A cellulose-based metal current collector and its preparation method and application

Abstract

The present invention provides a cellulose-based metal current collector, a preparation method, and applications thereof, including a cellulose-based single-metal layer current collector, a cellulose-based bimetallic layer current collector, or a cellulose-based inorganic nanoparticle-metal composite layer current collector. The cellulose-based single-metal layer current collector comprises: a cellulose substrate; a single metal layer is attached to both sides of the cellulose substrate; the cellulose-based bimetallic layer current collector comprises: a cellulose substrate; a first metal layer is attached to both sides of the cellulose substrate, and a second metal layer is attached to the first metal layer; the cellulose-based inorganic nanoparticle-metal composite layer current collector comprises: a cellulose substrate; an inorganic nanoparticle-metal composite layer is attached to both sides of the cellulose substrate. The novel lightweight, bendable, and foldable cellulose-based current collector is suitable for lithium-free negative electrode batteries.

Description

Technical Field

[0001] The present invention relates to the technical field of battery material preparation, and in particular to a cellulose-based metal current collector suitable for lithium-free negative electrode batteries, and a preparation method and application thereof. Background Art

[0002] In lithium-free anode batteries, all lithium reserves come from the positive electrode material. During charging, lithium detaches from the positive electrode and is directly electroplated on the current collector in situ. As a key component of lithium-free anode batteries, the current collector has a crucial impact on the battery's electrochemical performance. In existing lithium-free anode batteries, copper foil is typically used as the current collector, but it is heavy and cannot withstand large deformations. In addition, copper foil can easily lead to uneven lithium deposition during charging, accelerating the formation of lithium dendrites and dead lithium, ultimately reducing the life of the lithium-free anode battery. Summary of the Invention

[0003] The present invention aims to provide a cellulose-based metal current collector, a preparation method and application thereof, a lightweight, bendable and foldable new cellulose-based current collector suitable for lithium-free negative electrode batteries.

[0004] The present invention is achieved through the following technical solutions:

[0005] A cellulose-based metal current collector, which is a cellulose-based single-metal layer current collector, a cellulose-based double-metal layer current collector, or a cellulose-based inorganic nanoparticle-metal composite layer current collector;

[0006] The cellulose-based single metal layer current collector comprises: a cellulose substrate; a single metal layer attached to both sides of the cellulose substrate;

[0007] The cellulose-based bimetallic layer current collector comprises a cellulose substrate; a first metal layer is attached to both sides of the cellulose substrate, and a second metal layer is attached to the first metal layer;

[0008] The cellulose-based inorganic nanoparticle-metal composite layer current collector comprises a cellulose substrate; a layer of inorganic nanoparticle-metal composite layer is attached to both sides of the cellulose substrate.

[0009] Preferably, the cellulose substrate is a hydrophilic cellulose-based film or cellulose paper.

[0010] Preferably, the single metal layer is a copper layer, a silver layer, or a copper-zinc composite layer.

[0011] Preferably, the first metal layer is a copper layer, the second metal layer is a silver layer, and the mass of the silver layer accounts for 0.1-10% of the total mass of the copper layer and the silver layer.

[0012] Preferably, the inorganic nanoparticles in the inorganic nanoparticle-metal composite layer are nano-niobium pentoxide, nano-aluminum trioxide, nano-niobium monoxide, nano-zinc oxide or nano-molybdenum disulfide; and the metal is copper.

[0013] Preferably, the thickness of the single metal layer is 1-5 μm, the thickness of the first metal layer is 1-5 μm, and the thickness of the inorganic nanoparticle-metal composite layer is 1-5 μm.

[0014] The preparation method of the cellulose-based metal current collector is one of the following preparation methods:

[0015] (1) The method for preparing the cellulose-based single metal layer current collector comprises:

[0016] The cellulose substrate is immersed in a metal chemical plating solution, taken out, washed, dried, and rolled to obtain a cellulose-based single metal layer current collector;

[0017] (2) The preparation method of the cellulose-based bimetallic layer current collector comprises:

[0018] The cellulose substrate is immersed in a metal chemical plating solution, taken out, washed, and dried to obtain a cellulose-based single metal layer current collector;

[0019] The obtained cellulose-based single metal layer current collector is immersed in a metal chemical plating solution again, and after being taken out, it is washed, dried, and rolled to obtain a cellulose-based double metal layer current collector; wherein the metals in the metal chemical plating solution used twice are different;

[0020] (3) The preparation method of the cellulose-based inorganic nanoparticle-metal composite layer current collector comprises:

[0021] Inorganic nanoparticles are added into a metal chemical plating solution, a cellulose substrate is immersed in the metal chemical plating solution, and after being taken out, washed, dried, and rolled, a cellulose-based inorganic nanoparticle-metal composite layer current collector is obtained.

[0022] Preferably, the cellulose substrate is pre-stretched.

[0023] Furthermore, the cellulose substrate after the stretching treatment is activated using palladium water.

[0024] Application of the cellulose-based metal current collector in lithium-free negative electrode batteries.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention uses cellulose as the substrate, which is light (<2.5mg / cm 2), porosity>50%, flexible (bendable, foldable), good hydrophilicity and low cost. Using it as a substrate to prepare a metal current collector can achieve the purpose of lightweight and flexibility. It is not only used in lithium-free negative electrode batteries, but also has broad application prospects in supercapacitors, other secondary batteries and electromagnetic shielding.

[0027] Furthermore, the invention uses copper as the main conductive metal layer, which can replace commercial copper foil and be directly used as a lithium-ion battery current collector.

[0028] Furthermore, the cellulose-based bimetallic current collector has an inner layer of copper and an outer layer of silver, a lithiophilic metal. Silver, acting as a functional layer to optimize the lithium deposition-stripping overpotential, provides lithium deposition sites during battery charge and discharge, reduces the lithium deposition overpotential, and achieves more uniform lithium deposition. By adjusting the ratio of the lithiophilic material to the copper conductive layer, when applied to lithium-free negative electrode batteries, the lithium metal deposition-stripping overpotential can be reduced without consuming excessive lithium from the positive electrode material.

[0029] Furthermore, the cellulose-based inorganic nanoparticle-metal composite layer current collector uses a lithiophilic metal compound as a functional layer for optimizing the lithium deposition-stripping overpotential, providing directional and diversified lithium deposition-stripping sites, which is beneficial to reducing the lithium deposition overpotential so as to be combined with different types of lithium-ion battery electrolytes to prepare high-performance lithium-free negative electrode batteries. The surface structure of the current collector prepared by changing the metal particles on the composite layer is changed to make it suitable for lithium-free negative electrode batteries and improve the uniformity of lithium deposition.

[0030] The present invention prepares cellulose-based current collectors with different lithium-affinity surfaces through the technical methods of chemical plating, chemical composite plating and inorganic particle mixed plating. The larger pores in the cellulose substrate improve the smooth discharge of bubbles during the chemical plating process, making the chemical plating layer uniform.

[0031] Furthermore, the porosity of the cellulose substrate is improved by longitudinal and transverse physical stretching, so that the cellulose substrate can be well extended in the plating solution. The operation is simple and the success rate is high, and the plating layers on the front and back of the cellulose substrate can be through and uniform.

[0032] Furthermore, the colloidal palladium particles are uniformly adsorbed in the pores of the cellulose substrate through palladium water activation, so that the metal particles are uniformly plated and have good stability in the subsequent chemical plating process. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic structural diagram of the first type of cellulose-based single metal layer current collector proposed in the present invention;

[0034] Figure 2 This is a schematic structural diagram of the second type of cellulose-based bimetallic layer current collector proposed in the present invention;

[0035] Figure 3 This is a schematic structural diagram of the third type of cellulose-based chemically plated inorganic nanoparticle-metal mixed chemically plated current collector proposed in the present invention;

[0036] Figure 4 Comparison of the quality of the single metal layer current collectors prepared in Examples 1-4 and conventional copper foil current collectors; (a) is a commercial copper foil current collector; (b) is a cellulose-based film chemically plated copper single metal layer current collector of Example 1; (c) is a cellulose-based film chemically plated silver single metal layer current collector of Example 2; (d) is a cellulose paper-based chemically plated copper single metal layer current collector of Example 3; (e) is a cellulose paper-based chemically plated silver single metal layer current collector of Example 4;

[0037] Figure 5 Digital photos of the second type of novel cellulose-based metal current collectors prepared in Examples 3, 6, 7, 8, and 9, respectively; (a) is the cellulose paper-based chemically plated copper single metal layer current collector of Example 3; (b) is the cellulose paper-based chemically plated copper-silver bimetallic layer current collector of Example 6; (c) is the cellulose paper-based chemically plated zinc oxide particles-copper composite layer current collector of Example 7; (d) is the cellulose paper-based chemically plated niobium oxide particles-copper composite layer current collector of Example 8; (e) is the cellulose paper-based chemically plated molybdenum disulfide particles-copper composite layer current collector of Example 9;

[0038] Figure 6 This is a thickness diagram of the cellulose-based chemically plated copper-silver bimetallic layer current collector prepared in Example 6;

[0039] Figure 7 Lithium deposition curves of commercial copper foil and cellulose-based current collectors prepared in Examples 3, 4, 6, 7, 8 and 10; (a) is the cellulose paper-based chemically plated silver single metal layer current collector of Example 4; (b) is the cellulose paper-based chemically plated copper single metal layer current collector of Example 3; (c) is the cellulose paper-based chemically plated copper-silver bimetallic layer current collector of Example 6; (d) is the cellulose paper-based chemically plated zinc oxide particles-copper composite layer current collector of Example 7; (e) is the cellulose paper-based chemically plated niobium oxide particles-copper composite layer current collector of Example 8; (f) is the cellulose paper-based chemically plated molybdenum disulfide particles-copper composite layer current collector of Example 9; (g) is commercial copper foil.

[0040] In the figure: 1 is a cellulose substrate; 2 is a single metal layer; 3 is a first metal layer; 4 is a second metal layer; 5 is an inorganic nanoparticle-metal composite layer. DETAILED DESCRIPTION

[0041] In order to further understand the present invention, the present invention is described below in conjunction with embodiments. These descriptions are only for further explaining the features and advantages of the present invention and are not intended to limit the claims of the present invention.

[0042] The present invention provides a cellulose-based metal current collector suitable for lithium-free negative electrode batteries. It uses a renewable, easily degradable, light, thin and flexible cellulose substrate, and symmetrically coats a metal layer or a double layer of different metal layers, an inorganic nanoparticle-metal composite layer on its surface using chemical plating, chemical composite plating and inorganic particle mixed plating technology. The porosity of the cellulose substrate is increased by a physical stretching method, and the cellulose substrate is well extended in the plating solution to adapt to the subsequent continuous chemical plating process. By regulating time and temperature to control the thickness of the coating, three types of new cellulose-based metal current collectors are obtained. Among them, the first type is a cellulose-based single metal layer current collector, such as Figure 1 As shown, the cellulose-based single metal layer current collector consists of a cellulose substrate 1 and a single metal layer 2. The cellulose substrate is a hydrophilic cellulose-based film or cellulose paper. The single metal layer is on the surface of the hydrophilic cellulose-based film or cellulose paper and runs through it from top to bottom. The second type is a cellulose-based double metal layer current collector, such as Figure 2 As shown, the cellulose-based bimetallic layer current collector consists of a cellulose substrate 1, a first metal layer 3, and a second metal layer 4. The cellulose substrate is a hydrophilic cellulose-based film or cellulose paper. The first metal layer is located on the surface of the cellulose paper, and the second metal layer is located on the surface of the first metal layer. The third type is a cellulose-based inorganic nanoparticle-metal composite layer current collector, such as Figure 3 As shown, the cellulose-based inorganic nanoparticle-metal composite layer current collector includes a cellulose substrate 1 and an inorganic nanoparticle-metal composite layer 5. The cellulose substrate is a hydrophilic cellulose-based film or cellulose paper. The inorganic nanoparticle-metal composite layer is located on the surface of the cellulose paper and runs through it from top to bottom.

[0043] The preparation methods of three types of inorganic nanoparticles-metal are described below.

[0044] (1) The preparation method of the cellulose-based single metal layer current collector is as follows:

[0045] Step 1, physically stretching the cellulose substrate so that the cellulose substrate can extend well in the plating solution;

[0046] Step 2, palladium water activation of the cellulose substrate;

[0047] Step 3, immersing the cellulose substrate activated with palladium water into a metal chemical plating solution, taking it out, washing it, and drying it to obtain a cellulose-based single metal layer current collector;

[0048] Step 4: further rolling the obtained cellulose-based single metal layer current collector.

[0049] In step 1, the cellulose substrate includes a hydrophilic cellulose-based membrane and cellulose paper, wherein the hydrophilic cellulose-based membrane has a thickness of 9 to 20 μm, a porosity of more than 50%, and a pore size of 0.2 to 25 μm; the cellulose paper has a thickness of 25 to 100 μm, a porosity of more than 60%, and a pore size of 20 to 200 μm; and physical stretching includes longitudinal stretching and transverse stretching. Depending on the type of cellulose substrate material, the transverse and longitudinal stretching rates of the hydrophilic cellulose-based membrane are 1% to 8%, and the transverse and longitudinal stretching rates of the cellulose paper are 1% to 5%.

[0050] In step 2, the palladium content in the palladium water is 1-5 g / L.

[0051] In the step 3, the metal chemical plating solution is a chemical copper plating solution or a chemical silver plating solution or a chemical copper-zinc composite solution. The reaction temperature of the chemical copper plating solution is 30-60°C, the reaction time is 1-5min, the copper ion concentration is 1-5g / L, and the plating rate is about 2um / min. The reaction temperature of the chemical silver plating solution is 15-30°C, the reaction time is 1-5min, the silver ion concentration is 0.05-2g / L, and the plating rate is about 1μm / min. The reaction temperature of the chemical copper-zinc composite solution is 30-60°C, the reaction time is 1-5min, and the ratio of copper and zinc ions is 100:(0.05-3). The thickness of the single metal layer in the obtained cellulose-based single metal layer current collector is 1-5μm.

[0052] In step 4, the rolling speed is 50-300 r / min, the rolling thickness is 10-25 μm, and the overall thickness of the cellulose-based single metal layer current collector after rolling is 10-25 μm.

[0053] (2) Cellulose-based bimetallic layer current collector

[0054] Step 1, physically stretching the cellulose substrate so that the cellulose substrate can extend well in the plating solution;

[0055] Step 2, palladium water activation of the cellulose substrate;

[0056] Step 3, immersing the cellulose substrate activated with palladium water into a metal chemical plating solution, taking it out, washing it, and drying it to obtain a cellulose-based single metal layer current collector;

[0057] Step 4, immersing the cellulose-based single metal layer current collector obtained in step 3 into the metal chemical plating solution again, taking it out, washing it, and drying it to obtain a cellulose-based double metal layer current collector;

[0058] Step 5: further rolling the obtained cellulose-based bimetallic layer current collector.

[0059] In step 1, the cellulose substrates are a hydrophilic cellulose-based membrane and cellulose paper, wherein the hydrophilic cellulose membrane has a thickness of 9 to 20 μm, a porosity of 50% or greater, and a pore size of 0.2 to 25 μm; and the cellulose paper has a thickness of 60 to 100 μm, a porosity of 60% or greater, and a pore size of 20 to 200 μm. Physical stretching includes longitudinal stretching and transverse stretching. Depending on the type of cellulose substrate, the transverse and longitudinal stretching rates of the hydrophilic cellulose-based membrane and the transverse and longitudinal stretching rates of the cellulose paper are 1% to 10%, and 1% to 5%.

[0060] In step 2, the palladium content in the palladium water is 1-5 g / L.

[0061] In step 3, the metal electroless plating solution is an electroless copper plating solution. The reaction temperature of the electroless copper plating solution is 30-60°C, the reaction time is 1-5 minutes, the copper ion concentration is 1-5g / L, and the plating rate is about 2μm / min. The resulting copper plating layer has a thickness of 1-5μm.

[0062] In step 4, the metal electroless plating solution is a chemical silver plating solution. The reaction temperature of the chemical silver plating solution is 15-30°C, the reaction time is 30 seconds to 5 minutes, and the silver ion concentration of the plating solution is 0.05-2 g / L. The first metal layer on the outer side of the cellulose substrate is a copper metal layer, and the second metal layer is a silver metal layer. The silver content of the bimetallic layer (copper and silver) is 0.1-10%.

[0063] In step 5, the rolling speed is 50-300 r / min, the rolling thickness is 10-25 μm, and the thickness of the cellulose-based bimetallic layer current collector after rolling is 10-25 μm.

[0064] (3) Cellulose-based inorganic nanoparticle-metal composite layer current collector

[0065] Step 1, physically stretching the cellulose substrate so that the cellulose substrate can be well extended in the plating solution;

[0066] Step 2, palladium water activation of the cellulose substrate;

[0067] Step 3, adding inorganic nanoparticles to a metal chemical plating solution, performing inorganic particle mixed plating on the cellulose substrate, washing, and drying to obtain a cellulose-based inorganic nanoparticle-metal composite layer current collector on a mixed metal surface;

[0068] Step 4: further rolling the obtained cellulose-based inorganic nanoparticle-metal composite layer current collector.

[0069] In the step 1, the cellulose substrate includes a hydrophilic cellulose-based membrane and cellulose paper, wherein the hydrophilic cellulose-based membrane has a thickness of 9 to 20 μm, a porosity of more than 50%, and a pore size of 0.2 to 25 μm; the cellulose paper has a thickness of 60 to 100 μm, a porosity of more than 60%, and a pore size of 20 to 200 μm; in the step 1, the physical stretching includes longitudinal stretching and transverse stretching, and according to different types of cellulose substrates, the transverse and longitudinal stretching rates of the hydrophilic cellulose-based membrane are 1% to 10%, and the transverse and longitudinal stretching rates of the cellulose paper are 1% to 5%.

[0070] In step 2, the palladium content in the palladium water is 1-5 g / L.

[0071] In step 3, the inorganic nanoparticles include one of the following: nano-niobium pentoxide, nano-aluminum trioxide, nano-niobium monoxide, nano-zinc oxide, nano-molybdenum disulfide, and other lithiophilic metal compounds, with a particle size of 10 nm to 1 μm. The inorganic nanoparticles are preferably nano-niobium pentoxide or nano-molybdenum disulfide. The metal electroless plating solution is an electroless copper plating solution; the molar ratio of copper in the electroless copper plating solution to metal atoms in the added inorganic nanoparticles is 100:(0.05-3). The reaction temperature of the electroless copper plating solution is 30-60°C, the reaction time is 1-5 minutes, and the copper ion concentration is 1-5 g / L. The resulting inorganic nanoparticle-metal composite layer has a thickness of 1-5 μm.

[0072] In the step 4, the thickness of the cellulose-based inorganic nanoparticle-metal composite layer current collector after rolling is 10-25 μm.

[0073] The invention selects different cellulose-based materials, such as hydrophilic cellulose membranes and paper, and regulates the chemical plating time and reaction temperature to obtain an ideal metal layer thickness (1-5 μm) and a lower current collector surface density (2.5-3.5 mg / cm 2 ), so that the cellulose metal composite film has excellent conductivity and good mechanical properties, which can meet the market needs of flexible electronic devices.

[0074] Example 1

[0075] Step 1: Taking a commercial hydrophilic cellulose-based membrane with a porosity of 60%-70% and a thickness of about 9 μm, physically stretching the membrane by 10% in the transverse and longitudinal directions to further increase the porosity of the membrane, and then fixing the membrane so that the membrane can be well extended in the chemical plating solution;

[0076] Step 2: prepare a palladium water activation solution with a palladium content of 2.5 g / L, immerse the stretched hydrophilic cellulose-based membrane in the activation solution, and soak it at room temperature for 10 minutes to obtain an activated hydrophilic cellulose-based membrane, which is then rinsed with deionized water and set aside for use;

[0077] Step 3: Immerse the activated hydrophilic cellulose-based film in a 55°C chemical copper plating solution, continuously aerating the solution to expel bubbles on the surface of the hydrophilic cellulose-based film and maintain uniform plating on both sides; remove the film after about 2 minutes, rinse it with deionized water three times, and then air-dry it at 80°C to obtain a non-rolled cellulose-based film chemical copper-plated single metal layer current collector;

[0078] Step 4: Roll the material obtained in step 3 using a roller press. The speed is adjusted to 120 r / min, the rolling thickness is adjusted to 10 μm, and the material is rolled to obtain a cellulose-based film chemically plated copper single metal layer current collector with a uniform thickness of 10±0.5 μm.

[0079] Example 2

[0080] Step 1: Taking a commercial hydrophilic cellulose-based membrane with a porosity of 60%-70% and a thickness of about 9 μm, physically stretching the membrane by 10% in the transverse and longitudinal directions to further increase the porosity of the membrane, and then fixing the membrane so that the membrane can be well extended in the chemical plating solution;

[0081] Step 2: prepare a palladium water activation solution with a palladium content of 3 g / L, immerse the stretched hydrophilic cellulose-based membrane in the activation solution, and soak it at room temperature for 10 minutes to obtain an activated hydrophilic cellulose-based membrane, which is then rinsed with deionized water and set aside for use;

[0082] Step 3, immersing the activated hydrophilic cellulose-based film in a 20° C. chemical silver plating solution, taking it out after about 2 minutes, washing it with deionized water three times, and then drying it with air at 80° C. to obtain an unrolled cellulose-based film chemical silver-plated single metal layer current collector;

[0083] Step 4: Roll the material obtained in step 3 using a roller press. The speed is adjusted to 120 r / min, the rolling thickness is adjusted to 10 μm, and the material is rolled to obtain a cellulose-based film chemically silver-plated single metal layer current collector with a uniform thickness of 10±0.5 μm.

[0084] Example 3

[0085] Step 1: Take commercial cellulose paper (dust-free paper, wet strength >50%) with a porosity of 70%, a pore size of about 20-200 μm, and a thickness of about 80 μm, and physically stretch the paper by 5% in the transverse and longitudinal directions to further increase the pores of the paper, and then fix it so that the cellulose paper can extend well in the chemical plating solution;

[0086] Step 2: preparing a palladium water activation solution with a palladium content of 3 g / L, immersing the stretched cellulose paper in the activation solution, and soaking the cellulose paper at room temperature for 10 minutes to obtain the activated cellulose paper, which is then washed with deionized water and set aside for use;

[0087] Step 3: Immerse the activated cellulose paper in a 55°C chemical copper plating solution, continuously aerating the solution to expel bubbles from the surface of the cellulose paper and maintain uniform plating on both sides. After approximately 2 minutes, remove the paper and rinse it with deionized water three times, followed by air drying at 80°C to obtain an unrolled cellulose paper-based chemical copper-plated single metal layer current collector.

[0088] Step 4: Roll the material obtained in step 3 using a roller press. The speed is adjusted to 120 r / min, the rolling thickness is adjusted to 15 μm, and the material is rolled to obtain a cellulose paper-based chemical copper-plated single metal layer current collector with a uniform thickness of 15±0.5 μm.

[0089] Example 4

[0090] Step 1: Take commercial cellulose paper (dust-free paper, wet strength >50%) with a porosity of 70%, a pore size of about 20-200 μm, and a thickness of about 80 μm, and physically stretch the paper by 5% in the transverse and longitudinal directions to further increase the pores of the paper, and then fix it so that the cellulose paper can extend well in the chemical plating solution;

[0091] Step 2: preparing a palladium water activation solution with a palladium content of 3 g / L, immersing the stretched cellulose paper in the activation solution, and soaking the cellulose paper at room temperature for 10 minutes to obtain the activated cellulose paper, which is then washed with deionized water and set aside for use;

[0092] Step 3: immersing the activated cellulose paper in a 20° C. chemical silver plating solution, taking it out after about 2 minutes, washing it with deionized water three times, and then drying it with air at 80° C. to obtain an unrolled cellulose paper-based chemical silver-plated single metal layer current collector;

[0093] Step 4: Roll the material obtained in step 3 using a roller press. The speed is adjusted to 120 r / min, the rolling thickness is adjusted to 15 μm, and the material is rolled to obtain a cellulose-based chemical silver-plated single metal layer current collector with a uniform thickness of 15±0.5 μm.

[0094] Example 5

[0095] Step 1: Take commercial cellulose paper (dust-free paper, wet strength >50%) with a porosity of 70%, a pore size of about 20-200 μm, and a thickness of about 80 μm, and physically stretch the paper by 5% in the transverse and longitudinal directions to further increase the pores of the paper, and then fix it so that the cellulose paper can extend well in the chemical plating solution;

[0096] Step 2: preparing a palladium water activation solution with a palladium content of 2.5 g / L, immersing the stretched cellulose paper in the activation solution, and soaking the cellulose paper at room temperature for 10 minutes to obtain the activated cellulose paper, which is then washed with deionized water and set aside for use;

[0097] Step 3, immersing the activated cellulose paper in a 55°C chemical copper-zinc composite plating solution. During the chemical plating process, air is continuously blown to expel bubbles on the surface of the cellulose paper and maintain uniform plating on both sides. After about 2 minutes, the paper is taken out, washed with deionized water three times, and then dried at 80°C to obtain an unrolled cellulose paper-based chemical copper-zinc composite metal layer current collector. The ion ratio of copper to zinc in the chemical copper-zinc composite plating solution used is 100:1. Using a small amount of metal zinc composite can enhance the lithium affinity of the surface of the obtained material, which is beneficial to the uniform deposition of lithium during the charge and discharge cycle of the battery.

[0098] Step 4: Roll the material obtained in step 3 using a roller press. The speed is adjusted to 120 r / min, the rolling thickness is adjusted to 15 μm, and the material is rolled to obtain a cellulose-based chemically plated copper-zinc composite metal layer current collector with a uniform thickness of 15±0.5 μm.

[0099] Example 6

[0100] Steps 1 and 2 are the same as steps 1 and 2 in Example 3 or 4;

[0101] Step 3: Immerse the activated cellulose paper in a 55°C chemical copper plating solution, continuously aerating the solution to expel bubbles from the surface of the cellulose paper and maintain uniform plating on both sides. After about 2 minutes, remove the paper, rinse it with deionized water three times, and then air dry it at 80°C to obtain a cellulose paper-based copper single metal layer current collector.

[0102] Step 4: Prepare a chemical silver plating solution, quickly immerse the cellulose paper-based copper single metal layer current collector in the chemical silver plating solution, remove it after about 5 seconds, rinse it with deionized water three times, and then transfer it to a blast drying oven for drying at a temperature of 50° C. for 6 hours, wherein the silver plating layer has a thickness of 1 μm and a mass of 5% of the total mass of the copper layer and the silver layer;

[0103] Step 5 is the same as step 4 in Example 3 or 4.

[0104] Example 7

[0105] Steps 1 and 2 are the same as steps 1 and 2 in Example 3 or 4;

[0106] Step 3: Add nano zinc oxide particles to the chemical copper plating solution under uniform stirring, disperse and mix evenly by ultrasonication to obtain a mixed plating solution; then add the activated cellulose paper, take it out after about 2 minutes, wash it with deionized water 3 times, and transfer it to a blast drying oven for drying at a drying temperature of 50°C and a drying time of 6 hours; wherein the molar ratio of copper to zinc in the mixed plating solution is 100:1.

[0107] Step 4 is the same as step 4 in Example 2.

[0108] Example 8

[0109] Steps 1 and 2 are the same as steps 1 and 2 in Example 3 or 4;

[0110] Step 3: Add nano-niobium pentoxide particles to the chemical copper plating solution under uniform stirring, disperse and mix uniformly by ultrasonication to obtain a mixed plating solution; then add the activated cellulose paper, take it out after about 2 minutes, wash it with deionized water three times, and transfer it to a blast drying oven for drying at a drying temperature of 50° C. and a drying time of 6 hours; wherein the molar ratio of copper to niobium in the mixed plating solution is 100:0.1.

[0111] Step 4 is the same as step 4 in Example 2.

[0112] Example 9

[0113] Steps 1 and 2 are the same as steps 1 and 2 in Example 3 or 4;

[0114] Step 3: Add nano-molybdenum disulfide particles to the chemical copper plating solution under uniform stirring, disperse and mix evenly by ultrasonication to obtain a mixed plating solution; then add the activated cellulose paper, take it out after about 2 minutes, wash it with deionized water 3 times, and transfer it to a blast drying oven for drying at a drying temperature of 50°C and a drying time of 6 hours; wherein the molar ratio of copper to molybdenum in the mixed plating solution is 100:1.

[0115] Step 4 is the same as step 4 in Example 2.

[0116] Example 10

[0117] Steps 1 and 2 are the same as steps 1 and 2 in Example 3 or 4;

[0118] Step 3: Add nano-molybdenum disulfide particles to the chemical copper plating solution under uniform stirring, disperse and mix evenly by ultrasonication to obtain a mixed plating solution; then add activated commercial cellulose paper, take it out after about 2 minutes, wash it with deionized water three times, and transfer it to a blast drying oven for drying at a drying temperature of 50°C and a drying time of 6 hours; wherein the molar ratio of copper to molybdenum in the chemical plating solution is 100:0.1.

[0119] Step 4 is the same as step 4 in Example 2.

[0120] Example 11

[0121] Steps 1 and 2 are the same as steps 1 and 2 in Example 3 or 4;

[0122] Step 3: Add nano-niobium pentoxide particles to the chemical nickel plating solution under uniform stirring, disperse and mix uniformly by ultrasonication to obtain a mixed plating solution; then add the activated cellulose paper, take it out after about 2 minutes, wash it with deionized water three times, and transfer it to a blast drying oven for drying at a drying temperature of 50° C. and a drying time of 6 hours; wherein the molar ratio of nickel to niobium in the mixed plating solution is 100:0.1.

[0123] Step 4 is the same as step 4 in Example 2.

[0124] Figure 4 The quality comparison of the single metal layer current collector prepared in Examples 1-4 and the traditional copper foil current collector is shown in Figure 1. (a) is a commercial copper foil current collector; (b) is a cellulose-based film chemically copper-plated single metal layer current collector of Example 1; (c) is a cellulose-based film chemically silver-plated single metal layer current collector of Example 2; (d) is a cellulose paper-based chemically copper-plated single metal layer current collector of Example 3; (e) is a cellulose paper-based chemically silver-plated single metal layer current collector of Example 4. The diameter of the cut disc is 12 mm. The calculated surface density of the commercial copper foil and the current collector prepared by the present invention when the thickness is the same is about 12-15 mg / cm 2 , and the surface density of the single metal layer current collector of the present invention is about 2-5 mg / cm 2 .

[0125] Figure 5 These are digital photos of the second type of novel cellulose-based metal current collectors prepared in Examples 3, 6, 7, 8, and 9 respectively; (a) is the cellulose paper-based chemically plated copper single metal layer current collector in Example 3; (b) is the cellulose paper-based chemically plated copper-silver double metal layer current collector in Example 6; (c) is the cellulose paper-based chemically plated zinc oxide particles-copper composite layer current collector in Example 7; (d) is the cellulose paper-based chemically plated niobium oxide particles-copper composite layer current collector in Example 8; (e) is the cellulose paper-based chemically plated molybdenum disulfide particles-copper composite layer current collector in Example 9. Figure 5 It can be seen that the second type of novel cellulose-based metal current collectors prepared in Examples 3, 6, 7, 8, and 9 have good flexibility.

[0126] Figure 6 This graph shows the thickness of the paper-based electroless copper-silver bimetallic current collector prepared in Example 6, showing a sample thickness of 15 μm. The silver content of the paper-based electroless copper-silver bimetallic current collector can be controlled to 0.5-5% by adjusting the electroless plating time and temperature. As a lithiophilic material, this current collector can guide the uniform deposition of lithium during the charging process of lithium-free negative electrode batteries. Furthermore, because the amount of silver plated can be controlled, excessive alloying reactions between lithium and silver can be avoided, which could lead to excessive lithium consumption.

[0127] Figure 7The lithium deposition curves of commercial copper foil and cellulose-based current collectors prepared in Examples 3, 4, 6, 7, 8 and 10 are shown; it can be seen that, compared with copper foil, each example significantly reduces the overpotential of lithium deposition. The cellulose paper-based chemically plated copper-silver bimetallic layer current collector prepared in Example 6 has an outermost layer of chemically plated silver and an inner layer close to the paper is a chemically plated copper layer. In the lithium-free negative electrode battery assembled with this current collector material, a small amount of silver plating on the outer layer acts as a lithium-philic material, providing lithium deposition sites during the battery charge and discharge process, and the overpotential drops by an average of 0.1V, making the lithium deposition more uniform. Figure 7 It can be seen from Example 3 that the overpotential of the lithium-free negative electrode battery assembled with a cellulose paper-based chemically plated copper single metal layer current collector is relatively high, while in Examples 7, 8 and 10, the overpotential is significantly reduced. It can be seen that the cellulose-based materials plated with different lithium-philic inorganic materials and metallic copper composites have the effect of reducing the overpotential of the battery.

[0128] In Examples 7-10, lithiophilic inorganic metal compound particles are added to a conventional electroless plating solution and co-deposited with copper to form a mixed particle-metal layer surface. While the metal layer (copper) provides excellent conductivity, the lithiophilic particles provide preferred sites for lithium deposition, which helps reduce the lithium deposition overpotential. It should be noted that lithiophilic metal compounds of different types and sizes can form SEI (Solid Electrolyte Interface) films of varying compositions when depositing lithium in a given electrolyte. Because the formation of the SEI requires the consumption of a certain lithium source, the lithium consumption of different metal compound-copper composite layers corresponding to the formation of different SEI films also varies. Electrochemical charge-discharge testing can be used to screen metal systems that consume less lithium and facilitate uniform lithium deposition and stripping, thereby fully utilizing the lithium source in the positive electrode of a lithium-free negative electrode battery. In the present invention, niobium oxides and molybdenum disulfide are specifically selected, which are both compatible with the electroless plating process and can reduce the lithium deposition overpotential without consuming too much lithium source in the positive electrode of a lithium-free negative electrode battery.

[0129] The technical means disclosed in the solutions of the present invention are not limited to those disclosed in the above-mentioned embodiments, but also include technical solutions composed of any combination of the above-mentioned technical features. It should be noted that those skilled in the art may make various improvements and modifications without departing from the principles of the present invention, and such improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A cellulose-based metal current collector, characterized in that: It is a cellulose-based inorganic nanoparticle-metal composite layer current collector; The cellulose-based inorganic nanoparticle-metal composite layer current collector comprises a cellulose substrate; a layer of inorganic nanoparticle-metal composite layer is attached to both sides of the cellulose substrate; the inorganic nanoparticles in the inorganic nanoparticle-metal composite layer are nano-niobium pentoxide, nano-niobium monoxide or nano-molybdenum disulfide, and the metal is copper; The method for preparing the cellulose-based metal current collector comprises: Inorganic nanoparticles are added to a metal chemical plating solution, and a cellulose substrate is immersed in the metal chemical plating solution. The substrate is taken out, washed, dried, and rolled to obtain a cellulose-based inorganic nanoparticle-metal composite layer current collector; the cellulose substrate is pre-stretched, and the stretched cellulose substrate is activated with palladium water; wherein the metal chemical plating solution is a chemical copper plating solution; and the molar ratio of copper in the chemical copper plating solution to metal atoms in the added inorganic nanoparticles is 100:(0.05-3).

2. The cellulose-based metal current collector according to claim 1, characterized in that The cellulose substrate is a hydrophilic cellulose-based film or cellulose paper.

3. The cellulose-based metal current collector according to claim 1, wherein The thickness of the inorganic nanoparticle-metal composite layer is 1-5 μm.

4. The method for preparing the cellulose-based metal current collector according to any one of claims 1 to 3, characterized in that: include: Inorganic nanoparticles are added to a metal chemical plating solution, and a cellulose substrate is immersed in the metal chemical plating solution. After being taken out, it is washed, dried, and rolled to obtain a cellulose-based inorganic nanoparticle-metal composite layer current collector; the cellulose substrate is pre-stretched, and the stretched cellulose substrate is activated using palladium water.

5. Use of the cellulose-based metal current collector according to any one of claims 1 to 3 in a lithium-free negative electrode battery.

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