Corrosion-resistant positive electrode current collector and preparation method thereof, positive electrode sheet, and zinc ion battery

Abstract

The application relates to the technical field of batteries, in particular to a corrosion-resistant positive electrode current collector, a preparation method thereof, a positive electrode sheet and a zinc ion battery. The positive electrode current collector comprises a current collector body and a protective layer arranged on both sides of the current collector body; the protective layer comprises Ti metal, Ti alloy, Ti oxide, Ti carbide or Ti nitride. The positive electrode current collector of the application solves the problem that an aluminum foil is not resistant to electrolyte corrosion in a water-based battery by performing a protective layer preparation treatment on the surface of the aluminum foil or the composite aluminum foil.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a corrosion-resistant positive electrode current collector and its preparation method, a positive electrode sheet, and a zinc-ion battery. Background Technology

[0002] Lithium-ion batteries, with their high energy density and long cycle life, have become the preferred choice for consumer, power, and energy storage batteries. However, lithium metal resources are scarce and expensive, and lithium is extremely reactive, reacting violently in air and water. For safety, its processing must be carried out in a dry environment. Furthermore, lithium-ion batteries typically use organic solvents as electrolytes, which can easily cause fires or explosions in the event of a collision, leading to safety accidents. Therefore, low-cost and inherently safe aqueous batteries have become the development direction for high-safety batteries. Aqueous batteries typically use salt water as an electrolyte. Compared to batteries with organic electrolytes, aqueous batteries have advantages such as lower cost, no need for a dry environment during manufacturing, environmental friendliness, and high safety; they will never catch fire during use.

[0003] Aluminum foil is generally used as the positive electrode current collector in organic batteries. However, the electrolytes in aqueous batteries are typically acidic or alkaline. Since aluminum foil reacts with acids or alkalis, it can cause the current collector to fail, leading to battery performance degradation. Therefore, aluminum foil, composite aluminum foil, and carbon-coated aluminum foil, commonly used in lithium-ion and sodium-ion batteries, cannot be used in aqueous batteries. Currently, stainless steel foil, stainless steel mesh, titanium foil, titanium mesh, and carbon paper are commonly used as positive electrode current collectors in aqueous batteries. Titanium and stainless steel are inherently expensive, and the processing cost increases with the thickness of the foil as it is manufactured using a rolling process. Currently, the price of mass-producible 10 μm 316L stainless steel foil is 850 yuan / kg, and titanium foil is 12,000 yuan / kg, while aluminum foil of the same thickness costs 40 yuan / kg. It is evident that for the same 10 μm thickness, steel and titanium foil are 21-300 times more expensive than aluminum foil. Furthermore, the processing cost of fabricating steel and titanium materials into mesh-structured current collectors further increases the cost. The high cost of current collectors has significantly increased the price of zinc-ion batteries, a key reason hindering their mass production. Traditional aluminum foil corrodes severely in aqueous zinc-ion batteries, causing the current collector to fail during the first charge and rendering the battery unusable. Carbon-based current collectors, on the other hand, have poor toughness, making them difficult to use in rolls for mass production. They are prone to breakage during coating, rolling, and slitting stages, further preventing large-scale production. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings and defects of the prior art and to provide a corrosion-resistant positive electrode current collector, its preparation method, a positive electrode sheet, and a zinc-ion battery.

[0005] To achieve the above objectives, this application adopts the following solution: A corrosion-resistant positive electrode current collector (hereinafter referred to as positive electrode current collector) includes a current collector body and a protective layer disposed on both sides of the current collector body; the protective layer includes Ti metal, Ti alloy, Ti oxide, Ti carbide or Ti nitride.

[0006] The current collector body is an aluminum foil or a composite aluminum foil; Preferably, the composite aluminum foil includes a polymer layer and aluminum foil disposed on both sides of the polymer layer; preferably, the thickness of the current collector body is 5-40 μm, more preferably 8-20 μm.

[0007] The thickness of the protective layer is 30 nm-5 μm, preferably 40 nm-1 μm; preferably, the protective layer is one layer or multiple layers.

[0008] The protective layer is provided with a carbon coating layer on its outer side; preferably, the thickness of the carbon coating layer is 0.3 μm-10 μm, more preferably 0.5 μm-3 μm.

[0009] The carbon coating layer includes a conductive agent and a binder; Preferably, the conductive agent is one or more of carbon black, graphite, superconducting carbon, acetylene black, Ketjen black, carbon dots, carbon nanotubes, carbon nanofibers, and graphene. Preferably, the adhesive is one or more of polyvinylidene fluoride or its modified adhesive, polyacrylic acid or its modified adhesive, isopropanol, modified acrylic resin, and fluororubber.

[0010] The present invention also includes a method for preparing the positive current collector, comprising the following steps: 1) preparing a protective layer on both sides of the current collector body; optionally, including step 2) setting a carbon coating layer on the surface of the protective layer.

[0011] Step 1) The preparation method is magnetron sputtering or chemical vapor deposition (CVD).

[0012] Step 2) is prepared by: preparing a carbon coating slurry, coating the carbon coating slurry on the outside of the protective layer, and drying the carbon coating layer.

[0013] The present invention also includes a positive electrode sheet, comprising the aforementioned positive current collector and an active material layer disposed on the surface of the positive current collector.

[0014] The present invention also includes a zinc-ion battery comprising the aforementioned positive electrode.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The positive electrode current collector of this invention solves the problem of aluminum foil's poor corrosion resistance by preparing a protective layer on the surface of aluminum foil or composite aluminum foil. Compared with currently used steel foil, steel mesh, titanium foil, titanium mesh, etc., the current collector cost is reduced to 1 / 300-1 / 20, the battery energy density is increased by 3%-5%, the corrosion problem of low-cost aluminum foil used in aqueous batteries is solved, and the mass production process of aqueous batteries is accelerated. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the positive electrode current collector containing only the protective layer of the present invention; Figure 2 This is a schematic diagram of the positive electrode current collector containing a double protective layer according to the present invention. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0018] Comparative Example 1: Using conventional double-sided aluminum foil with a thickness of 10 μm, this material is a commonly used positive electrode current collector.

[0019] Comparative Example 2: Carbon-coated aluminum foil with a thickness of 2+10+2 μm was used. A 10 μm double-sided aluminum foil with a 2 μm thick carbon coating layer was applied to both sides. This material is a commonly used positive electrode current collector to enhance protection performance. Compared with the conventional 1 μm thick carbon coating layer, the carbon coating layer thickness was increased by 2 μm.

[0020] Comparative Example 3: Carbon-coated aluminum foil with a thickness of 5+10+5 μm was used. A carbon coating layer with a thickness of 5 μm was applied to both sides of the aluminum foil. Compared with the conventional carbon coating layer with a thickness of 1 μm, the thickness of the carbon coating layer was increased by 5 μm.

[0021] Comparative Example 4: A composite aluminum foil with a thickness of 1+8+1 μm was used, along with a PET thickness of 8 μm and Al thicknesses of 1 μm on each side. Comparative Example 4 uses a common positive electrode current collector found in organic electrolyte batteries.

[0022] Example 1: Preparation method of corrosion-resistant positive current collector: A Ti layer with a thickness of 40 nm is deposited on both sides of a 10 μm double-sided aluminum foil by magnetron sputtering to obtain an aluminum foil with corrosion resistance, such as... Figure 1 As shown, it includes a current collector body 110 and protective layers 120 disposed on both sides of the current collector; Example 2: The difference between Example 2 and Example 1 is that the preparation method of the positive current collector is different, specifically the thickness of the protective layer is different.

[0023] Preparation method of positive current collector: A Ti layer with a thickness of 500 nm is deposited on both sides of an aluminum foil (10 μm double-bright aluminum foil) by magnetron sputtering to obtain an aluminum foil with corrosion resistance. Example 3: The difference between Example 2 and Example 1 is that the preparation method of the positive current collector is different, specifically the aluminum foil is different.

[0024] Preparation method of positive current collector: A Ti layer with a thickness of 100 nm was deposited on both sides of a 1+8+1 μm composite aluminum foil (the thickness of the polymer layer PET is 8 μm, and there are 1 μm Al foils on both sides of the polymer layer) by magnetron sputtering to obtain a composite aluminum foil with corrosion resistance. The results show that, compared with Example 2, applying the protective layer to the field of composite aluminum foil can also play a role in corrosion prevention.

[0025] Example 4: The difference between Example 4 and Example 1 is that the preparation method of the positive current collector is different, specifically the aluminum foil is different.

[0026] Preparation method of positive current collector: A Ti layer with a thickness of 100 nm was deposited on both sides of a 0.5+8+0.5 μm composite aluminum (the thickness of the polymer layer PET is 8 μm, and there are 0.5 μm Al foils on both sides of the polymer layer) by magnetron sputtering to obtain an aluminum foil with corrosion resistance. The results show that applying the protective layer to the field of ultrathin composite aluminum foil can also play a role in corrosion prevention.

[0027] Example 5: The difference between Example 5 and Example 1 lies in the preparation method of the positive electrode current collector. Specifically, the protective layer material is different.

[0028] Preparation method of positive current collector: A TiO layer with a thickness of 100 nm is deposited on both sides of an aluminum foil (10 μm double-bright aluminum foil) by magnetron sputtering to obtain an aluminum foil with corrosion resistance. Example 6: The difference between Example 6 and Example 1 lies in the preparation method of the positive electrode current collector. Specifically, the protective layer materials are different; the protective layer is a double-layered protective layer made of different materials.

[0029] Preparation method of positive electrode current collector: A Ti layer with a thickness of 500 nm is deposited on both sides of a 10 μm double-sided aluminum foil by magnetron sputtering; a TiO layer with a thickness of 50 nm is deposited on the outer side of the current collector by magnetron sputtering, thus obtaining an aluminum foil with corrosion resistance. Figure 2 It includes a current collector body 110 and protective layers 120 disposed on both sides of the current collector body; the protective layers are two layers, including a first protective layer and a second protective layer 121.

[0030] Example 7: The difference between Example 7 and Example 1 is that the protective layer is different.

[0031] Preparation method of positive current collector: A TiC layer with a thickness of 1 μm is deposited on both sides of an aluminum foil (10 μm double-sided aluminum foil) by chemical vapor deposition (CVD) to obtain an aluminum foil with corrosion resistance.

[0032] Example 8: The difference between Example 8 and Example 1 is that a carbon coating layer is added.

[0033] Preparation method of positive electrode current collector: A Ti layer with a thickness of 40 nm is deposited on both sides of a 10 μm double-sided aluminum foil by magnetron sputtering to obtain an aluminum foil with corrosion resistance; a carbon coating layer with a thickness of 1 μm is prepared on each of the two surfaces of the positive electrode current collector. The carbon coating layer is composed of 30% carbon black, 30% flake graphite and 40% polyacrylic acid.

[0034] The current collector surface of the different embodiments described above is coated with a positive electrode and then assembled with a 10 Ah pouch cell.

[0035] Preparation of the positive electrode: A water-based V2O5 positive electrode slurry for zinc-ion batteries is coated onto the surface of the corrosion-resistant aluminum foil described above. The positive electrode slurry contains 93.1% V2O5 as the main material, 2% conductive carbon black, 1% carbon nanotubes, and 3.9% PVDF as a binder. The areal density of the positive electrode material on both sides is 40 mg / cm³. 2 .

[0036] Compared to Example 1, in Example 8, the adhesion strength of the rolled electrode increased from 300 gf to 480 gf, indicating improved electrode adhesion. Therefore, in some cathode systems with low adhesion, adding a carbon coating layer to the surface of the current collector can significantly improve the adhesion strength of the electrode.

[0037] Battery fabrication: Using the above positive electrode sheet, a Cu foil-plated Zn negative electrode is used, the current collector copper foil thickness is 10 μm, and the Zn plating thickness on both sides is 20 μm. The separator is a 60 μm cellulose composite separator, and the electrolyte is 2M ZnSO4. A 10 Ah soft-pack zinc-ion battery is assembled.

[0038] The above current collectors and their effects on the performance of aqueous zinc-ion batteries are compared, and the results are shown in Table 1 below.

[0039] Table 1

[0040] As shown in the table above, Comparative Example 1 showed no corrosion, exhibited normal battery performance, and had an energy density of 51.77 Wh / kg. Comparative Examples 2, 3, and 4, after battery assembly, failed to charge or discharge. Upon disassembly, corrosion was found in the corresponding positive electrode current collectors. Numerous corrosion pits appeared on the surfaces of the positive electrode active material coated with carbon-coated aluminum foil and composite aluminum foil. Furthermore, the foil tabs at locations without positive electrode material coating were corroded and broken. Therefore, carbon-coated aluminum foil and composite aluminum foil are unsuitable for use in aqueous batteries.

[0041] Compared to Comparative Example 1, Example 1 showed that the areal density of the 10 μm aluminum foil was less than one-third that of the stainless steel foil in Comparative Example 1, resulting in a 4% increase in battery energy density. In Example 2, compared to Comparative Example 1, the areal density of the current collector decreased by 63.64 g / m². 2 The battery energy density increased by 3.7%; compared with Comparative Example 1, the current collector surface density in Example 3 decreased by 71.90 g / m². 2 The battery energy density increased by 4.6%; compared with Comparative Example 1, the current collector surface density in Example 4 decreased by 74.60 g / m². 2 The battery energy density increased by 4.8%; compared with Comparative Example 1, the current collector surface density in Example 5 decreased by 62.79 g / m². 2 The battery energy density increased by 3.9%; compared with Comparative Example 1, the current collector surface density in Example 6 decreased by 59.08 g / m². 2 The battery energy density increased by 3.6%; compared with Comparative Example 1, the current collector surface density in Example 7 decreased by 49.72 g / m². 2 The battery energy density increased by 2.9%; compared with Comparative Example 1, the current collector surface density in Example 8 decreased by 62.64 g / m². 2 The battery energy density was increased by 3.9%. Disassembly of batteries from Examples 1-8 showed no corrosion at the current collector coating location of the positive electrode active material or at the foil tab location, indicating normal battery operation.

[0042] In summary, the positive electrode current collector of this invention solves the problem of aluminum foil's poor corrosion resistance by preparing a protective layer on the surface of aluminum foil or composite aluminum foil. Compared with currently used steel foil, steel mesh, titanium foil, titanium mesh, etc., the current collector cost is reduced by several times to 1 / 300-1 / 20, the battery energy density is increased by 3%-5%, the corrosion problem of low-cost aluminum foil used in aqueous batteries is solved, and the mass production process of aqueous batteries is accelerated.

[0043] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of the equivalents of the claims be included within the invention.

[0044] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A corrosion-resistant positive electrode current collector, characterized in that, It includes a current collector body and protective layers disposed on both sides of the current collector body; the protective layers include Ti metal, Ti alloy, Ti oxide, Ti carbide or Ti nitride.

2. The corrosion-resistant positive electrode current collector according to claim 1, characterized in that, The current collector body is an aluminum foil or a composite aluminum foil; Preferably, the composite aluminum foil includes a polymer layer and aluminum foil disposed on both sides of the polymer layer; preferably, the thickness of the current collector body is 5-40 μm, more preferably 8-20 μm.

3. The corrosion-resistant positive electrode current collector according to claim 1, characterized in that, The thickness of the protective layer is 30 nm-5 μm, preferably 40 nm-1 μm; preferably, the protective layer is one layer or multiple layers.

4. The corrosion-resistant positive electrode current collector according to claim 1, characterized in that, The protective layer is provided with a carbon coating layer on its outer side; preferably, the thickness of the carbon coating layer is 0.3 μm-10 μm, more preferably 0.5 μm-3 μm.

5. The corrosion-resistant positive electrode current collector according to claim 1, characterized in that, The carbon coating layer includes a conductive agent and a binder; preferably, the conductive agent is one or more of carbon black, graphite, superconducting carbon, acetylene black, Ketjen black, carbon dots, carbon nanotubes, carbon nanofibers, and graphene. Preferably, the adhesive is one or more of polyvinylidene fluoride or its modified adhesive, polyacrylic acid or its modified adhesive, isopropanol, modified acrylic resin, and fluororubber.

6. A method for preparing the corrosion-resistant positive electrode current collector according to any one of claims 1-5, characterized in that, The process includes the following steps: 1) preparing a protective layer on both sides of the current collector body; optionally, step 2) setting a carbon coating layer on the surface of the protective layer.

7. The preparation method according to claim 6, characterized in that, Step 1) The preparation method is magnetron sputtering or chemical vapor deposition.

8. The preparation method according to claim 6, characterized in that, Step 2) is prepared by: preparing a carbon coating slurry, coating the carbon coating slurry on the outside of the protective layer, and drying the carbon coating layer.

9. A positive electrode plate, characterized in that, It includes the corrosion-resistant positive electrode current collector as described in any one of claims 1-5 and the active material layer disposed on the surface of the corrosion-resistant positive electrode current collector.

10. A zinc-ion battery, characterized in that, Includes the positive electrode sheet as described in claim 9.

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