Lithium ion battery positive electrode with temperature control performance and preparation method thereof

Abstract

The invention discloses a lithium ion battery positive electrode with temperature control performance. The lithium ion battery positive electrode comprises a composite current collector and a positive electrode active material coating coated on at least one surface of the composite current collector, the composite current collector comprises a first aluminum foil layer, a second aluminum foil layer, and a first temperature control material layer and a second temperature control material layer which are arranged between the first aluminum foil layer and the second aluminum foil layer; a first groove and a second groove are formed in the surface of the first aluminum foil layer side by side, a third groove and a fourth groove are formed in the surface of the second aluminum foil layer side by side, the first groove corresponds to the third groove, and the second groove corresponds to the fourth groove; the first groove, the second groove, the third groove and the fourth groove are bent and extend in a zigzag shape from the center of the surface of the aluminum foil layer to the edge of the surface of the aluminum foil layer. A first temperature control material layer is embedded between the first groove and the third groove; and a second temperature control material layer is embedded between the second groove and the fourth groove. The lithium ion battery positive electrode provided by the invention has excellent temperature control performance.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium ion batteries, and in particular to a lithium ion battery positive electrode with temperature control performance and a preparation method thereof. Background Art

[0002] Lithium-ion batteries have been widely used in portable electronic devices, power tools, electric vehicles and other fields due to their high energy density, long cycle life and environmental friendliness. However, the performance and safety of lithium-ion batteries are greatly affected by temperature. In practical applications, lithium-ion batteries often face the challenges of low or high temperature environments, which not only affects the discharge performance of the battery, but may also cause serious safety hazards.

[0003] Under low temperature conditions, such as below -15°C, the discharge capacity of conventional lithium-ion batteries will drop significantly. This is because low temperatures will increase the viscosity of the electrolyte inside the battery, reduce ion mobility, and hinder charge transfer, thus limiting the battery's discharge capacity. This low-temperature performance degradation seriously restricts the application of lithium-ion batteries in cold environments. For example, when using electric vehicles in winter or at high altitudes, the battery's range will be greatly reduced.

[0004] In addition, in high temperature environments, such as above 60°C, lithium-ion batteries face the risk of thermal runaway. High temperatures will accelerate side reactions inside the battery, such as electrolyte decomposition, active material decomposition, etc., leading to gas release and heat accumulation. At the same time, high temperatures will also cause structural changes and performance degradation of positive and negative electrode materials, exacerbating the increase in internal resistance and capacity decay. What's more serious is that when the battery temperature exceeds a certain critical point, the exothermic reaction may get out of control, causing a thermal runaway accident, causing the battery to swell, smoke, catch fire, or even explode. This not only endangers the safety of equipment and users, but also brings great restrictions and hidden dangers to the application of lithium-ion batteries.

[0005] Therefore, the present invention develops a lithium-ion battery positive electrode with temperature control performance, which can not only improve the performance and safety of the battery under extreme temperature conditions, but also expand its application prospects in complex and harsh environments. Summary of the invention

[0006] The main purpose of the present invention is to provide a lithium ion battery positive electrode with temperature control performance and a preparation method thereof in view of the deficiency that existing lithium ion batteries cannot be used under high and low temperature conditions.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0008] A lithium-ion battery positive electrode with temperature control performance, comprising a composite current collector and a positive electrode active material coating coated on at least one surface of the composite current collector; the composite current collector comprises a first aluminum foil layer, a second aluminum foil layer, and a first temperature control material layer and a second temperature control material layer arranged between the first aluminum foil layer and the second aluminum foil layer;

[0009] The first aluminum foil layer surface is provided with a first groove and a second groove side by side, and the second aluminum foil layer surface is provided with a third groove and a fourth groove side by side, and the first groove is provided correspondingly to the third groove, and the second groove is provided correspondingly to the fourth groove; the first groove and the second groove are respectively extended from the center of the surface of the first aluminum foil layer to the edge of the surface of the first aluminum foil layer in a zigzag shape; the third groove and the fourth groove are respectively extended from the center of the surface of the second aluminum foil layer to the edge of the surface of the second aluminum foil layer in a zigzag shape;

[0010] A first temperature control material layer is embedded between the first groove and the third groove, and the phase change temperature of the first temperature control material layer is -12°C to -15°C; a second temperature control material layer is embedded between the second groove and the fourth groove, and the phase change temperature of the second temperature control material layer is 57°C to 62°C;

[0011] The depth of the first groove is h1, the depth of the second groove is h2, the depth of the third groove is h3, the depth of the fourth groove is h4, the thickness of the first temperature control material layer is H1, the thickness of the second temperature control material layer is H2, and the thickness of the first aluminum foil layer and the second aluminum foil layer are both H; wherein, h1, h2, h3, h4, H1, H2 and H satisfy the relationship: H1=h1+h3, H2=h2+h4; 0.2H≤H1≤0.5H; 0.2H≤H2≤0.5H.

[0012] Preferably, the forward projection area of ​​the first temperature control material layer is S1, the forward projection area of ​​the second temperature control material layer is S2, and the forward projection areas of the first aluminum foil layer and the second aluminum foil layer are S respectively; wherein S1, S2 and S satisfy the relationship: 0.6S≤S1+S2≤S.

[0013] Preferably, the first temperature control material layer comprises the following components in weight proportions: 40-50 parts of n-tridecane, 25-35 parts of n-dodecane, 10-15 parts of 2-methylpentane, 3-5 parts of polyvinyl alcohol, 2-4 parts of graphene, 1-2 parts of nano-alumina, and 0.5-1 part of silica aerogel.

[0014] Preferably, the preparation method of the first temperature control material layer is as follows:

[0015] (1) n-tridecane, n-dodecane and 2-methylpentane are mixed according to a proportion and stirred uniformly at room temperature;

[0016] (2) dissolving polyvinyl alcohol in deionized water, heating to 60° C. and stirring until completely dissolved;

[0017] (3) slowly adding the solution of step (2) into the mixture of step (1), and uniformly dispersing the mixture using a high-speed shearing machine for 30 minutes;

[0018] (4) dispersing graphene in a small amount of ethanol and ultrasonically treating for 20 minutes;

[0019] (5) adding the suspension of step (4), nano-alumina and silica aerogel to the mixture of step (3) in sequence, and continuing high-speed shearing for 15 minutes to obtain a first temperature control material layer slurry;

[0020] (6) Spray the first temperature control material layer slurry onto the first groove and dry it to obtain the first temperature control material layer with the desired shape and thickness.

[0021] Preferably, the second temperature control material layer comprises the following components in weight proportions: 45-55 parts of octadecanoic acid glycerol, 20-25 parts of palmitic acid, 10-15 parts of polyethylene glycol 4000, 3-5 parts of carbon nanotubes, 2-3 parts of boron nitride nanosheets, 1-2 parts of expanded graphite, and 0.5-1 parts of nano magnesium oxide.

[0022] Preferably, the preparation method of the second temperature control material layer is as follows:

[0023] (1) Stearyl glycerol and palmitic acid are mixed according to a ratio, heated to melt in an oil bath at 85-95° C., and stirred evenly;

[0024] (2) adding polyethylene glycol 4000 to the molten mixture of step (1) and continuing to stir until it is completely dissolved;

[0025] (3) dispersing carbon nanotubes and boron nitride nanosheets in N-methylpyrrolidone and ultrasonically treating for 30 minutes;

[0026] (4) slowly adding the suspension of step (3) into the molten mixture of step (2), and stirring at high speed for 45 minutes;

[0027] (5) adding expanded graphite and nano-magnesium oxide, and continuing high-speed stirring for 20 minutes to obtain a second temperature control material layer slurry;

[0028] (6) Spray the second temperature-control material layer slurry onto the second groove and dry it to obtain a second temperature-control material layer of desired shape and thickness.

[0029] Preferably, the surface of the first aluminum foil layer is further provided with a fifth groove, and the fifth groove is embedded side by side between the first groove and the second groove; and the fifth groove extends from the center of the surface of the first aluminum foil layer to the edge of the surface of the first aluminum foil layer in a zigzag shape;

[0030] The surface of the second aluminum foil layer is further provided with a sixth groove, and the sixth groove is embedded side by side between the third groove and the fourth groove; and the sixth groove extends from the center of the surface of the second aluminum foil layer to the edge of the surface of the second aluminum foil layer in a zigzag shape;

[0031] Modified thermally conductive silicone is embedded between the fifth groove and the sixth groove, and the porosity of the modified thermally conductive silicone is 65% to 85%. The first aluminum foil layer and the second aluminum foil layer are bonded and connected by the modified thermally conductive silicone.

[0032] Preferably, the surface of the first aluminum foil layer is further provided with a fifth groove, and the fifth groove is embedded side by side between the first groove and the second groove; and the fifth groove extends from the center of the surface of the first aluminum foil layer to the edge of the surface of the first aluminum foil layer in a zigzag shape;

[0033] The surface of the second aluminum foil layer is further provided with a sixth groove, and the sixth groove is embedded side by side between the third groove and the fourth groove; and the sixth groove extends from the center of the surface of the second aluminum foil layer to the edge of the surface of the second aluminum foil layer in a zigzag shape;

[0034] A foamed aluminum is embedded between the fifth groove and the sixth groove, and the density of the foamed aluminum is 0.2-0.5 g / cm 3 The porosity of foamed aluminum is 75% to 90%.

[0035] Preferably, a temperature sensor is embedded in the first temperature control material layer and / or the second temperature control material layer for real-time monitoring of the temperature of the positive electrode.

[0036] In addition, the present invention also provides a method for preparing the above-mentioned lithium ion battery positive electrode with temperature control performance, comprising the following steps:

[0037] 1) a first groove and a second groove are formed on the surface of the first aluminum foil layer by laser etching, and a third groove and a fourth groove are formed on the surface of the second aluminum foil layer by laser etching;

[0038] 2) preparing a first temperature control material layer slurry and a second temperature control material layer slurry respectively;

[0039] 3) spraying the first temperature control material layer slurry on the first groove and the third groove respectively, and spraying the second temperature control material layer slurry on the second groove and the fourth groove respectively;

[0040] 4) hot pressing the first aluminum foil layer and the second aluminum foil layer, and drying them to obtain a composite current collector;

[0041] 5) coating the positive electrode active material coating slurry on at least one surface of the composite current collector and drying it to obtain the positive electrode of the lithium ion battery.

[0042] Compared with the prior art, the present invention has at least the following beneficial effects:

[0043] 1) The present invention provides a first temperature control material layer and a second temperature control material layer between the first aluminum foil layer and the second aluminum foil layer, respectively, so that the positive electrode has a good temperature control effect, effectively solves the performance problem of lithium-ion batteries at extreme temperatures, and greatly expands the operating temperature range of the battery. Among them, the phase change temperature of the first temperature control material layer is -12℃~-15℃, and the phase change temperature of the second temperature control material layer is 57℃~62℃. The design of the temperature control material layer can absorb or release heat within a specific temperature range, so that the lithium-ion battery can work stably within the temperature range of -15℃ to 62℃.

[0044] 2) The present invention arranges a first groove and a second groove side by side on the surface of the first aluminum foil layer, and arranges a third groove and a fourth groove side by side on the surface of the second aluminum foil layer; the first groove and the second groove extend in a zigzag shape from the center of the surface of the first aluminum foil layer to the edge of the surface of the first aluminum foil layer respectively; the third groove and the fourth groove extend in a zigzag shape from the center of the surface of the second aluminum foil layer to the edge of the surface of the second aluminum foil layer respectively; the first temperature control material layer is embedded between the first groove and the third groove, and the second temperature control material layer is embedded between the second groove and the fourth groove; through this structural design, the first temperature control material layer and the second temperature control material layer can be embedded inside the first aluminum foil layer and the second aluminum foil layer without additionally increasing the thickness of the composite current collector, thereby ensuring that the high and low temperature resistance of the battery is effectively improved without losing the energy density of the battery, and the zigzag bend embedded design of the first temperature control material layer and the second temperature control material layer can not only ensure uniform temperature control, but also increase the contact area and improve the temperature regulation efficiency.

[0045] 3) The present invention precisely controls the size ratio of the first groove, the second groove, the third groove, the fourth groove, the first temperature control material layer, the second temperature control material layer, the first aluminum foil layer and the second aluminum foil layer to satisfy the relationship: H1 = h1 + h3, H2 = h2 + h4; 0.2H ≤ H1 ≤ 0.5H; 0.2H ≤ H2 ≤ 0.5H, thereby ensuring the effective performance of the overall structural strength and temperature control performance of the positive electrode. If the depth of the groove is too small, it is difficult to carry the temperature control material layer. If the depth of the groove is too large, it will affect the strength of the aluminum foil layer and it is easy to break. Therefore, the size ratio combination design ensures that the temperature control material layer does not affect the overall structural strength of the composite current collector, and can give full play to its temperature control function. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 is a schematic cross-sectional structure diagram of a positive electrode in one embodiment of the present invention;

[0047] Figure 2 It is a structural exploded diagram of a composite current collector of a positive electrode in one embodiment of the present invention;

[0048] Figure 3 One of the cross-sectional structural diagrams of the composite current collector of the positive electrode in one embodiment of the present invention;

[0049] Figure 4 This is a schematic structural diagram of the first aluminum foil layer of the composite current collector in one embodiment of the present invention;

[0050] Figure 5 The second cross-sectional structure diagram of the composite current collector of the positive electrode in one embodiment of the present invention;

[0051] Figure 6 This is a schematic diagram of the structure of the second aluminum foil layer of the composite current collector in one embodiment of the present invention;

[0052] Figure 7 is a cross-sectional structural diagram of a composite current collector of a positive electrode in another embodiment of the present invention;

[0053] Figure 8 It is a cross-sectional structural diagram of a composite current collector of a positive electrode in another embodiment of the present invention.

[0054] In the figure: 1. composite current collector; 10. positive electrode ear; 11. first aluminum foil layer; 111. first groove; 112. second groove; 12. second aluminum foil layer; 121. third groove; 122. fourth groove; 13. first temperature control material layer; 14. second temperature control material layer; 15. modified thermal conductive silicone; 16. foam aluminum; 2. positive electrode active material coating. DETAILED DESCRIPTION

[0055] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0056] Please see attached Figures 1 to 6 The present embodiment provides a lithium-ion battery positive electrode with temperature control performance, comprising a composite current collector 1 and a positive electrode active material coating 2 coated on at least one surface of the composite current collector 1; the composite current collector 1 is connected to a positive electrode tab 10; the composite current collector 1 comprises a first aluminum foil layer 11, a second aluminum foil layer 12, and a first temperature control material layer 13 and a second temperature control material layer 14 arranged between the first aluminum foil layer 11 and the second aluminum foil layer 12;

[0057] The first aluminum foil layer 11 has a first groove 111 and a second groove 112 arranged side by side on its surface, and the second aluminum foil layer 12 has a third groove 121 and a fourth groove 122 arranged side by side on its surface, and the first groove 111 is arranged correspondingly to the third groove 121, and the second groove 112 is arranged correspondingly to the fourth groove 122; the first groove 111 and the second groove 112 are respectively extended from the center of the surface of the first aluminum foil layer 11 to the edge of the surface of the first aluminum foil layer 11 in a zigzag bend; the third groove 121 and the fourth groove 122 are respectively extended from the center of the surface of the second aluminum foil layer 12 to the edge of the surface of the second aluminum foil layer 12 in a zigzag bend;

[0058] A first temperature control material layer 13 is embedded between the first groove 111 and the third groove 121, and the phase change temperature of the first temperature control material layer 13 is -12°C to -15°C; a second temperature control material layer 14 is embedded between the second groove 112 and the fourth groove 122, and the phase change temperature of the second temperature control material layer 14 is 57°C to 62°C;

[0059] The depth of the first groove 111 is h1, the depth of the second groove 112 is h2, the depth of the third groove 121 is h3, the depth of the fourth groove 122 is h4, the thickness of the first temperature control material layer 13 is H1, the thickness of the second temperature control material layer 14 is H2, and the thickness of the first aluminum foil layer 11 and the second aluminum foil layer 12 are both H; wherein, h1, h2, h3, h4, H1, H2 and H satisfy the relationship: H1=h1+h3, H2=h2+h4; 0.2H≤H1≤0.5H; 0.2H≤H2≤0.5H.

[0060] Among them, if the depth of the groove is too small, it is difficult to support the temperature control material layer. If the depth of the groove is too large, it will affect the strength of the aluminum foil layer. Therefore, this size ratio combination design ensures that the temperature control material layer does not affect the overall structural strength of the composite current collector 1, and can fully exert its temperature control function.

[0061] In one implementation of the present application, the thickness H of the first aluminum foil layer 11 and the second aluminum foil layer 12 are both 8 to 16 μm; the thickness H1 of the first temperature control material layer 13 and the thickness H2 of the second temperature control material layer 14 are both 1.6 to 8 μm; the depth h1 of the first groove 111 and the depth h3 of the third groove 121 are both 0.8 to 4 μm; the depth h2 of the second groove 112 and the depth h4 of the fourth groove 122 are both 0.8 to 4 μm.

[0062] In one implementation of the present application, the thickness H of the first aluminum foil layer 11 and the second aluminum foil layer 12 are both 10 μm; the thickness H1 of the first temperature control material layer 13 and the thickness H2 of the second temperature control material layer 14 are both 4 μm; the depth h1 of the first groove 111 and the depth h3 of the third groove 121 are both 2 μm; the depth h2 of the second groove 112 and the depth h4 of the fourth groove 122 are both 2 μm.

[0063] In one implementation of the present application, the forward projection area of ​​the first temperature control material layer 13 is S1, the forward projection area of ​​the second temperature control material layer 14 is S2, and the forward projection areas of the first aluminum foil layer 11 and the second aluminum foil layer 12 are S respectively; wherein S1, S2 and S satisfy the relationship: 0.6S≤S1+S2≤S. By controlling the sum of the forward projection areas of the first temperature control material layer and the second temperature control material layer 14 to satisfy the above relationship, it is ensured that the coverage of the material layer is large enough to effectively adjust the temperature of the entire positive electrode.

[0064] In one implementation of the present application, the first temperature control material layer 13 includes the following components in weight proportions: 40-50 parts of n-tridecane, 25-35 parts of n-dodecane, 10-15 parts of 2-methylpentane, 3-5 parts of polyvinyl alcohol, 2-4 parts of graphene, 1-2 parts of nano-alumina, and 0.5-1 part of silica aerogel.

[0065] Among them, n-tridecane and n-dodecane are used as the main phase change materials to provide low-temperature phase change ability. Mixing can adjust the phase change temperature and reduce the freezing point; 2-methylpentane further reduces the freezing point of the mixture, increases the fluidity of the material, and improves the low-temperature performance; polyvinyl alcohol (PVA) is used as a thickener and structural stabilizer to improve the mechanical strength and shape stability of the material; graphene significantly improves the thermal conductivity of the material and improves the distribution of heat in the phase change material; nano-alumina enhances the thermal stability of the material, improves thermal conductivity and mechanical strength; silica aerogel provides excellent thermal insulation performance, reduces heat loss, and improves the efficiency of the phase change material. The phase change temperature of the first temperature control material layer 13 is -12°C to -15°C. When the phase change temperature is reached, it can quickly release heat, effectively adjust the battery temperature, and improve the low-temperature resistance of the battery.

[0066] In one implementation of the present application, the preparation method of the first temperature control material layer 13 is as follows:

[0067] (1) n-tridecane, n-dodecane and 2-methylpentane are mixed according to a proportion and stirred uniformly at room temperature;

[0068] (2) dissolving polyvinyl alcohol in deionized water, heating to 60° C. and stirring until completely dissolved;

[0069] (3) slowly adding the solution of step (2) into the mixture of step (1), and uniformly dispersing the mixture using a high-speed shearing machine for 30 minutes;

[0070] (4) dispersing graphene in a small amount of ethanol and ultrasonically treating for 20 minutes;

[0071] (5) adding the suspension of step (4), nano-alumina and silica aerogel to the mixture of step (3) in sequence, and continuing high-speed shearing for 15 minutes to obtain a slurry of the first temperature control material layer 13;

[0072] (6) Spray the slurry of the first temperature control material layer 13 onto the first groove 111 and dry it to obtain the first temperature control material layer 13 of the desired shape and thickness.

[0073] In one implementation of the present application, the second temperature control material layer 14 includes the following components in weight proportions: 45-55 parts of octadecanoic acid glycerol, 20-25 parts of palmitic acid, 10-15 parts of polyethylene glycol 4000, 3-5 parts of carbon nanotubes, 2-3 parts of boron nitride nanosheets, 1-2 parts of expanded graphite, and 0.5-1 parts of nano-magnesium oxide.

[0074] Among them, octadecanoic acid glycerol and palmitic acid are used as the main phase change materials to provide high-temperature phase change capability, and the mixed use can adjust the phase change temperature range; polyethylene glycol 4000 adjusts the phase change temperature, increases the heat capacity of the material, and improves the heat storage capacity; carbon nanotubes significantly improve the thermal conductivity of the material and improve the rapid distribution of heat in the phase change material; boron nitride nanosheets further enhance heat conduction and improve the thermal stability of the material; expanded graphite increases the specific surface area of ​​the material, improves the heat exchange efficiency, and improves the thermal conductivity and flame retardancy of the material; nano-magnesium oxide enhances the thermal stability and flame retardancy of the material and improves the structural integrity of the material at high temperatures. The phase change temperature of the second temperature control material layer 14 is 57°C to 62°C. When the phase change temperature is reached, it can quickly absorb heat, effectively adjust the battery temperature, and improve the high temperature resistance of the battery.

[0075] In one implementation of the present application, the preparation method of the second temperature control material layer 14 is as follows:

[0076] (1) Stearyl glycerol and palmitic acid are mixed according to a ratio, heated to melt in an oil bath at 85-95° C., and stirred evenly;

[0077] (2) adding polyethylene glycol 4000 to the molten mixture of step (1) and continuing to stir until it is completely dissolved;

[0078] (3) dispersing carbon nanotubes and boron nitride nanosheets in N-methylpyrrolidone and ultrasonically treating for 30 minutes;

[0079] (4) slowly adding the suspension of step (3) into the molten mixture of step (2), and stirring at high speed for 45 minutes;

[0080] (5) adding expanded graphite and nano-magnesium oxide, and continuing high-speed stirring for 20 minutes to obtain a second temperature control material layer 14 slurry;

[0081] (6) Spray the slurry of the second temperature control material layer 14 onto the second groove 112 and dry it to obtain the second temperature control material layer 14 of the desired shape and thickness.

[0082] In one implementation according to the present application, Figure 7 As shown, the surface of the first aluminum foil layer 11 is further provided with a fifth groove, which is embedded side by side between the first groove 111 and the second groove 112; and the fifth groove extends from the center of the surface of the first aluminum foil layer 11 to the edge of the surface of the first aluminum foil layer 11 in a zigzag shape;

[0083] The surface of the second aluminum foil layer 12 is also provided with a sixth groove, which is embedded side by side between the third groove 121 and the fourth groove 122; and the sixth groove extends from the center of the surface of the second aluminum foil layer 12 to the edge of the surface of the second aluminum foil layer 12 in a zigzag shape;

[0084] A modified thermally conductive silica gel 15 is embedded between the fifth groove and the sixth groove, and the porosity of the modified thermally conductive silica gel 15 is 65% to 85%; the first aluminum foil layer 11 and the second aluminum foil layer 12 are bonded and connected by the modified thermally conductive silica gel 15. The modified thermally conductive silica gel 15 with a porosity of 65% to 85% is embedded between the fifth groove and the sixth groove, which not only has good thermal conductivity, but also has a good energy absorption and buffering effect, preventing stress concentration from causing deformation, fracture or damage of the composite current collector 1, thereby significantly improving the mechanical stability and reliability of the battery; in addition, the modified thermally conductive silica gel 15 can also bond and fix the first aluminum foil layer 11 and the second aluminum foil layer 12, absorb the expansion force of the negative electrode, adjust the stress distribution on the surface of the negative electrode to make it more uniform, and its thermal conductivity can reach 6-10W / (m·k), which can accelerate the heat conduction and dissipation of the battery at high temperature and reduce the battery temperature.

[0085] The preparation method of the modified thermally conductive silica gel 15 is as follows:

[0086] 1) Boron nitride and KH570 silane coupling agent are dispersed in 100 ml of aqueous solution at a mass ratio of 10:1, and the concentrations are 40 mg / ml and 4 mg / ml respectively. The mixed dispersion is placed in a water bath ultrasound at 0°C for 40 minutes, then centrifuged to remove excess solvent, and freeze-dried to obtain modified boron nitride powder.

[0087] 2) The modified boron nitride powder and graphene were dispersed in a mixed solvent of alcohol and water in a mass ratio of 1:5, with concentrations of 1.2 mg / ml and 6 mg / ml, respectively. 2 mg / ml carbon nanotubes were added at the same time, and ultrasonic cell crusher was used for 10 min at a power of 1200 W to obtain graphene slurry.

[0088] 3) The polyurethane sponge foam was immersed in a 2 mol / L NaOH solution, treated in 40°C warm water for 3.5 h, and then placed in a 5 mg / ml anilinemethyltriethoxysilane aqueous solution and immersed for 24 h to obtain a modified polyurethane porous foam.

[0089] 4) The modified polyurethane porous foam structure was immersed in the uniform graphene slurry prepared above, and ultrasonicated in a water bath for 20 minutes at 0°C. It was dried at 60°C, and then heated from 60°C to 200°C at a heating rate of 15°C per minute, and then heated from 200°C to 380°C at a heating rate of 3°C per minute for 30 minutes, and the porous material was removed to obtain a three-dimensional porous graphene-boron nitride composite material.

[0090] 5) The three-dimensional porous graphene-boron nitride composite material obtained above was immersed in silica gel (Wacker SEMICOSIL9212), the bubbles were removed by vacuum, and the composite material was placed in an oven at 125° C. and cured for 15 min to obtain the modified thermally conductive silica gel 15.

[0091] In one implementation according to the present application, Figure 8 As shown, the surface of the first aluminum foil layer 11 is further provided with a fifth groove, which is embedded side by side between the first groove 111 and the second groove 112; and the fifth groove extends from the center of the surface of the first aluminum foil layer 11 to the edge of the surface of the first aluminum foil layer 11 in a zigzag shape;

[0092] The surface of the second aluminum foil layer 12 is also provided with a sixth groove, which is embedded side by side between the third groove 121 and the fourth groove 122; and the sixth groove extends from the center of the surface of the second aluminum foil layer 12 to the edge of the surface of the second aluminum foil layer 12 in a zigzag shape;

[0093] A foamed aluminum 16 is embedded between the fifth groove and the sixth groove, and the density of the foamed aluminum 16 is 0.2-0.5 g / cm 3 , preferably 0.35 g / cm 3 The porosity of the aluminum foam 16 is 75% to 90%, preferably 85%.

[0094] The foam aluminum 16 can be disposed in the fifth groove of the first aluminum foil layer 11 and the sixth groove of the second aluminum foil layer 12 by spraying, 3D printing, etc. The foam aluminum 16 is a new lightweight functional material that has both metal and bubble characteristics, which enables it to have excellent energy absorption and buffering effects and thermal conductivity. It not only effectively conducts heat, but also effectively absorbs the expansion force of the negative electrode, inhibits the expansion and deformation of the battery cell, and minimizes the overall mass of the battery. In addition, the density of the foam aluminum 16 is 0.2-0.5 g / cm 3 The porosity of the foam aluminum 16 is 75% to 90%. The foam aluminum 16 with low density and high porosity has extremely high buffering and energy absorption capacity, which can effectively disperse the surface stress of the composite current collector 1, prevent the current collector from cracking or breaking due to stress concentration, and absorb the negative electrode expansion force, reduce the volume change amplitude of the negative electrode material, maintain the relative stability of the negative electrode structure, inhibit the generation of negative electrode lithium dendrites, and thus reduce the risk of internal short circuit of the battery, ensuring the safety and reliability of the battery. In addition, during the charging and discharging process of the battery, the positive electrode active material will undergo volume changes, causing repeated expansion and contraction of the positive electrode structure. Long-term accumulation may cause stratification or detachment between the positive electrode current collector and the active material, affecting the battery performance; the foam aluminum 16 can buffer and adapt to the volume changes of the active material, maintain the integrity of the positive electrode structure, reduce the interface damage between the current collector and the active material, and thus extend the cycle life of the battery. In addition, the foam aluminum 16 has good flexibility and bendability, which can give the composite current collector 1 higher flexibility and ductility, which makes it possible to realize the flexible design of the battery, so that the battery can adapt to deformations such as bending, folding, and winding, and meet the application requirements in the fields of flexible electronic devices, wearable devices, etc.

[0095] In one implementation of the present application, a temperature sensor is embedded in the first temperature control material layer 13 and / or the second temperature control material layer 14 to monitor the temperature of the positive electrode in real time. The temperature sensor is led out along the ear end of the positive electrode through a sensor conductive wire. By setting the temperature sensor, the temperature of the positive electrode or the battery can be monitored in real time, and linked with the battery management system (BMS) to dynamically adjust the working state to control the temperature.

[0096] In addition, the present application also provides a method for preparing the above-mentioned lithium-ion battery positive electrode with temperature control performance, comprising the following steps:

[0097] 1) a first groove 111 and a second groove 112 are formed on the surface of the first aluminum foil layer 11 by laser etching, and a third groove 121 and a fourth groove 122 are formed on the surface of the second aluminum foil layer 12 by laser etching;

[0098] 2) preparing the first temperature control material layer 13 slurry and the second temperature control material layer 14 slurry respectively;

[0099] 3) spraying the first temperature control material layer 13 slurry on the first groove 111 and the third groove 121 respectively, and spraying the second temperature control material layer 14 slurry on the second groove 112 and the fourth groove 122 respectively;

[0100] 4) The first aluminum foil layer 11 and the second aluminum foil layer 12 are thermally pressed and dried to obtain a composite current collector 1;

[0101] 5) The positive electrode active material coating 2 slurry is coated on at least one surface of the composite current collector 1 and dried to obtain the positive electrode of the lithium ion battery.

[0102] The positive electrode active material coating 2 generally includes a positive electrode active material, a binder and a conductive agent, wherein the types and amounts of the positive electrode active material, the binder and the conductive agent in the positive electrode active material coating 2, as well as the thickness of the positive electrode active material coating 2, etc. can all be conventionally selected in the art. For example, as some specific examples, the positive electrode active material in the positive electrode active material coating 2 may include but is not limited to lithium cobalt oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide, lithium iron phosphate, etc., the binder may include but is not limited to polyvinylidene fluoride, styrene-butadiene rubber, polyvinyl alcohol, polyurethane, etc., and the conductive agent may include but is not limited to carbon nanofibers, carbon nanotubes, conductive carbon black, graphene, etc.

[0103] The embodiments of the present application are described in detail below. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. The reagents or instruments used without indicating the manufacturer are all conventional products that can be obtained commercially.

[0104] Example 1

[0105] Preparation of positive electrode:

[0106] The positive electrode of this embodiment includes a composite current collector 1 and a positive electrode active material coating 2 coated on a surface of the composite current collector 1; the composite current collector 1 includes a first aluminum foil layer 11, a second aluminum foil layer 12, and a first temperature control material layer 13 and a second temperature control material layer 14 arranged between the first aluminum foil layer 11 and the second aluminum foil layer 12; the first aluminum foil layer 11 is provided with a first groove 111 and a second groove 112 arranged side by side on the surface, and the second aluminum foil layer 12 is provided with a third groove 121 and a fourth groove 122 arranged side by side on the surface, and the first groove 111 is provided correspondingly to the third groove 121, and the second groove 112 is provided correspondingly to the fourth groove 122; the first The groove 111 and the second groove 112 extend in a zigzag shape from the center of the surface of the first aluminum foil layer 11 to the edge of the surface of the first aluminum foil layer 11 respectively; the third groove 121 and the fourth groove 122 extend in a zigzag shape from the center of the surface of the second aluminum foil layer 12 to the edge of the surface of the second aluminum foil layer 12 respectively; a first temperature control material layer 13 is embedded between the first groove 111 and the third groove 121, and the phase change temperature of the first temperature control material layer 13 is -12°C to -15°C; a second temperature control material layer 14 is embedded between the second groove 112 and the fourth groove 122, and the phase change temperature of the second temperature control material layer 14 is 57°C to 62°C.

[0107] Among them, the composition of the first temperature control material layer 13 of this embodiment is: 45 parts of n-tridecane, 30 parts of n-dodecane, 12 parts of 2-methylpentane, 4 parts of polyvinyl alcohol, 3 parts of graphene, 1 part of nano-alumina, and 1 part of silica aerogel; the composition of the second temperature control material layer 14 is: 50 parts of octadecyl glyceride, 23 parts of palmitic acid, 12 parts of polyethylene glycol 4000, 4 parts of carbon nanotubes, 2 parts of boron nitride nanosheets, 1 part of expanded graphite, and 1 part of nano-magnesium oxide.

[0108] The depth of the first groove 111 is h1, the depth of the second groove 112 is h2, the depth of the third groove 121 is h3, the depth of the fourth groove 122 is h4, the thickness of the first temperature control material layer 13 is H1, the thickness of the second temperature control material layer 14 is H2, and the thickness of the first aluminum foil layer 11 and the second aluminum foil layer 12 are both H; wherein h1, h2, h3, h4, H1, H2 and H satisfy the relationship: H1 = h1 + h3, H2 = h2 + h4 ; 0.2H≤H1≤0.5H; 0.2H≤H2≤0.5H; Specifically, in the present embodiment, the thickness H of the first aluminum foil layer 11 and the second aluminum foil layer 12 are both 10 μm; the depth h1 of the first groove 111, the depth h2 of the second groove 112, the depth h3 of the third groove 121 and the depth h4 of the fourth groove 122 are respectively 2 μm; the thickness H1 of the first temperature control material layer 13 and the thickness H2 of the second temperature control material layer 14 are respectively 4 μm.

[0109] The preparation method of the positive electrode sheet is as follows:

[0110] 1) a first groove 111 and a second groove 112 with a depth of 2 μm are formed on the surface of a first aluminum foil layer 11 with a thickness of 10 μm by laser etching, and a third groove 121 and a fourth groove 122 with a depth of 2 μm are formed on the surface of a second aluminum foil layer 12 with a thickness of 10 μm by laser etching;

[0111] 2) preparing a slurry of the first temperature control material layer 13 according to the above-mentioned preparation method of the first temperature control material layer 13, and preparing a slurry of the second temperature control material layer 14 according to the above-mentioned preparation method of the second temperature control material layer 14;

[0112] 3) Spray the first temperature control material layer 13 slurry on the first groove 111 and the third groove 121 respectively, so that the total thickness of the first temperature control material layer 13 is 4 μm; spray the second temperature control material layer 14 slurry on the second groove 112 and the fourth groove 122 respectively, so that the total thickness of the second temperature control material layer 14 is 4 μm;

[0113] 4) The first aluminum foil layer 11 and the second aluminum foil layer 12 are thermally pressed and dried to obtain a composite current collector 1;

[0114] 5) The positive electrode active material lithium nickel cobalt manganese oxide, the conductive agent conductive carbon black, and the binder polyvinylidene fluoride are dispersed in the solvent NMP (N-methylpyrrolidone) in a mass ratio of 95:2:3, stirred evenly to obtain a positive electrode active material coating 2 slurry, coated on a surface of the composite current collector 1, and dried to obtain the lithium ion battery positive electrode sheet.

[0115] Preparation of negative electrode sheet:

[0116] Hard carbon, carbon black and aqueous carboxymethyl cellulose are dispersed in water at a mass ratio of 95:2:3 to form a uniformly dispersed slurry, the slurry is evenly coated on the surface of the current collector copper foil, and then transferred to a vacuum drying oven for complete drying to obtain a negative electrode sheet.

[0117] Preparation of electrolyte:

[0118] Ethylene carbonate (EC) and diethyl carbonate (DEC) are mixed at a volume ratio of 1:1, and then FEC (fluoroethylene carbonate) is added at a volume percentage of 5%. Then, the fully dried lithium salt LiPF6 is dissolved in a mixed organic solvent at a concentration ratio of 1 mol / L to prepare an electrolyte.

[0119] Preparation of isolation film: A PET / PP composite film with a thickness of 20 microns was selected.

[0120] Preparation of lithium-ion batteries:

[0121] The positive electrode sheet, the separator, and the negative electrode sheet are stacked in order, so that the separator is between the positive and negative electrode sheets to play an isolating role, and the electrolyte is added, and assembled into a stacked lithium-ion battery according to conventional processes.

[0122] Example 2

[0123] Different from Example 1, the surface of the first aluminum foil layer 11 in the composite current collector 1 of the positive electrode of this embodiment is further provided with a fifth groove, which is embedded side by side between the first groove 111 and the second groove 112; and the fifth groove extends in a zigzag shape from the center of the surface of the first aluminum foil layer 11 to the edge of the surface of the first aluminum foil layer 11; the surface of the second aluminum foil layer 12 is further provided with a sixth groove, which is embedded side by side between the third groove 121 and the fourth groove 122; and the sixth groove extends in a zigzag shape from the center of the surface of the second aluminum foil layer 12 to the edge of the surface of the second aluminum foil layer 12; a modified thermally conductive silicone 15 is embedded between the fifth groove and the sixth groove, wherein the specific composition and preparation method of the modified thermally conductive silicone 15 are as above, and the porosity of the prepared modified thermally conductive silicone 15 is 80%; the first aluminum foil layer 11 and the second aluminum foil layer 12 are bonded and connected by the modified thermally conductive silicone 15.

[0124] The rest is the same as in Example 1 and will not be described again here.

[0125] Example 3

[0126] Different from Example 1, the surface of the first aluminum foil layer 11 in the composite current collector 1 of the positive electrode of this embodiment is further provided with a fifth groove, which is embedded side by side between the first groove 111 and the second groove 112; and the fifth groove extends in a zigzag shape from the center of the surface of the first aluminum foil layer 11 to the edge of the surface of the first aluminum foil layer 11; the surface of the second aluminum foil layer 12 is further provided with a sixth groove, which is embedded side by side between the third groove 121 and the fourth groove 122; and the sixth groove extends in a zigzag shape from the center of the surface of the second aluminum foil layer 12 to the edge of the surface of the second aluminum foil layer 12; foam aluminum 16 is embedded between the fifth groove and the sixth groove, and the density of the foam aluminum 16 is 0.35g / cm 3 The porosity of the foam aluminum 16 is 85%. The foam aluminum 16 layer can be disposed in the fifth groove of the first aluminum foil layer 11 and the sixth groove of the second aluminum foil layer 12 by spraying or 3D printing.

[0127] The rest is the same as in Example 1 and will not be described again here.

[0128] Comparative Example 1

[0129] Different from Example 1, the composite current collector 1 of the positive electrode in this comparative example adopts a three-layer composite current collector 1 of aluminum foil-PET-aluminum foil.

[0130] The rest is the same as in Example 1 and will not be described again here.

[0131] The following electrochemical performance tests were performed on the lithium ion batteries of the above examples and comparative examples, respectively. The test results are shown in Table 1.

[0132] 1) Disassembly and lithium analysis test: After the battery is pre-charged in the formation stage, fully charge and disassemble to observe its interface.

[0133] 2) Needle penetration test: Use a 10mm diameter steel needle at a speed of 3mm / s to pierce the battery and stay inside the battery for 10 minutes to observe whether there is any reaction, sparks or fire.

[0134] 3) High temperature and low temperature cycle test: The cycle capacity retention rate (%) of the above lithium-ion battery during 300 charge and discharge cycles at high temperature (60°C) and 300 charge and discharge cycles at low temperature (-15°C) was tested at a charge and discharge voltage of 2.5V to 3.65V and a charge and discharge rate of 1C / 1C. That is, the discharge capacity of the first cycle of the lithium-ion battery at the corresponding temperature is set to 1, and the ratio of the discharge capacity during continuous charge and discharge cycles under the same conditions to the discharge capacity of the first cycle is the capacity retention rate (%) under the number of cycles.

[0135] Table 1

[0136]

[0137] It can be seen from the test results in Table 1 that, compared with the positive electrode prepared with the existing composite current collector, the lithium ion battery prepared with the positive electrode of the present invention has better resistance to high and low temperature cycles and safety performance, indicating that the positive electrode of the present invention has better temperature control effect and can improve the safety performance of the battery.

[0138] By comparing Example 1 and Example 2, it can be seen that when modified thermally conductive silicone is further provided inside the composite current collector of the positive electrode, it helps to further improve the lithium plating of the pole piece and enhance the high temperature cycle performance of the battery, indicating that the modified thermally conductive silicone has a good energy absorption and buffering effect, helps to absorb the expansion force of the pole piece, and adjusts the stress distribution on the surface of the negative electrode to make it more uniform, and can accelerate heat dispersion, thereby improving the high temperature resistance of the battery.

[0139] By comparing Example 1 and Example 3, it can be seen that when foam aluminum is further provided inside the composite current collector of the positive electrode, it helps to further improve the lithium deposition of the electrode sheet, indicating that foam aluminum has extremely high buffering energy absorption performance, can absorb the expansion force of the negative electrode, reduce the volume change of the negative electrode material, maintain the relative stability of the negative electrode structure, inhibit the generation of negative electrode lithium dendrites, and thus reduce the risk of internal short circuit of the battery.

[0140] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0141] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A lithium-ion battery positive electrode with temperature control performance, characterized in that: It comprises a composite current collector and a positive electrode active material coating coated on at least one surface of the composite current collector; the composite current collector comprises a first aluminum foil layer, a second aluminum foil layer, and a first temperature control material layer and a second temperature control material layer arranged between the first aluminum foil layer and the second aluminum foil layer; The first aluminum foil layer surface is provided with a first groove and a second groove side by side, and the second aluminum foil layer surface is provided with a third groove and a fourth groove side by side, and the first groove is provided correspondingly to the third groove, and the second groove is provided correspondingly to the fourth groove; the first groove and the second groove are respectively extended from the center of the surface of the first aluminum foil layer to the edge of the surface of the first aluminum foil layer in a zigzag shape; the third groove and the fourth groove are respectively extended from the center of the surface of the second aluminum foil layer to the edge of the surface of the second aluminum foil layer in a zigzag shape; A first temperature control material layer is embedded between the first groove and the third groove, and the phase change temperature of the first temperature control material layer is -12°C to -15°C; a second temperature control material layer is embedded between the second groove and the fourth groove, and the phase change temperature of the second temperature control material layer is 57°C to 62°C; The depth of the first groove is h1, the depth of the second groove is h2, the depth of the third groove is h3, the depth of the fourth groove is h4, the thickness of the first temperature control material layer is H1, the thickness of the second temperature control material layer is H2, and the thickness of the first aluminum foil layer and the second aluminum foil layer are both H; wherein, h1, h2, h3, h4, H1, H2 and H satisfy the relationship: H1=h1+h3, H2=h2+h4; 0.2H≤H1≤0.5H; 0.2H≤H2≤0.5H.

2. The lithium-ion battery positive electrode with temperature control performance according to claim 1, characterized in that: The forward projection area of ​​the first temperature control material layer is S1, the forward projection area of ​​the second temperature control material layer is S2, and the forward projection areas of the first aluminum foil layer and the second aluminum foil layer are S respectively; wherein S1, S2 and S satisfy the relationship: 0.6S≤S1+S2≤S.

3. The lithium-ion battery positive electrode with temperature control performance according to claim 1, characterized in that: The first temperature control material layer comprises the following components in weight proportion: 40-50 parts of n-tridecane, 25-35 parts of n-dodecane, 10-15 parts of 2-methylpentane, 3-5 parts of polyvinyl alcohol, 2-4 parts of graphene, 1-2 parts of nano-alumina, and 0.5-1 part of silica aerogel.

4. The lithium-ion battery positive electrode with temperature control performance according to claim 3, characterized in that: The preparation method of the first temperature control material layer is as follows: (1) n-tridecane, n-dodecane and 2-methylpentane are mixed according to a proportion and stirred uniformly at room temperature; (2) dissolving polyvinyl alcohol in deionized water, heating to 60° C. and stirring until completely dissolved; (3) slowly adding the solution of step (2) into the mixture of step (1), and uniformly dispersing the mixture using a high-speed shearing machine for 30 minutes; (4) dispersing graphene in a small amount of ethanol and ultrasonically treating for 20 minutes; (5) adding the suspension of step (4), nano-alumina and silica aerogel to the mixture of step (3) in sequence, and continuing high-speed shearing for 15 minutes to obtain a first temperature control material layer slurry; (6) Spray the first temperature control material layer slurry onto the first groove and dry it to obtain the first temperature control material layer with the desired shape and thickness.

5. The lithium-ion battery positive electrode with temperature control performance according to claim 1, characterized in that: The second temperature control material layer comprises the following components in weight proportion: 45-55 parts of octadecanoic acid glycerol, 20-25 parts of palmitic acid, 10-15 parts of polyethylene glycol 4000, 3-5 parts of carbon nanotubes, 2-3 parts of boron nitride nanosheets, 1-2 parts of expanded graphite, and 0.5-1 parts of nano magnesium oxide.

6. The lithium-ion battery positive electrode with temperature control performance according to claim 5, characterized in that: The preparation method of the second temperature control material layer is as follows: (1) Stearyl glycerol and palmitic acid are mixed according to a ratio, heated to melt in an oil bath at 85-95° C., and stirred evenly; (2) adding polyethylene glycol 4000 to the molten mixture of step (1) and continuing to stir until it is completely dissolved; (3) dispersing carbon nanotubes and boron nitride nanosheets in N-methylpyrrolidone and ultrasonically treating for 30 minutes; (4) slowly adding the suspension of step (3) into the molten mixture of step (2), and stirring at high speed for 45 minutes; (5) adding expanded graphite and nano-magnesium oxide, and continuing high-speed stirring for 20 minutes to obtain a second temperature control material layer slurry; (6) Spray the second temperature-control material layer slurry onto the second groove and dry it to obtain a second temperature-control material layer of desired shape and thickness.

7. The lithium-ion battery positive electrode with temperature control performance according to claim 1, characterized in that: The surface of the first aluminum foil layer is further provided with a fifth groove, and the fifth groove is embedded side by side between the first groove and the second groove; and the fifth groove extends from the center of the surface of the first aluminum foil layer to the edge of the surface of the first aluminum foil layer in a zigzag shape; The surface of the second aluminum foil layer is further provided with a sixth groove, and the sixth groove is embedded side by side between the third groove and the fourth groove; and the sixth groove extends from the center of the surface of the second aluminum foil layer to the edge of the surface of the second aluminum foil layer in a zigzag shape; Modified thermally conductive silicone is embedded between the fifth groove and the sixth groove, and the porosity of the modified thermally conductive silicone is 65% to 85%; the first aluminum foil layer and the second aluminum foil layer are bonded and connected by the modified thermally conductive silicone.

8. The lithium-ion battery positive electrode with temperature control performance according to claim 1, characterized in that: The surface of the first aluminum foil layer is further provided with a fifth groove, and the fifth groove is embedded side by side between the first groove and the second groove; and the fifth groove extends from the center of the surface of the first aluminum foil layer to the edge of the surface of the first aluminum foil layer in a zigzag shape; The surface of the second aluminum foil layer is further provided with a sixth groove, and the sixth groove is embedded side by side between the third groove and the fourth groove; and the sixth groove extends from the center of the surface of the second aluminum foil layer to the edge of the surface of the second aluminum foil layer in a zigzag shape; A foamed aluminum is embedded between the fifth groove and the sixth groove, and the density of the foamed aluminum is 0.2-0.5 g / cm 3 The porosity of foamed aluminum is 75% to 90%.

9. The lithium-ion battery positive electrode with temperature control performance according to claim 1, characterized in that: A temperature sensor is embedded in the first temperature control material layer and / or the second temperature control material layer for real-time monitoring of the temperature of the positive electrode.

10. A method for preparing a lithium-ion battery positive electrode with temperature control performance according to any one of claims 1 to 9, characterized in that: The following steps are involved: 1) a first groove and a second groove are formed on the surface of the first aluminum foil layer by laser etching, and a third groove and a fourth groove are formed on the surface of the second aluminum foil layer by laser etching; 2) preparing a first temperature control material layer slurry and a second temperature control material layer slurry respectively; 3) spraying the first temperature control material layer slurry on the first groove and the third groove respectively, and spraying the second temperature control material layer slurry on the second groove and the fourth groove respectively; 4) hot pressing the first aluminum foil layer and the second aluminum foil layer, and drying them to obtain a composite current collector; 5) coating the positive electrode active material coating slurry on at least one surface of the composite current collector and drying it to obtain the positive electrode of the lithium ion battery.

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