Conductive film, method for manufacturing the same, electrode, current collector, secondary battery, and device

Abstract

The conductive film comprises a base layer (100), the base layer (100) has a first surface (101) and a second surface (102) arranged oppositely, and the base layer (100) has a dense structure; a first porous layer (110) is combined to the first surface (101) of the base layer (100) in a laminated manner; the first porous layer (110) comprises a porous conductive material; the porous conductive material has pores (601) with a first pore diameter and pores (602) with a second pore diameter; the first pore diameter is n microns, and 0.5 ≤ n ≤ 10; the second pore diameter is m nanometers, and 20 < m < 200.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal materials, and in particular to a conductive film, a preparation method thereof, an electrode, a current collector, a secondary battery and a device. BACKGROUND

[0002] In recent years, with the application range of secondary batteries becoming more and more extensive, secondary batteries are widely used in energy storage power supply systems such as hydropower, thermal power, wind power and solar power stations, and in many fields such as electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc. Due to the great development of secondary batteries, higher requirements are put forward for their energy density, cycle performance, etc.

[0003] Metal lithium is considered to be an attractive high-energy lithium-ion battery anode material due to its high theoretical specific capacity (3860 mAh / g) and low electrochemical potential. However, a battery with metal lithium as an anode will produce the following problems during the cycle process: lithium dendrites are generated, a chemical reaction with the electrolyte is generated, and the lithium anode volume expands infinitely when it is deposited and peeled off, which will inevitably bring about battery safety hazards and low cycle efficiency, and seriously hinder the practical application of metal lithium anodes. SUMMARY

[0004] The present application is made in view of the above-mentioned problems, and aims to provide a novel conductive film, a preparation method thereof, an electrode, a current collector, a secondary battery and a device.

[0005] The novel conductive film of the present application has a base layer and a porous layer which are laminated and combined. The porous layer contains an innovative porous conductive material which has a unique multi-level pore size distribution characteristic. When the conductive film is used as an electrode or a current collector of a secondary battery, the porous conductive material is beneficial to the infiltration of the electrolyte and the deposition of the active material. The base layer of the conductive film plays a role in supporting the porous layer and improving the strength of the conductive film. The conductive film of the present application has good mechanical properties and electrochemical properties.

[0006] In view of this, in a first aspect, the present application provides a conductive film, comprising:

[0007] a base layer having a first surface and a second surface arranged oppositely, the base layer having a dense structure;

[0008] a first porous layer laminated and combined to the first surface of the base layer;

[0009] the first porous layer comprising a porous conductive material;

[0010] the porous conductive material having pores of a first pore size and pores of a second pore size;

[0011] the first aperture is n microns, 0.5≤n≤10;

[0012] the second aperture is m nanometers, 20

[0013] The conductive film of the above-mentioned scheme has a base layer and a porous layer which are laminated and combined. The porous layer has a relatively weak mechanical strength due to its porous structure. The above-mentioned scheme uses a base layer with a dense structure to laminate and combine with the porous layer to obtain a porous conductive film with enhanced mechanical properties. The base layer with a dense structure has good mechanical properties, and the porous layer with a unique porous structure shows good electrochemical performance for secondary batteries. The conductive film has both enhanced mechanical properties and electrochemical performance, and is suitable for use as an electrode / current collector for secondary batteries.

[0014] The conductive film of the above-mentioned scheme contains a new type of porous conductive material, which has a new type of hierarchical pore size distribution characteristic. The new type of porous conductive material is particularly suitable for use in anode-free metal batteries (such as anode-free lithium metal batteries or anode-free sodium metal batteries) or batteries containing active metal / alloy anodes. The inner wall of the pores with the first aperture (referred to as large pores) can serve as a substrate for active material deposition; in addition, the large pores also serve to provide a channel for electrolyte infiltration. The inner wall of the pores with the second aperture (referred to as small pores) can serve as a substrate for active material deposition. The small pores increase the specific surface area of the material, thereby enabling the porous conductive material to load more active material; in addition, the small pores also serve as a template for active material deposition. Specifically, due to the size limitation of the small pores, the active material deposited in the small pores has a nanoscale size, and the nanoscale active material has a high ionic conductivity due to its small size, thereby being able to improve the overall ionic conductivity of the electrode, thereby being able to improve the rate performance of the battery, and ultimately improving the capacity, cycle stability, and rate performance of the battery as a whole; in addition, the small pores also serve to limit the volume expansion of the active material, thereby preventing it from failing due to pulverization.

[0015] In some embodiments, the conductive film further comprises a second porous layer laminated and combined to a second surface of the base layer; the first porous layer and the second porous layer each independently comprise a porous conductive material; the porous conductive material has pores with a first aperture and pores with a second aperture; the first aperture is n microns, 0.5≤n≤10; the second aperture is m nanometers, 20

[0016] In some embodiments, the apparent volume of the porous conductive material is V, the total pore volume of the pores having the first pore diameter is VI, the total pore volume of the pores having the second pore diameter is V2, and the porous conductive material satisfies the following relationship: (VI + V2) / V = 60% - 90%. The conductive film based on this scheme has satisfactory strength, and when it is used in a secondary battery, the secondary battery exhibits improved capacity, cycle stability, and / or rate performance.

[0017] In some embodiments, the apparent volume of the porous conductive material is V, the total pore volume of the pores having the first pore diameter is VI, and the porous conductive material satisfies the following relationship: VI / V = 5% - 70%. The conductive film based on this scheme has satisfactory strength, and when it is used in a secondary battery, the secondary battery exhibits improved capacity, cycle stability, and / or rate performance.

[0018] In some embodiments, the apparent volume of the porous conductive material is V, the total pore volume of the pores having the second pore diameter is V2, and the porous conductive material satisfies the following relationship: V2 / V = 15% - 70%. The conductive film based on this scheme has satisfactory strength, and when it is used in a secondary battery, the secondary battery exhibits improved capacity, cycle stability, and / or rate performance.

[0019] In some embodiments, the pores having the first pore diameter are spaced apart from each other by first fibrils, and the average fibril diameter of the first fibrils is 0.89 - 3 μm. The conductive film based on this scheme has satisfactory strength, and when it is used in a secondary battery, the secondary battery exhibits improved capacity, cycle stability, and / or rate performance.

[0020] In some embodiments, the pores having the second pore diameter are spaced apart from each other by second fibrils, and the average fibril diameter of the second fibrils is 27 - 100 nm. The conductive film based on this scheme has satisfactory strength, and when it is used in a secondary battery, the secondary battery exhibits improved capacity, cycle stability, and / or rate performance.

[0021] In some embodiments, the total specific surface area of the pores having the first pore diameter is 0.08 - 1.32 m 2 / g. The conductive film based on this scheme has satisfactory strength, and when it is used in a secondary battery, the secondary battery exhibits improved capacity, cycle stability, and / or rate performance.

[0022] In some embodiments, the total specific surface area of the pores having the second pore diameter is 0.87 - 5.25 m 2 / g. The conductive film based on this scheme has satisfactory strength, and when it is used in a secondary battery, the secondary battery exhibits improved capacity, cycle stability, and / or rate performance.

[0023] In some embodiments, the specific surface area of the porous conductive material is 0.95-6.57 m 2 The conductive film based on this scheme has satisfactory strength, and when it is used in a secondary battery, the secondary battery exhibits improved capacity, cycle stability, and / or rate performance.

[0024] In some embodiments, the thickness of the base layer is 4.5-12 μm. The conductive film based on this scheme has satisfactory strength, and when it is used in a secondary battery, the secondary battery exhibits improved capacity, cycle stability, and / or rate performance.

[0025] In some embodiments, the thickness of the first porous layer is 50-200 μm. The conductive film based on this scheme has satisfactory strength, and when it is used in a secondary battery, the secondary battery exhibits improved capacity, cycle stability, and / or rate performance.

[0026] In some embodiments, the thickness of the second porous layer is 50-200 μm. The conductive film based on this scheme has satisfactory strength, and when it is used in a secondary battery, the secondary battery exhibits improved capacity, cycle stability, and / or rate performance.

[0027] In some embodiments, the material of the porous conductive material is a metal simple substance or alloy containing an M element selected from copper, aluminum, or a combination thereof. The conductive film based on this scheme has satisfactory strength, and when it is used in a secondary battery, the secondary battery exhibits improved capacity, cycle stability, and / or rate performance.

[0028] In some embodiments, the base layer has a tensile strength of 330 N / m 2 The conductive film based on this scheme has satisfactory strength, and when it is used in a secondary battery, the secondary battery exhibits improved capacity, cycle stability, and / or rate performance.

[0029] In some embodiments, the conductive film has a tensile strength of 100 N / m 2 The conductive film based on this scheme has satisfactory strength, and when it is used in a secondary battery, the secondary battery exhibits improved capacity, cycle stability, and / or rate performance.

[0030] In some embodiments, the material having a dense structure means that the apparent density of the material is substantially equal to the actual density, for example, the apparent density is equal to 90% or more, for example, 95% or more, for example, 100% of the actual density.

[0031] In some embodiments, the base layer has a single-layer structure or a multi-layer structure.

[0032] In some embodiments, the base layer has a multi-layer structure, and the base layer comprises a main layer and a first conductive adhesive layer laminated on one side surface of the main layer, and a surface of the first conductive adhesive layer opposite to the main layer constitutes a first surface of the base layer.

[0033] In some embodiments, the base layer has a multi-layer structure, and the base layer comprises a main layer and a first conductive adhesive layer and a second conductive adhesive layer laminated on opposite side surfaces of the main layer respectively, and a surface of the first conductive adhesive layer opposite to the main layer constitutes a first surface of the base layer, and a surface of the second conductive adhesive layer opposite to the main layer constitutes a second surface of the base layer.

[0034] In a second aspect, the present application provides a method for preparing a conductive film, wherein the conductive film is defined as any of the above-mentioned schemes, and the method comprises:

[0035] (1) providing a first raw multi-layer body, wherein the first raw multi-layer body comprises:

[0036] a raw base layer having a first surface and a second surface arranged oppositely, and the raw base layer has a dense structure;

[0037] a first A alloy layer laminated and combined with the first surface of the raw base layer, and the first A alloy layer is a multi-phase alloy containing an αMn phase and a (M, γMn) phase, and M elements are selected from copper, aluminum or a combination thereof; and

[0038] optionally, a first B alloy layer laminated and combined with the second surface of the raw base layer, and the first B alloy layer is a multi-phase alloy containing an αMn phase and a (M, γMn) phase, and M elements are selected from copper, aluminum or a combination thereof;

[0039] (2) removing at least part of Mn elements from the αMn phase of the multi-phase alloy and removing at least part of Mn elements from the (M, γMn) phase of the multi-phase alloy by a dealloying method;

[0040] wherein the raw base layer is configured to remain intact during the dealloying process.

[0041] The above-mentioned method ingeniously utilizes the different chemical reactions of the αMn phase and the (M, γMn) phase in the multi-phase alloy during the dealloying process, the αMn phase is removed to form pores with a first pore size during the dealloying process, and the Mn elements in the (M, γMn) phase are removed to form pores with a second pore size during the dealloying process, thereby obtaining the conductive film with a novel porous structure of the present application.

[0042] In some embodiments, the method for preparing the conductive film further comprises the step of preparing the first raw multilayer body, specifically comprising:

[0043] (1) providing a second raw multilayer body, the second raw multilayer body comprising:

[0044] a raw base layer having a first surface and a second surface arranged oppositely, the raw base layer having a dense structure;

[0045] a second A alloy layer laminatedly combined to the first surface of the raw base layer, the second A alloy layer containing a (M, γMn) phase; and

[0046] optionally, a second B alloy layer laminatedly combined to the first surface of the raw base layer, the second B alloy layer containing a (M, γMn) phase;

[0047] (2) performing a phase separation heat treatment on the product of the previous step to form a multi-phase alloy in the second A alloy layer and / or the second B alloy layer, the multi-phase alloy containing an αMn phase and a (M, γMn) phase, to obtain the first raw multilayer body.

[0048] In some embodiments, the method for preparing the conductive film further comprises the step of preparing the first raw multilayer body, specifically comprising:

[0049] (1) providing a γ single-phase alloy foil, the content of the (M, γMn) phase in the γ single-phase alloy foil being 95 vol% or more;

[0050] (2) performing a phase separation heat treatment on the γ single-phase alloy foil to obtain a multi-phase alloy foil containing an αMn phase and a (M, γMn) phase;

[0051] (3) providing a raw base layer comprising a main body layer and a first conductive adhesive layer laminated on one side surface of the main body layer, and optionally, a second conductive adhesive layer laminated on the other side surface of the main body layer;

[0052] (4) laminatingly combining the multi-phase alloy foil to the surface of the first conductive adhesive layer away from the raw base layer, and optionally, laminatingly combining the multi-phase alloy foil to the surface of the second conductive adhesive layer away from the raw base layer.

[0053] In some embodiments, the phase separation heat treatment is performed at a temperature of 500-700°C.

[0054] In some embodiments, the phase separation heat treatment is performed for 1-4 hours.

[0055] In some embodiments, the phase separation heat treatment is followed by cooling at a cooling rate of 20-1000°C / s.

[0056] In a second aspect, this application provides a current collector comprising the conductive film described in any of the preceding claims.

[0057] In a third aspect, this application provides a secondary battery comprising the current collector described in any of the preceding claims;

[0058] In some implementations, the secondary battery is a negative electrode-free metal battery;

[0059] In some embodiments, the negative electrode active material of the secondary battery contains a metal or alloy.

[0060] In a fourth aspect, this application provides an apparatus comprising a secondary battery as described in any of the preceding claims, wherein the secondary battery provides electrical energy to the apparatus.

[0061] Beneficial effects

[0062] One or more embodiments of this application have one or more of the following beneficial effects:

[0063] (1) The conductive film has a layered structure of a base layer and a porous layer. The base layer has good tensile strength, which provides good support for the porous layer and also improves the overall tensile strength of the conductive film.

[0064] (2) Fig. 3-5 Scanning electron microscope images of the porous conductive materials of the embodiments shown and Fig. 1 The diagram shows a porous conductive material. In the porous layer of the conductive film of this application, the porous conductive material has pores with a first pore size and pores with a second pore size. The inner wall of the pore with the first pore size (referred to as macropore) can serve as a substrate for the deposition of active material; in addition, another function of macropore is to provide electrolyte wetting channels. The inner wall of the pore with the second pore size (referred to as micropore) can serve as a substrate for the deposition of active material. Micropore increases the specific surface area of ​​the material, thereby enabling the porous conductive material to load more active material; in addition, another function of micropore is to serve as a template for the deposition of active material. Specifically, due to the limitation of micropore size, the active material deposited in the micropore has a nanoscale size. Nanoscale active material has a high ionic conductivity due to its small size, which can improve the overall ionic conductivity of the electrode, thereby improving the rate performance of the battery, and ultimately improving the overall capacity, cycle stability and rate performance of the battery; in addition, another function of micropore is to limit the volume expansion of the active material and prevent its pulverization and failure.

[0065] (3) The present application ingeniously utilizes the properties of multiphase alloys to prepare the porous layer of the conductive film. According to the Mn-Cu binary alloy phase diagram, the Mn-Cu binary alloy (Mn content 60-90 at.%) has (M, γMn) single-phase structure at the temperature range of 700-865°C, and α / γ dual-phase structure at the temperature range of 500-700°C. Therefore, the Mn-Cu alloy prepared by smelting can be first annealed at high temperature (700-865°C) to obtain (M, γMn) single-phase alloy with excellent plastic processing capability, and then aged at low temperature (500-700°C) to form α / γ dual-phase structure for preparing the final porous conductive material.

[0066] (4) In the method for preparing the porous conductive material, the second A alloy layer / second B alloy layer mainly contains (M, γMn) phase, which has good plasticity and can be processed into products with different shapes and sizes by plastic processing methods (forging, rolling, drawing, etc.). Subsequent phase separation heat treatment and dealloying operation of the processed products basically does not change the shape and size of the processed products. The method of the present application can obtain a dealloyed product that can maintain the shape and size of the parent body, and can prepare a large-size conductive film.

[0067] (5) The method of the present application can flexibly adjust the pore size and proportion of the pores with the second pore size and the pores with the first pore size in the porous conductive material. For example, by adjusting the temperature and time of the phase separation heat treatment, the content and size of the αMn phase in the second product can be controlled, and then the content and pore size of the pores with the first pore size in the porous conductive material can be controlled. For another example, by adjusting the dealloying corrosion temperature, the content and pore size of the pores with the second pore size in the porous conductive material can be controlled. BRIEF DESCRIPTION OF DRAWINGS

[0068] Fig. 1 Schematic diagram and partial enlarged view of the conductive film of some embodiments of the present application.

[0069] Fig. 2 Schematic diagram and cross-sectional scanning electron microscope photograph of the conductive film of some embodiments of the present application.

[0070] Fig. 3 Scanning electron microscope photograph of the first porous layer of the conductive film of Example 1 of the present application.

[0071] Fig. 4 Scanning electron microscope photograph of the first porous layer of the conductive film of Example 2 of the present application.

[0072] Fig. 5 Scanning electron microscope photograph of the first porous layer of the conductive film of Example 3 of the present application.

[0073] Fig. 6 is a binary phase diagram of Mn-Cu alloy.

[0074] Fig. 7 (a) of FIG. 1 is an XRD pattern of a second A-alloy layer of some embodiments of the present application; Fig. 7 (b) of FIG. 1 is an XRD pattern of a first A-alloy layer of some embodiments of the present application; Fig. 7 (c) of FIG. 1 is an XRD pattern of a first porous layer of some embodiments of the present application.

[0075] Fig. 8 is a cycle number-capacity curve of a secondary battery containing the conductive film of Example 2 and Comparative Example 2.

[0076] Fig. 9 is a whole view and an exploded view of a secondary battery of an embodiment of the present application.

[0077] Fig. 10 is a schematic view of a battery module of an embodiment of the present application.

[0078] Fig. 11 is a schematic view of a battery pack of an embodiment of the present application.

[0079] Fig. 12 is Fig. 11 is an exploded view of a battery pack of an embodiment of the present application shown in FIG. 4.

[0080] Fig. 13 is a schematic view of an apparatus using a secondary battery of an embodiment of the present application as a power source.

[0081] Fig. 14 shows a schematic view of a conductive film of yet another embodiment of the present application.

[0082] Fig. 15 shows a schematic view of a conductive film of yet another embodiment of the present application.

[0083] BRIEF DESCRIPTION OF DRAWINGS

[0084] Battery pack 1; upper case 2; lower case 3; battery module 4; secondary battery 5; housing 51; electrode assembly 52; top cover assembly 53; base layer 200; first surface 101; second surface 102; first porous layer 110; second porous layer 120; porous conductive material 60; hole 601 having a first pore diameter; first prismatic wire 600; hole 602 having a second pore diameter; second prismatic wire 604; main body layer 1005; first conductive adhesive layer 1001; second conductive adhesive layer 1002. DETAILED DESCRIPTION

[0085] Hereinafter, specific embodiments of the conductive film and the method for manufacturing the same, the electrode, the current collector, the secondary battery, and the device of the present application will be explained in detail with appropriate reference to the accompanying drawings. However, there will be cases of omitting unnecessary detailed explanation. For example, there will be cases of omitting detailed explanation of matters known well, and repeated explanation of substantially identical structures. This is to avoid the following explanation from becoming unnecessarily lengthy, and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following explanation are provided in order for those skilled in the art to fully understand the present application, and are not intended to limit the subject matter recited in the claims.

[0086] The ranges disclosed herein are defined by their lower and upper limits. Ranges created by the upper and lower limits are inclusive of the endpoints. Ranges created by the upper and lower limits are also inclusive of any point or sub-range falling within the range. For example, if a range is stated as 60-120 and 80-110, it is understood that the range created by the endpoints 60-110 and 80-120 are also contemplated. Additionally, if a range is stated as 1-2 and 3-5, it is understood that the ranges created by the endpoints 1-3, 1-5, 2-3, 2-5, and 3-5 are also contemplated. In the present application, unless otherwise indicated, a numerical range "a-b" means a shorthand manner of describing all individual real numbers that fall within the range, wherein "a" and "b" are both real numbers. For example, the numerical range "0-5" means that all real numbers that fall within the range "0-5" have been individually listed herein, and "0-5" is merely a shorthand manner of describing those numerical combinations. Additionally, when a parameter is stated to be an integer ≥ 2, it is equivalent to disclose that the parameter is, for example, integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0087] All embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, if not particularly stated.

[0088] All technical features and optional technical features of the present application can be combined with each other to form new technical solutions, if not particularly stated.

[0089] All steps of the present application can be performed in sequence or randomly, preferably in sequence, if not particularly stated. For example, a method comprising steps (a) and (b) means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, it is mentioned that the method can further comprise step (c), which means that step (c) can be added to the method in any sequence. For example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0090] If not specifically stated, "comprising" and "including" as used herein are open-ended and also include the case where only the listed components are present. For example, "comprising" and "including" can mean the listed components are present, but also that other components are present.

[0091] If not specifically stated, the term "or" as used herein is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following are satisfied: A is true (or present) and B is false (or not present); A is false (or not present) and B is true (or present); or both A and B are true (or present).

[0092] If not specifically stated, the porous layer refers to the first porous layer, the second porous layer, or a combination thereof.

[0093] If not specifically stated, the first porous layer and the second porous layer can have the same or different materials, the same or different compositions, the same or different pore size distribution characteristics, the same or different sizes, and the same or different thicknesses.

[0094] [Conductive film]

[0095] In some embodiments, the present application provides a conductive film, the conductive film comprising:

[0096] a base layer having a first surface and a second surface oppositely arranged, the base layer having a dense structure;

[0097] a first porous layer laminated to the first surface of the base layer;

[0098] the first porous layer comprising a porous conductive material;

[0099] the porous conductive material having pores of a first pore size and pores of a second pore size;

[0100] the first pore size is n micrometers, 0.5 ≤ n ≤ 10;

[0101] the second pore size is m nanometers, 20 < m < 200.

[0102] The conductive film of the above-mentioned solution has a base layer and a porous layer laminated together. The porous layer has a relatively weak mechanical strength due to its porous structure. The base layer having good tensile properties (e.g., tensile strength of 330 N / mm 2 The above) and the porous layer are laminated together to obtain a multi-layer conductive film, which has both enhanced mechanical properties and a porous structure, and is suitable for use as a secondary battery current collector.

[0103] In some embodiments, the term "laminated bonding" refers to the bonding of the base layer and the porous layer through a chemical bond (e.g., a metallic bond) at a position where the base layer and the porous layer are laminated to each other. The bonding strength of the base layer and the porous layer can be detected by a tape peeling test, in which a tape is adhered to the surface of the porous layer and then peeled off. The bonding strength of the base layer and the porous layer can resist a tape peeling of σ 180° 7 N / mm or more, and the porous layer does not fall off.

[0104] In some embodiments, the term "conductive film" refers to a film having an electrical conductivity of 10 3 ( Siemens / cm) or more, for example, 10 5 ( Siemens / cm) or more, for example, 10 7 ( Siemens / cm) or more.

[0105] In some embodiments, the base layer has a dense structure, and the porosity of the base layer is, for example, zero.

[0106] The conductive film of the above-mentioned scheme contains a porous conductive material having an innovative multi-level pore size distribution characteristic. This new porous conductive material is particularly suitable for use in an anode free metal battery (e.g., an anode free lithium metal battery or an anode free sodium metal battery) or a battery containing an active metal / alloy anode. The inner wall of the pores having a first pore size (referred to as macropores) can serve as a substrate for the deposition of active materials; in addition, another role of the macropores is to provide a channel for the infiltration of electrolyte. The inner wall of the pores having a second pore size (referred to as micropores) can serve as a substrate for the deposition of active materials. The micropores increase the specific surface area of the material, thereby enabling the porous conductive material to load more active materials; in addition, another role of the micropores is to act as a template for the deposition of active materials. Specifically, due to the limitation of the size of the micropores, the active materials deposited in the micropores have a nanoscale size, and the nanoscale active materials have a higher ionic conductivity due to their small size, thereby being able to improve the overall ionic conductivity of the electrode, thereby being able to improve the rate performance of the battery, and ultimately improving the capacity, cycle stability, and rate performance of the battery as a whole; in addition, another role of the micropores is to limit the volume expansion of the active materials, thereby avoiding their pulverization failure.

[0107] Fig. 1 A schematic diagram of a conductive film of one embodiment is shown, which includes a base layer 100 and a first porous layer 110. The base layer 100 has a first surface 101 and a second surface 102 arranged opposite to each other, and the base layer 100 has a tensile strength of 100 MPa or more; the first porous layer 110 is laminated and bonded to the first surface 101 of the base layer 110; and the material of the first porous layer 110 is a porous conductive material.

[0108] The dashed box on the first porous layer 110 leads to a partial enlarged schematic view of the porous conductive material 60. The porous conductive material 60 has a macro-pore structure with pores 601 of a first pore size, and adjacent pores 601 of the first pore size are separated by first ribbons 600. The dashed box on the first ribbons 600 leads to a partial enlarged schematic view of the first ribbons 600. The first ribbons 600 have a micro-pore structure with pores 602 of a second pore size, and adjacent pores 602 of the second pore size are separated by second ribbons 604.

[0109] The porous conductive material based on the above scheme has an innovative multi-level pore size distribution feature. This new type of porous conductive material is particularly suitable for use in anode-free metal batteries (such as anode-free lithium metal batteries or anode-free sodium metal batteries) or metal or alloy anode batteries. The inner wall of the pores with the first pore size (referred to as macro-pores) can serve as a substrate for active material deposition; in addition, another role of the macro-pores is to provide electrolyte infiltration channels. The inner wall of the pores with the second pore size (referred to as micro-pores) can serve as a substrate for active material deposition. The micro-pores increase the specific surface area of the material, thereby enabling the porous conductive material to load more active material; in addition, another role of the micro-pores is to act as a template for active material deposition. Specifically, due to the limitation of the size of the micro-pores, the active material deposited in the micro-pores has a nanoscale size, and the nanoscale active material has a higher ionic conductivity due to its small size, thereby being able to improve the overall ionic conductivity of the electrode, thereby being able to improve the rate performance of the battery, and ultimately improving the capacity, cycle stability, and rate performance of the battery as a whole; in addition, another role of the micro-pores is to limit the volume expansion of the active material and avoid its pulverization failure.

[0110] In some embodiments, the first pore size is n micrometers, 0.5≤n≤10; n can be 0.5-1, 1-2, 2-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9, or 9-10. The 0.5-10 micrometer micropores have better capacity performance, cycle stability, and rate performance of the battery compared to micropores with a larger size (300-700 um), the active material particle size is reduced, which can improve the ionic conductivity of the electrode material, thereby improving the overall conductivity of the electrode and improving the rate performance of the battery, and at the same time, the nanometer pores of the micropores can further improve the specific surface area of the metal current collector, thereby enabling the loading of more active material.

[0111] In some embodiments, the second pore size is m nanometers, 20

[0112] Fig. 2A schematic diagram of the conductive film according to some embodiments of the present application is shown. In some embodiments, reference is made to Fig. 2 The conductive film further includes a second porous layer 120 laminated to the second surface 102 of the base layer 100. The first porous layer 110 and the second porous layer 120 each independently include a porous conductive material; the porous conductive material has pores of a first pore diameter and pores of a second pore diameter; the first pore diameter is n micrometers, 0.5 ≤ n ≤ 10; the second pore diameter is m nanometers, 20 < m < 200. The conductive film according to this scheme has porous layers on both sides of the film, and both sides of the film can serve as current collector surfaces for active materials, and the conductive film is used in a secondary battery, which exhibits improved capacity, cycle stability, and / or rate performance.

[0113] In some embodiments, the apparent volume of the porous conductive material is V, the total pore volume of the pores having the first pore diameter is VI, and the total pore volume of the pores having the second pore diameter is V2, and the porous conductive material satisfies the following relationship: (VI + V2) / V = 60% - 90%. In some embodiments, the value of (VI + V2) / V is 20 - 30%, 30 - 40%, 40 - 50%, 50 - 60%, 60 - 70%, 70 - 80%, or 80 - 90%. In some embodiments, V = VI + V2. The conductive film according to this scheme has satisfactory strength, and when it is used in a secondary battery, the secondary battery exhibits improved capacity, cycle stability, and / or rate performance.

[0114] In some embodiments, the apparent volume of the porous conductive material is V, the total pore volume of the pores having the first pore diameter is VI, and the porous conductive material satisfies the following relationship: VI / V = 5% - 70%. In some embodiments, the value of VI / V is 5% - 15%, 10% - 15%, 15% - 20%, 20% - 30%, 30% - 40%, 40% - 50%, 50% - 60%, or 60% - 70%. The conductive film according to this scheme has satisfactory strength, and when it is used in a secondary battery, the secondary battery exhibits improved capacity, cycle stability, and / or rate performance.

[0115] In some embodiments, the apparent volume of the porous conductive material is V, the total pore volume of the pores having the second pore diameter is V2, and the porous conductive material satisfies the following relationship: V2 / V = 15% - 70%. In some embodiments, the value of V2 / V is 15% - 20%, 20% - 30%, 30% - 40%, 40% - 50%, 50% - 60%, or 60% - 70%. The conductive film according to this scheme has satisfactory strength, and when it is used in a secondary battery, the secondary battery exhibits improved capacity, cycle stability, and / or rate performance.

[0116] In some embodiments, the pores having the first pore size are spaced apart from each other by first land filaments having an average land filament diameter of 0.89 μm to 3 μm (e.g., 1 μm to 1.5 μm, 1.5 μm to 2 μm, 2 μm to 2.5 μm, 2.5 μm to 3 μm). The conductive film based on this scheme has satisfactory strength, and when it is used for a secondary battery, the secondary battery exhibits improved capacity, cycle stability, and / or rate performance.

[0117] In some embodiments, the pores having the second pore size are spaced apart from each other by second land filaments having an average land filament diameter of 27 nm to 100 nm (e.g., 30 nm to 40 nm, 40 nm to 50 nm, 50 nm to 60 nm, 60 nm to 70 nm, 70 nm to 80 nm, 80 nm to 90 nm, or 90 nm to 100 nm). The conductive film based on this scheme has satisfactory strength, and when it is used for a secondary battery, the secondary battery exhibits improved capacity, cycle stability, and / or rate performance.

[0118] In some embodiments, the total specific surface area of the pores having the first pore size is 0.08 m 2 / g to 1.32 m 2 / g (e.g., 0.1 m 2 / g to 0.3 m 2 / g, 0.3 m 2 / g to 0.5 m 2 / g, 0.5 m 2 / g to 0.7 m 2 / g, 0.7 m 2 / g to 0.9 m 2 / g, 0.9 m 2 / g to 1.1 m 2 / g, 1.1 m 2 / g to 1.3 m 2 / g). The conductive film based on this scheme has satisfactory strength, and when it is used for a secondary battery, the secondary battery exhibits improved capacity, cycle stability, and / or rate performance.

[0119] In some embodiments, the total specific surface area of the pores having the second pore size is 0.87 m 2 / g to 5.25 m 2 / g (e.g., 1 m 2 / g to 1.5 m 2 / g, 1.5 m 2 / g to 2 m 2 / g, 2 m 2 / g to 2.5 m 2 / g, 2.5 m 2 / g to 3 m 2 / g, 3 m2 / g-3.5m 2 / g, 3.5m 2 / g-4m 2 / g, 4m 2 / g-4.5m 2 / g, 4.5m 2 / g-5m 2 / g). The conductive film based on this scheme has satisfactory strength, and moreover, when it is used for a secondary battery, the secondary battery exhibits improved capacity, cycle stability, and / or rate performance.

[0120] In some embodiments, the specific surface area of the porous conductive material is 0.95m 2 / g-6.57m 2 / g (e.g. 1m 2 / g-1.5m 2 / g, 1.5m 2 / g-2m 2 / g, 2m 2 / g-2.5m 2 / g, 2.5m 2 / g-3m 2 / g, 3m 2 / g-3.5m 2 / g, 3.5m 2 / g-4m 2 / g, 4m 2 / g-4.5m 2 / g, 4.5m 2 / g-5m 2 / g, 5m 2 / g-5.5m 2 / g, 5.5m 2 / g-6m 2 / g). The specific surface area of the porous conductive material may, for example, be equal to the sum of the total specific surface area of pores having a first pore diameter and the total specific surface area of pores having a second pore diameter. The conductive film based on this scheme has satisfactory strength, and moreover, when it is used for a secondary battery, the secondary battery exhibits improved capacity, cycle stability, and / or rate performance.

[0121] In some embodiments, the thickness of the base layer is 4.5pm-12pm, for example 4.5pm-6pm, 6pm-8pm, 8pm-10pm, 10pm-12pm. The conductive film based on this scheme has satisfactory strength, and moreover, when it is used for a secondary battery, the secondary battery exhibits improved capacity, cycle stability, and / or rate performance.

[0122] In some embodiments, the first porous layer has a thickness of 50 μm to 200 μm, for example, 50 μm to 100 μm, 100 μm to 150 μm, 150 μm to 200 μm. The conductive film based on this scheme has satisfactory strength, and moreover, when it is used for a secondary battery, the secondary battery exhibits improved capacity, cycle stability, and / or rate performance.

[0123] In some embodiments, the second porous layer has a thickness of 50 μm to 200 μm, for example, 50 μm to 100 μm, 100 μm to 150 μm, 150 μm to 200 μm. The conductive film based on this scheme has satisfactory strength, and moreover, when it is used for a secondary battery, the secondary battery exhibits improved capacity, cycle stability, and / or rate performance.

[0124] In some embodiments, the total thickness of the conductive film is 50 μm to 450 μm. The total thickness of the conductive film may, for example, be 50 μm to 100 μm, 100 μm to 150 μm, 150 μm to 200 μm, 200 μm to 250 μm, 250 μm to 300 μm, 300 μm to 350 μm, 350 μm to 400 μm, 400 μm to 450 μm.

[0125] In some embodiments, the porous conductive material is a metal simple substance or an alloy containing an M element selected from copper, aluminum, or a combination thereof. For example, the porous conductive material is copper or a copper alloy. The conductive film based on this scheme has satisfactory strength, and moreover, when it is used for a secondary battery, the secondary battery exhibits improved capacity, cycle stability, and / or rate performance.

[0126] In some embodiments, the porous conductive material is obtained by a dealloying method.

[0127] In some embodiments, the porous conductive material is gas permeable and / or liquid permeable.

[0128] In some embodiments, the base layer has a tensile strength of 330 N / m 2 or more. The conductive film based on this scheme has satisfactory strength, and moreover, when it is used for a secondary battery, the secondary battery exhibits improved capacity, cycle stability, and / or rate performance.

[0129] In some embodiments, the conductive film has a tensile strength of 100 N / mm 2 or more. The conductive film based on this scheme has satisfactory strength, and moreover, when it is used for a secondary battery, the secondary battery exhibits improved capacity, cycle stability, and / or rate performance.

[0130] In some embodiments, the base layer has a tensile strength of 330 N / mm 2~ 500 N / mm 2 a tensile strength of, for example, 330 N / mm 2 ~ 400 N / mm 2 a tensile strength of, for example, 400 N / mm 2 ~ 450 N / mm 2 a tensile strength of, for example, 450 N / mm 2 ~ 500 N / mm 2 a tensile strength of, for example, 500 N / mm

[0131] In some embodiments, the conductive film has a tensile strength of, for example, 330 N / mm 2 ~ 500 N / mm 2 a tensile strength of, for example, 330 N / mm 2 ~ 400 N / mm 2 a tensile strength of, for example, 400 N / mm 2 ~ 450 N / mm 2 a tensile strength of, for example, 450 N / mm 2 ~ 500 N / mm 2 a tensile strength of, for example, 500 N / mm

[0132] In some embodiments, the base layer has a single-layer structure or a multi-layer structure.

[0133] In some embodiments, the base layer 100 has a single-layer structure or a multi-layer structure, for example, the base layer can have a two-layer structure or a three-layer structure. In the technical solution in which the base layer 100 has a multi-layer structure, the base layer with good comprehensive performance can be obtained by designing the materials of the layers of the base layer 100 in a targeted manner. For example, a dense metal material layer is arranged in the base layer, so that the base layer has a higher tensile strength. For example, one or more conductive adhesive layers are arranged in the base layer, so that the base layer can be conveniently and firmly laminated with the porous layer.

[0134] Fig. 14 A schematic diagram of a conductive film illustrating yet some embodiments of the present application is shown. As shown in the figure, in some embodiments, the base layer 100 has a multi-layer structure, and the base layer 100 includes a main body layer 1005 and a first conductive adhesive layer 1001 laminated on one side surface of the main body layer 1005, and the surface of the first conductive adhesive layer 1001 away from the main body layer 1005 constitutes a first surface 101 of the base layer 100.

[0135] Fig. 15A schematic diagram showing a conductive film according to some embodiments of the present application. As shown, in some embodiments, the base layer 100 has a multi-layer structure, which includes a main layer 1005 and a first conductive adhesive layer 1001 and a second conductive adhesive layer 1002 respectively laminated on the opposite surfaces of the main layer 1005, the surface of the first conductive adhesive layer 1001 opposite to the main layer 1005 constitutes the first surface 101 of the base layer, and the surface of the second conductive adhesive layer 1002 opposite to the main layer 1005 constitutes the second surface 102 of the base layer.

[0136] In some embodiments, the thickness ratio of the main layer 1005 to the first conductive adhesive layer 1001 is 4.5-12:1-10, for example, 4.5-8:2, for example, 5-7:2.

[0137] In some embodiments, the thickness ratio of the main layer 1005 to the second conductive adhesive layer 1002 is 4.5-12:1-10, for example, 4.5-8:2, for example, 5-7:2.

[0138] In some embodiments, the conductive adhesive contains a viscous component and a conductive component.

[0139] In some embodiments, the viscous component is selected from one or more of epoxy resin, silicone resin, polyimide resin, polyurethane, and acrylic resin.

[0140] In some embodiments, the conductive component is selected from one or more of carbon material (such as carbon nanotube) and metal material (such as Au, Ag, Cu, Ni).

[0141] In some embodiments, the conductive adhesive has an electrical conductivity of, for example, 1.1 x 10 -10 Siemens / m or more.

[0142] In a second aspect, the present application provides a method for preparing a conductive film, the conductive film being defined as in any of the above embodiments, the method comprising:

[0143] (1) providing a first raw multi-layer body, the first raw multi-layer body comprising:

[0144] a raw base layer, the raw base layer having a first surface and a second surface oppositely arranged, the raw base layer having a dense structure;

[0145] a first A alloy layer, the first A alloy layer being laminated to the first surface of the raw base layer, the first A alloy layer having a multi-phase alloy, the multi-phase alloy containing an αMn phase and a (M, γMn) phase, M being selected from copper, aluminum or a combination thereof; and

[0146] Optionally, the first B alloy layer is laminated to the second surface of the base material layer, and the first B alloy layer is a multi-phase alloy containing an aMn phase and a (M, yMn) phase, and the M element is selected from copper, aluminum, or a combination thereof.

[0147] (2) removing at least part of the Mn element from the aMn phase of the multi-phase alloy and removing at least part of the Mn element from the (M, yMn) phase of the multi-phase alloy by dealloying;

[0148] Optionally, the base material layer is configured to remain intact during the dealloying process.

[0149] In some embodiments, the base material layer does not undergo a dealloying reaction during the dealloying process. The base material layer can be made of a relatively inert metal, such as a metal having a standard electrode potential greater than zero, such as Cu, Ni, Ag, Pt, Au, or an alloy thereof.

[0150] The above method ingeniously utilizes the different chemical reactions of the aMn phase and the (M, yMn) phase of the multi-phase alloy during the dealloying process. The aMn phase is removed to form pores having a first pore size during the dealloying process, and the Mn element in the (M, yMn) phase is removed to form pores having a second pore size during the dealloying process, thereby obtaining the conductive film having the novel porous structure of the present application. According to the Mn-Cu binary alloy phase diagram, the Mn-Cu binary alloy (Mn content 90-60 at.%) has a (M, yMn) single-phase structure at a temperature range of 700-865°C, and an a / y dual-phase structure at a temperature range of 500-700°C. Therefore, the Mn-Cu alloy prepared by smelting can be first annealed at a high temperature (700-865°C) to obtain a (M, yMn) single-phase alloy having excellent plastic processing capability, and a precursor alloy of different shapes is prepared. Subsequently, aging treatment is performed at a low temperature (500-700°C) to form an a / y dual-phase structure, which is used to prepare the final porous conductive material.

[0151] In some embodiments, the aMn is a polymorph of manganese having a cbcc structure.

[0152] In some embodiments, the (M, yMn) phase is a solid solution phase formed by dissolving the element M in yMn. For example, the (Cu, yMn) phase is a solid solution phase formed by dissolving the element Cu in yMn.

[0153] In some embodiments, a solid solution is a single-phase crystalline solid formed by dissolving one or more solute components into a crystalline solvent while maintaining the crystal lattice type of the solvent.

[0154] In some embodiments, at least 90 at.% of Mn is removed from the aMn phase by dealloying, based on the total amount of Mn in the aMn phase. Based on this, the obtained porous conductive material has an innovative pore distribution feature.

[0155] In some embodiments, at least 90 at.% of Mn is removed from the (M, γMn) phase by dealloying, based on the total amount of Mn in the (M, γMn) phase. Based on this, the obtained porous conductive material has an innovative pore distribution feature.

[0156] In some embodiments, the amount of M removed by dealloying is less than 10 at.%, based on the total amount of M in the multiphase alloy. Based on this, the obtained porous conductive material has an innovative pore distribution feature.

[0157] In some embodiments, the content of Mn in the aMn phase is > 99 at.%. Based on this, the obtained porous conductive material has an innovative pore distribution feature.

[0158] In some embodiments, the content of Mn in the (M, γMn) phase is 40-80 at.%. Based on this, the obtained porous conductive material has an innovative pore distribution feature.

[0159] In some embodiments, the (M, γMn) phase is a solid solution. Based on this, the obtained porous conductive material has an innovative pore distribution feature.

[0160] In some embodiments, the content of the aMn phase in the multiphase alloy is 22-70 vol.%. Based on this, the obtained porous conductive material has an innovative pore distribution feature. In some embodiments, the content of the aMn phase in the multiphase alloy is 22-70 vol.%, for example, 22-30 vol.%, 30-40 vol.%, 40-50 vol.%, 50-60 vol.%, 60-70 vol.%, and the content of the (M, γMn) phase is 30-78 vol.%, for example, 30-40 vol.%, 40-50 vol.%, 50-60 vol.%, 60-78 vol.%.

[0161] In some embodiments, the content of the (M, γMn) phase in the multiphase alloy is 30-78 vol.%. Based on this, the obtained porous conductive material has an innovative pore distribution feature.

[0162] In some embodiments, the aMn phase and the (M, γMn) phase are uniformly dispersed in the multiphase alloy. Based on this, the obtained porous conductive material has an innovative pore distribution feature.

[0163] In some embodiments, the multi-phase alloy contains Mn element and M element, the content of Mn element is 60-90 at.%, the content of M element is 10-40 at.%, and M element is selected from copper, aluminum or a combination thereof. Based on this, the obtained porous conductive material has innovative pore distribution characteristics.

[0164] In some embodiments, the dealloying process is mainly based on the difference in standard electrochemical potential of the precursor components, and the relatively active elements in the system are selectively removed, and the remaining metal atoms are connected to each other to obtain a porous conductive material.

[0165] In some embodiments, the dealloying method is selected from chemical corrosion, electrochemical corrosion, or a combination thereof. Based on this, the obtained porous conductive material has innovative pore distribution characteristics.

[0166] In some embodiments, the method for preparing a conductive film further comprises the step of preparing a first raw material multilayer, specifically comprising:

[0167] (1) providing a second raw material multilayer, the second raw material multilayer comprising:

[0168] a raw material base layer, the raw material base layer having oppositely arranged first and second surfaces, and the raw material base layer having a dense structure;

[0169] a second A alloy layer, the second A alloy layer being laminated to the first surface of the raw material base layer, and the content of (M, γMn) phase in the second A alloy layer being 95 vol% or more; and

[0170] optionally, a second B alloy layer, the second B alloy layer being laminated to the first surface of the raw material base layer, and the content of (M, γMn) phase in the second B alloy layer being 95 vol% or more;

[0171] (2) phase separation heat treatment is performed on the product of the previous step to form a multi-phase alloy in the second A alloy layer and / or the second B alloy layer, the multi-phase alloy containing αMn phase and (M, γMn) phase, and a first raw material multilayer is obtained.

[0172] In some embodiments, the method for preparing a conductive film further comprises the step of preparing a first raw material multilayer, specifically comprising:

[0173] (1) providing a γ single-phase alloy foil, the content of (M, γMn) phase in the γ single-phase alloy foil being 95 vol% or more;

[0174] (2) phase separation heat treatment is performed on the product of the previous step to form a multi-phase alloy in the second A alloy layer and / or the second B alloy layer, the multi-phase alloy containing αMn phase and (M, γMn) phase, and a first raw material multilayer is obtained.

[0175] (3) providing a raw material base layer, which comprises a main layer and a first conductive adhesive layer laminated on one side surface of the main layer, and optionally, a second conductive adhesive layer laminated on the other side surface of the main layer;

[0176] (4) laminating and bonding a multiphase alloy foil on the surface of the first conductive adhesive layer away from the raw material base layer, and optionally, laminating and bonding a multiphase alloy foil on the surface of the second conductive adhesive layer away from the raw material base layer, to obtain a first raw material multilayer body.

[0177] The second A alloy layer / second B alloy layer containing the (M, γMn) phase has excellent room temperature plasticity. The first product is processed by plastic processing methods such as forging, rolling, and drawing, to obtain a processed product with different shapes and sizes. The processed product can maintain the stability of the shape and size during subsequent heat treatment and dealloying.

[0178] In some embodiments, the second raw material multilayer body is obtained by a lamination rolling method, for example, by a lamination hot rolling method. In one embodiment, the (M, γMn) phase alloy foil and the copper foil can be laminated in the required order and then hot rolled to obtain the second raw material multilayer body.

[0179] In some embodiments, the temperature of the phase separation heat treatment is 500-700°C.

[0180] In some embodiments, the time of the phase separation heat treatment is 1-4 hours.

[0181] In some embodiments, the phase separation heat treatment is followed by cooling at a cooling rate of 20-1000°C / s.

[0182] In some embodiments, the second A alloy layer and / or the material of the second A alloy layer is a copper-manganese alloy, and the content of Mn element is 60%-90%.

[0183] In some embodiments, the (M, γMn) phase content is 95vol% or more of a γ single-phase alloy, which can be obtained by first heat treatment of a copper-manganese alloy.

[0184] In some embodiments, the temperature of the first heat treatment is 700-865°C. Based on this, the obtained porous conductive material has an innovative pore distribution feature.

[0185] In some embodiments, the time of the first heat treatment is 0.16 hours or more, for example, 1-2 hours. Based on this, the obtained porous conductive material has an innovative pore distribution feature.

[0186] In some embodiments, the first heat treatment is followed by cooling at a cooling rate of 20-1000℃ / s, such as water quenching. Based thereon, the obtained porous conductive material has innovative pore distribution characteristics.

[0187] In some embodiments, the method further comprises an operation of plastic working the first product before the phase separation heat treatment is performed.

[0188] In some embodiments, the phase separation heat treatment is configured to convert part of the (M, γMn) phase to the αMn phase.

[0189] In some embodiments, the raw material base layer has a tensile strength of 330 N / mm 2 The above tensile strength (e.g. the base layer has a tensile strength of 330 N / mm 2 ~ 500 N / mm 2 The above tensile strength (e.g. the base layer has a tensile strength of 330 N / mm 2 ~ 400 N / mm 2 The above tensile strength (e.g. the base layer has a tensile strength of 330 N / mm 2 ~ 500 N / mm 2 The above tensile strength (e.g. the base layer has a tensile strength of 330 N / mm

[0190] In a second aspect, the present application provides a current collector comprising the porous conductive material of any one of the above.

[0191] In a third aspect, the present application provides a secondary battery comprising the current collector of any one of the above.

[0192] In some embodiments, the secondary battery is a metal anode-free battery.

[0193] In some embodiments, the negative active material of the secondary battery contains a metal or an alloy.

[0194] In a fourth aspect, the present application provides a device comprising the secondary battery of any one of the above, the secondary battery providing electric energy to the device.

[0195] [Secondary battery]

[0196] A secondary battery, also known as a rechargeable battery or a storage battery, refers to a battery that can continue to be used through the activation of active materials by charging after the battery is discharged.

[0197] Generally, a secondary battery comprises a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte. During the charging and discharging process of the battery, active ions (e.g. lithium ions) are inserted and extracted between the positive electrode sheet and the negative electrode sheet. The separator is arranged between the positive electrode sheet and the negative electrode sheet, mainly to prevent short circuiting of the positive and negative electrodes, while allowing the active ions to pass through. The electrolyte is between the positive electrode sheet and the negative electrode sheet, mainly to conduct the active ions.

[0198] [Positive electrode sheet]

[0199] The positive electrode sheet generally includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, the positive electrode film layer including a positive electrode active material. A surface treatment composition can be disposed between the positive electrode current collector and the positive electrode film layer.

[0200] As an example, the positive electrode current collector has two surfaces opposite in the thickness direction thereof, and the positive electrode film layer is disposed on either one or both of the two surfaces of the positive electrode current collector.

[0201] In some embodiments, the positive electrode current collector can contain the porous conductive material of any one of the above embodiments. The positive electrode current collector can also be a composite current collector, for example, which can be formed by compounding the porous conductive material of any one of the above embodiments with a high molecular material substrate such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), or the like.

[0202] In some embodiments, the positive electrode active material can employ a positive electrode active material for a battery known in the art. As an example, the positive electrode active material can include at least one of a lithium-containing phosphate of olivine structure, a lithium transition metal oxide, and a modified compound of each thereof. However, the present application is not limited to these materials, and other conventional materials that can be used as a positive electrode active material for a battery can also be used. These positive electrode active materials can be used alone only one or in combination of two or more. Among them, examples of the lithium transition metal oxide can include, but are not limited to, lithium cobalt oxide (e.g., LiCoO2), lithium nickel oxide (e.g., LiNiO2), lithium manganese oxide (e.g., LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g., LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (which can also be referred to simply as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (which can also be referred to simply as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (which can also be referred to simply as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (which can also be referred to simply as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (which can also be referred to simply as NCM811), lithium nickel cobalt aluminum oxide (e.g., LiNi0.85 Co 0.15 Al 0.05 O2) and modified compounds thereof, etc. Examples of the olivine-structured lithium-containing phosphate can include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (which can also be referred to simply as LFP)), a composite of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite of lithium manganese phosphate and carbon, lithium manganese iron phosphate, a composite of lithium manganese iron phosphate and carbon.

[0203] In some embodiments, the positive electrode film layer can further optionally include a surface treatment. As an example, the surface treatment can include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene-fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene-fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0204] In some embodiments, the positive electrode film layer can further optionally include a conductive agent. As an example, the conductive agent can include at least one of super-P, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0205] In some embodiments, the positive electrode tab can be prepared by dispersing the above-mentioned components for preparing the positive electrode tab, such as the positive electrode active material, the conductive agent, the surface treatment, and any other components, in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on a positive electrode current collector, and after processes such as drying, cold pressing, etc., the positive electrode tab can be obtained.

[0206] [Negative electrode current collector and negative electrode tab]

[0207] The conductive film of the present application can be directly used as the negative side current collector (or electrode) of an anode free metal battery (such as an anode free lithium metal battery or an anode free sodium metal battery).

[0208] In a lithium-free negative electrode battery, all active lithium ions are initially stored in the positive electrode material. During the initial charging process, lithium ions are extracted from the positive electrode, move to the negative electrode, and are directly plated in situ on the negative electrode bare current collector to form a lithium metal negative electrode. Subsequently, during discharging, active lithium ions are stripped from the lithium metal negative electrode formed in situ and are embedded in the positive electrode. The lithium-free negative electrode battery has a small volume and a large energy density.

[0209] The porous conductive material of the present application can also be used as the negative side current collector of a battery with an active metal / alloy negative electrode.

[0210] In some embodiments, the active metal / alloy is, for example, lithium metal or a lithium alloy.

[0211] In some embodiments, the negative electrode tab of the lithium metal battery uses the porous conductive material of the present application as the negative current collector, and a lithium metal layer is deposited on the outer surface and / or inside the pores of the porous conductive material.

[0212] The term "lithium alloy" as used herein is intended to mean a substance capable of forming an alloy with lithium by charging and capable of reversibly adsorbing and releasing lithium. Examples of substances capable of forming an alloy with lithium include elements such as metals of tin (Sn), silicon (Si), zinc (Zn), aluminum (Al), magnesium (Mg), indium (In), cadmium (Cd), lead (Pb), bismuth (Bi), and antimony (Sb), and compounds and alloys thereof, including alloys of lithium with these elemental metals. One or two or more of these substances can be suitably used by appropriate selection.

[0213] In some embodiments, the other active metal / alloy other than lithium metal or lithium alloy includes elements such as metals of tin (Sn), silicon (Si), zinc (Zn), aluminum (Al), magnesium (Mg), indium (In), cadmium (Cd), lead (Pb), bismuth (Bi), and antimony (Sb), and compounds and alloys thereof, including alloys of lithium with these elemental metals.

[0214] In some embodiments, the active metal / alloy can be deposited on the surface and inside the pores of the porous conductive material by methods such as electrodeposition, vapor deposition (such as physical / chemical vapor deposition), magnetron sputtering, etc., thereby obtaining a battery negative electrode.

[0215] [Electrolyte]

[0216] The electrolyte functions to conduct ions between the positive electrode tab and the negative electrode tab. The present application does not have a specific limitation on the type of electrolyte, which can be selected as needed. For example, the electrolyte can be liquid, gel, or all-solid.

[0217] In some embodiments, the electrolyte is liquid and includes an electrolyte salt and a solvent.

[0218] In some embodiments, the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonylimide, lithium bistrifluoromethylsulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorobisoxalate borate, lithium bisoxalate borate, lithium difluorodibisoxalate phosphate, and lithium tetrafluorodibisoxalate phosphate.

[0219] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclobutane sulfone, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0220] In some embodiments, the electrolyte solution can further optionally include an additive. As an example, the additive can include a negative electrode film-forming additive, a positive electrode film-forming additive, and can further include an additive capable of improving certain performance of the battery, such as an additive for improving overcharge performance of the battery, an additive for improving high-temperature or low-temperature performance of the battery, etc.

[0221] [Separator]

[0222] In some embodiments, the secondary battery further includes a separator. The type of the separator is not particularly limited in the present application, and any known porous structure separator having good chemical stability and mechanical stability can be used.

[0223] In some embodiments, the material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single layer film or a multi-layer composite film, and is not particularly limited. When the separator is a multi-layer composite film, the materials of the respective layers can be the same or different, and are not particularly limited.

[0224] In some embodiments, the positive electrode tab, the negative electrode tab, and the separator can be made into an electrode assembly through a winding process or a stacking process.

[0225] In some embodiments, the secondary battery can include an outer package. The outer package can be used to package the above-described electrode assembly and the electrolyte solution.

[0226] In some embodiments, the outer package of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package of the secondary battery can also be a soft package, such as a pouch-type soft package. The material of the soft package can be plastic, and as the plastic, polypropylene, polybutylene terephthalate, polybutylene succinate, etc. can be listed.

[0227] The shape of the secondary battery is not particularly limited in the present application, and it can be cylindrical, square, or any other shape. For example, Fig. 9 is a general view and an exploded view of a secondary battery 5 of a square structure as an example.

[0228] In some embodiments, with reference to Fig. 9The outer package can include a housing 51 and a cover plate 53. The housing 51 can include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be arranged on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet, and the separator can form the electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is packaged in the receiving cavity. The electrolyte is impregnated in the electrode assembly 52. The number of electrode assemblies 52 contained in the secondary battery 5 can be one or more, and the number can be selected by a person skilled in the art according to the actual needs.

[0229] In some embodiments, the secondary battery can be assembled into a battery module, and the number of secondary batteries contained in the battery module can be one or more, and the specific number can be selected by a person skilled in the art according to the application and capacity of the battery module.

[0230] Fig. 10 The battery module 4 is an example. Referring to Fig. 10 In the battery module 4, a plurality of secondary batteries 5 can be arranged in sequence along the length direction of the battery module 4. Of course, other arbitrary arrangements can also be used. Further, the plurality of secondary batteries 5 can be fixed by fasteners.

[0231] Optionally, the battery module 4 can further include a housing having a receiving space, and the plurality of secondary batteries 5 are received in the receiving space.

[0232] In some embodiments, the above-mentioned battery module can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, and the specific number can be selected by a person skilled in the art according to the application and capacity of the battery pack.

[0233] Fig. 11 and Fig. 12 The battery pack 1 is an example. Referring to Fig. 11 and Fig. 12 The battery pack 1 can include a battery box and a plurality of battery modules 4 arranged in the battery box. The battery box includes an upper box body 2 and a lower box body 3, and the upper box body 2 can be arranged on the lower box body 3 to form a closed space for receiving the battery module 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0234] In addition, the application also provides a device, the device comprising at least one of the secondary battery, the battery module or the battery pack provided by the application. The secondary battery, the battery module or the battery pack can be used as a power supply of the device, and can also be used as an energy storage unit of the device. The device can include a mobile device (such as a mobile phone, a notebook computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship and a satellite, an energy storage system, etc., but is not limited thereto.

[0235] As the device, the secondary battery, the battery module or the battery pack can be selected according to the use requirement of the device.

[0236] Fig. 13 The device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the requirement of high power and high energy density of the secondary battery for the device, the battery pack or the battery module can be used.

[0237] Embodiment 1:

[0238] (1) Preparation of the second raw material multilayer body

[0239] Copper metal (purity > 99%) and manganese metal (purity > 99%) are provided, and are smelted into alloy ingots by using a vacuum induction smelting furnace. In this example, the composition of the alloy ingot is Mn 60 Cu 40 (subscript represents atomic ratio).

[0240] The alloy ingot is forged, and the forging pressure is 20 t. After each forging, a stress relief annealing operation is performed, the annealing temperature is 800°C, the annealing time is 60 min, and the alloy ingot is water-cooled after annealing.

[0241] The alloy ingot after forging is subjected to first heat treatment, the first heat treatment temperature is 800°C, and the time is 60 min. Referring to the Mn-Cu phase diagram shown in Fig. 6 , it can be known that the product after the first heat treatment is a single-phase alloy (referred to as γ single-phase alloy) composed of (Cu, γMn) phase.

[0242] The γ single-phase alloy is subjected to preliminary hot rolling to obtain an alloy foil. The alloy foil and a red copper foil raw material (tensile strength 370 N / mm 2 ) are stacked in the stacking mode of “alloy foil / red copper foil / alloy foil”, and then subjected to multiple rolling until the product reaches the target thickness to obtain a second raw material multilayer body.

[0243] The second raw material multilayer body comprises a raw material base layer, a second A alloy layer and a second B alloy layer. The raw material base layer has a first surface and a second surface arranged oppositely, and the raw material base layer has a tensile strength of 370 N / mm2 a tensile strength of 370 N / mm2. A second A alloy layer is laminated and combined to the first surface of the base material layer, and the material of the second A alloy layer is (Cu, γMn). A second B alloy layer is laminated and combined to the second surface of the base material layer, and the material of the second B alloy layer is (Cu, γMn).

[0244] (2) Preparation of the first raw material multilayer

[0245] The second raw material multilayer is subjected to a phase separation heat treatment at a temperature of 650°C for 4h to obtain the first raw material multilayer. Referring to the Mn-Cu phase diagram shown in FIG. 1, after the phase separation heat treatment, the second A alloy layer will be converted into the first A alloy layer, and the material of the first A alloy layer will be converted into a multi-phase alloy containing αMn phase and (Cu, γMn) phase. The second B alloy layer will be converted into the first B alloy layer, and the material of the first B alloy layer will be converted into a multi-phase alloy containing αMn phase and (Cu, γMn). Fig. 6

[0246] The first raw material multilayer comprises a base material layer, a first alloy layer and a second alloy layer. The base material layer has a first surface and a second surface arranged oppositely, and the base material layer has a dense structure and a tensile strength of 370 N / mm2. The first alloy layer is laminated and combined to the first surface of the base material layer, and the material of the first alloy layer is a multi-phase alloy containing αMn phase and (Cu, γMn) phase. The second alloy layer is laminated and combined to the second surface of the base material layer, and the material of the second alloy layer is a multi-phase alloy containing αMn phase and (Cu, γMn) phase. 2 a tensile strength of 370 N / mm2. A second A alloy layer is laminated and combined to the first surface of the base material layer, and the material of the second A alloy layer is (Cu, γMn). A second B alloy layer is laminated and combined to the second surface of the base material layer, and the material of the second B alloy layer is (Cu, γMn).

[0247] (3) Dealloying

[0248] The first raw material multilayer is placed in a sufficient amount of 2.38 mol / L HCl aqueous solution to perform free corrosion method dealloying at a temperature of 25°C. After no obvious bubbles escape, the dealloying is completed, and the conductive film of Example 1 is obtained.

[0249] For the base material layer, the structure and properties thereof are basically unchanged during the dealloying process, and after the dealloying, the composition and tensile strength thereof are consistent with those of the red copper foil raw material. For the first alloy layer and the second alloy layer, the multi-phase alloy containing αMn phase and (Cu, γMn) phase can form a porous conductive material (herein, porous copper) after the dealloying treatment. Referring to the schematic diagram of the porous conductive material shown in FIG. 2, the principle of the dealloying is as follows: Fig. 1

[0250] (1) After the dealloying treatment, the αMn phase in the multi-phase alloy will be removed, and the position where the αMn is removed will form a pore 601 with a first pore diameter;

[0251] ​​(2) After the dealloying treatment, the (Cu, γMn) phase in the multiphase alloy is partially removed, the Mn element in the (Cu, γMn) phase is partially removed, the Cu element is partially reserved, the reserved Cu element partially forms the first wire 600, and the removed Mn element forms the hole 602 with the second pore size.

[0252] Fig. 2 A cross-sectional schematic diagram and a scanning electron microscope photograph of a cross section of the conductive film of Example 1 are shown. The conductive film includes a base layer 100, a first porous layer 110, and a second porous layer 120. The base layer 100 has a first surface 101 and a second surface 102 disposed opposite to each other, the base layer 100 has a dense structure and has a tensile strength of 330 N / mm 2 The above tensile strength; the first porous layer 110 is laminated and combined to the first surface 101 of the base layer 110; and the second porous layer 120 is laminated to the second surface 120 of the base layer. The material of the first porous layer 110 and the second porous layer 120 is a porous conductive material (here, porous copper). The thickness of the base layer 100 is 6 μm, the thickness of the first porous layer 110 is 120 μm, and the thickness of the second porous layer 120 is 120 μm. The material of the base layer 100 is dense red copper, and the tensile strength is 330 N / mm

[0253] Fig. 3 A scanning electron microscope photograph of the surface of the first porous layer 101 of Example 1 is shown. As shown in the figure, the material of the first porous layer 101 is a porous conductive material, and the porous conductive material has holes with a first pore size (referred to as large holes) and holes with a second pore size (referred to as small holes). 50-100 large holes and 50-100 small holes are selected from the scanning electron microscope photograph, the pore size and the wire diameter of the large holes and the small holes are measured respectively, and the average values are calculated respectively. The results are shown in Table 1.

[0254] Example 2

[0255] The difference between Example 2 and Example 1 is that the composition of the alloy ingot in step (1) is Mn 75 Cu 25 .

[0256] The preparation method of the conductive film of Example 2 is as follows:

[0257] (1) Preparation of the second raw material multilayer body

[0258] Copper metal (purity > 99%) and manganese metal (purity > 99%) are provided, and a vacuum induction melting furnace is used to melt the alloy ingot. In this example, the composition of the alloy ingot is Mn 75 Cu 25 (subscript represents atomic ratio).

[0259] The alloy ingot is forged with a forging pressure of 20 t, and after each forging, a stress relief annealing operation is performed at an annealing temperature of 800 °C for 60 min, and then water-cooled. The alloy ingot after forging is subjected to a first heat treatment at a temperature of 800 °C for 60 min to obtain a single-phase alloy (referred to as a γ single-phase alloy) composed of a (Cu, γMn) phase.

[0260] The γ single-phase alloy is subjected to preliminary hot rolling to obtain an alloy foil. The alloy foil and a red copper foil raw material are stacked in a stacking manner of "alloy foil / red copper foil / alloy foil", and then subjected to multiple rolling until the product reaches the target thickness to obtain a second raw material multilayer body.

[0261] The second raw material multilayer body includes a raw material base layer, a second A alloy layer, and a second B alloy layer. The raw material base layer has a first surface and a second surface arranged opposite to each other, and has a dense structure and a tensile strength of 359 N / mm 2 The second A alloy layer is laminated and combined with the first surface of the raw material base layer, and the second B alloy layer is composed of a (Cu, γMn) phase. The XRD pattern of the second A alloy layer is shown in (a) of FIG. 6, and the diffraction peaks of the (Cu, γMn) phase can be observed in the figure. Fig. 7

[0262] (2) Preparation of a first raw material multilayer body

[0263] The second raw material multilayer body is subjected to a phase separation heat treatment at a temperature of 650 °C for 4 h to obtain a first raw material multilayer body.

[0264] The first raw material multilayer body includes a raw material base layer, a first A alloy layer, and a first B alloy layer. The raw material base layer has a first surface and a second surface arranged opposite to each other, and has a tensile strength of 359 N / mm 2 The first A alloy layer is laminated and combined with the first surface of the raw material base layer, and the first B alloy layer is composed of a (Cu, γMn) phase. The XRD pattern of the first A alloy layer is shown in (b) of FIG. 6, and the diffraction peaks of the αMn phase and the (Cu, γMn) phase can be observed in the figure. Fig. 7

[0265] (3) Dealloying

[0266] The first raw material multilayer body is placed in a sufficient amount of 2.38 mol / L HCl aqueous solution, and dealloying is performed by a free corrosion method at a temperature of 25 °C. After no obvious bubbles escape, the dealloying is completed, and the conductive film of Example 2 is obtained.

[0267] ​​The conductive film of Example 2 includes: a base layer 100, a first porous layer 110, and a second porous layer 120. The base layer 100 has a first surface 101 and a second surface 102 disposed opposite to each other, and the base layer 100 has a strength of 359 N / mm². 2 The tensile strength is [not specified]. A first porous layer 110 is laminated to the first surface 101 of the base layer 110; a second porous layer 120 is laminated to the second surface 120 of the base layer. The first porous layer 110 and the second porous layer 120 are made of porous conductive material (in this case, porous copper). The thickness of the base layer 100 is 6 μm, the thickness of the first porous layer 110 is 120 μm, and the thickness of the second porous layer 120 is 120 μm. The base layer 100 is made of dense copper; both the first porous layer 110 and the second porous layer 120 are made of porous copper.

[0268] Fig. 4 A scanning electron microscope (SEM) image of the surface of the first porous layer 101 in Example 2 is shown. As shown, the first porous layer 101 is made of a porous conductive material, which has pores with a first pore size (referred to as macropores) and pores with a second pore size (referred to as micropores). 50-100 macropores and 50-100 micropores were selected from the SEM image, and the pore size and prism diameter of the macropores and micropores were measured respectively. The average values ​​were calculated, and the results are detailed in Table 1.

[0269] The XRD pattern of the first porous layer is as follows: Fig. 7 As shown in (c), diffraction peaks of the Cu phase can be observed in the figure.

[0270] Example 3:

[0271] The difference between Example 3 and Example 1 is that the alloy ingot composition in step (1) is Mn. 90 Cu 10 .

[0272] The conductive film preparation method in Example 3 is as follows:

[0273] (1) Preparation of the second raw material multilayer

[0274] Copper metal (purity > 99%) and manganese metal (purity > 99%) are provided and melted into alloy ingots using a vacuum induction melting furnace. In this example, the alloy ingot composition is Mn. 90 Cu 10 (Subscripts indicate atomic ratios.)

[0275] The alloy ingot is forged with a forging pressure of 20 t, and after each forging, a stress relief annealing operation is performed at an annealing temperature of 800 °C for 60 min, and then water-cooled. The alloy ingot after forging is subjected to a first heat treatment at a temperature of 800 °C for 60 min to obtain a single-phase alloy (referred to as a γ single-phase alloy) composed of a (Cu, γMn) phase.

[0276] The γ single-phase alloy is subjected to preliminary hot rolling to obtain an alloy foil. The alloy foil and a red copper foil raw material are stacked in a stacking manner of "alloy foil / red copper foil / alloy foil", and then subjected to multiple rolling until the product reaches the target thickness to obtain a second raw material multilayer body.

[0277] (2) Preparation of a first raw material multilayer body

[0278] The second raw material multilayer body is subjected to a phase separation heat treatment at a temperature of 650 °C for 4 h to obtain a first raw material multilayer body.

[0279] The first raw material multilayer body includes a raw material base layer, a first A alloy layer, and a first B alloy layer. The raw material base layer has a first surface and a first surface oppositely arranged, and has a dense structure and a tensile strength of 360 N / mm 2 ; the first A alloy layer is laminated and combined with the first surface of the raw material base layer, and the first A alloy layer is made of a multi-phase alloy; and the first B alloy layer is made of a multi-phase alloy.

[0280] (3) Dealloying

[0281] The first raw material multilayer body is placed in a sufficient amount of 2.38 mol / L HCl aqueous solution, and dealloying is performed by free corrosion method at a temperature of 25 °C. After no obvious bubbles escape, the dealloying is completed, and the conductive film of Example 2 is obtained.

[0282] The conductive film of Example 2 includes a base layer 100, a first porous layer 110, and a second porous layer 120. The base layer 100 has a first surface 101 and a second surface 102 oppositely arranged, and has a tensile strength of 360 N / mm 2 ; the first porous layer 110 is laminated and combined with the first surface 101 of the base layer 110; and the second porous layer 120 is laminated with the second surface 120 of the base layer. The first porous layer 110 and the second porous layer 120 are made of a porous conductive material (here, porous copper). The thickness of the base layer 100 is 6 μm, the thickness of the first porous layer 110 is 120 μm, and the thickness of the second porous layer 120 is 120 μm. The base layer 100 is made of dense red copper; and the first porous layer 110 and the second porous layer 120 are both made of porous copper.

[0283] Fig. 5A scanning electron microscope photograph of the surface of the first porous layer 101 of Example 3 is shown. As shown, the material of the first porous layer 101 is a porous conductive material having pores of a first pore size (referred to as large pores) and pores of a second pore size (referred to as small pores). 50-100 large pores and 50-100 small pores are selected from the scanning electron microscope photograph, and the pore size and filament diameter of the large pores and the small pores are measured respectively, and the average values are calculated respectively, and the results are shown in Table 1.

[0284] Examples 4-9

[0285] Examples 4-9 differ from Example 2 in one or more of the following:

[0286] (1) the thicknesses of the first porous layer and the second porous layer are different from those of Example 2;

[0287] (2) the thickness of the base layer is different from that of Example 2.

[0288] The parameters of the conductive films of Examples 4-9 are shown in Table 1.

[0289] Examples 10-12

[0290] Examples 10-12 differ from Example 2 in that the large pore size of the porous conductive material is different from that of Example 2, as shown in Table 1.

[0291] The large pore size is changed by adjusting the dealloying parameters.

[0292] In Example 10, the dealloying etching solution is 2.2 mol / L HCl aqueous solution, the dealloying temperature is 25°C, and the dealloying time is 6 h.

[0293] In Example 11, the dealloying etching solution is 2.38 mol / L HCl aqueous solution, the dealloying temperature is 25°C, and the dealloying time is 36 h.

[0294] In Example 12, the dealloying etching solution is 2.38 mol / L HCl aqueous solution, the dealloying temperature is 25°C, and the dealloying time is 60 h.

[0295] Examples 13-15

[0296] Examples 13-15 differ from Example 2 in that the small pore size of the porous conductive material is different from that of Example 2, as shown in Table 1.

[0297] The small pore size is changed by adjusting the dealloying parameters.

[0298] In Example 13, the dealloying temperature is 25°C.

[0299] In Example 14, the dealloying temperature is 35°C.

[0300] In Example 15, the temperature of dealloying is 40°C.

[0301] Example 16

[0302] (1) Preparation of γ single-phase alloy foil

[0303] Copper metal (purity > 99%) and manganese metal (purity > 99%) were provided and melted into an alloy ingot by a vacuum induction melting furnace. In this example, the alloy ingot had a composition of Mn 75 Cu 25 (subscript denotes atomic ratio).

[0304] The alloy ingot was forged at a forging pressure of 20 t, and after each forging, a stress relief annealing operation was performed at an annealing temperature of 800°C for 60 min, and then water-cooled.

[0305] The forged alloy ingot was subjected to a first heat treatment at a temperature of 800°C for 60 min. Referring to Fig. 6 the Mn-Cu phase diagram shown, it can be seen that the product after the first heat treatment is a single-phase alloy (referred to as a γ single-phase alloy) composed of a (Cu, γMn) phase.

[0306] The γ single-phase alloy was hot-rolled to a thickness of 120 um to obtain a final γ single-phase alloy foil.

[0307] (2) Preparation of multi-phase alloy foil

[0308] The above-mentioned γ single-phase alloy foil was subjected to a phase separation heat treatment at a temperature of 650°C for 4 h to obtain a multi-phase alloy foil. Referring to Fig. 6 the Mn-Cu phase diagram shown, it can be seen that after the phase separation heat treatment, the γ single-phase alloy foil having a (Cu, γMn) phase is converted into a multi-phase alloy foil containing an αMn phase and a (Cu, γMn) phase.

[0309] (3) Preparation of first raw material multi-layer body

[0310] Two multi-phase alloy foils were laminated with two layers of red copper foil (tensile strength 350 N / mm 2 ) having conductive adhesive coated on both surfaces. The lamination order was "multi-phase alloy foil / red copper foil / multi-phase alloy foil". Then they were pressed to be combined at a pressing pressure of 0.3 T to obtain a first raw material multi-layer body. The conductive adhesive was carbon nanotube-filled E-44 epoxy resin. The content of carbon nanotubes in the conductive adhesive was 2 wt%, and the electrical conductivity of the conductive adhesive was 2.1 x 10 -7 Siemens / m (S / m).

[0311] The first raw material multilayer body includes a raw material base layer, a first alloy layer, and a second alloy layer. The raw material base layer has a multilayer structure (a sandwich-like multilayer structure). The raw material base layer includes a main body layer (made of copper) and first and second conductive adhesive layers respectively laminated on both sides of the copper main body layer. The surface of the first conductive adhesive layer facing away from the copper main body layer constitutes a first surface of the raw material base layer; the surface of the second conductive adhesive layer facing away from the copper main body layer constitutes a second surface of the raw material base layer. The raw material base layer has a dense structure and has a tensile strength of 350 N / mm 2 The first alloy layer is laminated and combined to the first surface of the raw material base layer, and the first alloy layer is made of a multi-phase alloy containing an αMn phase and a (Cu, γMn) phase. The second alloy layer is laminated and combined to the second surface of the raw material base layer, and the second alloy layer is made of a multi-phase alloy containing an αMn phase and a (Cu, γMn) phase.

[0312] (3) Dealloying

[0313] The first raw material multilayer body is placed in a sufficient amount of 2.38 mol / L HCl aqueous solution to perform free corrosion method dealloying at a temperature of 25°C. After no obvious bubbles escape, the dealloying is completed, and the conductive film of Example 16 is obtained.

[0314] Fig. 15 A schematic diagram of the conductive film of the present embodiment is shown. As shown in the figure, the conductive film includes a base layer 100 and a first porous layer 110. The base layer 100 has a first surface 101 and a second surface 102 arranged opposite to each other, and the base layer 100 has a tensile strength of 100 MPa or more; the first porous layer 110 is laminated and combined to the first surface 101 of the base layer 110; and the first porous layer 110 is made of a porous conductive material. The conductive film further includes a second porous layer 120 laminated and combined to the second surface 102 of the base layer 100.

[0315] The base layer 100 has a multilayer structure, and the base layer 100 includes a main body layer 1005 and first and second conductive adhesive layers 1001 and 1002 respectively laminated on the opposite surfaces of the main body layer 1005. The surface of the first conductive adhesive layer 1001 facing away from the main body layer 1005 constitutes the first surface 101 of the base layer, and the surface of the second conductive adhesive layer 1002 facing away from the main body layer 1005 constitutes the second surface 102 of the base layer. The thicknesses of the main body layer 1005, the first conductive adhesive layer 1001, and the second conductive adhesive layer 1002 are 6 μm, 2 μm, and 2 μm, respectively.

[0316] Comparative Example 1

[0317] The conductive film of Comparative Example 1 is composed of a single porous layer with a thickness of 200 μm. The preparation method is as follows:

[0318] (1) Provide Mn75 Cu 25 Foil material, whose composition is a single-phase alloy of (Cu,γMn) phase (abbreviated as γ single-phase alloy).

[0319] (2) The above Mn 75 Cu 25 The foil was subjected to phase separation heat treatment at a temperature of 650℃ for 4 hours to obtain an α / γ dual-phase alloy product.

[0320] (3) Place the product from the previous step into a sufficient amount of 2.38 mol / L HCl aqueous solution and perform free corrosion dealloying at 25°C. When no obvious bubbles escape from the solution, take out the dealloyed foil to obtain the conductive film of Comparative Example 1.

[0321] Comparative Example 2

[0322] The conductive film of Comparative Example 2 is a commercially available single-layer copper foam with a thickness of 120 μm, a porosity of 80%, an average pore size of 400 μm, and a pore size distribution range of 300 μm-500 μm.

[0323] Structural and performance analysis

[0324] 1. Pore volume

[0325] Based on the original composition and heat treatment process of the alloy ingot, and combined with Fig. 6 The Cu-Mn alloy phase diagram shown can reasonably derive the percentage of the total pore volume of macropores in porous copper to the apparent volume of porous copper (V1 / V), the percentage of the total pore volume of micropores in porous copper to the apparent volume of porous copper (V2 / V), and the percentage of the total pore volume of macropores and micropores to the apparent volume of porous copper ((V1+V2) / V) based on the following formulas. The results are detailed in Table 1.

[0326] Considering the thorough dealloying process of the Mn-Cu alloy, it can be reasonably inferred that all manganese was removed from the Mn-Cu alloy. After the complete removal of manganese from the αMn phase of the Mn-Cu multiphase alloy, the αMn phase disappears, and a pore structure with the first pore size (referred to as macropore) is formed in the corresponding position of the αMn phase. After the removal of manganese from the (Cu,γMn) phase of the Mn-Cu multiphase alloy, the manganese metal in the (Cu,γMn) phase disappears, but the copper metal is retained, and a pore structure with the second pore size (referred to as micropore) is formed in the (Cu,γMn) phase. The above macropore structure and micropore structure together constitute the hierarchical porous structure of porous copper.

[0327] Let V be the apparent volume of porous copper. The volume ratio of macropores (V1 / V) and micropores (V2 / V) can be calculated using the following formula:

[0328]

[0329]

[0330] x is the Mn content (at.%) in the alloy precursor;

[0331] x γ is the Mn content (at.%) in the (Cu, γMn) phase;

[0332] 1.045 is the Mn:Cu atomic volume ratio.

[0333] The macropore volume and micropore volume of the porous copper in each of the above examples are shown in Table 1.

[0334] 2. Specific surface area of pores

[0335] In addition, the total specific surface area of the porous copper is S (unit m 2 / g), wherein the total specific surface area of the macropores is S1, and the total specific surface area of the micropores is S2. The values of the total specific surface area of the macropores (S1) and the total specific surface area of the micropores (S2) are obtained by referring to the calculation formula and method provided in Celal Soyarslan, et al., Acta Materialia, (2018), 149, 326. The total specific surface area S = S1 + S2. The relevant results are shown in Table 3 below

[0336] The calculation formula of the total specific surface area S1 of the macropores is as follows

[0337]

[0338] C1 is an empirical constant, and the value is referred to in Table 3 below;

[0339] Ψ1 is the macropore volume fraction V1 / V, and the value is referred to in Table 1;

[0340] L1 is the average diameter of the rib filaments forming the macroporous structure;

[0341] ρ Cu is the density of copper, and the value is 8.9 g / cm 3 ;

[0342] p is the atomic percentage of manganese in the alloy;

[0343] V is 1 cm 3 .

[0344] The calculation formula of the total specific surface area S2 of the micropores is as follows:

[0345]

[0346] C2 is an empirical constant, and the value is referred to in Table 1 below;

[0347] Ψ2 is the volume fraction of small pores V2 / V, which is referred to Table 1;

[0348] L2 is the average diameter of the prongs forming the small pore structure;

[0349] ρ Cu is the density of copper, which is 8.9 g / cm 3 ;

[0350] p is the atomic percentage of manganese in the alloy;

[0351] V is 1 cm 3 .

[0352] The total specific surface area of the large pores and the total specific surface area of the small pores of the porous copper in each of the above examples are shown in Table 1.

[0353] 3. Pore size and prong diameter

[0354] 50-100 large pores and 50-100 small pores are selected from the scanning electron microscope photos, and the pore size and prong diameter of the large pores and the small pores are measured respectively, and the average values are calculated respectively, and the results are shown in Table 1.

[0355] 4. Tensile strength

[0356] The tensile strength of the conductive film and the raw material base layer can be obtained by the following method.

[0357] An electronic universal testing machine, model CZ-8010, is used, and the test method is as follows: the sample (the conductive film or the raw material base layer to be tested) is cut into a size of 18 mm*100 mm for standby, and when testing, the two ends of the sample are clamped to the two clamps of the universal testing machine respectively, the speed is set to 5 mm / min, and the tensile test is carried out. The calculation formula of the tensile strength is as follows:

[0358] σ = P b / A0

[0359] P b is the maximum force borne by the sample when it is broken, N (Newton);

[0360] A0 is the original cross-sectional area of the sample, mm 2 ;

[0361] σ is the tensile strength, unit N / mm 2 .

[0362] The results are shown in Table 1.

[0363] 5. Secondary battery cycle test

[0364] (1) The conductive film of Example 2 and Comparative Example 2 was used as an electrode (current collector), and a secondary battery was assembled according to the following method, and the secondary battery included a first electrode and a second electrode disposed opposite each other:

[0365] The first electrode used an aluminum foil as a current collector, and the surface of the current collector was coated with a positive active material, lithium cobalt oxide (Dv50: 8.1 μm). The size of the first electrode was φ 16 mm, and the loading amount of the active material was 0.169 mg / mm 2 ;

[0366] The second electrode used the conductive film mentioned in the present patent, and the size was φ 18 mm;

[0367] The separator used a polyethylene separator film, and the size was φ 20 mm;

[0368] The electrolyte used a solution of 1 mol / L lithium hexafluorophosphate in ethylene carbonate-dimethyl carbonate (volume ratio 1:1);

[0369] A CR2032 type coin cell battery case was used, and the assembly of the secondary battery was completed in a glove box.

[0370] (2) The battery test parameters were as follows:

[0371] (1) The charge and discharge cut-off voltage was 2.8-4.2 V;

[0372] (2) The charge and discharge current was 1 mA / cm 2 .

[0373] The capacity-cycle number test results of the secondary battery are shown in Table 2 below. Fig. 8 The capacity-cycle number curve of the secondary battery is shown.

[0374]

[0375]

[0376] The conductive film of Examples 1-16 has a laminated combination structure of a base layer and a porous layer, and the conductive film exhibits satisfactory tensile strength. The base layer with good tensile strength plays a role of bearing the porous layer, and provides a stable matrix for the porous layer. The mechanical properties of the conductive film as a whole are improved, and thus the conductive film can play a role in the secondary battery, and improve one or more properties of the secondary battery, such as capacity, cycle performance, rate performance, etc. The conductive film of Comparative Example 1 has only a single porous layer structure, and is brittle and fragile, and has too low strength, so that effective data cannot be obtained in the tensile test.

[0377] The conductive film of Example 1-16 as an electrode or current collector of a secondary battery works as follows: pores with a first pore size and pores with a second pore size. The inner wall of the pores with the first pore size (hereinafter referred to as macropores) can serve as a substrate for deposition of active materials; in addition, another role of the macropores is to provide a channel for electrolyte infiltration. The inner wall of the pores with the second pore size (hereinafter referred to as micropores) can serve as a substrate for deposition of active materials. The micropores increase the specific surface area of the material, thus enabling the porous conductive material to load more active materials; in addition, another role of the micropores is to serve as a template for deposition of active materials. Specifically, limited by the size of the micropores, the active materials deposited in the micropores have a nanoscale size, and the nanoscale active materials have a high ionic conductivity due to the small size, thus being able to improve the overall ionic conductivity of the electrode, and thus being able to improve the rate performance of the battery, and ultimately improving the capacity, cycle stability and rate performance of the battery as a whole; in addition, another role of the micropores is to limit the volume expansion of the active materials, avoiding their pulverization failure.

[0378] The conductive film of Comparative Example 2 has only a single pore size distribution, and the pore size distribution interval is 300-500 μm. As shown in Table 2, the conductive films of Example 2 and Comparative Example 2 are used for secondary batteries, and the secondary battery of Example 2 exhibits improved specific capacity (150 mAh) and cycle retention rate (retaining 87% after 77 cycles). The secondary battery of Comparative Example 2 exhibits low specific capacity (146 mAh) and cycle retention rate (retaining 77% after 77 cycles).

[0379] It should be noted that the present application is not limited to the above-described embodiments. The above-described embodiments are only examples, and embodiments having substantially the same configuration and playing the same role and effect as the technical idea within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, within the scope of the main idea of the present application, various modifications that can be thought of by those skilled in the art, other modes constructed by combining part of the configuration elements of the embodiments are also included in the scope of the present application.

Claims

1. A secondary battery, which is a negative electrode metal-free battery, comprising a negative electrode sheet, the negative electrode sheet being an electrically conductive film, the electrically conductive film comprising: a base layer having a first surface and a second surface disposed opposite to each other, the base layer having a dense structure; a first porous layer laminated to the first surface of the base layer; the first porous layer comprising a porous electrically conductive material, the porous electrically conductive material being a metal element or an alloy containing an M element selected from copper, aluminum, or a combination thereof; the porous electrically conductive material having pores of a first pore diameter and pores of a second pore diameter; the first pore diameter being n micrometers, 0.5≤n≤10; the second pore diameter being m nanometers, 20 The porous electrically conductive material has one or more of the following characteristics: (1) the pores of the first pore diameter are separated by first filaments, the average filament diameter of the first filaments being 0.89 μm - 3 μm; (2) the pores of the second pore diameter are separated by second filaments, the average filament diameter of the second filaments being 27 nm - 100 nm. The porous electrically conductive material has one or more of the following characteristics: (1) the pores of the first pore diameter are separated by first filaments, the average filament diameter of the first filaments being 0.89 μm - 3 μm; (2) the pores of the second pore diameter are separated by second filaments, the average filament diameter of the second filaments being 27 nm - 100 nm. In σ 180° The first porous layer does not fall off from the base layer when the adhesive tape is peeled off with a force of 7 N / mm or more. The conductive film has a tensile strength of 100 N / m 2 the above tensile strength.

2. The secondary battery according to claim 1, wherein The porous electrically conductive material has one or more of the following characteristics: The porous electrically conductive material has one or more of the following characteristics:

3. The secondary battery according to any one of claims 1-2, wherein The electrically conductive film has one or more of the following characteristics:

4. The secondary battery according to claim 1 or 2, wherein (1) the thickness of the base layer is 4.5 μm - 12 μm; 5. The secondary battery according to claim 3, wherein (2) the thickness of the first porous layer is 50 - 200 μm.

6. The secondary battery according to claim 1 or 2, wherein The electrically conductive film has one or more of the following characteristics:

7. The secondary battery according to claim 3, wherein (1) the thickness of the base layer is 4.5 μm - 12 μm; 8. The secondary battery according to claim 1 or 2, wherein ​ ​ ​ 9. The secondary battery according to claim 3, wherein ​ ​ ​ 10. The secondary battery according to claim 1 or 2, wherein ​ (1) the total specific surface area of the pores having the first pore diameter is 0.08 - 1.32 m2 / g 2 / g; (2) the total specific surface area of the pores having the second pore diameter is 0.87-5.25 m2 / g 2 / g; (3) the specific surface area of the porous conductive material is 0.95-6.57 m 2 / g.

11. The secondary battery according to claim 3, wherein ​ (1) the total specific surface area of the pores having the first pore diameter is 0.08 - 1.32 m2 / g 2 / g; (2) the total specific surface area of the pores having the second pore diameter is 0.87-5.25 m2 / g 2 / g; (3) the specific surface area of the porous conductive material is 0.95-6.57 m 2 / g.

12. The secondary battery according to claim 1, wherein ​ ​ ​ 13. The secondary battery according to claim 2, wherein ​ ​ (2) the first porous layer has a thickness of 50-200 μm; (3) the second porous layer has a thickness of 50-200 μm.

14. The secondary battery according to any one of claims 1-2, 12-13, wherein, The base layer has a tensile strength of 330 N / m 2 The above tensile strength.

15. The secondary battery according to any one of claims 1-2, 12-13, wherein, The base layer has a single-layer structure or a multi-layer structure.

16. The secondary battery according to claim 1 or 12, wherein The base layer has a multi-layer structure, and the base layer comprises a main layer and a first conductive adhesive layer laminated on one side surface of the main layer, and a surface of the first conductive adhesive layer opposite to the main layer constitutes a first surface of the base layer.

17. The secondary battery according to claim 2 or 13, wherein The base layer has a multi-layer structure, and the base layer comprises a main layer and a first conductive adhesive layer and a second conductive adhesive layer respectively laminated on opposite two side surfaces of the main layer, and a surface of the first conductive adhesive layer opposite to the main layer constitutes a first surface of the base layer, and a surface of the second conductive adhesive layer opposite to the main layer constitutes a second surface of the base layer.

18. A method for preparing the secondary battery according to any one of claims 1 to 17, the method comprising a method for preparing the conductive film, the method comprising: (1) providing a first raw multi-layer body, the first raw multi-layer body comprising: a raw base layer having a first surface and a second surface arranged oppositely, the raw base layer having a dense structure; a first A alloy layer laminated to the first surface of the raw base layer, the first A alloy layer having a multi-phase alloy containing an αMn phase and a (M, γMn) phase, M being selected from copper, aluminum or a combination thereof; and (2) removing at least part of Mn from the αMn phase of the multi-phase alloy and removing at least part of Mn from the (M, γMn) phase of the multi-phase alloy by a dealloying method; wherein the raw base layer is configured to remain intact during the dealloying treatment.

19. The method of making according to claim 18, wherein, The first raw multi-layer body further comprises a first B alloy layer laminated to the second surface of the raw base layer, the first B alloy layer having a multi-phase alloy containing an αMn phase and a (M, γMn) phase, M being selected from copper, aluminum or a combination thereof.

20. The method of making according to claim 18, wherein, The method for preparing the conductive film further comprises a step of preparing the first raw multi-layer body, specifically comprising: (1) providing a second raw multi-layer body, the second raw multi-layer body comprising: a raw base layer having a first surface and a second surface arranged oppositely, the raw base layer having a dense structure; and a second A alloy layer laminated to the first surface of the raw base layer, the second A alloy layer having a (M, γMn) phase content of 95 vol% or more; (2) performing a phase separation heat treatment on the product of the previous step to form a multi-phase alloy in the second A alloy layer, the multi-phase alloy containing an αMn phase and a (M, γMn) phase, thereby obtaining the first raw multi-layer body.

21. The method of making according to claim 20, wherein, The step of preparing the first raw multi-layer body further comprises: In the step (1), the second raw multi-layer body further comprises a second B alloy layer laminated to the second surface of the raw base layer, the second B alloy layer having a (M, γMn) phase content of 95 vol% or more; In step (2), the product of the previous step is subjected to a phase separation heat treatment to form a multi-phase alloy in the second B alloy layer, the multi-phase alloy containing an αMn phase and a (M, γMn) phase.

22. The method of making according to claim 18, wherein, The method for preparing the conductive film further comprises a step of preparing a first raw material multilayer body, specifically comprising: (1) providing a γ single-phase alloy foil, the content of the (M, γMn) phase in the γ single-phase alloy foil being 95 vol% or more; (2) subjecting the γ single-phase alloy foil to a phase separation heat treatment to obtain a multi-phase alloy foil, the multi-phase alloy foil containing an αMn phase and a (M, γMn) phase; (3) providing a raw material base layer, the raw material base layer comprising a main body layer and a first conductive adhesive layer laminated on one side surface of the main body layer; (4) laminating the multi-phase alloy foil on the surface of the first conductive adhesive layer away from the raw material base layer to obtain the first raw material multilayer body.

23. The method of making according to claim 22, wherein, The step of preparing the first raw material multilayer body further comprises: In step (3), the raw material base layer further comprises a second conductive adhesive layer, the second conductive adhesive layer being laminated on one side surface of the main body layer and arranged opposite to the first conductive adhesive layer; In step (4), the multi-phase alloy foil is laminated on the surface of the second conductive adhesive layer away from the raw material base layer.

24. The production method according to any one of claims 20 to 22, wherein, The method for preparing the conductive film has one or more of the following characteristics: (1) the temperature of the phase separation heat treatment is 500-700°C; (2) the time of the phase separation heat treatment is 1-4 hours; (3) after the phase separation heat treatment, cooling is performed at a cooling rate of 20-1000°C / s.

25. An apparatus comprising the secondary battery of any one of claims 1 to 17, the secondary battery providing electrical energy to the apparatus.

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