Battery pole piece integrated with self-heating function

Abstract

The application provides a battery pole piece integrated with a self-heating function, which comprises an insulating composite substrate formed by compounding at least two polymer film layers; an electrothermal conversion layer is arranged between the polymer films in the insulating composite substrate; at least one pair of conductive electrodes in electrical connection with the electrothermal conversion layer; a current collector and an electrode active material layer arranged on a first surface of the insulating composite substrate; a current collector and an electrode active material layer arranged on a second surface of the insulating composite substrate; and the electrothermal conversion layer, the conductive electrodes, the current collectors and the electrode active material layers are completely electrically isolated. The heating circuit and the battery pole piece are integrally compounded, the heat source is directly arranged in the pole piece, the negative influence on the energy density of the battery is minimized under the premise of ensuring the heating effect, the independent heating circuit and the precise insulating isolation structure are matched, and the efficient, uniform and safe heating of the pole piece is realized without affecting the original charging and discharging performance of the battery cell.

Description

Technical Field

[0001] This invention relates to the field of power battery thermal management technology, and in particular to a battery electrode with integrated self-heating function. Background Technology

[0002] The large-scale promotion and application of new energy vehicles and energy storage power stations have placed higher demands on the environmental adaptability of power batteries. Relevant test data shows that lithium-ion batteries experience significant performance degradation in low-temperature environments of -20℃ and below: the impedance of the SEI film on the negative electrode surface increases, the ionic conductivity of the electrolyte decreases, and the kinetic rate of lithium intercalation reaction in the active material slows down, resulting in a 40% to 60% decrease in battery discharge capacity compared to the normal temperature environment, and a 2 to 4-fold increase in DC internal resistance; in extremely cold environments of -40℃, the battery may not even be able to output electrical energy normally, directly limiting the driving range of new energy vehicles and the response efficiency of energy storage power stations.

[0003] The current mainstream low-temperature thermal management solution in the industry involves installing heating devices inside the battery pack or outside the cells to achieve low-temperature heating through indirect heat transfer to the cell casing. However, this traditional solution has four inherent technical drawbacks: First, low heat conduction efficiency, as heat must first pass through the air gap between the heating device and the cell casing before being conducted to the inside of the cell, resulting in a heat loss rate of 30% to 50% during this process; second, poor heating uniformity, with the temperature rising rapidly in areas near the heating device, while heat conduction is slow in the central area and areas far from the heating device, easily forming local temperature differences of 10°C to 15°C, which exacerbates the local decay of active materials inside the cell; third, the heating device occupies additional internal space in the battery pack, reducing the overall energy density of the battery pack; and fourth, high thermal resistance and slow heating rate, requiring 10 to 15 minutes to heat from -40°C to 0°C, which cannot meet the needs of rapid heating.

[0004] Recently, a few built-in heating technologies have emerged in the industry, such as setting a heating element separately inside the battery cell or integrating a heating layer on the outside of the electrode. However, these solutions still have significant technical shortcomings: First, the heating layer in these solutions can only heat the electrode on one side, failing to cover the entire active area of ​​the electrode, resulting in uneven heating. Second, the insulation isolation between the heating circuit and the electrode charging and discharging circuit in these solutions is not perfect, making it prone to safety risks such as insulation layer damage and short circuits during long-term charge-discharge cycles of the battery cell or during long-term thermal cycles of the heating circuit. In addition, the integration of the heating device and the electrode in these solutions is low, requiring additional fixing structures, which not only further occupies valuable space inside the battery cell but also increases the complexity of the battery cell manufacturing process.

[0005] More importantly, most existing built-in heating electrode solutions are only compatible with traditional liquid-state power battery systems, failing to fully consider the special structural characteristics of semi-solid and all-solid batteries, as well as the different requirements of various battery systems for electrode heating thermal conductivity efficiency, interface compatibility, and insulation. For example, the insulation structure of the heating layer in some existing solutions cannot adapt to the interface characteristics of the polymer-inorganic composite electrolyte system of semi-solid batteries, which can easily lead to poor interface contact during long-term use; in addition, the heating layer arrangement of some solutions cannot match the solid-solid heat transfer characteristics of all-solid batteries, making it difficult to form a uniform and efficient heat flow distribution inside the cell.

[0006] Therefore, developing an integrated self-heating battery electrode that is compact, has high heating efficiency, good heating uniformity, high safety and reliability, and strong process adaptability, so as to meet the thermal management requirements of liquid, semi-solid, and all-solid power battery systems, has become a technical necessity in the field of power battery thermal management. Summary of the Invention

[0007] This invention provides a battery electrode with integrated self-heating function to solve one or more technical problems encountered in the prior art.

[0008] In a first aspect, embodiments of the present invention provide a battery electrode with integrated self-heating function, comprising: An insulating composite substrate formed by combining at least two polymer film layers; An electrothermal conversion layer is disposed between the polymer films inside the insulating composite substrate, and the electrothermal conversion layer is used to perform electrothermal conversion when energized. At least one pair of conductive electrodes forms an electrical connection with the electrothermal conversion layer; Current collector and electrode active material layer disposed on the first surface of the insulating composite substrate; Current collector and electrode active material layer disposed on the second surface of the insulating composite substrate; The electrothermal conversion layer, the conductive electrode, the current collector, and the electrode active material layer are completely electrically isolated.

[0009] In a preferred embodiment, the insulating composite substrate comprises any one of two, three, or four polymer film layers; the polymer film constituting the insulating composite substrate is at least one of polyester polymer film, polyimide polymer film, or special high-temperature resistant engineering polymer film; the insulating composite substrate as a whole is an insulating and waterproof structure, and the battery electrode is as a whole a rectangular sheet shape, suitable for battery winding or stacking processes; the thickness of a single layer of the polymer film is 10~300μm.

[0010] In a preferred embodiment, the electrothermal conversion layer is a conductive heating structure layer formed by physical vapor deposition of at least one metal oxide semiconductor material selected from fluorine-doped tin dioxide, antimony-doped tin dioxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, vanadium pentoxide, indium zinc oxide, molybdenum-doped indium oxide, and indium tin oxide, wherein the thickness of the electrothermal conversion layer is 15nm~50nm.

[0011] In a preferred embodiment, the electrothermal conversion layer is one or more of graphene, carbon nanotubes, metal alloys, or conductive polymers, which are conductive heating structural layers made by physical vapor deposition, printing, or coating processes.

[0012] In a preferred embodiment, the electrothermal conversion layer has a positive temperature coefficient (PTC) self-limiting temperature characteristic.

[0013] In a preferred embodiment, the conductive electrode is disposed along two parallel long sides of the insulating composite substrate and is completely encapsulated inside the insulating composite substrate.

[0014] In a preferred embodiment, the current collector and electrode active material layer are prepared by at least one of vacuum evaporation, wet process, dry process, and screen printing.

[0015] In a preferred embodiment, the current collector layer and the electrode active material layer disposed on the first surface of the insulating composite substrate are a positive current collector layer and a positive active material layer; the current collector layer and the electrode active material layer disposed on the second surface of the insulating composite substrate are a positive current collector layer and a positive active material layer. Alternatively, the current collector layer and the electrode active material layer on the first surface of the insulating composite substrate may be a negative electrode current collector layer and a negative electrode active material layer; the current collector layer and the electrode active material layer on the second surface of the insulating composite substrate may be a negative electrode current collector layer and a negative electrode active material layer. Alternatively, the current collector layer and the electrode active material layer on the first surface of the insulating composite substrate may be a positive current collector layer and a positive active material layer; the current collector layer and the electrode active material layer on the second surface of the insulating composite substrate may be a negative current collector layer and a negative active material layer.

[0016] In a preferred embodiment, the positive electrode active material layer is at least one of layered oxide positive electrode, spinel oxide positive electrode, olivine phosphate positive electrode, and lithium-rich manganese-based positive electrode.

[0017] In a preferred embodiment, the negative electrode active material layer is at least one of carbon-based negative electrode, silicon-based negative electrode, titanium-based negative electrode, and alloy-based negative electrode.

[0018] One of the above technical solutions has the following advantages or beneficial effects: (1) High heating efficiency: This invention integrates the electrothermal conversion layer directly inside the composite battery electrode. The entire electrothermal conversion layer is completely wrapped by the electrode layer. The heat generated during operation is directly transferred to the active material layer of the electrode through thermal conduction, and then further transferred to the inside of the battery cell. This eliminates the additional air layer thermal resistance and shell conduction thermal resistance in traditional external heating schemes, and greatly improves the thermal conduction efficiency. Actual test data shows that in an environment of -40℃, the battery cell using the composite electrode of this invention can achieve a heating rate of more than 5℃ / min, and the time required to heat to 0℃ is only 1 / 5 to 1 / 10 of that of the traditional external heating scheme; and the energy consumption during the heating process accounts for less than 5% of the battery's own energy.

[0019] (2) Good heating uniformity: The electrothermal conversion layer of the present invention adopts a full-surface heating structure, and its contour shape is perfectly matched with the contour shape of the electrode layer, which can uniformly heat the entire active area of ​​the electrode. At the same time, the electrothermal conversion layer is located in the middle of the electrode layer, and the heat can be conducted to the electrode layers on both sides simultaneously, effectively reducing the local temperature difference on the electrode surface. Even in areas with large differences in heat transfer characteristics, such as the arc area and the straight area of ​​the wound cell, the full-surface heating characteristic of the electrothermal conversion layer can compensate for the differences in heat transfer resistance in different areas. Actual test data show that the maximum local temperature difference on the electrode surface of the cell using the composite electrode of the present invention is ≤5℃ during the heating process, which is much lower than the 10℃~15℃ of the traditional external heating scheme, effectively avoiding local overheating or overcooling, and is conducive to improving the cycle life of the battery.

[0020] (3) High safety and reliability: This invention completely isolates the electrothermal conversion layer, conductive electrode, and electrode layer through a double-layer sealed structure of an insulating composite substrate, with the width of the sealed isolation structure not less than 1 mm, forming a reliable insulating barrier. At the same time, the heating-specific electrode tabs and the charge / discharge electrode tabs are spatially staggered, avoiding the risk of electrical short circuits between the electrode tabs. In addition, the use of insulating materials with good compatibility with the electrolyte can effectively avoid the risks of corrosion and insulation layer damage in the heating circuit during long-term use. The electrothermal conversion layer has a PTC positive temperature coefficient self-limiting temperature characteristic, which can automatically reduce the heating power when the temperature exceeds a preset threshold, further preventing the risk of thermal runaway. Experimental data show that after more than 1,000 thermal cycle tests, the composite electrode of this invention still meets the battery safety standards in terms of insulation isolation performance, and the risk of short circuit is almost zero.

[0021] (4) High integration and low energy density loss: The present invention designs the heating circuit and the electrode layer as an integrated composite structure. The electrothermal conversion layer and the conductive electrode are completely encapsulated inside the insulating composite substrate without occupying additional radial space inside the cell. At the same time, by optimizing the thickness parameters of each layer, the total thickness of the insulating composite substrate is controlled within 1 mm and the thickness of the electrothermal conversion layer is controlled within 50 nm. The negative impact on the energy density of the cell is controlled within 5%, which is far lower than the 10% to 15% of the traditional built-in heating scheme. Under the premise of ensuring the heating effect, the battery energy density and low temperature heating performance are taken into account to the maximum extent.

[0022] (5) Strong adaptability to multiple battery systems: Through optimized interlayer structure design and adaptability design of electrolyte layer and separator, this invention can perfectly adapt to liquid, semi-solid and all-solid power battery systems. For liquid batteries, it can be used with conventional porous separator structure; for semi-solid batteries, a polymer-inorganic composite solid electrolyte layer can be added to the outside of the electrode to improve interface compatibility; for all-solid batteries, it can be used with oxide or sulfide solid electrolyte layer to meet solid-solid heat transfer requirements; in addition, the material design of the insulating composite substrate takes into account the different requirements of different battery systems for insulation, thermal conductivity and corrosion resistance.

[0023] (6) Strong process adaptability: The composite electrode of the present invention can be combined with the separator and the paired electrode to be prefabricated into a fixed structure by the thermal composite process, and then directly adapted to the winding or stacking process to manufacture the cell. There is no need to make large-scale modifications to the existing power battery mass production process line. Only the corresponding deposition or coating process needs to be added in the electrode manufacturing process to complete the mass production upgrade. At the same time, by adjusting the material, power density and contour size of the electrothermal conversion layer, it can be flexibly adapted to power batteries with different chemical systems and different shapes and specifications, and has strong process compatibility and mass production feasibility.

[0024] (7) Significantly Improved Low-Temperature Performance: The built-in electrothermal conversion layer of this invention can raise the temperature of the electrode itself to the optimal operating range in a very short time, directly accelerating the electrochemical reaction rate between the active material of the electrode and the electrolyte, and significantly improving the discharge performance of the battery in low-temperature environments. Actual test data show that in an environment of -40℃, the discharge capacity retention rate of the battery cell using the composite electrode of this invention is more than 30% higher than that of the battery cell using the traditional external heating solution; at 50% state of charge (SOC), the discharge power density is 5 to 6 times that of ordinary battery cells; in the extremely cold environment of -40℃, the battery cell temperature can still be raised to 0℃ within 45s, meeting the normal charging and discharging requirements.

[0025] (8) The heating and charging / discharging circuits do not interfere with each other: The heating circuit of the present invention adopts an independent conductive electrode and a dedicated heating tab design, which is completely isolated from the charging / discharging circuit of the electrode layer in terms of structure. The two are only connected through the internal heat conduction path of the electrode layer. At the same time, in conjunction with the interlock control function of the vehicle BMS, the working status of the charging / discharging circuit can be monitored in real time during the heating process, effectively avoiding electromagnetic interference and short circuit risk between the heating circuit and the charging / discharging circuit, and ensuring the safety of the battery heating and charging / discharging in low temperature environments.

[0026] The above overview is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of the invention will become readily apparent from the accompanying drawings and the following detailed description. Attached Figure Description

[0027] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the various drawings denote the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings depict only some embodiments disclosed in the invention and should not be construed as limiting the scope of the invention.

[0028] Figure 1 This is a cross-sectional schematic diagram of the battery electrode with integrated self-heating function in this embodiment. Detailed Implementation

[0029] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0030] This embodiment provides a battery electrode with integrated self-heating function; see [link / reference]. Figure 1 As shown, the battery electrode includes an insulating composite substrate 100, an electrothermal conversion layer 200, at least one pair of conductive electrodes 300, a current collector 400, and an electrode active material layer 500; the insulating composite substrate 100 is formed by laminating at least two polymer film layers; the electrothermal conversion layer 200 is disposed inside the insulating composite substrate 100; the electrothermal conversion layer 200 is used for electrothermal conversion when energized; the conductive electrodes 300 are electrically connected to the electrothermal conversion layer 200; The current collector 400 and the electrode active material layer 500 are disposed on the first and second surfaces of the insulating composite substrate 100.

[0031] The electrothermal conversion layer 200, the conductive electrode 300, the current collector 400, and the electrode active material layer 500 are completely electrically isolated.

[0032] In this embodiment, the electrothermal conversion layer is directly integrated inside the composite battery electrode. The entire electrothermal conversion layer is completely encapsulated by the electrode layer. The heat generated during operation is directly transferred to the active material layer of the electrode through thermal conduction, and then further transferred to the inside of the battery cell. This eliminates the additional thermal resistance of the air layer and the thermal resistance of the casing in traditional external heating schemes, significantly improving thermal conduction efficiency. Actual test data shows that in an environment of -40℃, the battery cell using the composite electrode of this invention can achieve a heating rate of over 5℃ / min, and the time required to heat to 0℃ is only 1 / 5 to 1 / 10 of that of traditional external heating schemes; moreover, the energy consumption during the heating process accounts for less than 5% of the battery's own energy.

[0033] In one specific embodiment, see Figure 1 As shown, the insulating composite substrate 100 comprises any one of two, three, or four polymer films in a composite structure; the polymer film constituting the insulating composite substrate 100 is at least one of polyester polymer film, polyimide polymer film, and special high-temperature resistant engineering polymer film; the insulating composite substrate 100 as a whole is an insulating and waterproof structure, and the battery electrode is a rectangular sheet shape, suitable for battery winding or stacking processes; the thickness of a single layer of the polymer film is 10~300μm.

[0034] In one specific embodiment, the electrothermal conversion layer 200 is a conductive heating structure layer formed by physical vapor deposition of at least one metal oxide semiconductor material selected from fluorine-doped tin dioxide, antimony-doped tin dioxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, vanadium pentoxide, indium zinc oxide, molybdenum-doped indium oxide, and indium tin oxide, wherein the thickness of the electrothermal conversion layer 200 is 15nm~50nm.

[0035] In one specific embodiment, the electrothermal conversion layer 200 is a conductive heating structure layer made of one or more of graphene, carbon nanotubes, metal alloys or conductive polymers through physical vapor deposition, printing or coating processes.

[0036] In one specific embodiment, the electrothermal conversion layer 200 has a PTC positive temperature coefficient self-limiting temperature characteristic.

[0037] In one specific embodiment, the conductive electrode 300 is disposed along two parallel long sides of the insulating composite substrate and is completely insulated and encapsulated inside the insulating composite substrate 100.

[0038] In one specific embodiment, the current collector 400 and the electrode active material layer 500 are prepared by at least one of vacuum evaporation, wet process, dry process, and screen printing.

[0039] In one specific embodiment, see Figure 1As shown, the current collector layer 400 and the electrode active material layer 500 disposed on the first surface of the insulating composite substrate 100 are positive electrode current collector layer and positive electrode active material layer; the current collector layer 400 and the electrode active material layer 500 disposed on the second surface of the insulating composite substrate 100 are positive electrode current collector layer and positive electrode active material layer. Alternatively, the current collector layer 400 and the electrode active material layer 500 on the first surface of the insulating composite substrate 100 may be a negative current collector layer and a negative active material layer; the current collector layer 400 and the electrode active material layer 500 on the second surface of the insulating composite substrate 100 may also be a negative current collector layer and a negative active material layer. Alternatively, the current collector layer 400 and the electrode active material layer 500 on the first surface of the insulating composite substrate 100 may be a positive current collector layer and a positive active material layer; the current collector layer 400 and the electrode active material layer 500 on the second surface of the insulating composite substrate 100 may be a negative current collector layer and a negative active material layer.

[0040] Furthermore, the positive electrode active material layer is at least one of layered oxide positive electrode, spinel oxide positive electrode, olivine phosphate positive electrode, and lithium-rich manganese-based positive electrode.

[0041] Furthermore, the negative electrode active material layer is at least one of carbon-based negative electrode, silicon-based negative electrode, titanium-based negative electrode, and alloy-based negative electrode. Example 1

[0042] This embodiment provides a battery electrode with integrated self-heating function. The composite battery electrode consists of an electrode layer, an insulating composite substrate 100, and an electrode layer from bottom to top. The insulating composite substrate 100 is formed by hot-pressing at least two layers of polyimide (PI) polymer film base layer. The thickness of a single polymer film base layer is 150 μm. An electrothermal conversion layer 200 and a conductive electrode 300 are disposed in the internal region between the two polymer film base layers. A sealing insulating layer is disposed on both the upper and lower surfaces of the insulating composite substrate 100. The edge region of the sealing insulating layer extends 1.5 mm beyond the edge region of the electrothermal conversion layer 200, forming a complete sealing insulating structure.

[0043] Specifically, the electrothermal conversion layer 200 is made of indium tin oxide (ITO) semiconductor material, which is uniformly deposited on the upper surface of the lower polymer film substrate by physical vapor deposition (PVD) process. The thickness is 30nm, the power density is 0.8W / cm², and the resistance value is stable in the range of 8mΩ to 10mΩ. The electrothermal conversion layer 200 is a rectangular planar structure that continuously covers the entire surface. Its outline shape is perfectly matched with the outline size of the electrode layer, which can uniformly heat the entire active area of ​​the electrode. Between the two ends of the electrothermal conversion layer 200 and the inner edge of the conductive electrode 300, a conductive transition structure with a width of 0.8mm is provided. The material is conductive silver paste, which is used to improve the stability of electrical connection.

[0044] Specifically, the conductive electrode 300 consists of a positive conductive electrode and a negative conductive electrode, which are symmetrically arranged on the left and right edges of the electrothermal conversion layer 200 and extend continuously along the length of the electrode sheet. The conductive electrode 300 is made of copper plated with nickel, and its thickness is exactly the same as that of the electrothermal conversion layer 200. The leads of the positive and negative conductive electrodes are respectively welded with independent heating-specific tabs. The material of the heating-specific tabs is the same as that of the conductive electrode 300, and their lead-out direction is completely opposite to that of the charge and discharge electrode tabs, and the straight-line distance between them is 6mm. An insulating isolation component is provided between the heating-specific tabs and the charge and discharge electrode tabs to completely block the electrical connection path between them.

[0045] Specifically, the electrode layer includes a positive electrode layer and a negative electrode layer, which are respectively bonded to the lower and upper surfaces of the insulating composite substrate. The positive electrode layer consists of a positive current collector and a positive active material layer. The positive current collector is made of aluminum foil, and the positive active material layer is made of lithium iron phosphate. The negative electrode layer consists of a negative current collector and a negative active material layer. The negative current collector is made of copper foil, and the negative active material layer is made of artificial graphite. The electrode layer is prepared by a dry process, and its inner surface is flatly bonded to the sealing insulation layer of the insulating composite substrate 100 by a hot pressing process. The surface roughness of the bonding surface is ≤0.8μm, which ensures good heat conduction efficiency.

[0046] Specifically, in this embodiment, the composite electrode is adapted to a liquid power battery system. During the subsequent cell assembly process, a conventional porous separator is provided on the outer side of the electrode layer, and the wound electrode core of the cell is formed through a winding process. The end of the composite electrode has a reserved mounting point for a built-in temperature sensor. The detection end of the temperature sensor is directly attached to the surface of the positive electrode layer, and the output end is electrically connected to the temperature acquisition module of the BMS. The power drive module of the BMS is electrically connected to the heating-specific tab, and the power management module is electrically connected to the charge and discharge tabs. The BMS has a built-in liquid battery-specific adaptation algorithm that can automatically adjust the heating power, heating start threshold, and heating stop threshold according to the ambient temperature. Example 2

[0047] This embodiment provides a battery electrode with integrated self-heating function. The only difference from Embodiment 1 is the material and structural design of the electrothermal conversion layer 200; all other structural parameters are identical. In this embodiment, the electrothermal conversion layer 200 is a graphene heating material, uniformly formed on the upper surface of the lower polymer film substrate using a screen printing process. It has a thickness of 20 nm and a power density of 0.6 W / cm². A 1 mm wide conductive transition structure, made of copper-plated nickel, is provided between the two ends of the electrothermal conversion layer 200 and the inner edge of the conductive electrode. The conductive electrode 300 is made of aluminum, and the straight-line distance between the heating electrode tab and the charge / discharge electrode tab is 7 mm.

[0048] The composite electrode in this embodiment is adapted to a semi-solid power battery system. In the subsequent cell assembly process, a polymer-inorganic composite solid electrolyte layer is provided on the outside of the electrode layer. The thickness of the composite solid electrolyte layer is 100μm, wherein the polymer matrix is ​​modified polyethylene oxide and the inorganic electrolyte filler is lanthanum lithium zirconium oxide (LLZO) powder. The composite electrode forms the stacked electrode core of the cell through a stacking process, which is adapted to the soft-pack packaging structure of the semi-solid battery. Example 3

[0049] This embodiment provides a battery electrode with integrated self-heating function. The only difference from Embodiment 1 is the material and structural design of the electrothermal conversion layer 200; all other structural parameters are completely identical. In this embodiment, the electrothermal conversion layer 200 is a carbon nanotube heating material, uniformly formed on the upper surface of the lower polymer film substrate by a scraping process, with a thickness of 40 nm and a power density of 0.7 W / cm². A conductive transition structure with a width of 0.5 mm is provided between the two ends of the electrothermal conversion layer and the inner edge of the conductive electrode; the material is conductive silver paste. The conductive electrode 300 is made of copper, and the straight-line distance between the heating electrode tab and the charge / discharge electrode tab is 5 mm.

[0050] The composite electrode in this embodiment is adapted to the all-solid-state power battery system. In the subsequent cell assembly process, an oxide solid electrolyte layer is provided on the outside of the electrode layer. The thickness of the solid electrolyte layer is 80μm and the material is lanthanum lithium zirconium oxide (LLZO). After the composite electrode is pre-formed by the thermal composite process, it is then formed into the wound electrode core of the cell by the winding process, which is adapted to the metal shell packaging structure of the all-solid-state battery. Example 4

[0051] This embodiment provides a battery electrode with integrated self-heating function. The only difference from Embodiment 1 is the combination of electrode layers; all other structural parameters are identical. In this embodiment, the electrode layers on both the upper and lower sides of the insulating composite substrate 100 are positive electrode layers, and the positive electrode active material layer is made of ternary lithium. The electrothermal conversion layer 200 is a nickel-chromium alloy heating material, uniformly formed on the upper surface of the lower polymer film layer using PVD technology, with a thickness of 50 nm and a power density of 0.9 W / cm². The electrothermal conversion layer 200 possesses a PTC positive temperature coefficient self-limiting temperature characteristic. When the electrode surface temperature rises to 45°C, its resistance increases significantly with increasing temperature, automatically reducing the heating power and stabilizing the electrode temperature below 50°C, further improving safety performance.

[0052] The composite electrode in this embodiment is adapted to high-rate liquid power battery system. In the subsequent cell assembly process, a high-porosity porous membrane is provided on the outside of the electrode layer. The stacked electrode core of the cell is formed by the stacking process, which is adapted to high-rate discharge scenarios. Example 5

[0053] This embodiment provides a heating control system for a battery cell. The control system includes the composite battery electrode sheet described in Embodiment 1, a battery management system (BMS), and a temperature sensor. The BMS integrates a power drive module, a temperature acquisition module, a power management module, and a multi-battery system adaptation algorithm. The temperature sensor is positioned at a pre-reserved mounting point at the end of the composite electrode sheet, with its detection end directly attached to the surface of the positive electrode layer, and its output end electrically connected to the temperature acquisition module. The power drive module is electrically connected to a dedicated heating tab via a wire, and the power management module is electrically connected to the charge / discharge tab via a wire.

[0054] Specifically, the control system has three operating modes that can be automatically switched according to different actual scenarios: (1) Low temperature static preheating mode: When the vehicle is in a static state and the ambient temperature is lower than the preset low temperature start threshold of -20℃ in the BMS, the temperature acquisition module will transmit the collected real-time temperature data of the electrode to the BMS, and the BMS will control the power drive module to deliver rated power to the electrothermal conversion layer to quickly raise the temperature of the electrode itself to the preset working range of 10℃. (2) Driving constant temperature maintenance mode: When the vehicle is in driving state and the battery cell is in charging and discharging state, the BMS dynamically adjusts the output power of the power drive module according to the real-time temperature data fed back by the temperature acquisition module, so as to accurately maintain the electrode temperature within the optimal working range of 25℃~35℃. (3) Preheating mode before charging: When the vehicle is connected to the charging equipment, the BMS will first start the power drive module to preheat the electrode when it detects that the internal temperature of the battery cell is lower than the low temperature charging threshold of 0℃. After the temperature of the electrode rises to above 10℃, the charging process will be started automatically to avoid irreversible damage to the battery cell caused by low temperature charging. Comparative Example

[0055] This comparative example uses a traditional external heating scheme, which involves adding an electric heating film with the same rated power to the outer surface of the cell casing, with a thermally conductive silicone pad filling the space between the electric heating film and the cell casing. The structural parameters, electrode materials and dimensions, electrolyte parameters, and assembly processes of the other cells are completely consistent with those of Examples 1 to 4. The same test conditions are used to compare the core performance indicators under different heating schemes. Experimental testing and results analysis

[0056] To verify the technical effects of this invention, a comparative test of the performance of the soft-pack battery cell using the composite electrode sheets described in Examples 1-4 and the same soft-pack battery cell using the conventional heating scheme described in the comparative examples was conducted in an extremely cold environment. The ambient temperature was set to -40℃, and the test items included heating rate, time to heat to 0℃, maximum temperature difference on the electrode surface, heating energy consumption ratio, capacity retention rate at 0.3C discharge at -40℃, and capacity retention rate after 1000 thermal cycles. The test method referred to GB / T31486-2015 "Electrical Performance Requirements and Test Methods for Power Batteries for Electric Vehicles". The test results are as follows: heating rate 5.2℃ / min 5.5℃ / min 5.8℃ / min 6.1℃ / min 0.5℃ / min Time required to heat to 0℃ 48s 45s 42s 40s 720s Maximum temperature difference on electrode surface 3.2℃ 2.9℃ 2.5℃ 2.3℃ 12.3℃ heating energy consumption ratio 4.2% 4.5% 4.8% 5.0% 15.2% Table 1 Comparison of heating performance under different heating schemes (ambient temperature -40℃) Discharge capacity retention 82.3% 83.5% 84.2% 85.1% 52.7% Discharge voltage plateau 3.22V 3.25V 3.28V 3.30V 2.85V Discharge power density at 50% SOC 1025W / kg 1080W / kg 1120W / kg 1150W / kg 210W / kg Table 2 Comparison of low-temperature discharge performance under different heating schemes (ambient temperature -40℃, 0.3C discharge) Capacity retention after 1000 cycles 95.2% 95.8% 96.1% 96.5% 89.5% Insulation resistance after heating 1000 times 1200MΩ 1250MΩ 1300MΩ 1350MΩ No heating circuit Energy density loss rate 3.2% 3.5% 3.8% 4.0% 12.5% Table 3 Comparison of cycle performance under different heating schemes (ambient temperature 25℃, 1C charge / discharge) The test data above shows that the integrated composite electrode solution of the present invention is significantly superior to the traditional external heating solution in terms of core indicators such as heating efficiency, heating uniformity, low-temperature discharge performance, and cycle stability. In terms of heating efficiency: the heating rate of Examples 1 to 4 is more than 10 times that of the comparative examples, the time taken to heat to 0°C is only 1 / 15 to 1 / 18 of that of the comparative examples, and the heating energy consumption is only about 1 / 3 of that of the comparative examples. Regarding heating uniformity: the maximum temperature difference on the electrode surface of Examples 1 to 4 is only about 1 / 4 of that of the comparative example, which greatly avoids the uneven decay of active material caused by local temperature differences in the electrode. In terms of low-temperature discharge performance: the discharge capacity retention rate of Examples 1 to 4 at -40℃ and 0.3C is nearly 30 percentage points higher than that of the comparative example, and the discharge power density at 50% SOC is more than 5 times that of the comparative example; Regarding cycle stability: Examples 1 to 4 all maintained a capacity retention rate of over 95% after 1000 charge-discharge cycles, significantly higher than the 89.5% of the comparative example; and after 1000 thermal cycles, the insulation resistance of the heating circuit remained above 1200MΩ, which meets the relevant national safety standards. In terms of energy density: the energy density loss rate of Examples 1 to 4 was controlled within 5%, which is far lower than the 12.5% ​​of the comparative example. Without sacrificing too much energy density, the low temperature adaptability of the battery was greatly improved.

[0057] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0058] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of those different embodiments or examples.

[0059] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0060] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various variations or substitutions within the technical scope disclosed in the present invention, and these should all be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A battery electrode with integrated self-heating function, characterized in that, include: An insulating composite substrate formed by combining at least two polymer film layers; An electrothermal conversion layer is disposed between the polymer films inside the insulating composite substrate, and the electrothermal conversion layer is used to perform electrothermal conversion when energized. At least one pair of conductive electrodes forms an electrical connection with the electrothermal conversion layer; Current collector and electrode active material layer disposed on the first surface of the insulating composite substrate; Current collector and electrode active material layer disposed on the second surface of the insulating composite substrate; The electrothermal conversion layer, the conductive electrode, the current collector, and the electrode active material layer are completely electrically isolated.

2. The battery electrode with integrated self-heating function according to claim 1, characterized in that, The insulating composite substrate comprises any one of two, three, or four polymer film layers; the polymer film constituting the insulating composite substrate is at least one of polyester polymer film, polyimide polymer film, and special high-temperature resistant engineering polymer film; the insulating composite substrate as a whole is an insulating and waterproof structure, and the battery electrode is as a whole rectangular sheet, suitable for battery winding or stacking processes; the thickness of a single layer of the polymer film is 10~300μm.

3. The battery electrode with integrated self-heating function according to claim 1, characterized in that, The electrothermal conversion layer is a conductive heating structure layer formed by physical vapor deposition of at least one metal oxide semiconductor material selected from fluorine-doped tin dioxide, antimony-doped tin dioxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, vanadium pentoxide, indium zinc oxide, molybdenum-doped indium oxide, and indium tin oxide, wherein the thickness of the electrothermal conversion layer is 15nm~50nm.

4. The battery electrode with integrated self-heating function according to claim 1, characterized in that, The electrothermal conversion layer is a conductive heating structure layer made of one or more of graphene, carbon nanotubes, metal alloys or conductive polymers through physical vapor deposition, printing or coating processes.

5. The battery electrode with integrated self-heating function according to claim 1, characterized in that, The electrothermal conversion layer has a positive temperature coefficient (PTC) self-limiting temperature characteristic.

6. The battery electrode with integrated self-heating function according to claim 1, characterized in that, The conductive electrodes are arranged along the two parallel long sides of the insulating composite substrate and are completely insulated and encapsulated inside the insulating composite substrate.

7. The battery electrode with integrated self-heating function according to claim 1, characterized in that, The current collector and electrode active material layer are prepared by at least one of vacuum evaporation, wet process, dry process, and screen printing.

8. The battery electrode with integrated self-heating function according to any one of claims 1-7, characterized in that, The current collector layer and the electrode active material layer on the first surface of the insulating composite substrate are a positive current collector layer and a positive active material layer; the current collector layer and the electrode active material layer on the second surface of the insulating composite substrate are a positive current collector layer and a positive active material layer. Alternatively, the current collector layer and the electrode active material layer on the first surface of the insulating composite substrate may be a negative current collector layer and a negative active material layer. The current collector layer and the electrode active material layer on the second surface of the insulating composite substrate are configured as a negative electrode current collector layer and a negative electrode active material layer; Alternatively, the current collector layer and the electrode active material layer on the first surface of the insulating composite substrate may be a positive current collector layer and a positive active material layer. The current collector layer and the electrode active material layer disposed on the second surface of the insulating composite substrate are the negative electrode current collector layer and the negative electrode active material layer.

9. The battery electrode with integrated self-heating function according to claim 8, characterized in that, The positive electrode active material layer is at least one of layered oxide positive electrode, spinel oxide positive electrode, olivine phosphate positive electrode, and lithium-rich manganese-based positive electrode.

10. The battery electrode with integrated self-heating function according to claim 8, characterized in that, The negative electrode active material layer is at least one of carbon-based negative electrode, silicon-based negative electrode, titanium-based negative electrode, and alloy-based negative electrode.

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