Current collector, method for manufacturing the same, secondary battery, battery module, and power consumption device

Abstract

The present application provides a current collector, a method for manufacturing the same, a secondary battery, a battery module, a battery pack, and an electric power consumption device. The current collector includes a metal substrate and a surface treatment layer formed on at least one side of the metal substrate, and the surface treatment layer contains an oxide and / or a nitride of the metal substrate. The surface treatment layer can protect the metal from corrosion by anions in the electrolyte or optimize the metal nucleation behavior, improve the Coulomb efficiency and cycle capacity retention rate of the battery, and improve the storage performance of the battery.

Description

Technical Field

[0001] The present application relates to the field of secondary battery technology, and in particular provides a current collector, a method for manufacturing the same, a secondary battery, a battery module, a battery pack, and an electric power consumption device.

Background Art

[0002] In recent years, secondary batteries have been widely used in energy storage power systems such as hydraulic, thermal, wind, and solar power plants, as well as in multiple fields such as electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace.

[0003] During the charge and discharge cycle process of a secondary battery, the components in the electrolyte corrode the electrode material, cause side reactions, and deteriorate the cycle life, storage performance, and safety of the battery.

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present application is made in view of the above problems, and its purpose is to provide a current collector, which includes a metal substrate and a surface treatment layer formed on at least one side of the metal substrate, and the surface treatment layer includes an oxide and / or a nitride of the metal substrate. The surface treatment layer of the current collector can protect the metal from corrosion by anions in the electrolyte, improve the resistance at high voltages, effectively improve the Coulomb efficiency and cycle capacity retention rate of the battery, and improve the storage performance of the battery.

Means for Solving the Problems

[0005] The first aspect of the present application provides a current collector for a sodium secondary battery, the current collector including a metal substrate and a surface treatment layer formed on at least one side of the metal substrate, and the surface treatment layer includes an oxide and / or a nitride of the metal substrate.

[0006] In any embodiment, the thickness of the surface treatment layer is 2 - 200 nm, and optionally 5 - 50 nm.

[0007] Control the thickness of the surface treatment layer to 2 - 200 nm, ensuring that it does not affect the electronic conductivity of the current collector, while protecting it from corrosion by anions in the electrolyte, improving its resistance at high voltages, thereby improving the Coulomb efficiency and cycle capacity retention rate of the battery. Also, by controlling the thickness of the surface treatment layer to 2 - 200 nm, an increase in the internal resistance of the battery, a decrease in battery cycle performance and energy density due to excessive thickness can be avoided. The thickness of the surface treatment layer is 5 - 50 nm, which is advantageous for further improving the Coulomb efficiency and cycle capacity retention rate of the battery.

[0008] In any embodiment, the surface treatment layer includes one or more of aluminum oxide, titanium oxide, copper oxide, nickel oxide, and titanium nitride.

[0009] A surface treatment layer including one or more of aluminum oxide, titanium oxide, copper oxide, nickel oxide, and titanium nitride can ensure that it does not affect the electronic conductivity of the current collector, while protecting it from corrosion by anions in the electrolyte and improving its resistance at high voltages.

[0010] In any embodiment, the surface treatment layer is obtained by heat - treating the metal substrate, and the metal substrate includes at least one of aluminum, nickel, copper, and titanium.

[0011] The heat - treatment process is simple and low - cost. By controlling the heat - treatment method, the surface treatment layer can be effectively adjusted and controlled, making it suitable for large - scale popularization and use. By heat - treating the metal substrate of the current collector to form a surface treatment layer on the current collector, it does not affect the electronic conductivity of the current collector, while protecting it from corrosion by anions in the electrolyte and improving its resistance at high voltages, avoiding or alleviating the reaction between the electrolyte and metal ions, and improving the Coulomb efficiency and cycle life of the battery.

[0012] In some embodiments, the thickness of the surface treatment layer is 100 - 3000 nm, and optionally 500 - 1000 nm.

[0013] In some embodiments, the surface treatment layer contains nano - needle - shaped copper oxide, and the nano - needle - shaped copper oxide is substantially perpendicular to the surface of the metal substrate. Optionally, the length of the nano - needles is 0.1 - 3 micrometers, and the width of the nano - needles is 30 - 200 nanometers.

[0014] The current collector containing nano - needle - shaped copper oxide can be used as a negative electrode. The nano - needle - shaped copper oxide on its surface can provide more sufficient nucleation sites and effectively reduce the local current density, promote more uniform deposition of metal ions on the surface of the current collector, suppress the formation of metal dendrites, and is advantageous for improving the Coulomb efficiency and cycle capacity retention rate of the battery.

[0015] In some embodiments, the surface treatment layer is obtained by chemically treating the metal substrate containing copper.

[0016] In some embodiments, the areal density of the surface treatment layer is 0.1 - 20 g / m 2 is.

[0017] Controlling the areal density of the surface treatment layer to 0.1 - 20 g / m 2 can protect the metal from corrosion by anions in the electrolyte, while ensuring that the conductivity of the current collector is not too low, further improving the resistance of the current collector at high voltages, and optimizing the Coulomb efficiency and cycle capacity retention rate of the battery.

[0018] In some embodiments, the thickness of the foil - shaped metal substrate is 5 - 500 μm, and optionally 10 - 80 μm. The porosity of the foam - shaped metal substrate is greater than 90%.

[0019] When the thickness of the foil-shaped metal substrate is 5 - 500 μm and the porosity of the foamed metal substrate is greater than 90%, it can be ensured that the current collector has good conductivity, high mechanical strength, and low internal resistance, which is advantageous for the stability and safety of the battery.

[0020] In any embodiment, the conductivity of the current collector is 0.1 S / cm or more.

[0021] When the conductivity of the current collector is 0.1 S / cm or more, it can be ensured that the current collector has good conductivity, promote the transport of electrons between the components of the battery, and improve the specific capacity and rate performance of the battery.

[0022] The second aspect of the present application provides a method for manufacturing a current collector, including the step of heat-treating and / or chemically treating a metal substrate to form a surface treatment layer located on at least one side of the metal substrate.

[0023] By the above heat treatment method, a surface treatment layer is formed on the surface of at least one side of the metal substrate, which does not affect the electronic conductivity of the current collector, protects it from corrosion by anions in the electrolyte, improves its resistance at high voltages, avoids or alleviates the reaction between the electrolyte and metal ions, and can improve the Coulomb efficiency and cycle life of the battery. And the heat treatment process is simple and suitable for large-scale popularization and use.

[0024] In any embodiment, the metal substrate is aluminum, the atmosphere of the heat treatment is air or oxygen gas, the temperature of the heat treatment is 80 - 350 °C, optionally 160 - 280 °C, the time of the heat treatment is 2 - 120 minutes, optionally 5 - 30 minutes, and the surface treatment layer contains aluminum oxide.

[0025] In some embodiments, the metal substrate is titanium, the atmosphere of the heat treatment is air or oxygen gas, the temperature of the heat treatment is 200 - 500 °C, optionally 300 - 500 °C, the time of the heat treatment is 2 - 120 minutes, optionally 5 - 30 minutes, and the surface treatment layer contains titanium oxide.

[0026] In some embodiments, the metal substrate is copper, the atmosphere of the heat treatment is air or oxygen gas, the temperature of the heat treatment is 200 - 500 °C, optionally 200 - 400 °C, the time of the heat treatment is 2 - 120 minutes, optionally 5 - 30 minutes, and the surface treatment layer contains copper oxide.

[0027] In some embodiments, the metal substrate is nickel, the atmosphere of the heat treatment is air or oxygen gas, the temperature of the heat treatment is 80 - 450 °C, optionally 180 - 300 °C, the time of the heat treatment is 2 - 120 minutes, optionally 5 - 30 minutes, and the surface treatment layer contains nickel oxide.

[0028] In some embodiments, the metal substrate is titanium, the atmosphere of the heat treatment is nitrogen gas, the ventilation rate is 10 - 200 mL / min, optionally 20 - 80 mL / min, the temperature of the heat treatment is 500 - 800 °C, optionally 650 - 800 °C, the time of the heat treatment is 2 - 120 minutes, optionally 5 - 30 minutes, and the surface treatment layer contains titanium nitride.

[0029] By simply controlling the process parameters, the composition and morphology of the surface treatment layer can be adjusted to match different cathode / anode active materials, thereby realizing the optimization of the battery structure design and performance. In some embodiments, the manufacturing method specifically includes heat-treating the metal substrate and then performing post-treatment under different atmospheres to form a surface treatment layer located on at least one side of the metal substrate.

[0030] In some embodiments, the metal substrate is titanium, the atmosphere of the heat treatment is air or oxygen gas, the temperature of the heat treatment is 200 - 500 °C, the time of the heat treatment is 2 - 120 minutes, the atmosphere of the post-treatment is nitrogen gas, the temperature of the post-treatment is 600 - 900 °C, the time of the post-treatment is 2 - 120 minutes, and the surface treatment layer includes titanium oxide and titanium nitride.

[0031] By performing nitridation treatment after oxidation, a heterostructure of titanium oxide and titanium nitride can be formed on the surface of the titanium foil, further improving the stability of the current collector. At the same time, this heterostructure improves the affinity for metal ions of the current collector, enhances the surface diffusion dynamics of metal ions, reduces the nucleation overpotential of metal ions, induces uniform and regular deposition of metal ions, further improves the Coulomb efficiency and cycle capacity retention rate of the battery, and can improve the storage stability of the battery.

[0032] In some embodiments, specifically, the manufacturing method chemically treats the metal substrate in an alkaline solution to form a surface treatment layer located on at least one side of the metal substrate.

[0033] In some embodiments, the metal substrate is copper, the surface treatment layer includes nano-needle-shaped copper oxide, the pH value of the alkaline solution is 11 - 12, the temperature of the chemical treatment is 45 - 90 °C, and the time of the chemical treatment is 0.5 - 12 hours.

[0034] Using the method of immersing the copper current collector in a simple alkaline solution, that is, a nano-needle-shaped copper oxide layer can be formed on the surface of the copper current collector, improving the deposition site and active area of the current collector, being advantageous for the diffusion of metal ions at the electrode / electrolyte interface, reducing the nucleation overpotential and local current density, and inducing uniform deposition of metal ions. While improving the performance, it further improves the production efficiency and significantly reduces the manufacturing cost and energy consumption.

[0035] A third aspect of the present application provides a secondary battery including a positive electrode plate and a negative electrode plate, wherein the positive electrode plate and / or the negative electrode plate includes a current collector described in any of the embodiments or a current collector obtained by manufacturing using the manufacturing method described in any of the embodiments.

[0036] This secondary battery has excellent cycle performance.

[0037] In any of the embodiments, the secondary battery is a sodium battery.

[0038] In any of the embodiments, the secondary battery is a sodium secondary battery without a negative electrode. This sodium secondary battery without a negative electrode can have a high energy density.

[0039] In any of the embodiments, the positive electrode plate includes a positive electrode active material, and the positive electrode active material includes one or more of a Prussian blue-based compound, a polyanion-type compound, and a layered oxide.

[0040] In any of the embodiments, the surface of the positive electrode active material particles has a coating layer, and the coating layer includes one or more of a carbon material, polyaniline, polypyrrole, poly(3,4-ethylenedioxythiophene), aluminum oxide, zinc oxide, titanium oxide, zirconium oxide, magnesium oxide, silicon oxide, lanthanum oxide, sodium fluoride, lithium fluoride, and aluminum fluoride.

[0041] In any of the embodiments, the thickness of the coating layer is 2 nm - 1000 nm.

[0042] A coating layer with an appropriate thickness can play an effective improvement role, and it is possible to avoid the situation where the coating layer is too thick and the resistance of the positive electrode film is too high, resulting in a decrease in battery performance.

[0043] A fourth aspect of the present application provides a battery module, and this battery module includes the secondary battery of the third aspect of the present application.

[0044] The fifth aspect of the present application provides a battery pack, which includes the secondary battery of the third aspect of the present application or the battery module of the fourth aspect of the present application.

[0045] The sixth aspect of the present application provides a power consumption device, which includes at least one of the secondary battery of the third aspect of the present application, the battery module of the fourth aspect of the present application, or the battery pack of the fifth aspect of the present application.

Brief Description of the Drawings

[0046]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0047] Hereinafter, embodiments specifically disclosing the current collector, secondary battery, battery module, battery pack, and power consumption device of the present application will be described in detail with appropriate reference to the drawings. However, detailed descriptions that are not necessary may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of structures that are actually the same may be omitted. This is to avoid making the following description unnecessarily redundant and to enable those skilled in the art to easily understand. Note that the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0048] The "ranges" disclosed in this application are limited in the form of a lower limit and an upper limit. A given range is limited by selecting one lower limit and one upper limit, and the selected lower limit and upper limit define the boundaries of a specific range. The range thus defined may or may not include the limit values, and any combination is possible, that is, any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60 - 120 and 80 - 110 are listed for a specific parameter, it is understood that ranges of 60 - 110 and 80 - 120 are also conceivable. In addition, if 1 and 2 are listed as the minimum range values and 3, 4, and 5 are listed as the maximum range values, all of the ranges 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4, and 2 - 5 are conceivable. In this application, unless otherwise specified, the numerical range "a - b" represents a shortened expression of any combination of real numbers between a and b, where both a and b are real numbers. For example, the numerical range "0 - 5" represents that all real numbers between "0 - 5" have already been listed in this specification, and "0 - 5" is only a shortened expression of the combination of these numerical values. Also, when a certain parameter is expressed as an integer ≧ 2, it is equivalent to disclosing that this parameter is, for example, the integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0049] Unless otherwise specified, all embodiments and alternative embodiments of this application can be combined with each other to form a new technical solution.

[0050] Unless otherwise specified, all technical features and alternative technical features of this application can be combined with each other to form a new technical solution.

[0051] Unless otherwise specified, all steps of this application may be performed in order or randomly, and preferably, they are performed in order. For example, the fact that the method includes steps (a) and (b) means that the method may include steps (a) and (b) performed in order, or steps (b) and (a) performed in order. For example, the fact that the method mentioned above may further include step (c) means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0052] Unless otherwise specified, the terms "comprising" and "including" mentioned in this application may represent an open type or a closed type. For example, the above "comprising" and "including" may mean that they may further comprise or include other components not listed, or may comprise or include only the components listed.

[0053] Unless otherwise specified, in this application, the term "or" is inclusive. For example, the phrase "A or B" represents "A, B, or both A and B". More specifically, any of the conditions where A is true (or exists) and B is false (or does not exist), where A is false (or does not exist) but B is true (or exists), and where both A and B are true (or exist) satisfy "A or B".

[0054] Metal materials are common current collector materials in secondary batteries. However, during the charge-discharge cycle process of sodium secondary batteries, the current collectors of metal materials are difficult to match the high voltage on the positive electrode side of sodium secondary batteries, are easily oxidized on the high voltage positive electrode side, and cause deterioration of the battery's storage performance and calendar life. Especially in secondary batteries without a negative electrode, there is no negative electrode active material on the surface of the current collector, so that the current collector and the electrolyte are in direct contact. All current collectors in the prior art are difficult to meet the usage requirements of sodium secondary batteries without a negative electrode. And in the prior art, surface coating is generally used to improve the surface properties of the current collector, thereby reducing the oxidation and corrosion of metal materials. However, this process is costly, has a long cycle, and cannot meet the market demand.

[0055] [Current collector] Based on this, the present application provides a current collector for a sodium secondary battery, the current collector includes a metal substrate and a surface treatment layer formed on at least one side of the metal substrate, and the surface treatment layer includes an oxide and / or a nitride of the metal substrate.

[0056] The surface treatment layer of the current collector can protect the metal from corrosion by anions in the electrolyte, improve the resistance at high voltage, effectively improve the Coulomb efficiency and cycle capacity retention rate of the battery, and improve the storage performance of the battery.

[0057] In this specification, the term "surface treatment layer" means a layer formed on the surface of the metal substrate of the current collector by a physical or chemical method, which changes the surface state of the current collector substrate.

[0058] In some embodiments, the thickness of the surface treatment layer is 2-200 nm, and optionally 5-50 nm.

[0059] In some embodiments, the thickness of the surface treatment layer is selectively 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm or 200 nm.

[0060] By controlling the thickness of the surface treatment layer to 2 - 200 nm, it is ensured that the electronic conductivity of the current collector is not affected, while protecting it from corrosion by anions in the electrolyte, improving its resistance at high voltages, thereby improving the Coulomb efficiency and cycle capacity retention rate of the battery. Also, by controlling the thickness of the surface treatment layer to 2 - 200 nm, an increase in the internal resistance of the battery due to excessive thickness, and a decrease in the battery cycle performance and energy density can be avoided. The thickness of the surface treatment layer is 5 - 50 nm, which is advantageous for further improving the Coulomb efficiency and cycle capacity retention rate of the battery.

[0061] In some embodiments, the surface treatment layer contains one or more of aluminum oxide, titanium oxide, copper oxide, nickel oxide, titanium nitride.

[0062] In some embodiments, the surface treatment layer is obtained by heat-treating the metal substrate, and the metal substrate contains at least one of aluminum, nickel, copper, titanium.

[0063] The heat treatment process is simple and low-cost. By controlling the heat treatment method, the surface treatment layer can be effectively adjusted and controlled, which is suitable for large-scale popularization and use. By heat-treating the metal substrate of the current collector to form a surface treatment layer on the current collector, it does not affect the electronic conductivity of the current collector, while protecting it from corrosion by anions in the electrolyte and improving its resistance at high voltages, avoiding or mitigating the reaction between the electrolyte and metal ions, and improving the Coulomb efficiency and cycle life of the battery.

[0064] In some embodiments, the metal substrate of the current collector includes aluminum, the surface treatment layer includes aluminum oxide, and the aluminum oxide is produced by heat-treating aluminum. In some embodiments, the metal substrate of the current collector includes titanium, the surface treatment layer includes titanium oxide and / or titanium nitride, and the titanium oxide and / or titanium nitride is produced by heat-treating titanium. In some embodiments, the metal substrate of the current collector includes nickel, the surface treatment layer includes nickel oxide, and the nickel oxide is produced by heat-treating nickel. In some embodiments, the metal substrate of the current collector includes copper, the surface treatment layer includes copper oxide, and the copper oxide is produced by heat-treating copper.

[0065] In some embodiments, the thickness of the surface treatment layer is 100 - 3000 nm, and optionally 500 - 1000 nm. In some embodiments, the thickness of the surface treatment layer is optionally 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 850 nm, 900 nm, 950 nm, 1000 nm, 1500 nm, 2000 nm, 2500 nm, 3000 nm.

[0066] In some embodiments, the surface treatment layer includes nanoneedle-shaped copper oxide, and the nanoneedle-shaped copper oxide grows perpendicular to the surface of the metal substrate. Optionally, the length of the nanoneedles is 100 - 3000 nm, and the width of the nanoneedles is 30 - 200 nm.

[0067] The length and width of the nanoneedles can be characterized by methods such as scanning electron microscopy and transmission electron microscopy. Different from nanowires, the width of the root part of the nanoneedles close to the metal substrate is different from that of the end part far from the metal substrate. The average width of the root part and the end part of the nanoneedles is defined as the width of the nanoneedles.

[0068] In some embodiments, the length of the nanoneedles is 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, 1500 nm, 2000 nm, 2500 nm, 3000 nm.

[0069] In some embodiments, the width of the nanoneedles is 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, or 200 nm.

[0070] The current collector including nanoneedle shapes can be used as a negative electrode, and the copper oxide nanoneedles on its surface can provide more sufficient nucleation sites and effectively reduce the local current density, promote more uniform deposition of metal ions on the surface of the current collector, suppress the formation of metal dendrites, and is advantageous for improving the Coulomb efficiency and cycle capacity retention rate of the battery.

[0071] As used herein, the term "nucleation site" refers to the position where metal ions obtain electrons at the negative electrode to form metal atoms and deposit.

[0072] In some embodiments, the surface treatment layer is obtained by chemically treating the metal substrate containing copper.

[0073] This application can effectively control the morphology of the surface treatment layer by means of low-energy-consuming chemical treatment and improve the cycle and storage stability of the battery.

[0074] In some embodiments, the areal density of the surface treatment layer is 0.1 - 20 g / m 2 is.

[0075] In some embodiments, the areal density of the surface treatment layer is selectively 0.1 g / m 2 , 0.2 g / m 2 , 0.3 g / m 2 , 0.4 g / m 2 , 0.5 g / m2 , 0.6 g / m 2 , 0.7 g / m 2 , 0.8 g / m 2 , 0.9 g / m 2 , 1 g / m 2 , 1.5 g / m 2 , 2 g / m 2 , 2.5 g / m 2 , 3 g / m 2 , 3.5 g / m 2 , 4 g / m 2 , 4.5 g / m 2 , 5 g / m 2 , 6 g / m 2 , 7 g / m 2 , 8 g / m 2 , 9 g / m 2 , 10 g / m 2 , 11 g / m 2 , 12 g / m 2 , 13 g / m 2 , 14 g / m 2 , 15 g / m 2 , 16 g / m 2 , 17 g / m 2 , 18 g / m 2 , 19 g / m 2 , 20 g / m 2 is as follows.

[0076] The areal density of the surface treatment layer is controlled to be 0.1 - 20 g / m 2 , protecting the metal from corrosion by anions in the electrolytic solution, while ensuring that the conductivity of the current collector is not too low, further improving the resistance of the current collector at high voltages, and optimizing the Coulombic efficiency and cycle capacity retention rate of the battery.

[0077] In some embodiments, the form of the metal substrate is foil-like or foam-like, and the metal substrate of the current collector selectively includes at least one of aluminum foil, copper foil, titanium foil, and foamed nickel.

[0078] In some embodiments, the thickness of the foil-like metal substrate is 5 - 500 μm, selectively 10 - 80 μm, and the porosity of the foam-like metal substrate is greater than 90%.

[0079] In some embodiments, the thickness of the foil-shaped metal substrate is selectively 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm or 500 μm.

[0080] When the thickness of the foil-shaped metal substrate is 5 - 500 μm and the porosity of the foam-shaped metal substrate is greater than 90%, it can be ensured that the current collector has good conductivity, high mechanical strength and low internal resistance, which is advantageous for the stability and safety of the battery.

[0081] In some embodiments, the conductivity of the current collector is 0.1 S / cm or more. In some embodiments, the conductivity of the current collector is 0.2 S / cm or more. In some embodiments, the conductivity of the current collector is 0.3 S / cm or more. In some embodiments, the conductivity of the current collector is 0.4 S / cm or more. In some embodiments, the conductivity of the current collector is 0.5 S / cm or more. In some embodiments, the conductivity of the current collector is 0.6 S / cm or more. In some embodiments, the conductivity of the current collector is 0.7 S / cm or more. In some embodiments, the conductivity of the current collector is 0.8 S / cm or more. In some embodiments, the conductivity of the current collector is 0.9 S / cm or more. In some embodiments, the conductivity of the current collector is 1.0 S / cm or more.

[0082] When the conductivity of the current collector is 0.1 S / cm or more, it can be ensured that the current collector has good conductivity, promote the transport of electrons between the components of the battery, and improve the specific capacity and rate performance of the battery.

[0083] In some embodiments, the current collector functions as the positive electrode current collector of the secondary battery.

[0084] In some embodiments, the current collector serves as the positive current collector of the secondary battery. The metal substrate of the current collector is aluminum foil. The current collector includes a surface treatment layer formed on at least one side of the aluminum foil, and the surface treatment layer contains aluminum oxide. The aluminum oxide surface treatment layer of the positive current collector can increase the thickness of the passivation layer of the current collector itself, increasing the thickness of the passivation layer on the surface of the current collector. Such an increase in thickness ensures that it does not affect the conductivity of the current collector, while reducing or avoiding the corrosion of the current collector due to the destruction of the oxide layer by some anions in the electrolyte, and can improve its resistance at high voltages.

[0085] In some embodiments, the current collector serves as the positive current collector of the secondary battery. The metal substrate of the current collector is titanium foil. The current collector includes a surface treatment layer formed on at least one side of the titanium foil, and the surface treatment layer contains titanium oxide or titanium nitride. The titanium oxide or titanium nitride surface treatment layer of the positive current collector does not affect the conductivity of the current collector, while protecting it from corrosion by anions in the electrolyte and improving its resistance at high voltages, and can improve the Coulomb efficiency and cycle capacity retention rate of the battery.

[0086] In some embodiments, the current collector serves as the positive current collector of the secondary battery. The metal substrate of the current collector is titanium foil. The current collector includes a surface treatment layer formed on at least one side of the titanium foil, and the surface treatment layer contains titanium oxide and titanium nitride. The titanium oxide and titanium nitride surface treatment layer of the positive current collector can further improve the stability of the current collector due to the hetero-structure, improve the Coulomb efficiency and cycle capacity retention rate of the battery, and improve the storage stability of the battery.

[0087] In some embodiments, the current collector serves as the negative electrode current collector of the secondary battery, and the metal substrate of the current collector is aluminum foil. The current collector includes a surface treatment layer formed on at least one side of the aluminum foil, and the surface treatment layer contains aluminum oxide. The aluminum oxide surface treatment layer of the negative electrode current collector can improve the affinity for metal ions of the current collector, make the deposition of metal ions more uniform and denser, and form a dense deposition morphology to alleviate the reaction between the electrolyte and metal ions, improve the Coulomb efficiency and cycle capacity retention rate of the battery, and improve the storage stability of the battery.

[0088] In some embodiments, the current collector functions as the negative electrode current collector of the secondary battery.

[0089] As used herein, the term "nucleation overpotential" means the additional potential required for nucleation, or the value deviating from the deposition stripping potential it should have, which is derived from the critical nucleation radius.

[0090] As used herein, the nucleation overpotential is mainly used to characterize the kinetics of metal ion deposition and can also characterize the uniformity of metal ion deposition, which can be tested by any known method.

[0091] In some embodiments, the current collector serves as the negative electrode current collector of the secondary battery, and the metal substrate of the current collector is titanium foil. The current collector includes a surface treatment layer formed on at least one side of the titanium foil, and the surface treatment layer contains titanium oxide. The titanium oxide surface treatment layer of the negative electrode current collector can reduce or avoid the reaction between the electrolyte and metal ions, while reducing the nucleation overpotential of metal ions, making the deposition of metal ions more uniform and denser, improving the Coulomb efficiency and cycle capacity retention rate of the battery, and improving the storage stability of the battery.

[0092] In some embodiments, the current collector serves as the negative electrode current collector of a secondary battery, and the metal substrate of the current collector is a titanium foil. The current collector includes a surface treatment layer formed on at least one side of the titanium foil, and the surface treatment layer includes titanium oxide and titanium nitride. The stability of the current collector can be further improved by means of a hybridization treatment on the current collector surface. In addition, the heterostructure of titanium oxide and titanium nitride improves the affinity for metal ions of the negative electrode current collector, enhances the surface diffusion dynamics of metal ions, reduces the nucleation overpotential of metal ions, makes the deposition of metal ions more uniform and denser, improves the Coulomb efficiency and cycle capacity retention rate of the battery, and can improve the storage stability of the battery.

[0093] In some embodiments, the current collector serves as the negative electrode current collector of a secondary battery, and the metal substrate of the current collector is foamed nickel. The current collector includes a surface treatment layer formed on at least one side of the foamed nickel, and the surface treatment layer includes nickel oxide. The nickel oxide surface treatment layer of the negative electrode current collector improves the affinity for metal ions of the current collector, improves the deposition morphology of metal ions, avoids or reduces the reaction between the electrolyte and metal ions, improves the Coulomb efficiency and cycle capacity retention rate of the battery, and can improve the storage stability of the battery.

[0094] In some embodiments, the current collector serves as the negative electrode current collector of a secondary battery, and the metal substrate of the current collector is a copper foil. The current collector includes a surface treatment layer formed on at least one side of the copper foil, and the surface treatment layer includes copper oxide. The copper oxide surface treatment layer of the negative electrode current collector improves the affinity for metal ions of the current collector, induces uniform and regular deposition of metal ions, avoids or reduces the reaction between the electrolyte and metal ions, improves the Coulomb efficiency and cycle capacity retention rate of the battery, and can improve the storage stability of the battery.

[0095] [Method for manufacturing a current collector] In one embodiment of the present application, there is provided a method for manufacturing a current collector, including the step of heat-treating and / or chemically treating a metal substrate to form a surface treatment layer located on at least one side of the metal substrate.

[0096] A surface treatment layer is formed on at least one side surface of the metal substrate by the above heat treatment method, which does not affect the electronic conductivity of the current collector, simultaneously protects it from corrosion by anions in the electrolytic solution, improves its resistance at high voltages, avoids or alleviates the reaction between the electrolytic solution and metal ions, and can improve the Coulomb efficiency and cycle life of the battery. Moreover, the heat treatment process is simple and suitable for large-scale popularization and use.

[0097] In some embodiments, the metal substrate is aluminum, the atmosphere of the heat treatment is air or oxygen gas, the temperature of the heat treatment is 80 - 350 °C, optionally 160 - 280 °C, the time of the heat treatment is 2 - 120 minutes, optionally 5 - 30 minutes, and the surface treatment layer contains aluminum oxide.

[0098] In some embodiments, the metal substrate is aluminum, the atmosphere of the heat treatment is air or oxygen gas, the surface treatment layer contains aluminum oxide, the temperature of the heat treatment is optionally 80 °C, 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, 160 °C, 170 °C, 180 °C, 190 °C, 200 °C, 210 °C, 220 °C, 230 °C, 240 °C, 250 °C, 260 °C, 270 °C, 280 °C, 290 °C, 300 °C, 310 °C, 320 °C, 330 °C, 340 °C or 350 °C, and the time of the heat treatment is optionally 2 minutes, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, 65 minutes, 70 minutes, 75 minutes, 80 minutes, 85 minutes, 90 minutes, 95 minutes, 100 minutes, 105 minutes, 110 minutes, 115 minutes or 120 minutes.

[0099] In some embodiments, the metal substrate is titanium, the atmosphere of the heat treatment is air or oxygen gas, the temperature of the heat treatment is 200 - 500 °C, optionally 300 - 500 °C, the time of the heat treatment is 2 - 120 minutes, optionally 5 - 30 minutes, and the surface treatment layer contains titanium oxide.

[0100] In some embodiments, the metal substrate is titanium, the heat treatment atmosphere is air or oxygen gas, the surface treatment layer contains titanium oxide, the heat treatment temperature is selectively 200 °C, 210 °C, 220 °C, 230 °C, 240 °C, 250 °C, 260 °C, 270 °C, 280 °C, 290 °C, 300 °C, 310 °C, 320 °C, 330 °C, 340 °C, 350 °C, 360 °C, 370 °C, 380 °C, 390 °C, 400 °C, 410 °C, 420 °C, 430 °C, 440 °C, 450 °C, 460 °C, 470 °C, 480 °C, 490 °C or 500 °C, and the heat treatment time is selectively 2 minutes, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, 65 minutes, 70 minutes, 75 minutes, 80 minutes, 85 minutes, 90 minutes, 95 minutes, 100 minutes, 105 minutes, 110 minutes, 115 minutes or 120 minutes.

[0101] In some embodiments, the metal substrate is copper, the heat treatment atmosphere is air or oxygen gas, the heat treatment temperature is 200 - 500 °C, selectively 200 - 400 °C, the heat treatment time is 2 - 120 minutes, selectively 5 - 30 minutes, and the surface treatment layer contains copper oxide.

[0102] In some embodiments, the metal substrate is copper, the heat treatment atmosphere is air or oxygen gas, the surface treatment layer contains copper oxide, the heat treatment temperature is selectively 200 °C, 210 °C, 220 °C, 230 °C, 240 °C, 250 °C, 260 °C, 270 °C, 280 °C, 290 °C, 300 °C, 310 °C, 320 °C, 330 °C, 340 °C, 350 °C, 360 °C, 370 °C, 380 °C, 390 °C, 400 °C, 410 °C, 420 °C, 430 °C, 440 °C, 450 °C, 460 °C, 470 °C, 480 °C, 490 °C or 500 °C, and the heat treatment time is selectively 2 minutes, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, 65 minutes, 70 minutes, 75 minutes, 80 minutes, 85 minutes, 90 minutes, 95 minutes, 100 minutes, 105 minutes, 110 minutes, 115 minutes or 120 minutes.

[0103] In some embodiments, the metal substrate is nickel, the heat treatment atmosphere is air or oxygen gas, the heat treatment temperature is 80 - 450 °C, optionally 180 - 300 °C, the heat treatment time is 2 - 120 minutes, optionally 5 - 30 minutes, and the surface treatment layer contains nickel oxide.

[0104] In some embodiments, the metal substrate is nickel, the heat treatment atmosphere is air or oxygen gas, the surface treatment layer contains nickel oxide, the heat treatment temperature is optionally 80 °C, 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, 160 °C, 170 °C, 180 °C, 190 °C, 200 °C, 210 °C, 220 °C, 230 °C, 240 °C, 250 °C, 260 °C, 270 °C, 280 °C, 290 °C, 300 °C, 310 °C, 320 °C, 330 °C, 340 °C, 350 °C, 360 °C, 370 °C, 380 °C, 390 °C, 400 °C, 410 °C, 420 °C, 430 °C, 440 °C or 450 °C, and the heat treatment time is optionally 2 minutes, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, 65 minutes, 70 minutes, 75 minutes, 80 minutes, 85 minutes, 90 minutes, 95 minutes, 100 minutes, 105 minutes, 110 minutes, 115 minutes or 120 minutes.

[0105] In some embodiments, the metal substrate is titanium, the heat treatment atmosphere is nitrogen gas, the ventilation rate is 10 - 200 mL / min, optionally 20 - 80 mL / min, the heat treatment temperature is 500 - 800 °C, optionally 650 - 800 °C, the heat treatment time is 2 - 120 minutes, optionally 5 - 30 minutes, and the surface treatment layer contains titanium nitride.

[0106] In some embodiments, the metal substrate is titanium, the heat treatment atmosphere is nitrogen gas, the surface treatment layer contains titanium nitride, and the ventilation rate is selectively 10 mL / min, 20 mL / min, 30 mL / min, 40 mL / min, 50 mL / min, 60 mL / min, 70 mL / min, 80 mL / min, 90 mL / min, 100 mL / min, 110 mL / min, 120 mL / min, 130 mL / min, 140 mL / min, 150 mL / min, 160 mL / min, 170 mL / min, 180 mL / min, 190 mL / min or 200 mL / min. The heat treatment temperature is selectively 500 °C, 550 °C, 560 °C, 570 °C, 580 °C, 590 °C, 600 °C, 610 °C, 620 °C, 630 °C, 640 °C, 650 °C, 660 °C, 670 °C, 680 °C, 690 °C, 700 °C, 710 °C, 720 °C, 730 °C, 740 °C, 750 °C, 760 °C, 770 °C, 780 °C, 790 °C or 800 °C, and the heat treatment time is selectively 2 minutes, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, 65 minutes, 70 minutes, 75 minutes, 80 minutes, 85 minutes, 90 minutes, 95 minutes, 100 minutes, 105 minutes, 110 minutes, 115 minutes or 120 minutes.

[0107] By controlling the heat treatment temperature and time within an appropriate range, a uniform, dense and stable surface treatment layer can be formed on the surface of the current collector. This surface treatment layer does not affect the electronic conductivity of the current collector, while protecting it from corrosion by anions in the electrolyte and improving its resistance at high voltages, avoiding or alleviating the reaction between the electrolyte and metal ions, and improving the Coulomb efficiency and cycle life of the battery. By adjusting different process parameters and through simple control of process parameters, the composition and morphology of the surface treatment layer can be adjusted to match different cathode / anode active materials, thereby realizing the optimization of the battery structure design and performance.

[0108] In some embodiments, this manufacturing method specifically involves performing post-treatment on the metal substrate under different atmospheres after heat treatment to form a surface treatment layer located on at least one side of the metal substrate.

[0109] In some embodiments, the metal substrate is titanium, the atmosphere of the heat treatment is air, the temperature of the heat treatment is 200 - 500 °C, the time of the heat treatment is 2 - 120 minutes, the atmosphere of the post-treatment is nitrogen gas, the temperature of the post-treatment is 600 - 900 °C, the time of the post-treatment is 2 - 120 minutes, and the surface treatment layer contains titanium oxide and titanium nitride.

[0110] In some embodiments, the metal substrate is titanium, the atmosphere of the heat treatment is air, the temperature of the heat treatment is selectively 200 °C, 210 °C, 220 °C, 230 °C, 240 °C, 250 °C, 260 °C, 270 °C, 280 °C, 290 °C, 300 °C, 310 °C, 320 °C, 330 °C, 340 °C, 350 °C, 360 °C, 370 °C, 380 °C, 390 °C, 400 °C, 410 °C, 420 °C, 430 °C, 440 °C, 450 °C, 460 °C, 470 °C, 480 °C, 490 °C or 500 °C, the time of the heat treatment is selectively 2 minutes, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, 65 minutes, 70 minutes, 75 minutes, 80 minutes, 85 minutes, 90 minutes, 95 minutes, 100 minutes, 105 minutes, 110 minutes, 115 minutes or 120 minutes, the atmosphere of the post-treatment is nitrogen gas, the temperature of the post-treatment is selectively 600 °C, 610 °C, 620 °C, 630 °C, 640 °C, 650 °C, 660 °C, 670 °C, 680 °C, 690 °C, 700 °C, 710 °C, 720 °C, 730 °C, 740 °C, 750 °C, 760 °C, 770 °C, 780 °C, 790 °C, 800 °C, 810 °C, 820 °C, 830 °C, 840 °C, 850 °C, 860 °C, 870 °C, 880 °C, 890 °C or 900 °C, the time of the post-treatment is selectively 2 minutes, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, 65 minutes, 70 minutes, 75 minutes, 80 minutes, 85 minutes, 90 minutes, 95 minutes, 100 minutes, 105 minutes, 110 minutes, 115 minutes or 120 minutes, and the surface treatment layer contains titanium oxide and titanium nitride.

[0111] By performing a nitriding treatment after oxidation, a heterostructure of titanium oxide and titanium nitride can be formed on the surface of the titanium foil, further improving the stability of the current collector. At the same time, this heterostructure improves the affinity of the current collector for metal ions, enhances the surface diffusion dynamics of metal ions, reduces the nucleation overpotential of metal ions, induces uniform and regular deposition of metal ions, further improves the Coulomb efficiency and cycle capacity retention rate of the battery, and can improve the storage stability of the battery.

[0112] In some embodiments, the manufacturing method specifically includes chemically treating a metal substrate in an alkaline solution to form a surface treatment layer located on at least one side of the metal substrate.

[0113] In some embodiments, the metal substrate is copper, the pH value of the alkaline solution is 11 - 12, the temperature of the chemical treatment is 45 - 90 °C, and the time of the chemical treatment is 0.5 - 12 hours.

[0114] In some embodiments, the metal substrate is copper, the pH of the alkaline solution is selectively 11, 11.1, 11.2, 11.3, 11.4, 11.5, 11.6, 11.7, 11.8, 11.9 or 12, the temperature of the chemical treatment is selectively 45 °C, 50 °C, 55 °C, 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, 85 °C or 90 °C, and the time of the chemical treatment is selectively 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 7.5 hours, 8 hours, 8.5 hours, 9 hours, 9.5 hours, 10 hours, 10.5 hours, 11 hours, 11.5 hours or 12 hours. In some embodiments, the alkaline solution is ammonia water, sodium hydroxide, or potassium hydroxide. In some embodiments, the alkaline solution is selectively ammonia water.

[0115] By using a method of immersing a copper current collector in a simple alkaline solution, that is, a nano-needle-like copper oxide layer can be formed on the surface of the copper current collector, improving the deposition site and active area of the current collector, being advantageous for the diffusion of metal ions at the electrode / electrolyte interface, reducing the nucleation overpotential and local current density, and inducing uniform deposition of metal ions. While improving the performance, the production efficiency is further improved, and the manufacturing cost and energy consumption are significantly reduced. Ammonia water is used as the alkaline solution, and the performance of the battery is further improved by the mutual cooperation between its cations and the surface treatment layer.

[0116] [Secondary battery] In some embodiments, the secondary battery includes a positive electrode plate and a negative electrode plate, and the positive electrode plate and / or the negative electrode plate includes a current collector in some embodiments or a current collector obtained by manufacturing with the manufacturing method in some embodiments.

[0117] In some embodiments, the secondary battery is a sodium battery.

[0118] A sodium battery is a battery in which the negative electrode active material contains sodium metal. Metallic sodium may be pre-deposited on one side of the current collector to serve as the negative electrode, or may be deposited in-situ during the charge and discharge process of the battery, that is, the sodium battery includes a sodium battery without a negative electrode.

[0119] In some embodiments, the secondary battery is a sodium battery without a negative electrode. This sodium battery without a negative electrode can have a high energy density.

[0120] The sodium battery without a negative electrode contains no negative electrode active material and only contains a negative electrode current collector. During the first charge, sodium ions obtain electrons on the negative electrode side and deposit on the surface of the current collector as metallic sodium to form a sodium metal phase. During discharge, metallic sodium can be converted into sodium ions and return to the positive electrode, realizing cycle charge and discharge. Compared with sodium secondary batteries and sodium batteries, the sodium battery without a negative electrode is not restricted by the negative electrode material, so a higher energy density can be obtained.

[0121] In some embodiments, the CB value of a sodium battery without a negative electrode is 0.1 or less. The CB value is the value obtained by dividing the capacity per unit area of the negative electrode plate in a secondary battery by the capacity per unit area of the positive electrode plate. Since a battery without a negative electrode does not contain a negative electrode active material, the capacity per unit area of the negative electrode plate is relatively small, and the CB value of the secondary battery is 0.1 or less.

[0122] In some embodiments, the positive electrode plate further includes a positive electrode active material layer formed on at least a part of the surface of the positive electrode current collector. The positive electrode active material layer contains a positive electrode active material, and the positive electrode active material may contain one or more of Prussian blue-based compounds, polyanion-type compounds, and layered transition metal oxides.

[0123] The transition metal in the layered transition metal oxide may be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. Optionally, the layered transition metal oxide is, for example, Na x MO2, where M is one or more of Ti, V, Mn, Co, Ni, Fe, Cr, and Cu, and 0 < x ≦ 1.

[0124] The polyanion-type compound may be a kind of compound having metal ions, transition metal ions, and tetrahedral (YO4) n- anion units. The metal ions are optionally one of sodium ions, lithium ions, potassium ions, and zinc ions. The transition metal is optionally at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. Y is optionally at least one of P, S, and Si, and n represents the valence of (YO4) n- .

[0125] The Prussian blue-based compound may be a kind of compound having sodium ions, transition metal ions, and cyanide ions (CN-). The transition metal may be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. The Prussian blue-based compound is, for example, Naa Me b Me’ c (CN)6, where Me and Me’ are each independently at least one of Ni, Cu, Fe, Mn, Co, and Zn, and 0 < a ≤ 2, 0 < b < 1, 0 < c < 1.

[0126] The positive electrode active material layer may further contain a conductive agent to improve the conductive performance of the positive electrode. The conductive agent is selectively one or more of Super P, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphite, graphene, and carbon nanofibers.

[0127] The positive electrode active material layer may further contain an adhesive for firmly adhering the positive electrode active material and the selective conductive agent to the positive electrode current collector. The adhesive is selectively at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyacrylic acid (PAA), polyvinyl alcohol (PVA), ethylene-vinyl acetate copolymer (EVA), styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), sodium alginate (SA), polymethacrylic acid (PMA), and carboxymethyl chitosan (CMCS).

[0128] In some embodiments, the surface of the positive electrode active material particles has a coating layer, and the coating layer contains one or more of a carbon material, polyaniline (PANI), polypyrrole (PPy), poly(3,4-ethylenedioxythiophene) (PEDOT), aluminum oxide (Al2O3), zinc oxide (ZnO), titanium oxide (TiO2), zirconium oxide (ZrO2), magnesium oxide (MgO), silicon oxide (SiO2), lanthanum oxide (La2O3), sodium fluoride (NaF), lithium fluoride (LiF), and aluminum fluoride (AlF3), and the carbon material contains one or more of amorphous carbon, graphite, and graphene.

[0129] The coating of the coating layer can effectively improve the stability of the positive electrode active material, reduce the metal elution and particle destruction phenomena during the cycling process of the positive electrode active material, and effectively improve the cycle performance and storage stability of the battery.

[0130] In some embodiments, the thickness of the coating layer is 2 nm - 1000 nm, and optionally 10 nm - 100 nm.

[0131] In some embodiments, the thickness of the coating layer is optionally 2 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm or 500 nm.

[0132] A coating layer with an appropriate thickness can play an effective improvement role and avoid the situation where the coating layer is too thick, the resistance of the positive electrode film is too high, and the battery performance deteriorates.

[0133] In some embodiments, the positive electrode plate may be manufactured in the following manner. Components for manufacturing the positive electrode plate, such as the positive electrode active material, conductive agent, adhesive, and any other components, are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry. The positive electrode slurry is coated on the positive electrode current collector, and after processes such as drying and cold pressing, a positive electrode plate can be obtained.

[0134] In some embodiments, the secondary battery further includes an electrolyte.

[0135] The electrolyte serves to conduct ions between the positive electrode plate and the negative electrode plate. The present application is not specifically limited to the type of electrolyte and may be selected according to requirements. For example, the electrolyte may be liquid, gel-like or all-solid.

[0136] In some embodiments, an electrolytic solution is employed as the electrolyte. The electrolytic solution contains an electrolyte salt and a solvent.

[0137] In some embodiments, the electrolyte salt may be selected from at least one of sodium nitrate (NaNO3), sodium perchlorate (NaClO4), sodium hexafluorophosphate (NaPF6), sodium tetrafluoroborate (NaBF4), sodium tetrafluoroyttrium (NaYF6), sodium hexafluoroarsenate (NaAsF6), sodium acetate (CH3COONa), sodium trifluoroacetate (CF3COONa), sodium bis(oxalato)borate (NaBOB), sodium difluoro(oxalato)borate (NaDFOB), sodium tetraphenylborate (NaB(C6H5)4), sodium trifluoromethanesulfonate (NaOTf), sodium bis(fluorosulfonyl)imide (NaFSI), sodium bistrifluoromethanesulfonylimide (NaTFSI), (normal perfluorobutylsulfonyl)imide sodium (NaFNFSI).

[0138] In some embodiments, the electrolyte solution contains an ester-based solvent, and the ester-based solvent contains one or more of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylene carbonate (VC), fluoroethylene carbonate (FEC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), γ-butyrolactone (BL), 1,3-propane sultone (1,3-PS), methyl propionate (MP), methyl butyrate (MB), ethyl acetate (EA), ethyl propionate (EP), propyl propionate (PP), ethyl butyrate (EB).

[0139] In some embodiments, the electrolyte includes an ether-based solvent, and the ether-based solvent includes one or more of ethylene glycol dimethyl ether (DME), diethylene glycol dimethyl ether (DEGDME), triethylene glycol dimethyl ether (TRGDME), tetraethylene glycol dimethyl ether (TEGDME), ethylene glycol diethyl ether (DEE), diethylene glycol diethyl ether (DEGDEE), diisopropyl ether (DIE), dibutyl ether (DBE), diethylene glycol dibutyl ether (DEGDBE), 1,4-dimethoxybutane (DMB), 1,4-diethoxybutane (DEB), 1,3-dioxolane (DOL), tetrahydrofuran (THF), 15-crown-5 (15-Crown-5), 12-crown-4 (12-Crown-4), 18-crown-6 (18-Crown-6).

[0140] For sodium batteries, the electrolytes containing the above ether-based solvents can all reduce the overpotential of sodium ions, promote the uniform deposition of sodium ions, reduce side reactions during the cycling process, and are advantageous for improving the Coulombic efficiency and cycle capacity retention rate of the battery.

[0141] In some embodiments, the electrolyte further selectively includes additives. For example, the additives may include a negative electrode film-forming additive and a positive electrode film-forming additive, and may further include additives that can improve some performances of the battery, such as additives that improve the overcharge performance of the battery, additives that improve the high-temperature or low-temperature performance of the battery, and the like.

[0142] In some embodiments, the secondary battery further includes a separator.

[0143] This application is not particularly limited to the type of separator, and any known porous structure separator with good chemical stability and mechanical stability may be selected.

[0144] In some embodiments, the separator material may be selected from at least one of polyethylene, polypropylene, polyvinylidene fluoride, aramid, polyethylene terephthalate, polytetrafluoroethylene, polyacrylonitrile, polyimide, polyamide, polyester, and natural fibers. The separator may be a single-layer film or a multi-layer composite film, and there is no particular limitation. When the separator is a multi-layer composite film, the materials of each layer may be the same or different, and there is no particular limitation.

[0145] In some embodiments, the positive electrode plate, negative electrode plate, and separator can be manufactured into an electrode assembly by a winding process or a lamination process.

[0146] In some embodiments, the secondary battery may include an outer package. This outer package may be used to package the above electrode assembly and electrolyte.

[0147] In some embodiments, the outer package of the secondary battery may be a hard case, such as a hard plastic case, an aluminum case, a steel case, etc. The outer package of the secondary battery may be a pouch, such as a bag-shaped pouch. The material of the pouch may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0148] This application does not particularly limit the shape of the secondary battery, and it may be cylindrical, rectangular, or any other arbitrary shape. For example, FIG. 1 shows a rectangular-structured secondary battery 5 as an example.

[0149] In some embodiments, referring to FIG. 2, the exterior body may include a case 51 and a cover plate 53. Here, the case 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates form an accommodating cavity by surrounding. The case 51 has an opening communicating with the accommodating cavity, and the cover plate 53 can be covered on the opening so as to seal the accommodating cavity. The positive electrode plate, the negative electrode plate and the separator may form an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is packaged in the accommodating cavity. The electrolytic solution is infiltrated into the electrode assembly 52. The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and those skilled in the art can select according to specific actual needs.

[0150] In some embodiments, the secondary battery may be assembled into a battery module, and the number of secondary batteries included in the battery module may be one or more. The specific number may be selected by those skilled in the art according to the application and capacity of the battery module.

[0151] FIG. 3 shows a battery module 4 as an example. Referring to FIG. 3, a plurality of secondary batteries 5 may be arranged in sequence along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other way. Further, these plurality of secondary batteries 5 may be fixed by fasteners.

[0152] Optionally, the battery module 4 may further include a housing having an accommodating space, and the plurality of secondary batteries 5 are accommodated in this accommodating space.

[0153] In some embodiments, the above battery module may be assembled into a battery pack, and the number of battery modules included in the battery pack may be one or more. The specific number may be selected by those skilled in the art according to the application and capacity of the battery pack.

[0154] Figures 4 and 5 show a battery pack 1 as an example. Referring to Figures 4 and 5, the battery pack 1 may include a battery box and a plurality of battery modules 4 installed in the battery box. The battery box includes an upper housing 2 and a lower housing 3. The upper housing 2 can be covered on the lower housing 3 to form a sealed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

[0155] In addition, the present application further provides a power consumption device, which includes at least one of the secondary battery, battery module, or battery pack according to the present application. The secondary battery, battery module, or battery pack may be used as a power source of the power consumption device or as an energy storage unit of the power consumption device. The power consumption device may include, but is not limited to, mobile devices (such as mobile phones, notebook computers, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0156] As the power consumption device, a secondary battery, battery module, or battery pack can be selected according to its usage requirements.

[0157] Figure 6 shows a power consumption device as an example. This power consumption device is a pure electric vehicle, hybrid electric vehicle, or plug-in hybrid electric vehicle, etc. In order to meet the requirements for high output and high energy density of the secondary battery of this power consumption device, a battery pack or battery module can be adopted.

[0158] Another example of the device may be a mobile phone, tablet computer, notebook computer, etc. This device generally requires thinness and light weight, and a secondary battery may be adopted as the power source.

[0159] Embodiment The following are examples of this application. The examples described below are illustrative and are only used to interpret this application and should not be understood as a limitation to this application. When specific technologies or conditions are not specified in the examples, they are carried out according to the technologies or conditions described in the literature in the relevant field or according to the product manuals. When the reagents or equipment used are not specified by the manufacturer, they are all ordinary commercially available products.

[0160] I. Manufacturing Method Example 1 1) Manufacturing of Current Collector An aluminum foil with a thickness of 65 μm was taken, and the aluminum foil was ultrasonically cleaned in ethanol and acetone for more than 10 minutes in sequence, then placed flat in a blower oven and heat-treated in an air atmosphere to produce an oxide layer on the surface.

[0161] 2) Manufacturing of Positive Electrode Plate A 2.5 wt% polyvinylidene fluoride adhesive was fully dissolved in N-methylpyrrolidone (NMP), and further 2.0 wt% Super P, 1.0 wt% carbon nanotubes, and sodium iron pyrophosphate (Na4Fe3(PO4)2P2O7 / C) coated with 94.5 wt% positive electrode active material carbon were added and stirred uniformly to obtain a positive electrode slurry. The slurry was uniformly coated on the surface of the current collector manufactured in step 1, and then transferred to a vacuum oven and completely dried. The dried electrode plate was roll-pressed, punched, and a positive electrode plate was obtained.

[0162] 3) Manufacturing of Negative Electrode Plate An aluminum foil with a thickness of 65 μm was taken, and the aluminum foil was ultrasonically cleaned in ethanol and acetone for 10 minutes in sequence and then dried for use.

[0163] 4) Manufacturing of Electrolyte In an argon gas atmosphere glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), sodium hexafluorophosphate (NaPF6) was dissolved in an ethylene glycol dimethyl ether (DME) organic solvent and stirred uniformly. Here, the concentration of NaPF6 was 1 mol / L based on the total volume of the electrolyte.

[0164] 5) Manufacture of the battery The positive electrode plate, electrolyte, and negative electrode plate were stacked in order, then wound to obtain a bare cell. Tabs were welded to the bare cell, and the bare cell was placed in an aluminum case and baked at 80 °C to remove water. Then, the electrolyte was injected and sealed to obtain a non-charged battery. The non-charged battery further underwent processes such as standing, hot pressing and cold pressing, formation, shaping, and capacity testing in sequence to obtain the sodium metal battery product without the negative electrode of Example 1.

[0165] Examples 2 - 36 adjusted the type of current collector of the positive or negative electrode plate, the method and parameters of surface treatment, or the positive electrode active material.

[0166] Examples 2 - 7 The manufacturing method of Examples 2 - 7 was almost the same as that of Example 1, and the difference was that the temperature or time for performing surface heat treatment on the positive electrode current collector was adjusted.

[0167] Example 8 The manufacturing method of Example 8 was almost the same as that of Example 3, and the difference was that the current collector after the same heat treatment was used as both the positive and negative electrode current collectors simultaneously.

[0168] Example 9 The manufacturing method of Example 9 was almost the same as that of Example 1, and the difference was that a titanium foil was used as the positive electrode current collector and the temperature and time for performing surface heat treatment on the positive electrode current collector were adjusted.

[0169] Examples 10 - 14 The manufacturing method of Examples 10 - 14 was almost the same as that of Example 9, and the difference was that the temperature and / or time for performing surface heat treatment on the positive electrode current collector were adjusted.

[0170] Example 15 The manufacturing method of Example 15 is almost the same as that of Example 13, and the difference lies in using a titanium foil as the negative electrode current collector.

[0171] Example 16 The manufacturing method of Example 16 is almost the same as that of Example 15, and the difference lies in using the current collector after the same heat treatment as both the positive electrode and negative electrode current collectors simultaneously.

[0172] Example 17 The manufacturing method of Example 17 is almost the same as that of Example 9, and the difference lies in adjusting the atmosphere, temperature, and time for surface heat treatment of the positive electrode current collector.

[0173] Examples 18 - 19 The manufacturing method of Examples 18 - 19 is almost the same as that of Example 17, and the difference lies in adjusting the temperature for surface heat treatment of the positive electrode current collector.

[0174] Example 20 The manufacturing method of Example 20 is almost the same as that of Example 18, and the difference lies in using the current collector after the same heat treatment as both the positive electrode and negative electrode current collectors simultaneously.

[0175] Example 21 The manufacturing method of Example 21 is almost the same as that of Example 17, and the difference lies in the method of surface heat treatment of the positive electrode current collector. In Example 21, after performing surface heat treatment on the positive electrode current collector in an air atmosphere, post - treatment was performed on the positive electrode current collector in a nitrogen gas atmosphere. The specific method is as follows.

[0176] Take a titanium foil with a thickness of 65 μm, ultrasonically clean the titanium foil in ethanol and acetone for more than 10 minutes in sequence, then place it flat in a forced - air oven, and perform heat treatment at 420 °C for 10 minutes in an air atmosphere. Then, change the air atmosphere to a nitrogen gas atmosphere, and further perform heat treatment at 680 °C for 10 minutes in a nitrogen gas atmosphere to obtain a heterojunction structure containing titanium nitride and titanium oxide on the surface.

[0177] Example 22 The manufacturing method of Example 22 is almost the same as that of Example 21, and the difference is that the current collector after the same heat treatment is used as both the positive electrode current collector and the negative electrode current collector at the same time.

[0178] Example 23 The manufacturing method of Example 23 is almost the same as that of Example 1, and the difference is that the aluminum foil negative electrode current collector is heat-treated and the aluminum foil positive electrode current collector is not heat-treated. The aluminum foil of the negative electrode current collector was heat-treated in air at 200 °C for 10 minutes.

[0179] Example 24 The manufacturing method of Example 24 is almost the same as that of Example 23, and the difference is that foamed nickel is used as the negative electrode current collector and the aluminum foil positive electrode current collector is not heat-treated. The foamed nickel of the negative electrode current collector was heat-treated in air at 240 °C for 10 minutes.

[0180] Example 25 The manufacturing method of Example 25 is almost the same as that of Example 22, and the difference is that aluminum foil is used as the positive electrode current collector and no surface heat treatment is performed on the positive electrode current collector.

[0181] Example 26 The manufacturing method of Example 26 is almost the same as that of Example 24, and the difference is that surface heat treatment was performed on the aluminum foil positive electrode current collector. The method of performing surface heat treatment on the aluminum foil positive electrode current collector in Example 26 is the same as the method of performing surface heat treatment on the aluminum foil positive electrode current collector in Example 3.

[0182] Example 27 The manufacturing method of Example 27 is almost the same as that of Example 25, and the difference is that surface heat treatment was performed on the aluminum foil positive electrode current collector. The method of performing surface heat treatment on the aluminum foil positive electrode current collector in Example 27 is the same as the method of performing surface heat treatment on the aluminum foil positive electrode current collector in Example 3.

[0183] Example 28 The manufacturing method of Example 28 is almost the same as that of Example 1. The differences are: 1) no surface heat treatment is performed on the aluminum foil positive current collector; 2) a copper foil is used as the negative current collector, and surface chemical treatment is performed on the copper foil negative current collector. The method of performing surface chemical treatment on the copper foil negative current collector is specifically as follows.

[0184] Take a copper foil with a thickness of 65 μm, ultrasonically clean the copper foil in ethanol and acetone for more than 10 minutes in sequence, and then immerse it in 5 wt.% HCl for 10 minutes or ultrasonically clean it. After that, the copper foil current collector is washed with deionized water and vacuum dried, and then immersed in ammonia water with a concentration of 0.1 - 1×10 -2 mol / L (place one side flat upward), and a nitride layer on the surface is manufactured and obtained.

[0185] Examples 29 - 31 The manufacturing methods of Examples 29 - 31 are almost the same as that of Example 28. The difference is that the concentration and / or type of the alkaline solution are adjusted.

[0186] Example 32 The manufacturing method of Example 32 is almost the same as that of Example 28. The difference is that surface heat treatment is performed on the aluminum foil positive current collector. The method of performing surface heat treatment on the aluminum foil positive current collector in Example 32 is the same as the method of performing surface heat treatment on the aluminum foil positive current collector in Example 3.

[0187] Example 33 The manufacturing method of Example 33 is almost the same as that of Example 8. The difference is that the positive electrode active material is adjusted to Na[Cu 1 / 9 Ni 2 / 9 Fe 1 / 3 Mn 1 / 3 O2.

[0188] Example 34 The manufacturing method of Example 34 is almost the same as that of Example 8. The difference is that the positive electrode active material is Na 2 / 3 Ni 1 / 6 Mn 2 / 3 Cu 1 / 9 Mg 1 / 18Adjusted to O2, with the thickness of the coating layer being 30 nm.

[0189] Example 35 The manufacturing method of Example 35 is almost the same as that of Example 22. The difference is that the cathode active material is adjusted to Na[Cu 1 / 9 Ni 2 / 9 Fe 1 / 3 Mn 1 / 3 O2.

[0190] Example 36 The manufacturing method of Example 36 is almost the same as that of Example 22. The difference is that the cathode active material is Na 2 / 3 Ni 1 / 6 Mn 2 / 3 Cu 1 / 9 Mg 1 / 18 coated with ZrO2 and adjusted to O2, with the thickness of the coating layer being 30 nm.

[0191] The current collectors in Comparative Examples 1 - 10 are all current collectors that are not heat - treated or chemically treated. Here, the cathode active materials of Comparative Examples 1 - 5 and 8 are Na4Fe3(PO4)2P2O7 / C, the cathode active materials of Comparative Examples 6 and 9 are Na[Cu 1 / 9 Ni 2 / 9 Fe 1 / 3 Mn 1 / 3 O2, and the cathode active materials of Comparative Examples 7 and 10 are Na 2 / 3 Ni 1 / 6 Mn 2 / 3 Cu 1 / 9 Mg 1 / 18 coated with ZrO2 and adjusted to O2, and the thickness of the coating layer is 30 nm.

[0192] II. Performance Tests 1) Surface Treatment Layer Thickness Test The thickness of the surface treatment layer was tested using a Bruker step profiler Dektak XT.

[0193] 2) Surface Treatment Layer Areal Density Test When performing the areal density test, at room temperature, for a predetermined area S (m 2) Take the current collector after heat treatment, punch a circular hole in the electrode plate using a punching machine, then weigh its mass m1 (unit: g) with an electronic balance. Next, punch out a current collector of the same area and the same type before heat treatment in the same manner, weigh its mass m2 (unit: g) with an electronic balance, and finally calculate the test by the formula (m1 - m2) / S (unit: g / m 2 )

[0194] 3) Conductivity test of the current collector Determine the conductivity of the current collector using the four-probe method. Fix four copper plates with a length of 1.5 cm * width of 1 cm * thickness of 2 mm at equal distances in a line. The distance between the two middle copper plates is L (1 - 2 cm). The base material for fixing the copper plates is an insulating material. During the test, press the lower end surfaces of the four copper plates against the current collector to be tested, apply a direct current I to the two end copper plates, test the voltage V with the two middle copper plates, read the values of I and V three times, take the average values of I and V, and V / I is the resistance value of the current collector at the test location. Next, obtain the resistivity of the current collector according to the resistance formula, and the conductivity is the reciprocal of the resistivity.

[0195] 4) Nucleation overpotential test The test process of the nucleation overpotential is as follows: At 25°C, in a three-electrode battery system, use the current collector after heat treatment as the working electrode, a sodium metal sheet as the counter electrode, and at the same time use another sodium metal sheet as the reference electrode. Discharge at a constant current of 0.1 mA / cm 2 until 0.3 mAh / cm 2 and record the most negative potential obtained during the process as the nucleation overpotential.

[0196] 5) Average Coulomb efficiency test At 25°C, charge and discharge cycles were repeated for the fabricated full battery. The Coulomb efficiency for one cycle is defined as Discharge capacity (Cd1) / Charge capacity (Cc1) × 100%. The cycle number n is the number of cycles until the capacity retention rate reaches 80%. The average value of the Coulomb efficiency from the second cycle to the nth cycle during the cycling process was calculated as the Coulomb efficiency of the full battery, which can characterize the stability of the battery performance during the cycling process. The test processes for the comparative examples and other examples are the same as above.

[0197] 6) Cycle number test until the retention rate reaches 80% At 25°C and normal pressure (0.1 MPa), the fabricated full battery was charged at a constant current of 1C until the voltage reached 4V (layered oxide cathode) or 3.7V (sodium iron pyrophosphate cathode), and then discharged at a constant current of 1C until the voltage reached 3.0V. This was considered one charge-discharge cycle. Taking the capacity of the first discharge as 100%, the charge-discharge cycles were repeated. When the discharge capacity decayed to 80%, the test was stopped, the cycle number was recorded, and the cycle number until the capacity retention rate reached 80% was used as an index to evaluate the cycle performance of the full battery. The test processes for the comparative examples and other examples are the same as above.

[0198] 7) Storage performance At 25°C, after the fabricated full battery was left standing for 4 hours, it was charged at a constant current of 0.1C to 4V, then charged at a constant voltage of 4V to 0.01C, left standing for 5 minutes, and the thickness of the full battery was measured. After storing at 25°C for 60 days, the thickness of the full battery was measured again, and the thickness expansion rate of the battery was calculated using the following formula: Thickness expansion rate of the full battery = [(Thickness after storage - Thickness before storage) / Thickness before storage] × 100%. The test processes for the comparative examples and other examples are the same as above.

[0199] III. Analysis of the test results of each example and comparative example According to the above method, the batteries of each example and comparative example were fabricated respectively, and the performance parameters of each item were measured. The results are shown in Tables 1, 2, and 3 below.

[0200]

Table 1-1

Table 1-2

Table 1-3

Table 1-4

[0201]

Table 2-1

Table 2-2

[0202]

Table 3-1

Table 3-2

Table 3-3

[0203] As can be seen from the above results, the current collectors of Examples 1 to 36 include a metal substrate and a surface treatment layer formed on at least one side of the metal substrate, and the surface treatment layer contains an oxide and / or nitride of this metal substrate. Compared with Comparative Examples 1 to 10 in which the current collector does not have a surface treatment layer, at least one side of the positive current collector and / or negative current collector of the present application has a surface treatment layer containing an oxide and / or nitride, and the surface treatment layer does not significantly reduce the conductivity of the current collector, and at the same time, can effectively improve the Coulomb efficiency and cycle capacity retention rate of the battery, and can improve the storage performance of the battery.

[0204] As can be seen from Examples 1 to 7, 9 to 15, 17 to 19, and 21, using a current collector including a surface treatment layer as the positive electrode can significantly improve the cycle performance of the battery and reduce the storage gas generation expansion rate of the battery. The surface treatment layer of the positive electrode current collector may include one or more of aluminum oxide, titanium oxide, and titanium nitride, and the thickness of the surface treatment layer is 2 - 200 nm.

[0205] As can be seen from Examples 23 to 25 and 28 to 31, using a current collector including a surface treatment layer as the negative electrode can reduce the nucleation overpotential of sodium ions depositing on the negative electrode of the battery, improve the cycle performance of the battery, and reduce the storage gas generation expansion rate of the battery. The surface treatment layer of the negative electrode current collector may include one or more of aluminum oxide, titanium oxide, titanium nitride, and nickel oxide, and the thickness of the surface treatment layer is 2 - 200 nm. The surface treatment layer of the negative electrode current collector may include nanoneedle-shaped copper oxide, and the thickness of the surface treatment layer is 500 - 1000 nm.

[0206] Compared with aluminum foil alone, the reduction width of the nucleation overpotential of sodium ions in Example 8 where the negative electrode current collector has a surface treatment layer containing aluminum oxide exceeded 60%. Compared with titanium foil alone, the reduction width of the nucleation overpotential of sodium ions in Examples 16 and 20 where the negative electrode current collector has a surface treatment layer containing titanium oxide exceeded 30%, and the reduction width of the nucleation overpotential of sodium ions in Example 20 where the negative electrode current collector has a surface treatment layer containing titanium nitride exceeded 70%. The reduction width of the nucleation overpotential of sodium ions in Example 22 where the negative electrode current collector has a surface treatment layer containing titanium oxide and titanium nitride exceeded 85%. That is, the surface treatment layer containing the heterojunction structure of titanium oxide and titanium nitride contributes to sodium ion deposition and can further improve the cycle performance and storage performance of the battery.

[0207] As can be seen from Examples 8, 16, 20, 22, 26, 27, and 32, using a current collector including a surface treatment layer as the positive electrode and a current collector including a surface treatment layer as the negative electrode simultaneously can have a synergistic effect, further improve the cycle performance of the battery, and reduce the storage gas generation expansion rate of the battery.

[0208] As can be seen from the comparison between Examples 30 and 31, surface treatment of the copper foil with aqueous ammonia can more effectively improve the cycle performance of the battery than sodium hydroxide.

[0209] As can be seen from Examples 33 to 36, this current collector is applied to a plurality of positive electrode active materials and can improve the high-voltage cycle performance of the layered metal oxide.

[0210] It should be noted that the present application is not limited to the above embodiments. The above embodiments are merely examples, and embodiments having substantially the same configuration as the technical idea within the scope of the technical solution of the present application and achieving the same effects are all included within the technical scope of the present application. In addition, various modifications conceivable by those skilled in the art can be made to the embodiments without departing from the spirit of the present application, and other embodiments configured by combining some components in the embodiments are also included within the scope of the present application.

Description of Reference Numerals

[0211] 1: Battery pack, 2: Upper housing, 3: Lower housing, 4: Battery module, 5: Secondary battery, 51: Case, 52: Electrode assembly, 53: Cover plate.

Claims

1. A current collector for a sodium secondary battery, wherein the current collector includes a metal substrate and a surface treatment layer formed on at least one side of the metal substrate, and the surface treatment layer includes an oxide and / or a nitride of the metal substrate. A current collector for a sodium secondary battery, characterized in that.

2. The thickness of the surface treatment layer is 2 nm - 200 nm, or 5 nm - 50 nm. The current collector according to claim 1, characterized in that.

3. The surface treatment layer includes one or more of aluminum oxide, titanium oxide, copper oxide, nickel oxide, and titanium nitride. The current collector according to claim 1, characterized in that.

4. The surface treatment layer is obtained by heat-treating the metal substrate, and the metal substrate includes at least one of aluminum, nickel, copper, and titanium. The current collector according to claim 1, characterized in that.

5. The thickness of the surface treatment layer is 100 - 3000 nm, or 500 - 1000 nm. The current collector according to claim 1, characterized in that.

6. The surface treatment layer includes nano-needle-shaped copper oxide, the nano-needle-shaped copper oxide is substantially perpendicular to the surface of the metal substrate, the length of the nano-needle copper oxide is 100 - 3000 nm, and the width of the nano-needle copper oxide is 30 - 200 nm. The current collector according to claim 5, characterized in that.

7. The surface treatment layer is obtained by chemically treating a metal substrate containing copper. The current collector according to claim 5, characterized in that.

8. The areal density of the surface treatment layer is 0.1 - 20 g / m ２ The current collector according to claim 1, characterized in that it is so.

9. The form of the metal substrate is foil-shaped or foam-shaped. The thickness of the foil-shaped metal substrate is 5 - 500 μm, or 10 - 80 μm. The porosity of the foam-shaped metal substrate is greater than 90%. The current collector according to claim 1, characterized in that.

10. The conductivity of the current collector is 0.1 S / cm or more. The current collector according to claim 1, characterized in that.

11. A method for manufacturing a current collector, including the step of heat-treating and / or chemically treating a metal substrate to form a surface treatment layer located on at least one side of the metal substrate, and the surface treatment layer includes an oxide and / or a nitride of the metal substrate. A method for manufacturing a current collector, characterized in that.

12. The metal substrate is aluminum, the atmosphere of the heat treatment is air or oxygen gas, the temperature of the heat treatment is 80 - 350 °C, or 160 - 280 °C, the time of the heat treatment is 2 - 120 minutes, or 5 - 30 minutes, and the surface treatment layer contains aluminum oxide. The manufacturing method according to claim 11 is characterized by the above.

13. The metal substrate is titanium, the atmosphere of the heat treatment is air or oxygen gas, the temperature of the heat treatment is 200 - 500 °C, or 300 - 500 °C, the time of the heat treatment is 2 - 120 minutes, or 5 - 30 minutes, and the surface treatment layer contains titanium oxide. The manufacturing method according to claim 11 is characterized by the above.

14. The metal substrate is copper, the atmosphere of the heat treatment is air or oxygen gas, the temperature of the heat treatment is 200 - 500 °C, or 200 - 400 °C, the time of the heat treatment is 2 - 120 minutes, or 5 - 30 minutes, and the surface treatment layer contains copper oxide. The manufacturing method according to claim 11 is characterized by the above.

15. The metal substrate is nickel, the atmosphere of the heat treatment is air or oxygen gas, the temperature of the heat treatment is 80 - 450 °C, or 180 - 300 °C, the time of the heat treatment is 2 - 120 minutes, or 5 - 30 minutes, and the surface treatment layer contains nickel oxide. The manufacturing method according to claim 11 is characterized by the above.

16. The metal substrate is titanium, the atmosphere of the heat treatment is nitrogen gas, the ventilation rate is 10 - 200 mL / min, or 20 - 80 mL / min, the temperature of the heat treatment is 500 - 800 °C, or 650 - 800 °C, the time of the heat treatment is 2 - 120 minutes, or 5 - 30 minutes, and the surface treatment layer contains titanium nitride. The manufacturing method according to claim 11 is characterized by the above.

17. Specifically, the manufacturing method is as follows: After heat - treating the metal substrate, post - treatment is carried out under different atmospheres to form a surface treatment layer located on at least one side of the metal substrate. The manufacturing method according to claim 11 is characterized by the above.

18. The metal substrate is titanium, the atmosphere of the heat treatment is air or oxygen gas, the temperature of the heat treatment is 200 - 500 °C, the time of the heat treatment is 2 - 120 minutes, the atmosphere of the post-treatment is nitrogen gas, the temperature of the post-treatment is 600 - 900 °C, the time of the post-treatment is 2 - 120 minutes, and the surface treatment layer contains titanium oxide and titanium nitride. The manufacturing method according to claim 17 is characterized by the above.

19. Specifically, the manufacturing method is to chemically treat the metal substrate in an alkaline solution to form a surface treatment layer located on at least one side of the metal substrate. The manufacturing method according to claim 11 is characterized by the above.

20. The metal substrate is copper, the pH value of the alkaline solution is 11 - 12, the temperature of the chemical treatment is 45 - 90 °C, and the time of the chemical treatment is 0.5 - 12 hours. The manufacturing method according to claim 19 is characterized by the above.

21. A secondary battery, comprising a positive electrode plate and a negative electrode plate, wherein the positive electrode plate and / or the negative electrode plate contains the current collector according to any one of claims 1 to 10. The secondary battery is characterized by the above.

22. The secondary battery is a sodium battery. The secondary battery according to claim 21 is characterized by the above.

23. The secondary battery is a sodium secondary battery without a negative electrode. The secondary battery according to claim 21 is characterized by the above.

24. The positive electrode plate contains a positive electrode active material, and the positive electrode active material contains one or more of a Prussian blue-based compound, a polyanion-type compound, and a layered oxide. The secondary battery according to claim 21 is characterized by the above.

25. The particle surface of the positive electrode active material has a coating layer, and the coating layer contains one or more of a carbon material, polyaniline, polypyrrole, poly(3,4-ethylenedioxythiophene), aluminum oxide, zinc oxide, titanium oxide, zirconium oxide, magnesium oxide, silicon oxide, lanthanum oxide, sodium fluoride, lithium fluoride, and aluminum fluoride. The secondary battery according to claim 24 is characterized by the above.

26. The thickness of the coating layer is 2 nm - 1000 nm. The secondary battery according to claim 25 is characterized by the above.

27. A power consumption device, characterized by including the secondary battery according to claim 21.

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