Current collector, secondary battery, and electric device

Abstract

The application belongs to the technical field of batteries, and particularly relates to a current collector, a secondary battery and an electric device. The current collector comprises a metal base material, at least one surface of which is provided with a first groove; a first heat dissipation protrusion is arranged in the first groove and protrudes from the surface of the metal base material; and the first heat dissipation protrusion comprises a ceramic heat dissipation material. The current collector provided with the first heat dissipation protrusion breaks the mirror reflection of the smooth surface, changes the reflection of infrared waves from the main to absorption and radiation, the former is reflection of heat, and the latter is absorption of heat and then radiation, thereby reducing the radial heat conduction loss. Moreover, compared with the smooth surface, the effective radiation area of the current collector provided with the first heat dissipation protrusion for heat radiation exchange with the outside world is increased by tens of times, the larger the area of radiation heat is, the more heat is radiated per unit time, so that the heat dissipation efficiency can be improved and the battery life can be prolonged.

Description

Technical Field

[0001] This application belongs to the field of battery technology, specifically relating to a current collector, a secondary battery, and an electrical device. Background Technology

[0002] With the surge in demand for high-energy-density, long-cycle-life batteries from electric vehicles, wound batteries (such as 46-series large cylindrical lithium-ion batteries) are currently the mainstream product. The core heat generation of this type of battery is located in the central axis region (where the winding is located), with heat transferred radially perpendicular to the winding direction, such as positive electrode → separator → negative electrode… → casing. However, the electrodes and separator have extremely low thermal conductivity, resulting in insufficient radial heat transfer efficiency and causing high temperatures to easily accumulate in the central region. Simultaneously, the heat generated during battery operation also radiates outwards in the form of infrared waves. However, traditional current collectors have smooth surfaces and low infrared emissivity, causing most of the infrared heat to be reflected back into the battery, exacerbating the high-temperature state in the central axis region. This high temperature state accelerates the decomposition of the SEI film and the degradation of electrode materials, severely reducing battery life. Summary of the Invention

[0003] This application aims to provide a current collector, a secondary battery, and an electrical device to solve the problem of poor heat dissipation of batteries under fast charging.

[0004] To address the aforementioned technical problems, this application provides a current collector comprising: a metal substrate having a first groove on at least one surface; a first heat dissipation protrusion disposed in the first groove and protruding from the surface of the metal substrate; the first heat dissipation protrusion comprising a ceramic heat dissipation material.

[0005] In one embodiment, the first heat dissipation protrusion is a nanopillar; wherein the axial direction of the nanopillar is perpendicular to the surface of the metal substrate.

[0006] In one embodiment, there are multiple nanopillars, and the array of multiple nanopillars is arranged on the bottom surface of the first groove.

[0007] In one embodiment, the shape of the nanopillar includes at least one of the following: cylinder, right prism.

[0008] In one embodiment, at least one of the following conditions is met: a. the diameter of the nanopillar is 50 nm to 100 nm; b. the height of the nanopillar protruding from the surface of the metal substrate is 0.1 μm to 0.4 μm; c. the spacing between adjacent nanopillars is 0.6 μm to 0.96 μm; d. the thickness of the metal substrate is 3.5 μm to 20 μm; e. the depth of the first groove is 0.4 μm to 0.7 μm; f. the material of the metal substrate includes one of the following: aluminum foil and copper foil; g. the projection of the first groove on the metal substrate is circular, and the diameter of the circle is 55 nm to 105 nm; h. the spacing between adjacent first grooves is 0.6 μm to 0.96 μm.

[0009] In one embodiment, the ceramic heat dissipation material includes at least one of the following: SiO2, SiC, Si3N4, and Al2O3.

[0010] This application also provides a secondary battery, the secondary battery comprising: a housing and a core disposed within the housing, the core comprising an electrode and a separator, the electrode comprising the current collector described above.

[0011] In one embodiment, the housing includes a second heat dissipation protrusion; wherein, the inner surface of the housing is provided with a second groove; the second heat dissipation protrusion is disposed in the second groove and protrudes from the inner surface of the housing; the second heat dissipation protrusion comprises a ceramic heat dissipation material.

[0012] In one embodiment, at least one of the following conditions is met: a. the depth of the second groove is 0.4 μm to 0.7 μm; b. the height of the second heat dissipation protrusion protruding from the inner surface of the housing is 0.1 μm to 0.4 μm; c. the projection of the second groove onto the inner surface of the housing is circular, and the diameter of the circle is 55 nm to 105 nm; d. the interval between adjacent second grooves is 0.6 μm to 0.96 μm.

[0013] This application also provides an electrical device, characterized in that the electrical device includes the above-mentioned secondary battery; wherein the secondary battery is used to provide electrical energy to the electrical device.

[0014] This application provides a current collector comprising a metal substrate, at least one surface having a first groove; a first heat dissipation protrusion disposed in the first groove and protruding from the surface of the metal substrate; the first heat dissipation protrusion comprising a ceramic heat dissipation material. The current collector with the first heat dissipation protrusion breaks the specular reflection of a smooth surface, changing infrared waves from being primarily reflected to being primarily absorbed and radiated. The former reflects heat, while the latter absorbs heat and then radiates it, reducing radial heat conduction loss. Furthermore, compared to a smooth surface, the current collector with the first heat dissipation protrusion has an effective radiation area for heat exchange with the outside world increased by tens of times. The larger the area for radiating heat, the more heat is radiated per unit time, thus improving heat dissipation efficiency and extending battery life.

[0015] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0016] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a plan view of the current collector according to an embodiment of this application; Figure 2 A perspective view of a current collector according to an embodiment of this application; Figure 3 for Figure 1 A cross-sectional view along the middle AA.

[0017] Reference numerals: 101-metal substrate, 102-first groove, 201-first heat dissipation protrusion. Detailed Implementation

[0018] The embodiments of this application will now be described in detail. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0019] The terms "first" and "second" in the specification and claims of this application may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise stated, "multiple" means two or more. Furthermore, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0020] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0021] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0022] This application discloses a current collector, such as Figure 1-3 As shown, it includes: a metal substrate 101, at least one surface of which is provided with a first groove 102; a first heat dissipation protrusion 201, disposed in the first groove 102 and protruding from the surface of the metal substrate 101; the first heat dissipation protrusion 201 comprises a ceramic heat dissipation material.

[0023] The current collector with the first heat dissipation protrusion breaks the specular reflection of the smooth surface, changing the infrared wave from being mainly reflected to being mainly absorbed and radiated. The former reflects heat, while the latter absorbs heat and then radiates it, reducing radial heat conduction loss. Moreover, compared to a smooth surface, the current collector with the first heat dissipation protrusion has an effective radiation area for heat exchange with the outside world that is tens of times larger. The larger the area for radiating heat, the more heat is radiated per unit time, thus improving heat dissipation efficiency and extending battery life.

[0024] The ceramic heat dissipation material has a slow corrosion rate in the electrolyte, which helps maintain the long-term stability of the raised structure. At the same time, the ceramic heat dissipation material is formed in the first groove by deposition, thereby achieving a firm bond with the metal substrate.

[0025] In one embodiment, the first heat dissipation protrusion 201 is a nanopillar, and the axial direction of the nanopillar is perpendicular to the surface of the metal substrate. This nanopillar has a simple fabrication process and can provide a large effective radiation area. Since the heat dissipation path of a wound battery is positive electrode → separator → negative electrode… → casing, the perpendicularity of the nanopillar's axial direction to the metal substrate surface helps to transfer heat to the casing through directional radiation, reducing heat conduction loss.

[0026] In one embodiment, there are multiple nanopillars, and the array of multiple nanopillars is arranged on the bottom surface of the first groove. Multiple nanopillars can enhance the effect of radiative heat dissipation, such as increasing the infrared emissivity of the current collector surface from 0.04~0.1 of the metal substrate to more than 0.8, thereby increasing the radiative heat dissipation power by 8 to 20 times.

[0027] The spacing between adjacent nanopillars is 0.6 μm to 0.96 μm. This range can reduce the risk of lateral thermal radiation shielding between adjacent nanopillars, thereby improving thermal radiation capability.

[0028] Specifically, the spacing between adjacent nanopillars is 0.6 μm, 0.7 μm, 0.8 μm, 0.96 μm, or any value within the above range.

[0029] The nanopillars can be cylindrical or rectangular prisms. Since the nanopillars are set in the first groove and protrude from the surface of the metal substrate, the cross-sectional dimension of the first groove must be larger than the diameter of the nanopillars, and the depth of the first groove must be smaller than the height of the nanopillars themselves.

[0030] In one embodiment, the depth of the first groove is 0.4 μm to 0.7 μm, and the projection of the first groove onto the metal substrate is circular with a diameter of 55 nm to 105 nm. The corresponding height of the nanopillar is 0.5 μm to 0.8 μm (i.e., the height of the nanopillar protruding from the current collector surface is 0.1 μm to 0.4 μm), and the diameter of the nanopillar is 50 nm to 100 nm. These parameters not only simplify the processing but also ensure both thermal radiation capability and the mechanical strength of the current collector.

[0031] Specifically, the depth of the first groove is 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, or any value within the above range, and the diameter of the circle is 55 nm, 60 nm, 80 nm, 105 nm, or any value within the above range. The height of the nanopillar is 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, or any value within the above range, and the diameter of the nanopillar is 50 nm, 55 nm, 75 nm, 100 nm, or any value within the above range.

[0032] In one embodiment, the ceramic heat dissipation material includes at least one of the following: SiO2, SiC, Si3N4, and Al2O3. Mid-infrared emissivity refers to the infrared radiation energy emitted by an object in the mid-infrared band (typically 2.5μm~25μm). These ceramic materials all have emissivity above 0.8, exhibiting good thermal radiation capabilities.

[0033] In one embodiment, the metal substrate material includes one of the following: aluminum foil or copper foil. The selection of this material depends on whether the current collector is used as a positive or negative electrode current collector. Aluminum foil has oxidation resistance and high potential resistance, ensuring the stability of the current collector, and can be used for positive electrode current collectors. Copper foil has reduction resistance and low potential resistance, making it difficult to be reduced or react with the electrolyte, and can be used for negative electrode current collectors.

[0034] This application also provides a method for preparing a current collector. For clarity, the following uses aluminum foil as an example, including: 1. Pre-treat the surface of the aluminum foil.

[0035] Specifically, the process involves: immersing the aluminum foil in an acetone solution for ultrasonic cleaning to remove surface oil; then transferring it to an alkaline solution for immersion to corrode the oxide layer (Al2O3) on the surface, exposing fresh metallic aluminum; and finally rinsing it clean with deionized water.

[0036] The ultrasound time is 8 to 12 minutes.

[0037] Specifically, the ultrasound time is 8 min, 10 min, 12 min, or any value within the above range.

[0038] The alkaline solution is a 5 wt% NaOH solution. The soaking time is 3 to 7 minutes.

[0039] Specifically, the soaking time is 3 minutes, 5 minutes, 7 minutes, or any value within the above range.

[0040] 2. Etch the first groove on the surface of the aluminum foil.

[0041] For example, a laser direct writing system can be used to etch the first groove on the surface of the aluminum foil.

[0042] The etching parameters include: laser power of 1.6W~1.8W and scanning speed of 430mm / s~470mm / s. These etching parameters ensure the uniformity of the grooves and also save processing time.

[0043] Specifically, the laser power is 1.6W, 1.7W, 1.8W or any value within the above range, and the scanning speed is 430mm / s, 450mm / s, 470mm / s or any value within the above range.

[0044] The etched first grooves are arranged in an array, with a spacing of 0.6μm to 0.96μm between adjacent first grooves, a depth of 0.4μm to 0.7μm, and a circular projection of the first groove onto the metal substrate with a diameter of 55nm to 105nm. Of course, the cross-section of the first groove can also be of other shapes.

[0045] Specifically, the interval between adjacent first grooves is 0.6μm, 0.7μm, 0.8μm, 0.96μm or any value within the above range, the depth of the first groove is 0.4μm, 0.5μm, 0.6μm, 0.7μm or any value within the above range, and the diameter of the circle is 55nm, 60nm, 80nm, 105nm or any value within the above range.

[0046] 3. Deposit the first heat dissipation protrusion in the first groove.

[0047] If an atomic layer deposition (ALD) system is used, the first heat dissipation protrusion material is deposited in the first groove.

[0048] The deposition process parameters include: a pulse time of 0.3s to 0.7s for the first heat dissipation protrusion material, a nitrogen purging time of 2s to 4s, and 70 to 80 deposition cycles. This deposition process ensures the stability and thickness of the first heat dissipation protrusion material deposition.

[0049] Specifically, the pulse time of the first heat dissipation protrusion material is 0.3s, 0.5s, 0.7s or any value within the above range, the nitrogen purging time is 2s, 3s, 4s or any value within the above range, and the number of depositions is 70, 75, 80 or any value within the above range.

[0050] In addition, the sample stage can be rotated during the deposition process to improve the uniformity of the deposition.

[0051] The deposition height of the first heat dissipation protrusion is greater than the depth of the first groove, and the deposition cross-section of the first heat dissipation protrusion is smaller than the cross-section of the first groove.

[0052] 4. Perform post-processing on the current collector.

[0053] Specifically, the process involves placing the deposited sample in an N2 atmosphere annealing furnace to decompose unreacted byproducts and avoid residual contamination. Then, the sample is ultrasonically cleaned with a 75 vol% ethanol solution to remove surface organic matter, and finally dried with nitrogen to obtain the current collector.

[0054] This application also provides a secondary battery, which includes: a casing and a core disposed within the casing, the core including an electrode and a separator, the electrode including a current collector.

[0055] To improve the heat dissipation of the battery, a second groove can be provided on the inner surface of the casing; a second heat dissipation protrusion is provided in the second groove and protrudes from the inner surface of the casing; the second heat dissipation protrusion contains ceramic heat dissipation material.

[0056] In one embodiment, the second heat dissipation protrusion is a nanopillar. The nanopillar can be cylindrical or rectangular prism. Since the nanopillar is disposed in the second groove and protrudes from the surface of the shell, the cross-sectional dimension of the second groove is larger than the diameter of the second heat dissipation protrusion nanopillar, and the depth of the second groove is smaller than the height of the second heat dissipation protrusion nanopillar.

[0057] In one embodiment, the depth of the second groove is 0.4 μm to 0.7 μm, and the projection of the second groove onto the inner surface of the shell is circular with a diameter of 55 nm to 105 nm. The corresponding height of the second heat dissipation protrusion nanopillar is 0.5 μm to 0.8 μm (i.e., the height of the second heat dissipation protrusion protruding from the inner surface of the shell is 0.1 μm to 0.4 μm), and the diameter of the second heat dissipation protrusion nanopillar is 50 nm to 100 nm. These parameters not only simplify the manufacturing process but also ensure both thermal radiation capability and the mechanical strength of the current collector.

[0058] Specifically, the depth of the second groove is 0.4μm, 0.5μm, 0.6μm, 0.7μm, or any value within the above range, and the diameter of the circle is 55nm, 60nm, 80nm, 105nm, or any value within the above range. The height of the second heat dissipation protrusion nanopillar is 0.5μm, 0.6μm, 0.7μm, 0.8μm, or any value within the above range, and the diameter of the second heat dissipation protrusion nanopillar is 50nm, 55nm, 75nm, 100nm, or any value within the above range.

[0059] In one embodiment, there are multiple second grooves arranged in a row on the inner surface of the shell, and the interval between adjacent second grooves is 0.6μm to 0.96μm. This range can reduce the risk of lateral thermal radiation shielding of adjacent nanopillars, thereby improving thermal radiation capability.

[0060] Specifically, the interval between adjacent second grooves is 0.6μm, 0.7μm, 0.8μm, 0.9μm, 0.96μm or any value within the above range.

[0061] In one embodiment, the ceramic heat dissipation material of the second protrusion corrodes slowly in the electrolyte, which is beneficial to maintaining the long-term stability of the protrusion structure; at the same time, the ceramic heat dissipation material is formed in the second groove by deposition, thereby achieving a firm bond with the shell.

[0062] This application also provides an electrical device, which includes a secondary battery; wherein the secondary battery is used to provide electrical energy to the electrical device.

[0063] To better explain this solution, embodiments and comparative examples are also provided below.

[0064] Example 1 Methods for preparing current collectors include: 1. Immerse the aluminum foil in acetone solution and ultrasonically clean for 10 minutes; then transfer it to 5wt% NaOH solution and soak for 5 minutes; finally rinse it clean with deionized water.

[0065] 2. The first groove is etched on the aluminum foil surface using a laser direct writing system.

[0066] The etching parameters include: laser power of 1.7W and scanning speed of 450mm / s.

[0067] The interval between adjacent first grooves is 0.75 μm, the depth of the first groove is 0.4 μm, the projection of the first groove on the metal substrate is circular, and the diameter of the circle is 105 nm.

[0068] 3. Using an atomic layer deposition (ALD) system, SiO2 nanopillars are deposited in the first groove.

[0069] The pulse time of the first heat dissipation protrusion material is 0.5s, the nitrogen purging time is 3s, and the deposition number is 75 times.

[0070] The SiO2 nanopillars have a height of 0.8 μm and a diameter of 50 nm.

[0071] 4. Place the deposited sample in an N2 atmosphere annealing furnace to decompose unreacted byproducts; then ultrasonically clean it with 75 vol% ethanol solution to obtain the current collector.

[0072] Example 2 The difference from implementing step 1 is that the aluminum foil in step 1 is changed to copper foil, and the data is detailed in Table 1.

[0073] Example 3 The difference from implementation 1 is that in step 2, the spacing between adjacent first grooves is adjusted to 0.96 μm.

[0074] Example 4 The difference from implementation 1 is that in step 2, the spacing between adjacent first grooves is adjusted to 0.6 μm.

[0075] Example 5 The difference from implementing step 1 is that in step 2, the depth of the first groove is adjusted to 0.5 μm.

[0076] Example 6 The difference from implementing step 1 is that in step 2, the depth of the first groove is adjusted to 0.6 μm.

[0077] Example 7 The difference from implementing step 1 is that in step 2, the depth of the first groove is adjusted to 0.7 μm.

[0078] Example 8 The difference from implementing step 1 is that in step 2, the circular diameter of the first groove is adjusted to 75nm.

[0079] Example 9 The difference from implementing step 1 is that in step 2, the circular diameter of the first groove is adjusted to 55 nm.

[0080] Example 10 The difference from implementing step 1 is that in step 3, the height of the nanopillar is adjusted to 0.5 μm.

[0081] Example 11 The difference from implementing step 1 is that in step 3, the height of the nanopillar is adjusted to 0.6 μm.

[0082] Example 12 The difference from implementing step 1 is that in step 3, the height of the nanopillar is adjusted to 0.7 μm.

[0083] Example 13 The difference from implementing step 1 is that the diameter of the nanopillars is adjusted to 60 nm in step 3.

[0084] Example 14 The difference from implementing step 1 is that the diameter of the nanopillars is adjusted to 80 nm in step 3.

[0085] Example 15 The difference from implementing step 1 is that in step 3, the diameter of the nanopillars is adjusted to 100 nm.

[0086] Example 16 The difference from implementing step 1 is that the material of the nanopillars in step 3 is changed to SiC.

[0087] Example 17 The difference from implementing step 1 is that the material of the nanopillars in step 3 is changed to Si3N4.

[0088] Example 18 The difference from implementing step 1 is that the material of the nanopillars in step 3 is changed to Al2O3.

[0089] Comparative Example 1 The difference from Example 1 is that the current collector is a smooth aluminum foil.

[0090] Comparative Example 2 The difference from Example 1 is that the height of the SiO2 nanopillars in step 3 is adjusted to 0.3 μm.

[0091] Comparative Example 3 The difference from Example 1 is that the height of the SiO2 nanopillars in step 3 is adjusted to 0.4 μm.

[0092] Infrared emissivity, thermal radiation performance, and cycle capacity retention were tested on the current collector surfaces of the examples and comparative examples. The test data are shown in Table 2.

[0093] I. Infrared emissivity testing method.

[0094] Test principle: Based on Kirchhoff's law (ε=α=1-R, neglecting transmission), Fourier transform infrared spectroscopy (FTIR) is used to measure the sample's thermal radiation in the main wavelength range (5~20μm, corresponding to wavenumbers 500~2000cm). - ¹) The reflectivity R is obtained, and then the emissivity ε is calculated.

[0095] Test steps: 1. Cut the current collector into 2cm×2cm squares and wipe the surface with anhydrous ethanol to ensure there are no contaminants.

[0096] 2. Preheat the unit for 30 minutes. Use a standard gold plate (99.9% reflectivity) to calibrate the integrating sphere baseline and set the wavenumber range to 500~2000cm. -1 4cm resolution -1 The number of scans was 32.

[0097] 3. Fix the sample at the entrance of the integrating sphere, ensuring the surface is flat and wrinkle-free, and collect the reflectance spectrum R(λ). Measure the reflectance at 3 different locations (center + edge) for each sample and take the average value.

[0098] 4. Select 10 characteristic points (λ=5μm, 8μm, 10μm, 12μm, 14μm, 16μm, 18μm, 20μm) in the 5~20μm band (corresponding to the main peak of mid-infrared thermal radiation), calculate the average reflectivity R, and the emissivity ε=1-R.

[0099] II. Test methods for thermal radiation performance.

[0100] Test principle: Simulate the heating scenario of 1C fast charging of 46 series large cylindrical battery. By controlling the temperature of the battery center, measure the temperature difference between the center and the outer shell (radial temperature difference), and then evaluate the uniformity of heat radiation through the temperature difference.

[0101] Test steps: 1. Attach a 45mm diameter circular current collector sample to the inner wall of the simulated battery using thermally conductive silicone grease (covering 80% of the area), ensuring no air bubbles are present.

[0102] The simulated battery is a cylinder with a diameter of 46mm and a height of 80mm. The outer shell is made of aluminum alloy, and the inside is filled with paraffin to simulate the heat capacity of the core. A 50W heating element is embedded in the center.

[0103] 2. The test was conducted in a constant temperature chamber at an ambient temperature of 25℃±1℃, without forced convection.

[0104] 3. Turn on the DC power supply and adjust the heating element power to 50W to simulate the central heating power of a 1C fast-charging battery; then wait for the temperature to stabilize (center temperature fluctuation < 0.5℃, and stabilize for about 30 minutes), and record the temperatures of the center thermocouple (T1) and the outer shell thermocouple (T2). Finally, calculate the radial temperature difference ΔT = T1 - T2 (unit: ℃). The smaller the radial temperature difference, the better the heat dissipation effect.

[0105] III. Cyclic capacity retention test method.

[0106] Test principle: A simulated battery with assembled current collector was subjected to 1C constant current charge-discharge cycles, and the capacity retention rate was calculated after 500 cycles. The simulated battery had a capacity of 2 Ah, and the active material and metal substrate of the positive electrode were LiNi. 0.8 Co 0.1 Mn 0.1 O2 and aluminum foil, the active material of the negative electrode and the metal substrate are graphite and copper foil.

[0107] Test steps: 1. In the embodiment, a positive electrode sheet is obtained by coating the surface of the current collector with a positive electrode active material slurry. The aluminum foil in the method of Example 1 is replaced with copper foil to prepare a negative electrode current collector. Then, a negative electrode sheet (covering 80% of the area) is obtained by coating the surface of the negative electrode current collector with a negative electrode active material slurry. Then, a core is made by winding process, which is then inserted into a steel shell with a diameter of 46mm and a height of 80mm. Electrolyte (1mol / L LiPF6 / EC:DEC=3:7) is injected and the shell is sealed to obtain a battery.

[0108] 2. Place the battery in a constant temperature chamber at 25℃ for 4 hours, charge it at a constant current of 0.5C to 4.2V, switch to constant voltage charging until the current is ≤0.05C, and let it stand for 10 minutes; then discharge it at a constant current of 0.5C to 3.0V, record the discharge capacity C0 (Ah), and repeat 3 times to take the average value.

[0109] 3. Charge the battery at a constant current of 1C to 4.2V, then switch to constant voltage charging until the current is ≤0.05C, and let it stand for 10 minutes; then discharge it at a constant current of 1C to 3.0V, and record the discharge capacity C for each discharge. i The loop runs 500 times, and the capacity is recorded every 50 iterations.

[0110] 4. Capacity retention rate after 500 cycles = (C 500 / C0)×100%; where C 500 This is the capacity for the 500th discharge.

[0111] Table 1. Parameter table for the embodiments and comparative examples

[0112] Table 2 Test Data for Examples and Comparative Examples

[0113] According to the data in Table 2, compared with the comparative example, the embodiment significantly improved the infrared emissivity and enhanced the radiation heat dissipation capability by setting a first heat dissipation protrusion containing ceramic heat dissipation material on the surface of the current collector; at the same time, it effectively reduced the radial temperature difference and made the temperature distribution more uniform; and, thanks to the above-mentioned heat dissipation optimization and the excellent corrosion resistance of the ceramic material, the capacity retention rate of the embodiment after 500 cycles was significantly higher than that of the comparative example.

[0114] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0115] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A current collector, characterized in that, include: A metal substrate, at least one surface of which has a first groove; A first heat dissipation protrusion is disposed in the first groove and protrudes from the surface of the metal substrate; The first heat dissipation protrusion comprises a ceramic heat dissipation material.

2. The current collector according to claim 1, characterized in that, The first heat dissipation protrusion is a nanopillar; The axial direction of the nanopillar is perpendicular to the surface of the metal substrate.

3. The current collector according to claim 2, characterized in that, There are multiple nanopillars, and the array of multiple nanopillars is arranged on the bottom surface of the first groove.

4. The current collector according to claim 2, characterized in that, The shape of the nanopillar includes at least one of the following: cylinder, right prism.

5. The current collector according to claim 4, characterized in that, Meet at least one of the following: a. The diameter of the nanopillars is 50 nm to 100 nm; b. The height of the nanopillar protruding from the surface of the metal substrate is 0.1 μm to 0.4 μm; c. The spacing between adjacent nanopillars is 0.6 μm to 0.96 μm; d. The thickness of the metal substrate is 3.5 μm to 20 μm; e. The depth of the first groove is 0.4μm~0.7μm; f. The material of the metal substrate includes one of the following: aluminum foil or copper foil; g. The projection of the first groove on the metal substrate is circular, and the diameter of the circle is 55nm~105nm; h. The spacing between adjacent first grooves is 0.6μm~0.96μm.

6. The current collector according to claim 1, characterized in that, The ceramic heat dissipation material includes at least one of the following: SiO2, SiC, Si3N4, and Al2O3.

7. A secondary battery, characterized in that, The secondary battery includes: a housing and a winding core disposed within the housing, the winding core including an electrode and a separator, the electrode including a current collector as described in any one of claims 1 to 6.

8. The secondary battery according to claim 7, characterized in that, The housing includes a second heat dissipation protrusion; The inner surface of the housing is provided with a second groove; the second heat dissipation protrusion is disposed in the second groove and protrudes from the inner surface of the housing; the second heat dissipation protrusion comprises ceramic heat dissipation material.

9. The secondary battery according to claim 7, characterized in that, Meet at least one of the following: a. The depth of the second groove is 0.4μm~0.7μm; b. The height of the second heat dissipation protrusion protruding from the inner surface of the housing is 0.1μm~0.4μm; c. The projection of the second groove onto the inner surface of the housing is circular, and the diameter of the circle is 55nm~105nm; d. The spacing between adjacent second grooves is 0.6μm~0.96μm.

10. Electrical equipment, characterized in that, The electrical equipment includes the secondary battery as described in any one of claims 7 to 9; The secondary battery is used to provide power to the electrical equipment.

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