Conductive material and manufacturing method, pressure sensor, battery cell and power consumption device

Abstract

This application discloses a conductive material and manufacturing method, a pressure sensor, a battery cell, and a power consumption device. The conductive material includes a flexible substrate and conductive particles dispersed in the flexible substrate. The conductive particles include a temperature-raising material and a temperature-decreasing material. The temperature-raising material is a material whose resistivity increases with increasing temperature, and the temperature-decreasing material is a material whose resistivity decreases with increasing temperature. The temperature-decreasing material and the temperature-raising material are blended in a temperature range of -40°C to +200°C, and the absolute value of the rate of change in resistivity of the conductive material is 0.01 or less. By blending the temperature-raising material and the temperature-decreasing material, the resistance of the mixed material does not change significantly with temperature changes, i.e., the resistivity of the mixed material is hardly affected by temperature, thereby improving the detection sensitivity of the sensor at different temperatures and reducing detection errors due to temperature changes.

Description

[Technical Field]

[0001] This application relates to the field of measurement technology, and in particular to conductive materials and manufacturing methods, pressure sensors, battery cells and power consuming devices. [Background technology]

[0002] A pressure sensor is a device that converts applied pressure into an electrical signal. Its features include a simple structure, low power consumption, and fast dynamic response. It is widely used in a variety of fields. For example, it can be embedded in a battery to detect behaviors such as electrode expansion inside the battery, reflect the changes in the battery's internal structure, and grasp the battery's operating status in real time. However, the measurement interference of pressure sensors due to temperature is very large. Achieving temperature suppression is key to determining whether the sensor can be used in practice, especially in application environments where the temperature changes inside lithium batteries are complex. Summary of the Invention [Problem to be solved by the invention]

[0003] The main technical problem solved by this application is to provide a conductive material and manufacturing method, a pressure sensor, a battery cell, and a power consumption device, whose resistivity does not change significantly with temperature changes, i.e., whose resistivity is hardly affected by temperature, thereby improving the detection sensitivity of the sensor at different temperatures and reducing detection errors caused by temperature changes. [Means for solving the problem]

[0004] In a first aspect, the present application provides a conductive material including a flexible substrate and conductive particles dispersed in the flexible substrate, the conductive particles including a temperature-raising material and a temperature-decreasing material, the temperature-raising material being a material whose resistivity increases with increasing temperature, and the temperature-decreasing material being a material whose resistivity decreases with increasing temperature, the temperature-decreasing material and the temperature-decreasing material being a material whose resistivity decreases with increasing temperature, the blending ratio of the temperature-decreasing material to the temperature-decreasing material being set within a temperature range of -40°C to +200°C, and the absolute value of the rate of change in resistivity of the conductive material being 0.01 or less. By mixing the temperature-raising material and the temperature-decreasing material, the resistance of the mixed material does not change significantly even when the temperature changes, i.e., the resistivity of the mixed material is hardly affected by temperature, thereby improving the detection sensitivity of the sensor at different temperatures and reducing detection errors caused by temperature changes.

[0005] In some embodiments of the present application, the compounding ratio of the temperature lowering material and the temperature increasing material is set to be within the temperature range of +25°C to +80°C, and the absolute value of the resistivity change rate of the conductive material is 0.008 or less. The closer the resistivity change rate of the conductive material is to zero, the better, making the resistivity of the conductive material insensitive to temperature and reducing errors in the sampled resistance due to temperature changes.

[0006] In some embodiments of the present application, the compounding ratio of the temperature lowering material and the temperature increasing material is set to be within the temperature range of -40°C to +200°C, and the absolute value of the resistance change rate of the conductive material is 0.01 or less. This arrangement makes the resistance of the material almost unaffected by temperature, improving the detection sensitivity of the sensor at different temperatures and reducing detection errors caused by temperature changes.

[0007] In some embodiments of the present application, the temperature lowering material and the temperature increasing material are mixed in a ratio within the temperature range of +25°C to +80°C, and the absolute value of the resistance change rate of the conductive material is 0.008 or less, which effectively reduces the influence of temperature on the resistance of the material within the normal temperature range.

[0008] In some embodiments of the present application, within the temperature range of -40°C to +200°C, the absolute ratio of the temperature coefficient of resistance of the temperature-raising material to the temperature-decreasing material is 30:1 to 1:30, optionally 15:1 to 1:10, where the temperature coefficient of resistance is the relative change in resistance of the material when the temperature changes by 1°C. This arrangement allows the ratio of the content of the temperature-raising material to the content of the temperature-decreasing material to be adjusted within a more preferable range, preventing the difference in content between the two from becoming too large, thereby avoiding a large difference in content between the two that would result in uneven mixing.

[0009] In some embodiments of the present application, the absolute value of the ratio of the resistivity change rate of the temperature-increasing material to the resistivity change rate of the temperature-decreasing material is 25:1 to 1:25, and optionally 10:1 to 1:5, within the temperature range of −40° C. to +200° C. This allows the ratio of the content of the temperature-increasing material to the content of the temperature-decreasing material to be adjusted within a more preferable range, preventing the difference between the contents of the two from becoming too large, thereby avoiding a large difference in the content of the two that would result in uneven mixing.

[0010] In some embodiments of the present application, the mass ratio of the temperature-increasing material to the temperature-decreasing material is 15:1 to 1:20, and optionally 12:1 to 1:8. This arrangement allows the ratio of the content of the temperature-increasing material to the content of the temperature-decreasing material to be adjusted within a more preferable range, preventing the difference between the contents of the two from becoming too large, thereby avoiding a large difference in the content of the two that would result in uneven mixing.

[0011] In some embodiments of the present application, the temperature-raising material has an electrical conductivity of 1 S m -1 and / or the temperature drop is greater than 1 S m -1 and / or the electrical conductivity of the conductive material is greater than 1 S m -1 By controlling the conductivity and improving the conductivity of the conductive material, the sensor detection can be made more sensitive.

[0012] In some embodiments of the present application, the temperature-raising material includes one or more of graphite, gold powder, silver powder, nickel powder, zinc-chromium alloy, nickel-copper alloy, etc. The selection of these materials can make the sensor detection more sensitive.

[0013] In some embodiments of the present application, the temperature-reducing material includes one or more of carbon nanotubes, Ketjenblack, graphene, carbon black, and ceramic materials based on metal oxides of manganese, cobalt, nickel, and copper, which can be selected to make the sensor more sensitive.

[0014] In some embodiments of the present application, the conductive particles include graphite particles and carbon nanotube particles, and the mass ratio of the graphite particles to the carbon nanotube particles is 1:1 to 1:20, and optionally 1:9 to 1:15. By selecting a mixture of graphite particles and carbon nanotube particles, the conductivity is strong and the conductive particles can be made nanometer-scale, which makes them easier to disperse and more uniformly mixed, thereby making the signal feedback more sensitive and improving the sensitivity.

[0015] In some embodiments of the present application, the carbon nanotube particles include multi-walled carbon nanotube particles having an outer diameter of 6-13 nm and a length of 2.5-20 μm. Selecting carbon nanotubes of this size provides better conductive properties for the material and more sensitive detection.

[0016] In some embodiments of the present application, the particle size Dv50 of the graphite particles is 7-10 μm, and by selecting graphite of this size, the conductive performance of the material is better and the detection is more sensitive.

[0017] In some embodiments of the present application, the mass ratio of the flexible substrate to the conductive particles is 15:1 to 5:1, and optionally 12:1 to 8:1, which can improve the elasticity and conductivity of the sensing layer.

[0018] In some embodiments of the present application, the flexible substrate comprises one or more of thermoplastic polyurethane, polyvinyl alcohol, chloroprene rubber, nitrile rubber, styrene-butadiene block copolymer, polyacrylic acid, and optionally an aliphatic thermoplastic polyurethane. Such an arrangement can provide the sensing layer with high durability and abrasion resistance.

[0019] In a second aspect, the present invention provides a pressure sensor, which includes an electrode layer and a sensing layer, and the sensing layer uses any of the conductive materials described above, and can improve detection sensitivity and extend the applicable temperature range.

[0020] In some embodiments of the present application, the sensing layer includes a base layer and at least two protruding structures of different heights protruding from the base layer, each protruding structure including at least one protrusion, each protruding portion being located on a side of the base layer facing the electrode layer, and configured such that the contact area between each protrusion and the electrode layer changes with changes in pressure applied to the electrode layer. By providing two protruding structures of different heights, the pressure sensing ranges of the protruding structures of different heights can be set differently, allowing the pressure sensor to adapt to sensing environments under various pressures and further effectively achieving the range and sensitivity of the pressure sensor.

[0021] In a third aspect, the present invention provides a method for manufacturing a pressure-sensitive layer, the method including: providing a flexible substrate slurry; adding conductive particles to the flexible substrate slurry, the conductive particles including a temperature-raising material and a temperature-decreasing material, the temperature-raising material being a material whose resistivity increases with increasing temperature, and the temperature-decreasing material being a material whose resistivity decreases with increasing temperature, the temperature-decreasing material and the temperature-decreasing material being a material whose resistivity decreases with increasing temperature, the temperature-decreasing material and the temperature-decreasing material being in a temperature range of -40°C to +200°C, and the absolute value of the rate of change in resistivity of the conductive material being 0.01 or less; and curing the flexible substrate slurry to form the pressure-sensitive layer. The manufactured pressure-sensitive layer has a wide applicable temperature range.

[0022] In a fourth aspect, the present invention provides a battery cell, the battery cell including a casing and any one of the pressure sensors described above, the pressure sensor being installed inside the casing, which can obtain internal information of the battery, and the obtained data is more accurate.

[0023] In a fifth aspect, the present invention provides a power consumption device, which includes the battery cell as described above, and can achieve acquisition of internal information of the battery, and the acquired data is more accurate.

[0024] The above description is only a summary of the technical solution of the present application, and in order to more clearly understand the technical solution of the present application, which can be implemented according to the content of the specification, and to make the above and other objectives, features and advantages of the present application more obvious and understandable, specific embodiments of the present application are listed below.

[0025] In order to more clearly describe the technical solutions in the embodiments of the present application, the following briefly describes the drawings required for the embodiments of the present application. It is obvious that the drawings shown below are only some embodiments of the present application, and those skilled in the art can further obtain other drawings based on the drawings without any creative efforts. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a cross-sectional structural schematic diagram of a pressure sensor according to one or more embodiments of the present application. [Figure 2] 1A-1D are cross-sectional structural schematic diagrams of a pressure sensor under different pressure conditions according to one or more embodiments of the present application. [Figure 3a] 1 is a layout design diagram of the protrusion structure of the sensitive layer of the pressure sensor in one or more embodiments of the present application. [Figure 3b] 1 is a schematic diagram illustrating the layout of protrusion structures of a sensitive layer in a sample of a pressure sensor according to one or more embodiments of the present application. [Figure 4] 1 is a schematic planar structural view of a pressure sensor according to one or more embodiments of the present application; [Figure 5]FIG. 1 is an exploded schematic view of a battery according to one or more embodiments. [Figure 6] FIG. 1 is an exploded structural schematic diagram of a battery cell according to one or more embodiments. [Figure 7] FIG. 1 is a structural schematic diagram of a vehicle according to one or more embodiments. [Figure 8] FIG. 1 is a schematic diagram showing the resistance change rate versus temperature curves of Examples and Comparative Examples. DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, the technical solutions in the embodiments of the present application will be clearly and completely described with reference to the drawings of the embodiments of the present application, and it is obvious that the described embodiments are only some of the embodiments of the present application, and not all of the embodiments, and all other embodiments obtained by those skilled in the art based on the embodiments of the present application without any creative efforts belong to the protection scope of the present application.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular examples only and is not intended to be limiting of the application; the terms "comprises" and "having" and any variations thereof in the specification and claims of this application, as well as the description of the drawings above, are intended to cover a non-exclusive inclusion.

[0029] In the description of the embodiments of the present application, technical terms such as "first," "second," etc. are used only to distinguish between different objects, and should not be understood to express or suggest relative importance, or to implicitly indicate the number, specific order, or primary-subordinate relationship of the technical features of interest. In the description of the embodiments of the present application, unless otherwise specified, the term "plurality" means two or more (including two). Similarly, "multiple groups" means two or more groups (including two groups), and "multiple sheets" means two or more (including two sheets).

[0030] The term "embodiment" as used herein means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present application. Appearances of the term "embodiment" in various places in this specification do not necessarily refer to the same embodiment, nor do they refer to embodiments that are mutually exclusive, independent, or alternative to other embodiments. Those skilled in the art can explicitly and implicitly understand that the embodiments described herein may be combined with other embodiments.

[0031] In the description of the embodiments of this application, the term "and / or" merely describes the relationship between related objects and indicates that three relationships may exist. For example, A and / or B may represent three cases: a single A, a combination of A and B, and a single B. In addition, the character " / " in this specification generally indicates that the related objects before and after it are in an "or" relationship.

[0032] In describing the embodiments of the present application, the orientations or positional relationships indicated by technical terms such as "center," "longitudinal direction," "lateral direction," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial direction," "radial direction," and "circumferential direction" are based on the orientations or positional relationships shown in the accompanying drawings and are for the convenience or simplification of the description of the embodiments of the present application, and are not intended to indicate or imply that the referred-to devices or elements have a specific orientation or are required to be constructed and operated in a specific orientation, and should not be understood as limiting the embodiments of the present application.

[0033] In the description of the embodiments of the present application, unless otherwise clearly defined or limited, the technical terms "attached," "connected," "connected," "fixed," etc. should be understood in a broad sense, and may refer to, for example, a fixed connection, a detachable connection, or an integrated connection, a mechanical connection, an electrical connection, a direct connection, an indirect connection via an intermediate medium, an internal communication between two elements, or an interactive relationship between two elements. Those skilled in the art will be able to understand the specific meanings of the above terms in the embodiments of the present application according to specific circumstances.

[0034]

[0023] Quantities, ratios, and other numerical values ​​are presented herein in range form. Such range form is for convenience and brevity and should be understood flexibly to include not only the numerical values ​​explicitly set forth to limit the range, but also all individual numerical values ​​or subranges contained within said range, as if each numerical value and subrange were explicitly set forth.

[0035] With the widespread use of electrochemical devices (e.g., lithium-ion batteries), people are placing increasing demands on their performance, particularly in terms of battery safety, stability, and capacity. This demand calls for batteries to have superior overall performance in all respects. Lithium batteries are complex systems in which chemical, thermal, and electrical energy are highly coupled through (electro)chemical reactions. Therefore, real-time monitoring of the internal operating conditions of a battery is key to the development, design, and efficient, safe operation of novel batteries. At the microscopic level, lithium desorption and insertion reactions during the charge and discharge process of a lithium battery cause the electrode materials to expand, increasing the internal stress of the battery and making electrode delamination and SEI film thickness highly likely to occur. Research has shown that while graphite electrodes can expand by 10%, graphite-silicon composite electrodes can expand by 280%. During long-term cycling, changes in the battery potential make it difficult for lithium ions to desorb and intercalate. This leads to irreversible expansion of the internal electrode sheet, resulting in electrolyte consumption, reduced capacity, and lithium dendrites, which ultimately lead to reduced battery performance and a shortened service life. At the macro level, the expansion behavior of the multilayered electrode sheets causes the volume of the battery core to expand, deforming the battery through extrusion with the battery casing. The combined mechanical-thermal effect significantly changes the battery's internal and external stresses and heat generation behavior, leading to uncontrollable factors increasing over time. Electrode expansion behavior can reflect the evolution process of the internal structure and contains a wealth of information. Obtaining information on battery expansion behavior is highly significant for comprehensive and in-depth understanding of lithium battery operating modes, optimizing battery material selection, monitoring the battery's energy conversion state, gaining a deeper understanding of the battery's internal operating mechanisms, and establishing a more accurate digital twin model of the battery core. This information can provide important information for battery management systems (BMS) and further improve the safety, efficiency, and stability of lithium batteries during operation.

[0036] To obtain more comprehensive and accurate information about the battery's internal state, embedded sensors can be used to measure temperature and stress. However, temperature interference with pressure sensor measurements is significant. Achieving temperature suppression is key to determining whether a sensor can be used in practical applications, especially in applications where the temperature changes inside lithium batteries are complex. However, there has been little development or design work on high-performance embedded sensors.

[0037] In order to solve the above technical problems, the present invention provides a pressure sensor. Referring to Fig. 1, Fig. 1 is a cross-sectional structural schematic diagram of a pressure sensor according to one or more embodiments of the present application. The pressure sensor 400 includes an electrode layer 40 and a sensing layer 42.

[0038] Here, the pressure sensor 400 is an element that outputs an applied pressure as an electrical signal. The pressure sensor 400 may be a resistance sensor that uses a change in resistance to convert the measured pressure into an electrical signal that has a certain relationship with the pressure and outputs the electrical signal.

[0039] The pressure sensor 400 may be a thin-film sensor, which can be made of metal, semiconductor, or polymer materials to manufacture sensors for temperature, pressure, strain, etc., and can be embedded inside the battery to measure temperature and stress. This enables in-situ detection of the internal electrode expansion pressure signal and temperature in various operating states of the power battery, providing important data for building accurate battery numerical models and battery management systems, and providing an important tool for the industrial application of safe and efficient next-generation lithium batteries.

[0040] Specifically, the electrode layer 40 is used to collect changes in the electrical signal of the sensing layer 42, form a conductive network in contact with the sensing layer 42, and convert the pressure signal into an electrical signal. The sensing layer 42 is used to form a contact resistance with the electrode layer 40, so that the pressure sensor 400 acquires the applied pressure based on the contact resistance between the sensing layer 42 and the electrode layer 40. That is, it may be a resistive pressure sensor, which reflects the magnitude of the applied external force mainly by causing the deformation of the sensing layer under the action of an external force to induce the disconnection or reconstruction of its internal conductive network, thereby causing a change in resistance.

[0041] In some embodiments of the present application, the electrode layer 40 includes a first electrode 401 and a second electrode 402 arranged in an interdigitated pattern. Here, interdigitated electrodes refer to electrodes with a periodic, planar pattern, such as fingers or combs. The first electrode 401 and the second electrode 402 are located on the same side of the sensing layer 42, i.e., the first electrode 401 and the second electrode 402 are coplanar electrodes. Due to the limited space inside a battery, if the sensor is too thick, stress concentration at a single point may occur during placement inside the battery, causing problems such as damage to the battery electrode material and lithium precipitation. In this embodiment, the selection of coplanar electrodes based on interdigitated electrodes effectively reduces the sensor thickness and achieves sensitive resistance change collection without affecting the deformability of the sensing layer under pressure.

[0042] In some embodiments of the present application, the material of the sensing layer 42 includes a flexible substrate and conductive particles dispersed within the flexible substrate.

[0043] The flexible substrate allows the sensing layer 42 to deform under pressure and recover after the pressure is released. The conductive particles are used to form a conductive network after contacting the electrode layer 40. The selection of the flexible substrate significantly affects the mechanical properties of the pressure sensor, which in turn affects the sensor's deformation and recovery under pressure. The selection of the conductive particles is related to the magnitude of the contact resistance, which in turn affects the sensor's sensitivity, accuracy, and range. Therefore, the material of the sensing layer is key to determining the sensing layer's mechanical and electrical properties. When selecting the sensing layer material, the application environment of the sensor in a lithium battery must be taken into consideration. For example, the sensor must operate under high pressure (1.2 MPa or more) for a long period of time (more than three months) and multiple cycles (more than 100 times), which places high demands on the sensor's mechanical properties. Furthermore, temperature significantly interferes with pressure sensor measurements, especially in the application environment where temperature changes are complex within a lithium battery. At the same time, after embedding the sensor in the lithium battery, subsequent processes such as drying, liquid injection, and aging are required, which can reach a maximum temperature of 105°C. Therefore, the sensor needs to be able to withstand higher temperatures while suppressing temperature drift. However, currently commonly used sensing layer materials have drawbacks such as incompressibility, the response speed is limited by the material's rebound speed, severe creep, a relatively large thickness, and large temperature drift.

[0044] In order to solve the above problems, the present application provides a conductive material for a pressure-sensitive layer, the conductive material including a flexible substrate and conductive particles dispersed in the flexible substrate, the conductive particles including a temperature-raising material and a temperature-decreasing material, the temperature-raising material being a material whose resistivity increases as the temperature increases, and the temperature-decreasing material being a material whose resistivity decreases as the temperature increases, the blending ratio of the temperature-decreasing material and the temperature-raising material being set to be within a temperature range of -40°C to +200°C, and the absolute value of the rate of change in resistivity of the conductive material is 0.01 or less.

[0045] In this embodiment, the resistivity change rate is determined by taking the resistivity of the conductive particles at 25°C as the reference, calculating the difference between the resistivity at different temperatures and the reference resistivity, and then calculating the ratio to the reference resistivity. For example, the resistivity change rate from 25°C to 50°C = (resistivity 50℃ -Resistivity 25℃ ) / resistivity 25℃ is.

[0046] Here, resistivity is a physical quantity that indicates the resistance characteristics of an individual substance. 2 The resistance of a conductor is numerically equal to the resistivity of this material. Resistivity reflects the material's ability to resist electric current, and it is affected not only by the type of material but also by external factors such as temperature. That is, as the temperature changes, the resistivity of a material also changes. The resistivity of some materials increases with increasing temperature, while the resistivity of some materials decreases with increasing temperature. Alternatively, if the length and cross-sectional area of ​​a material remain unchanged, the resistance of a temperature-increasing material increases with increasing temperature, and the resistance of a temperature-decreasing material decreases with increasing temperature.

[0047] In this embodiment, by mixing a temperature-raising material and a temperature-decreasing material, the resistance decrease caused by the temperature-decreasing material is used to balance the resistance increase caused by the temperature-raising material, or the resistance increase caused by the temperature-decreasing material is used to balance the resistance decrease caused by the temperature-decreasing material, so that the resistance of the mixed material does not change significantly when the temperature changes, i.e., the resistivity of the mixed material is hardly affected by temperature, thereby reducing the detection sensitivity of the sensor at different temperatures and the detection error caused by temperature changes.

[0048] In some embodiments of the present application, the composition ratio of the temperature-lowering material and the temperature-increasing material is set within a temperature range of +25°C to +80°C, and the absolute value of the resistivity change rate of the conductive material is 0.008 or less. For example, the resistivity change rate of the conductive material may be 0.001, 0.0015, 0.002, 0.0025, 0.003, 0.004, 0.005, 0.0055, 0.006, 0.007, 0.008, etc. The closer the resistivity change rate of the conductive material is to zero, the better, making the resistivity of the conductive material less sensitive to temperature and reducing errors due to temperature changes in the measured resistance. This arrangement allows the pressure sensor to operate at extreme temperatures such as -40°C to +200°C with small detection errors, and at normal temperatures of +25°C to +80°C, the resistivity change rate is smaller, resulting in higher detection sensitivity.

[0049] In some embodiments of the present application, the compounding ratio of the temperature lowering material and the temperature increasing material is set to a temperature range of -40°C to +200°C, and the absolute value of the resistance change rate of the conductive material is 0.01 or less. Optionally, the compounding ratio of the temperature lowering material and the temperature increasing material is set to a temperature range of +25°C to +80°C, and the absolute value of the resistance change rate of the conductive material is 0.008 or less. For example, the compounding ratio may be 0.001, 0.0015, 0.002, 0.0025, 0.003, 0.004, 0.0045, 0.005, 0.0055, 0.006, 0.007, 0.008, etc. The resistance change rate is determined by taking the resistance of the conductive particles at 25°C as a reference, calculating the difference between the resistance at different temperatures and the reference resistance, and then calculating the ratio to the reference resistance. For example, the resistance change rate from 25°C to 50°C = (resistance 50℃ -resistance 25℃ ) / resistance 25℃ is.

[0050] Here, the present application aims to control the rate of change of resistivity to be relatively small from the viewpoint of the material properties of the conductive material, and further to control the contact resistance between the sensing layer 42 and the electrode layer 40 measured at different temperatures under the same pressure condition to be substantially the same from the viewpoint of sensor resistance. Alternatively, when the pressure does not change, the contact area between the sensing layer 42 and the electrode layer 40 does not change, and the contact resistance is not affected by temperature changes.

[0051] In one embodiment, the temperature coefficient can be used to represent the rate at which a material's physical properties change with a change in temperature. Specifically, the temperature coefficient of resistance (TCR) can be used to represent the relative change in resistance of a material per 1°C change in temperature. Specifically, TCR = (R2 - R1) / (R1 * (T2 - T1)) = (R2 - R1) / (R1 * ΔT), where R1 is the resistance (Ω) at temperature T1, and R 2は Resistance value (Ω) at temperature T2. The larger the temperature coefficient, the greater the change (increase or decrease) in resistance with the same temperature change.

[0052] Here, the temperature coefficient of resistance may be a positive temperature coefficient, a negative temperature coefficient, or a zero coefficient. A material with a positive temperature coefficient has the property that its resistivity increases with increasing temperature, while a material with a negative temperature coefficient has the property that its resistivity decreases with increasing temperature. A zero coefficient means that its resistivity hardly changes with temperature. The solution of the present application aims to make the temperature coefficient of the conductive material zero by adjusting the ratio of the temperature-increasing material and the temperature-decreasing material.

[0053] In some embodiments of the present application, within the temperature range of -40°C to +200°C, the absolute ratio of the temperature coefficient of resistance of the temperature-raising material to the temperature-decreasing material is 30:1 to 1:30, and optionally 15:1 to 1:10. For example, it may be 30:1, 20:1, 10:1, 5:1, 1:1, 1:5, 1:8, or 1:10. Specifically, a material with a small temperature coefficient, i.e., a material that is not itself temperature-sensitive, may be selected. Optimally, if the temperature coefficient value of the selected temperature-raising material is close to that of the selected temperature-decreasing material, i.e., if the materials are similar in size, the resistance increased by the same amount of temperature-raising material will be similar to the resistance decreased by the temperature-decreasing material. By setting the ratio of the absolute values ​​of the temperature-rising material's temperature coefficient of resistance to the temperature-decreasing material's temperature coefficient of resistance between 30:1 and 1:30, the content ratio of the temperature-rising material and the temperature-decreasing material can be adjusted to a more favorable range, preventing excessive differences in content between the two and avoiding uneven mixing due to large differences in content between the two. When the absolute ratio of the temperature-rising material's temperature coefficient of resistance to the temperature-decreasing material is between 15:1 and 1:10, the absolute values ​​of the temperature-rising material and the temperature-decreasing material's temperature coefficient of resistance can be made closer, thereby reducing the difference in content between the two and resulting in a more uniform mixture. When the ratio of the absolute values ​​of the temperature-rising material's temperature coefficient of resistance to the temperature-decreasing material is greater than 30:1 or less than 1:30, the difference in absolute values ​​between the temperature-rising material and the temperature-decreasing material becomes too large, resulting in a large difference in the ratio between the two and resulting in uneven mixing.

[0054] In some embodiments of the present application, the absolute value of the ratio of the resistivity change of the temperature-raising material to the resistivity change of the temperature-decreasing material within the temperature range of -40°C to +200°C is 25:1 to 1:25, and optionally 10:1 to 1:5. For example, the ratio may be 25:1, 20:1, 10:1, 5:1, 1:1, 1:2, 1:3, 1:5, etc. Specifically, a material with a small resistivity change, i.e., a material that is not itself temperature-sensitive, may be selected. Optimally, if the resistivity change of the selected temperature-raising material is close to the resistivity change of the selected temperature-decreasing material, i.e., if the materials are similar in size, the resistance increase by an equal amount of temperature-raising material will be similar to the resistance decrease by an equal amount of temperature-decreasing material. By setting the absolute value of the ratio of the resistivity change rate of the temperature-raising material to the resistivity change rate of the temperature-reducing material between 25:1 and 1:25, the content ratio of the temperature-raising material and the temperature-reducing material can be adjusted to a more favorable range, preventing excessive differences in content between the two and avoiding uneven mixing due to large differences in content between the two. When the absolute value of the ratio of the resistivity change rate of the temperature-raising material to the resistivity change rate of the temperature-reducing material is between 10:1 and 1:5, the absolute values ​​of the resistivity change rates of the temperature-raising material and the temperature-reducing material can be made closer, thereby reducing the difference in content between the two and resulting in a more uniform mixture. When the absolute value of the ratio of the resistivity change rate of the temperature-raising material to the resistivity change rate of the temperature-reducing material is greater than 10:1 or less than 1:5, the difference in the absolute values ​​of the resistivity change rates of the temperature-raising material and the temperature-reducing material becomes too large, resulting in a large difference in the ratio between the two and resulting in uneven mixing.

[0055] In some embodiments of the present application, the mass ratio of the temperature-increasing material to the temperature-decreasing material is 15:1 to 1:20, and optionally 12:1 to 1:8. Examples include 15:1, 13:1, 10:1, 5:1, 1:1, 1:3, 1:5, and 1:8. Controlling the mass ratio within this range prevents the difference in content between the two materials from becoming too large, thereby avoiding a large difference in content between the two materials, which could result in uneven mixing. When the mass ratio of the temperature-increasing material to the temperature-decreasing material is 12:1 to 1:8, the difference in content between the temperature-increasing material and the temperature-decreasing material can be reduced, resulting in more uniform mixing. When the mass ratio of the temperature-increasing material to the temperature-decreasing material is greater than 15:1 or less than 1:8, the difference in content between the temperature-increasing material and the temperature-decreasing material is too large, resulting in uneven mixing.

[0056] In some embodiments of the present application, the temperature-raising material has an electrical conductivity of 1 S m -1 and / or temperature drop, the electrical conductivity of the material is greater than 1 S m -1 and / or the electrical conductivity of the conductive material is greater than 1 S m -1 The electrical conductivity of the conductive material may be between the electrical conductivity of the temperature-increasing material and the electrical conductivity of the temperature-decreasing material, or may be greater than the electrical conductivity of the temperature-increasing material and the electrical conductivity of the temperature-decreasing material, or may be less than the electrical conductivity of the temperature-increasing material and the electrical conductivity of the temperature-decreasing material. By controlling the electrical conductivity and selecting a material with a relatively high electrical conductivity, the conductivity of the conductive material can be improved, making the sensor detection more sensitive.

[0057] In some embodiments of the present application, the temperature-raising material includes one or more of graphite, gold powder, silver powder, nickel powder, zinc-chromium alloy, nickel-copper alloy, etc. The selection of these materials can make the sensor detection more sensitive.

[0058] In some embodiments of the present application, the temperature-reducing material includes one or more of carbon nanotubes, Ketjenblack, graphene, carbon black, and ceramic materials based on metal oxides of manganese, cobalt, nickel, and copper, which can be selected to make the sensor more sensitive.

[0059] Here, when the temperature-increasing material and the temperature-decreasing material include a plurality of materials, the mass ratio of the temperature-increasing material to the temperature-decreasing material is the ratio of the total mass of all the temperature-increasing materials to the total mass of all the temperature-decreasing materials.

[0060] In some embodiments of the present application, the conductive particles include graphite particles and carbon nanotube particles, and the mass ratio of the graphite particles to the carbon nanotube particles is 1:1 to 1:20. Alternatively, the mass ratio may be 1:9 to 1:15. For example, it may be 1:1, 1:3, 1:5, 1:7, 1:9, 1:11, 1:12, 1:15, 1:18, 1:20, etc. By selecting a mixture of graphite particles and carbon nanotube particles, the material is relatively stable, has strong conductivity, and the conductive particles can be nanometer-scale, making them easier to disperse and more uniformly mixed, thereby making signal feedback more sensitive and improving sensitivity. When the mass ratio of the graphite particles to the carbon nanotube particles is 1:9 to 1:15, the difference in the content of the graphite particles and the carbon nanotube particles can be smaller, resulting in a more uniform mixture. If the mass content ratio of the graphite particles to the carbon nanotube particles is greater than 1:1 or less than 1:20, the difference in content between the graphite particles and the carbon nanotube particles becomes large, resulting in non-uniform mixing.

[0061] In some embodiments of the present application, the carbon nanotube particles include multi-walled carbon nanotube particles having an outer diameter of 6 to 13 nm and a length of 2.5 to 20 μm. The particle size Dv50 of the graphite particles is 7 to 10 μm. By selecting carbon nanotubes and graphite of this size, the conductive properties of the material and the detection sensitivity are improved.

[0062] In some embodiments of the present application, the flexible substrate comprises one or more of thermoplastic polyurethane, polyvinyl alcohol, chloroprene rubber, nitrile rubber, styrene-butadiene block copolymer, and polyacrylic acid. Optionally, it is an aliphatic thermoplastic polyurethane. By selecting polyurethane, it is more durable and abrasion-resistant compared to base materials such as polydimethylsiloxane (PDMS) and aliphatic-aromatic random copolyester (Eco-flex).

[0063] In some embodiments of the present application, the mass ratio of the flexible substrate to the conductive particles is 15:1 to 5:1, and optionally 12:1 to 8:1. For example, it may be 15:1, 12:1, 10:1, 8:1, 6:1, 5:1, etc. Here, if the content of the flexible substrate is too low, the elasticity of the material will be insufficient, resulting in a narrow sensor range. If the content of the flexible substrate is too high, the support of the sensing layer will be insufficient, which may cause collapse and reduce detection accuracy. By setting the mass ratio of the flexible substrate to the conductive particles to 15:1 to 5:1, the elasticity and conductivity of the sensing layer can be improved. By setting the mass ratio of the flexible substrate to the conductive particles to 12:1 to 8:1, the elasticity and conductivity of the sensing layer can be further improved.

[0064] In the above embodiments, by adjusting the components of the sensing layer material, particularly the components of the conductive material, the conductive material can be made less sensitive to temperature, thereby expanding the operating temperature range of the sensor, reducing detection errors caused by temperature changes, and improving detection sensitivity.

[0065] Continuing to refer to FIG. 1 , in some embodiments of the present application, the sensing layer 42 has a microstructure, specifically, includes a plurality of protrusion structures 422 with at least two different heights. The protrusion structures 422 contact two unconnected electrodes of the electrode layer 40, construct a conductive network, and form contact resistance. Here, the height direction is the direction from the base layer 420 to the electrode layer 40 (the X direction in the figure), and the height of the protrusion structures 422 can be measured using a scanning electron microscope. As the applied pressure gradually increases, the contact area between the protrusion structures 422 and the electrodes gradually increases, and the contact resistance gradually decreases. The change in the contact area of ​​the protrusion structures 422 is caused by compressive deformation that occurs when the protrusion structures 422 are subjected to pressure and the supporting effect of the electrode layer 40.

[0066] 2, which is a cross-sectional structural schematic diagram of a pressure sensor in different pressure states according to one or more embodiments of the present application. Here, (a) of FIG. 2 is a cross-sectional structural schematic diagram of a pressure sensor in a first pressure state according to one or more embodiments of the present application. (b) of FIG. 2 is a cross-sectional structural schematic diagram of a pressure sensor in a second pressure state according to one or more embodiments of the present application. (c) of FIG. 2 is a cross-sectional structural schematic diagram of a pressure sensor in a third pressure state according to one or more embodiments of the present application. With further increases in pressure, the protrusion structures 422 that were not involved in the construction of the conductive network come into contact with the electrodes and are incorporated into the conductive network, which is equivalent to connecting a new resistor in parallel to the original conductive network, thereby further reducing the overall resistance across the electrodes and representing changes in pressure values.

[0067] In this embodiment, three protrusion structures 422 of different heights are included. Protrusion 4221 is a protrusion of a protrusion structure of a first height, protrusion 4222 is a protrusion of a protrusion structure of a second height, and protrusion 4223 is a protrusion of a protrusion structure of a third height. The height of protrusion 4223 is higher than the height of protrusion 4221, which is higher than the height of protrusion 4222. As shown in FIG. 2(a), in a first pressure state, protrusion 4221 and protrusion 4223 contact the first electrode 401 and second electrode 402 of the electrode layer 40, respectively, to form a conductive network. At this time, the contact area between the protrusions and the electrodes is small. As shown in FIG. 2(b), as the pressure increases, the contact area between protrusion 4221 and protrusion 4223 and the electrodes increases in a second pressure state (the second pressure is greater than the first pressure). As shown in FIG. 2(c), as the pressure further increases, at a third pressure (the third pressure is greater than the second pressure), the protrusions 4222, which were not originally in contact with the electrodes, begin to contact the electrodes, and the protrusions 4222 simultaneously contact the first electrode 401 and the second electrode 402, forming a new conductive network. The contact area between the protrusions 4221 and the first electrode 401 gradually increases from state (a) to state (c) in FIG. 2, and the contact area between the protrusions 4223 and the second electrode 402 gradually increases from state (a) to state (b) in FIG. 2. However, the contact area between the protrusions 4223 and the second electrode 402 does not increase significantly from state (b) to state (c) in FIG. 2. This is because, when compressed to a certain extent, the protrusions 422 reach their deformation limit and no longer change significantly. In other words, when the amount of compression of the protrusion structure is within a certain range (pressure sensitivity range), the contact area changes significantly, allowing for effective pressure detection. However, beyond this range, the contact area does not change significantly or does not change at all, resulting in ineffective pressure detection or poor sensitivity. In this embodiment, by installing two protrusion structures of different heights, the pressure sensitivity ranges of the protrusion structures of each height are set differently, allowing the pressure sensor to adapt to detection environments under various pressures and effectively obtaining the range and sensitivity of the pressure sensor.For example, from state (b) to state (c) in FIG. 2, the contact area between the protrusion 4223 and the second electrode 402 does not increase significantly, but at this time, the protrusion 4222 begins to contact the electrode, forming a new conductive network, i.e., a new resistor is incorporated, which continues to realize more sensitive resistance changes and improves range and sensitivity.

[0068] In some embodiments of the present application, at least a portion of the relatively low-height protrusion structures 422 is spaced apart from the electrode layer 40 along the height direction of the protrusion structures 422 and contacts the electrode layer 40 after the applied pressure exceeds a predetermined threshold. At the same time, at least a portion of the tallest protrusion structures 422 is arranged to maintain contact with the electrode layer 40. This arrangement effectively delays a rapid decrease in resistance, thereby improving the sensor's range. The tallest protrusion structures can be used to provide support for the sensing layer, effectively reducing the adverse effects of the sensing layer's collapse. Specifically, collapse of the sensing layer can cause abnormal contact between the protrusion structures and the electrode layer, which in turn causes the change in the contact area of ​​the protrusion structures to deviate from the design expectations and affect measurement accuracy. At the same time, after the tallest protrusion structures are compressed to a certain extent, the shorter protrusion structures can contact the electrode layer, thereby effectively shifting the pressure-sensitive range of the tallest protrusion structures from that of the shorter protrusion structures, further improving the range and sensitivity.

[0069] In some embodiments of the present application, the protrusions of the protrusion structures 422 have a shape with a large base and a small tip, such as a cone shape or a frustum shape that gradually tapers from the bottom to the top, or a spherical truncated shape that changes in an arc. With this arrangement, when the protrusion structures are compressed by pressure, the contact area with the electrode layer gradually changes, effectively improving the sensitivity of the contact area of ​​the protrusion structures to pressure. When the upper microstructure reaches its compression limit under pressure, the lower microstructure augments the contact electrode. This gradual pressure distribution of the microstructures significantly improves the sensitivity of the sensor over a wide range and allows for better discrimination of pressure changes.

[0070] Referring to Figures 3a and 3b, Figure 3a illustrates the layout design of the protrusion structures of the sensing layer of a pressure sensor according to one or more embodiments of the present application, and Figure 3b illustrates a schematic diagram of the layout of the protrusion structures of the sensing layer in a sample pressure sensor according to one or more embodiments of the present application. In some embodiments of the present application, the protrusions of the protrusion structures 422 of the same height are spaced apart on a circular reference line centered on a predetermined reference point. Here, the protrusions may be spaced apart at equal intervals or at unequal intervals. As shown in Figure 3a, three protrusion structures 422 of different heights are included, where protrusion 4221 is a protrusion of a protrusion structure of a first height, protrusion 4222 is a protrusion of a protrusion structure of a second height, and protrusion 4223 is a protrusion of a protrusion structure of a third height. The height of protrusion 4223 is higher than the height of protrusion 4221, which is higher than the height of protrusion 4222. A plurality of protrusions 4221 are arranged at intervals on annular reference line 1 whose center is a preset reference point A, a plurality of protrusions 4222 are arranged at intervals on annular reference line 2 whose center is a preset reference point A, and a plurality of protrusions 4223 are arranged at intervals on annular reference line 3 whose center is also a preset reference point A. By arranging protrusions of protrusion structures of the same height on annular reference lines, design considerations can be made using annular reference lines as units in the design process, and the complexity of the arrangement of the protrusion structures can be reduced.

[0071] As shown in Figure 3a, a plurality of protrusions 4221 are spaced apart on annular reference line 1 whose center is a preset reference point A, a plurality of protrusions 4222 are spaced apart on annular reference line 2 whose center is a preset reference point A, and a plurality of protrusions 4223 are spaced apart on annular reference line 3 whose center is also a preset reference point A. By arranging protrusions of the same height on the annular reference line, design considerations can be made using the annular reference line as a unit in the design process, and the complexity of the arrangement of the protrusion structures can be reduced.

[0072] Some embodiments of the present application further provide a method for manufacturing a pressure-sensitive layer, specifically, the method includes: providing a flexible substrate slurry; adding conductive particles to the flexible substrate slurry, where the conductive particles include a temperature-increasing material and a temperature-decreasing material, the blending ratio of the temperature-decreasing material and the temperature-increasing material is set to be in a temperature range of -40°C to +200°C, and the absolute value of the change rate of resistivity of the conductive material is 0.01 or less; and curing the flexible substrate slurry to form a pressure-sensitive layer.

[0073] The sensing layer can be formed by molding using a mold. The mold for molding the sensing layer may consist of an outer acrylic plate and an inner PDMS (polydimethylsiloxane) layer, with the PDMS serving as the mold body and an acrylic outer frame used to support the PDMS. The PDMS solution and curing agent are mixed at a mass ratio of 10:1. The mixture is placed in a vacuum box for 30 minutes to completely remove air bubbles, and then heated at 80°C for 1 hour to fully crosslink and harden. After molding, an infrared / ultraviolet laser is used to machine the microstructure and grooves in the PDMS mold. Specifically, an infrared laser can be used to machine corresponding pits on the PDMS surface according to the designed structural pattern. The depth and diameter of the microstructure can be adjusted by changing the laser processing power, number of shots, and processing frequency. The sensing layer solution is then scraped and applied to the machined grooves to achieve molding.

[0074] 4, which is a schematic planar structural diagram of a pressure sensor according to one or more embodiments of the present application. The pressure sensor 400 further includes a corrosion-resistant protective layer 44, which is used to resist corrosion of the main electrolyte inside the lithium battery. The sensing layer 42 is used to sense external forces. The sensing layer 42 includes a base layer 420 and at least two types of protrusion structures 422 of different heights protruding from the base layer 420. The electrode layer 40 and the sensing layer 42 are packaged by a sensing layer adhesive 48, and the combination of the two forms a critical circuit that responds to pressure. The electrode layer 40 includes an electrode base 403 and a first electrode 401 and a second electrode 402 arranged in an interdigital pattern. The electrode base 403 is used to support the membrane structure such as the sensing layer 42. The isolation layer 46 is located between the sensing layer 42 and the corrosion-resistant protective layer 44 and is used to protect the sensing layer 42 from being affected or damaged during the processing and manufacturing process of the corrosion-resistant protective layer 44. The isolation layer 46 is connected to the electrode base 403 by an isolation layer adhesive 49. The pressure sensor 400 is a piezoresistive sensor driven by the change in contact resistance between the sensing layer microstructure and the coplanar interdigitated electrodes.

[0075] In the above embodiment, the sensing function is mainly achieved by utilizing the change in contact resistance between the conductive sensing layer and the electrode due to pressure, and by fabricating a specific microstructure, such as a pyramid or dome shape, on the sensing layer that contacts the electrode, the contact characteristics between the sensing layer and the electrode can be changed, thereby improving or adjusting the piezoresistance characteristics of the sensor. The introduction of a specific shape of the microstructure can improve the performance indexes, such as the sensitivity and range, of the pressure sensor to a certain extent.

[0076] In some embodiments of the present application, the pressure sensor can be used to detect the internal pressure of a battery. That is, the present invention provides a battery cell, the battery cell including a casing and the pressure sensor of any of the above embodiments, the pressure sensor being installed inside the casing.

[0077] Embodiments of the present invention may be applied to various types of batteries, including but not limited to lithium batteries, sodium batteries, etc. The shape of the battery may include but is not limited to cylindrical, prismatic, or any other shape.

[0078] In some embodiments, a battery 100 of the present application includes a housing 10 and battery cells 20, where the battery cells 20 are housed within the housing 10. See FIG. 5, which is a schematic exploded view of a battery according to one or more embodiments. The housing 10 is for providing a housing space for the battery cells 20, and the housing 10 may have various structures. In some embodiments, the housing 10 may include a first portion 11 and a second portion 12, where the first portion 11 and the second portion 12 are attached to each other, and the first portion 11 and the second portion 12 collectively define a housing space for housing the battery cells 10. The second part 12 may have a hollow structure with one end open, and the first part 11 may have a plate-like structure, with the first part 11 being attached to a cover on the open side of the second part 12, so that the first part 11 and the second part 12 jointly define an accommodation space, and the first part 11 and the second part 12 may both have a hollow structure with one end open, with the open side of the first part 11 being attached to a cover on the open side of the second part 12. Of course, the housing 10 formed by the first part 11 and the second part 12 may have various shapes such as a cylinder or a rectangular parallelepiped.

[0079] The battery 100 may include a plurality of battery cells 20, and the plurality of battery cells 20 may be connected in series, parallel, or series-parallel, where series-parallel connection includes both series and parallel connections of the plurality of battery cells 20. The plurality of battery cells 20 may be directly connected in series, parallel, or series-parallel, and then the entire battery cell set may be housed within the housing 10. Of course, the battery 100 may also be formed by first connecting the plurality of battery cells 20 in series, parallel, or series-parallel to form a battery module, and then connecting the plurality of battery modules in series, parallel, or series-parallel to form the entire battery module and housed within the housing 10. The battery 100 may further include other structures, for example, the battery 100 may further include busbar members for achieving electrical connection between the plurality of battery cells 20.

[0080] Here, each battery cell 20 may be a secondary battery, such as, but not limited to, a lithium ion battery, a sodium ion battery, a magnesium ion battery, or an aluminum ion battery, and may be cylindrical, flat, rectangular, or have any other shape.

[0081] Battery manufacturing methods include stacking and wound methods, meaning batteries can be divided into two types: stacked batteries and wound batteries. Stacked batteries have uniform current collection, low internal resistance, and high specific power output, but require very high mold precision, high capital investment, and complex processes, resulting in low production efficiency. Wound batteries are simple to manufacture, with typical equipment precision requirements for electrode sheet manufacturing and assembly, resulting in high production efficiency and low cost. In terms of performance, wound batteries have excellent high and low temperature performance, fast charging, a very long service life, stable high output voltage, a robust structure, and excellent earthquake resistance.

[0082] Referring to Figure 6, Figure 6 is an exploded structural schematic diagram of a battery cell 20 according to one or more embodiments. The battery cell 20 is a basic unit that realizes the interconversion of chemical energy and electrical energy within a battery. The battery cell 20 includes an end cap 21, a casing 22, an electrode assembly 23, and other functional components.

[0083] The end cap 21 is a member that is attached to the opening of the casing 22 and isolates the internal environment of the battery cell 20 from the external environment. The shape of the end cap 21 may be adapted to fit the casing 22, without limitation. Alternatively, the end cap 21 may be made of a material with a certain hardness and strength (e.g., an aluminum alloy). In this manner, the end cap 21 is not easily deformed by extrusion or impact, thereby providing the battery cell 20 with higher structural strength and improved safety. The end cap 21 may be provided with a functional member such as an electrode terminal 21a. The electrode terminal 21a may be used for electrical connection with the electrode assembly 23 to output or input electrical energy to or from the battery cell 20. In some embodiments, the end cap 21 may be provided with a pressure release mechanism for releasing internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold. The end cap 21 may be made of various materials, including, but not limited to, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. In some embodiments, an insulating member may also be installed inside the end cap 21, which can be used to isolate the electrical connections in the casing 22 from the end cap 21 to reduce the risk of short circuits. Illustratively, the insulating member may be plastic, rubber, or the like.

[0084] The casing 22, in combination with the end cap 21, is an assembly for forming an internal environment of the battery cell 20. The formed internal environment can be used to accommodate the electrode assembly 23, electrolyte, and other components. The casing 22 and the end cap 21 may be independent components, or an opening may be formed in the casing 22, and the end cap 21 may be attached to cover the opening to form the internal environment of the battery cell 20. The end cap 21 and the casing 22 may be integrated, but are not limited to these. Specifically, the end cap 21 and the casing 22 may form a common connecting surface before other components are inserted into the casing. When the interior of the casing 22 needs to be packaged, the end cap 21 is attached to the casing 22. The casing 22 may have various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, or a hexagonal prism. Specifically, the shape of the casing 22 may be determined according to the specific shape and size of the electrode assembly 23. The casing 22 may be made of a variety of materials, including, but not limited to, copper, iron, aluminum, stainless steel, aluminum alloys, plastics, and the like.

[0085] The electrode assembly 23 is a component where an electrochemical reaction occurs in the battery cell 20. One or more electrode assemblies 23 may be included within the casing 22. The electrode assembly 23 is primarily formed by winding or stacking a positive electrode sheet and a negative electrode sheet, with a separator typically being provided between the positive electrode sheet and the negative electrode sheet. The portions of the positive electrode sheet and the negative electrode sheet that contain active material constitute the main body of the electrode assembly, while the portions of the positive electrode sheet and the negative electrode sheet that do not contain active material constitute the tabs 23a, respectively. The positive electrode tab and the negative electrode tab may both be located at one end of the main body, or may be located at both ends of the main body. During the charge and discharge process of the battery, the positive electrode active material and the negative electrode active material react with the electrolyte, and the tabs 23a are connected to electrode terminals to form a current circuit.

[0086] The positive electrode sheet generally includes a positive electrode current collector and a positive electrode film layer disposed on the positive electrode current collector.

[0087] The positive electrode current collector is typically a conventional metal foil sheet or a composite current collector (metallic materials can be deposited on a polymeric substrate to form a composite current collector). For example, the positive electrode current collector may employ aluminum foil.

[0088] The positive electrode film layer includes a positive electrode active material, an adhesive, a conductive agent, and other optional auxiliary agents.

[0089] For example, the positive electrode active material may include one or more of lithium transition metal oxides, lithium-containing phosphates with an olivine structure and their respective modified compounds, transition metal oxides, polyanion compounds, and Prussian blue analogs. Examples of lithium transition metal oxides include one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their modified compounds. Examples of lithium-containing phosphates with an olivine structure include one or more of lithium iron phosphate, lithium iron phosphate and carbon composites, lithium manganese phosphate, lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, lithium manganese iron phosphate and carbon composites, and their modified compounds. The modified compounds of each of the above materials may be obtained by doping and / or surface coating. All of these materials are commercially available.

[0090] By way of example, the conductive agent may be one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, Super P (SP), graphene, and carbon nanofibers.

[0091] By way of example, the adhesive may be one or more of styrene butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB).

[0092] By way of example, other optional auxiliaries may be thickeners and dispersants (eg, sodium carboxymethylcellulose CMC-Na), PTC thermistor materials.

[0093] The negative electrode sheet generally includes a negative electrode current collector and a negative electrode film layer disposed on the negative electrode current collector.

[0094] The negative electrode current collector may be a conventional metal foil sheet or a composite current collector (e.g., a metal material may be applied to a polymer substrate to form a composite current collector). For example, the negative electrode current collector may employ copper foil.

[0095] The negative electrode film layer includes a negative electrode active material, an adhesive, a conductive agent, and other optional auxiliary agents.

[0096] The negative electrode active material may include one or more of a silicon-based material, a silicon-carbon material, a carbon material, and a selenium-based material. Specifically, the negative electrode active material may include one or more of artificial graphite, natural graphite, hard carbon, soft carbon, a silicon-based material, and a selenium-based material. The silicon-based material may be selected from one or more of silicon elemental, silicon oxide (e.g., silicon suboxide), a silicon-carbon composite, a silicon-nitrogen composite, and a silicon alloy. The selenium-based material may be selected from one or more of selenium elemental, selenium oxide, and a selenium alloy. All of these materials are commercially available. In some embodiments of the present application, the activity density design concept may also be applied to sodium batteries, or is not limited to the type of battery. The present application does not limit the selection and combination of electrode materials, and different positive and negative electrode materials may be combined with different activity density control criteria.

[0097] By way of example, the conductive agent may be one or more of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphite, and carbon nanofibers.

[0098] By way of example, the adhesive may be one or more of styrene butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB).

[0099] By way of example, other optional auxiliaries may be thickeners and dispersants (eg, sodium carboxymethylcellulose CMC-Na), PTC thermistor materials.

[0100] In one embodiment, a positive electrode active material, a negative electrode active material, an adhesive, and a conductive agent are mixed in a predetermined ratio to obtain a positive electrode slurry and a negative electrode slurry, which are then coated on corresponding current collectors and dried to obtain a positive electrode sheet and a negative electrode sheet.

[0101] Furthermore, the battery cell further includes a separator and an electrolyte.

[0102] The separator, located between the positive and negative electrode sheets, acts as an insulating layer to effectively prevent internal short circuits caused by contact between the positive and negative electrode sheets while allowing electrolyte ions to pass through smoothly. The performance of the separator determines the interfacial structure and internal resistance of the battery, and directly affects the mechanical strength and safety performance of the battery.

[0103] The specific type of separator material is not limited, and may be any known material in the art that can be used for battery separators, and a person skilled in the art can select the material according to actual needs. For example, the separator material may include one or more of polyolefin, fluorine-containing polymer, cellulose, and glass fiber. Polyolefins include, but are not limited to, one or more of polypropylene and polyethylene. All of these materials are commercially available.

[0104] In some embodiments, a separator includes a base film and a coating layer located on one or both sides of the base film, the coating layer including a filler. The filler may include an inorganic material, a polymer binder, and a dispersant. The inorganic material may include one or more of boehmite and silica. The polymer binder material may include one or more of PVDF (polyvinylidene fluoride) and polystyrene-acrylic ester. The dispersant material may include polyvinyl alcohol. By providing a coating layer on one or both sides of the separator, the separator's performance can be improved and adjusted. The separator's performance can be adjusted by adjusting the type of filler. For example, the heat resistance of the separator can be improved by adding a filler with insulating and heat-resistant properties. The specific type of material for the base film is not limited and may include one or more of polyethylene, polypropylene, and glass fiber. All of these materials are commercially available.

[0105] The electrolyte serves to conduct ions between the positive electrode sheet and the negative electrode sheet, and may include an electrolyte salt and a solvent.

[0106] By way of example, the electrolyte salt may be one or more selected from lithium hexafluorophosphate (LiPF), lithium tetrafluoroborate (LiBF), lithium perchlorate (LiClO), lithium hexafluoroarsenate (LiAsF), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), difluoroboranyl lithiooxalate (LiDFOB), lithium bisoxalatoborate (LiBOB), lithium difluorophosphate (LiPOF), lithium difluorobis(oxalato)phosphate (LiDFOP), and lithium tetrafluoro(oxalato)phosphate (LiTFOP).

[0107] Exemplary solvents include ethylene carbonate (EC), propylene carbonate (PC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), diisopropyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), n-propyl acetate (PA), methyl propionate (Methyl The compound may be selected from one or more of the following: n-Propyl Propionate (MP), n-Propyl Propionate (EP), n-Propyl Propionate (PP), n-Methyl Butyrate (MB), n-Butyrate (EB), 1,4-Butyrolactone (GBL), 1,4-Butyrolactone (SF), 1,4-Butyrolactone (MSM), 1,4-Butyrolactone (SF), 1,4-Butyrolactone (MSM), 1,4-Butyrolactone (MSE ...

[0108] In some embodiments, the electrolyte solution further includes additives. For example, the additives may include an anode film-forming additive, a cathode film-forming additive, or an additive that can improve some performance of the battery, such as an additive that improves the overcharge performance of the battery, an additive that improves the high-temperature performance of the battery, or an additive that improves the low-temperature performance of the battery.

[0109] The batteries disclosed in the embodiments of the present application can be used in power-consuming devices that use the batteries as a power source or various energy storage systems that use the batteries as an energy storage element. Examples of power-consuming devices include, but are not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric motorcycles, electric vehicles, boats, spacecraft, etc. Here, electric toys may include stationary or mobile electric toys, such as game consoles, electric toy cars, electric toy boats, and electric toy airplanes, and spacecraft may include airplanes, rockets, space shuttles, and spaceships.

[0110] The energy storage system may be an energy storage power system such as a hydroelectric power plant, a thermal power plant, a wind power plant, and a solar power plant.

[0111] In the following embodiment, for convenience of explanation, an example will be described in which the power consumption device of an embodiment of the present application is a vehicle 1000.

[0112] Referring to FIG. 7, FIG. 7 is a structural schematic diagram of a vehicle 1000 according to some embodiments of the present application. The vehicle 1000 may be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle, a range-extended vehicle, etc. A battery 100 is provided inside the vehicle 1000, and may be provided at the bottom, front, or rear of the vehicle 1000. The battery 100 can be used to power the vehicle 1000, for example, the battery 100 can be an operating power source for the vehicle 1000. The vehicle 1000 may further include a controller 200 and a motor 300, where the controller 200 controls the battery 100 to supply power to the motor 300, for example, for operating power needs during starting, navigation, and driving of the vehicle 1000.

[0113] In some embodiments of the present application, the battery 100 can be used not only as an operating power source for the vehicle 1000, but also as a driving power source for the vehicle 1000, providing driving power to the vehicle 1000 in place of, or in place of, gasoline or natural gas.

[0114] The above power consuming devices and energy storage systems are also included in the scope of protection of this application.

[0115] The beneficial effects of the present invention will be further explained below in conjunction with examples.

[0116] In order to clarify the technical problems, technical solutions, and beneficial effects solved by the embodiments of the present application, the following description will be given in more detail in conjunction with the embodiments and drawings. Obviously, the described embodiments are only some of the embodiments of the present application, and not all of the embodiments. The following description of at least one exemplary embodiment is for illustrative purposes only and does not limit the present application and its applications. All other embodiments obtained by those skilled in the art based on the embodiments in the present application without any creative effort are within the scope of protection of the present application.

[0117] 1. Manufacturing of the sensing layer

[0118] A certain amount of temperature-lowering material (e.g., multi-walled carbon nanotube (MWCNT) powder) and a certain amount of temperature-raising material (e.g., graphite flake (GP) powder) were weighed out and placed in a reagent bottle. A certain amount of acetone solution was added as a dispersion medium. The mixture was sonicated in an ultrasonic cleaner at 30 °C for 3 h to disperse the aggregated conductive material (e.g., MWCNT). The mixture was then added to a 20 wt% flexible substrate solution (e.g., TPU / DMAc (dimethylacetamide) solution) and stirred thoroughly using a magnetic stirrer at 50 °C for 12 h. The bottle was then opened to evaporate the acetone in the solution, increasing the viscosity of the precursor solution and facilitating the subsequent knife coating process. The details of the material components and proportions for each example are shown in Table 1.

[0119] An infrared laser was used to fabricate corresponding pits on the PDMS surface according to the designed structural pattern. The details of the obtained microstructure data are shown in Table 2.

[0120] The processed PDMS mold was placed in anhydrous ethanol for 30 min and ultrasonically cleaned. To reduce bubbles during the knife coating process, the mold was preheated to 30 °C on a heating table. A certain amount of precursor solution was then measured out with a pipette and placed on the mold surface. The solution was then smoothed with a glass rod. The mold was then placed on a heating plate at 50 °C for 1 h, and then heated at 120 °C to completely evaporate the DMAc and acetone solvents.

[0121] The cured sensing layer film was removed from the PDMS mold and cut. To ensure the flatness of the sensing layer film, it was placed in an oven at 80°C for heat press molding. Figure 3b shows an optical microscope image of the sensing layer film with a microstructure. The reverse molding of the microstructure is excellent, and the 1st, 2nd, and 3rd level microstructures can be clearly identified.

[0122] Second, performance testing

[0123] Resistance Test

[0124] The fabricated pressure sensor is placed in a high-temperature box and connected to the corresponding resistance meter. A 1000N weight is added, and the initial resistance R0 is recorded. The external temperature is changed, and the 1000N weight is continuously added, and the resistance R is recorded. The resistance change rate = (R-R0) / R0.

[0125] [Table 1]

[0126] [Table 2]

[0127] Referring to the data in Table 1 and Figure 8, Figure 8 is a schematic diagram of the resistance change rate versus temperature curves for the examples and comparative examples. In this embodiment, by mixing a temperature-raising material with a temperature-lowering material, the resistance decrease caused by the temperature-lowering material is used to balance the resistance increase caused by the temperature-raising material, or the resistance increase caused by the temperature-lowering material is used to balance the resistance decrease caused by the temperature-lowering material. This results in the resistance of the mixed material not changing significantly with temperature, i.e., the resistivity of the mixed material is hardly affected by temperature. This improves the detection sensitivity of the sensor at different temperatures, reduces detection errors caused by temperature changes, expands the sensor's operating temperature range, and improves detection sensitivity. Additionally, by fabricating a specific microstructure on the sensitive layer that contacts the electrode, the contact characteristics between the sensitive layer and the electrode can be changed, thereby improving or adjusting the piezoresistance characteristics of the sensor. Introducing a specific microstructure can improve performance indicators such as the sensitivity and measurement range of the pressure sensor to a certain extent.

[0128] The above is merely an embodiment of the present application and does not limit the patent scope of the present application. Any conversion of an equivalent structure or equivalent process made by utilizing the contents of the specification and drawings of the present application, or any direct or indirect application to other related technical fields, is also included in the patent protection scope of the present application. [Explanation of symbols]

[0129] 1000—vehicle, 300—motor, 200—controller, 100—battery, 10—casing, 11—first part, 12—second part, 20—battery cell, 21—end cap, 21a—electrode terminal, 22—casing, 23—electrode assembly, 400—pressure sensor, 40—electrode layer, 42—sensing layer, 420—base layer, 422—protrusion structure, 4221—protrusion, 4222—protrusion, 4223—protrusion, 401—first electrode, 402—second electrode, 403—electrode base, 44—corrosion-resistant protective layer, 46—isolation layer, 48—sensing layer adhesive, 49—isolation layer adhesive

Claims

1. A conductive material comprising: a flexible substrate; and conductive particles dispersed in the flexible substrate, the conductive particles comprising a temperature increasing material and a temperature decreasing material, the temperature increasing material being a material whose resistivity increases as temperature increases, and the temperature decreasing material being a material whose resistivity decreases as temperature increases, the blending ratio of the temperature decreasing material to the temperature increasing material being set to be within a temperature range of -40°C to +200°C, and the absolute value of the rate of change in resistivity of the conductive material being 0.01 or less.

2. 2. The conductive material according to claim 1, wherein a compounding ratio of the temperature lowering material to the temperature increasing material is set to be within a temperature range of +25°C to +80°C, and an absolute value of a rate of change in resistivity of the conductive material is 0.008 or less.

3. 3. The conductive material according to claim 1, wherein a compounding ratio of the temperature lowering material to the temperature increasing material is set to be within a temperature range of −40° C. to +200° C., and an absolute value of a rate of change in resistance of the conductive material is 0.01 or less.

4. The compounding ratio of the temperature lowering material and the temperature increasing material is set to be within a temperature range of +25°C to +80°C, The conductive material according to claim 3 , wherein the absolute value of the rate of change in resistance of the conductive material is 0.008 or less.

5. Within a temperature range of −40° C. to +200° C., the absolute value ratio of the temperature coefficient of resistance of the temperature-raising material to the temperature coefficient of resistance of the temperature-lowering material is 30:1 to 1:30; The conductive material according to any one of claims 1 to 4, wherein the temperature coefficient of resistance is a relative change in the resistance value of the material when the temperature changes by 1°C.

6. 6. The conductive material of claim 1, wherein the absolute value of the ratio of the rate of change of resistivity of the temperature increasing material to the rate of change of resistivity of the temperature decreasing material is 25:1 to 1:25 within the temperature range of -40°C to +200°C.

7. The conductive material according to any one of claims 1 to 6, wherein the mass ratio of the temperature increasing material to the temperature decreasing material is 15:1 to 1:

20.

8. The electrical conductivity of the temperature-raising material is 1 S·m －１ and / or The electrical conductivity of the temperature-reducing material is 1 S·m －１ and / or The electrical conductivity of the conductive material is 1 S m －１ The conductive material according to any one of claims 1 to 7, wherein

9. The conductive material according to any one of claims 1 to 8, wherein the temperature-raising material comprises one or more of graphite, gold powder, silver powder, nickel powder, zinc-chromium alloy, nickel-copper alloy, and the like.

10. 10. The conductive material according to claim 1, wherein the temperature-lowering material comprises one or more of carbon nanotubes, ketjen black, graphene, carbon black, and ceramic materials based on metal oxides of manganese, cobalt, nickel, and copper.

11. 11. The conductive material according to claim 1, wherein the conductive particles include graphite particles and carbon nanotube particles, and the mass ratio of the graphite particles to the carbon nanotube particles is 1:1 to 1:20, and optionally 1:9 to 1:

15.

12. The carbon nanotube particles include multi-walled carbon nanotube particles having an outer diameter of 6 to 13 nm and a length of 2.5 to 20 μm; and / or The conductive material according to claim 11, wherein the particle size Dv50 of the graphite particles is 7 to 10 μm.

13. 13. The conductive material according to any one of claims 1 to 12, wherein the mass ratio of the flexible substrate to the conductive particles is from 15:1 to 5:1, optionally from 12:1 to 8:

1.

14. 14. The conductive material of claim 13, wherein the flexible substrate comprises one or more of thermoplastic polyurethane, polyvinyl alcohol, chloroprene rubber, nitrile rubber, styrene-butadiene block copolymer, polyacrylic acid, and optionally an aliphatic thermoplastic polyurethane.

15. an electrode layer; and a sensing layer employing the conductive material of any one of claims 1 to 14.

16. 16. The pressure sensor of claim 15, wherein the sensing layer includes a base layer and at least two protruding structures of different heights protruding from the base layer, each protruding structure including at least one protrusion, each protrusion being located on a side of the base layer facing the electrode layer, and a contact area between each protrusion and the electrode layer being configured to change with changes in pressure applied to the electrode layer.

17. Providing a flexible substrate slurry; adding conductive particles to the flexible substrate slurry, the conductive particles including a temperature increasing material and a temperature decreasing material, the temperature increasing material being a material whose resistivity increases as the temperature increases, and the temperature decreasing material being a material whose resistivity decreases as the temperature increases, the compounding ratio of the temperature decreasing material and the temperature increasing material being set to be within a temperature range of -40°C to +200°C, and the absolute value of the rate of change in resistivity of the conductive material being 0.01 or less; and curing the flexible substrate slurry to form a pressure sensitive layer.

18. A battery cell comprising a casing and the pressure sensor according to claim 15 or 16, wherein the pressure sensor is located inside the casing.

19. 20. A power consuming device comprising the battery cell of claim 18.

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