub-cell in the battery pack; Based on the internal resistance and temperature of each of the sub-cells, the electrical characteristics of the electrical signal pulses of the sub-cells are adjusted, and the health status of the sub-cells after the electrical characteristics are adjusted is obtained. Based on the adjusted electrical characteristics and the health status of the cells in the battery pack after the adjustment of the electrical characteristics, the safe range of electrical characteristics of the electrical signal pulses connected to the sub-cells is determined. The safe range of electrical characteristics of the electrical signal pulses of the battery pack includes the safe range of electrical characteristics of the electrical signal pulses of each sub-cell.

14. The method according to any one of claims 10 to 13, characterized in that, The method of preparing the negative electrode of the battery cell using a first electrode material and a second electrode material includes: Based on the target characteristics of multiple electrode materials, the material characteristics of each electrode material are determined; wherein, the target characteristics include at least one of particle size, specific surface area, tapped density and compacted density, and the material characteristics include at least one of rate capability, energy and resistivity; Based on the material characteristics of each electrode material, the first electrode material and the second electrode material are selected from the plurality of electrode materials; The negative electrode is prepared using the first electrode material and the second electrode material.

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