Composite cellulose battery diaphragm as well as preparation method and application thereof

Abstract

The invention discloses a composite cellulose battery diaphragm as well as a preparation method and application thereof, and relates to the technical field of batteries. The preparation method of the composite cellulose battery diaphragm comprises the following steps: mixing carboxylated sisal fibers, sulfonated cotton fibers and water, putting the mixture into a film mold, and drying to obtain a primary composite fiber membrane; and placing the primary composite fiber membrane in a solution containing a cross-linking agent, and soaking for a preset time to obtain the composite cellulose battery diaphragm. The preparation method provided by the invention is simple, the adopted raw materials are wide in source, pollution-free to the environment and suitable for industrial large-scale production, and the prepared composite cellulose battery diaphragm has excellent mechanical property and acid and alkali corrosion resistance, is not easy to generate water-induced swelling deformation, and can accelerate Zn < 2 + > transmission and inhibit zinc dendrite growth on the surface of a zinc electrode.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a composite cellulose battery separator and a preparation method and application thereof. Background Art

[0002] The development of efficient, clean, and renewable energy systems has made significant progress in recent years. However, surface renewable energy sources such as solar, wind, and tidal energy generally have inherent intermittent characteristics, and there is an urgent need to develop efficient energy storage systems to achieve spatiotemporal energy allocation. Since the commercialization of lithium-ion batteries, this system has long dominated the energy storage market, but its inherent safety hazards, high costs, and lithium resource scarcity pose a continuous challenge to sustainable development. In this context, aqueous zinc-ion batteries, which combine high safety, environmental friendliness, easy processing, and the abundance of zinc resources, have shown potential to become the next generation of energy storage devices. However, this system still faces multiple technical bottlenecks, such as uncontrollable growth of zinc dendrites, electrode dissolution, interfacial side reactions, insufficient electrolyte / diaphragm ion transport efficiency, and poor mechanical adaptability of the diaphragm. Among them, the regulation of zinc electrode interface stability has become a key scientific issue.

[0003] To solve these problems, people have explored various strategies, including optimizing electrode structure, designing electrolyte formulation, using solid electrolyte and modifying separator. Among these methods, developing functional separator is a simple and effective method, but it is difficult to combine high mechanical strength, flexibility, acid-base stability, excellent ion transport and interface regulation. Therefore, it is necessary to develop a separator that can inhibit dendrites, passivate corrosion and block fast Zn 2+ A multifunctional membrane system for transport to promote the engineering application of aqueous zinc-ion batteries. Summary of the Invention

[0004] Based on the above-mentioned deficiencies in the prior art, the present invention aims to provide a composite cellulose battery separator and its preparation method and application, aiming to solve the problem that the existing aqueous zinc ion battery separator cannot simultaneously inhibit dendrites, corrosion passivation blocking and accelerate Zn 2+ Transfer function problem.

[0005] The technical solutions of the present invention are as follows: A first aspect of the present invention provides a method for preparing a composite cellulose battery separator, comprising the following steps: Carboxylated sisal fiber, sulfonated cotton fiber and water are mixed, placed in a film mold, and dried to obtain a primary composite fiber membrane; The primary composite fiber membrane is placed in a solution containing a cross-linking agent and soaked for a preset time to obtain the composite cellulose battery separator.

[0006] Optionally, the mass ratio of the carboxylated sisal fiber to the sulfonated cotton fiber is (10-1): (1-5).

[0007] Optionally, the cross-linking agent includes at least one of citric acid, malic acid, tartaric acid, oxalic acid, succinic acid and fumaric acid.

[0008] Optionally, in the solution containing the cross-linking agent, the mass percentage of the cross-linking agent is 1% to 20%.

[0009] Optionally, the preset time is 1 to 60 minutes.

[0010] Optionally, the step of mixing the carboxylated sisal fiber, the sulfonated cotton fiber and water specifically comprises: mixing a carboxylated sisal fiber aqueous dispersion and a sulfonated cotton fiber aqueous dispersion; Wherein, the mass content of the carboxylated sisal fiber in the carboxylated sisal fiber aqueous dispersion is 0.5% to 5%; the mass content of the sulfonated cotton fiber in the sulfonated cotton fiber aqueous dispersion is 1% to 10%.

[0011] Optionally, the method for preparing the carboxylated sisal fiber aqueous dispersion comprises the following steps: The sisal fiber is subjected to alkali boiling, bleaching, and carboxyl grafting to obtain carboxylated sisal fiber; The carboxylated sisal fibers are added into water, and mechanically crushed and dispersed to obtain the carboxylated sisal fiber aqueous dispersion.

[0012] A second aspect of the present invention provides a composite cellulose battery separator, which is prepared using the preparation method of the present invention as described above.

[0013] The third aspect of the present invention provides a use of the composite cellulose battery separator as described above in an aqueous zinc ion battery.

[0014] In a fourth aspect, the present invention provides an aqueous zinc ion battery, comprising a positive electrode, a negative electrode, and a separator located between the positive electrode and the negative electrode, wherein the separator comprises the composite cellulose battery separator of the present invention as described above.

[0015] Beneficial Effects: This invention constructs a primary composite cellulose membrane through self-assembly of carboxylated sisal fibers and sulfonated cotton fibers. This membrane is then chemically crosslinked with a crosslinker to produce a bio-based composite cellulose battery separator suitable for aqueous zinc-ion batteries. This invention employs a double crosslinking strategy to form a dense chemical crosslinking network, enhancing the intermolecular forces of the cellulose molecules and effectively inhibiting deformation of the cellulose membrane due to water-induced swelling.

[0016] In addition, the molecular chains of carboxylated sisal fiber and sulfonated cotton fiber contain a large number of hydrophilic and zinc-philic groups. Therefore, the composite cellulose battery separator prepared by the preparation method provided by the present invention has abundant hydrophilic and zinc-philic groups. The hydrophilic groups can form hydrogen bonds with free water, weakening the activity of free water (or effectively inhibiting the activity of water), thereby inhibiting the side reactions caused by free water; the zinc-philic groups can accelerate the desolvation of hydrated zinc (or accelerate the desolvation of hydrated zinc), thereby accelerating the desorption of Zn 2+ Transport, and regulate the deposition direction of zinc, thereby inhibiting the growth of zinc dendrites on the surface of the zinc electrode. In addition, the composite cellulose battery separator exhibits excellent mechanical properties (such as high mechanical strength) and acid and alkali corrosion resistance (such as corrosion passivation blocking) in terms of physical properties. The high mechanical strength composite cellulose battery separator can inhibit the growth of zinc dendrites in the vertical direction, and further inhibit the growth of zinc dendrites on the surface of the zinc electrode. Therefore, the composite cellulose battery separator can effectively solve the problem of zinc dendrite growth on the surface of the zinc electrode through a physical and chemical synergistic mechanism, improve the cycle life of aqueous zinc ion batteries, and has broad prospects in the application of aqueous zinc ion batteries.

[0017] The preparation method provided by the present invention is simple, uses a wide range of raw materials, is environmentally friendly, and is suitable for large-scale industrial production. The prepared composite cellulose battery separator has excellent mechanical properties and chemical stability (such as acid and alkali corrosion resistance), is not prone to water-induced swelling and deformation, and can accelerate the Zn 2+ transport, inhibiting the growth of zinc dendrites on the surface of the zinc electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the preparation process of the composite cellulose battery separator in an embodiment of the present invention.

[0019] Figure 2 Graphs showing the mechanical properties test results of the CSC diaphragm in Example 1, wherein a is a dry tensile stress-strain curve graph, and b is a wet tensile stress-strain curve graph.

[0020] Figure 3 Graph showing the acid and alkali resistance test results of the CSC diaphragm in Example 1, where a is the average wet tensile stress after immersion in solutions with different pH values ​​for 1 day, b is the average wet tensile stress after immersion in solutions with different pH values ​​for 7 days, and c is the average wet tensile stress after immersion in solutions with different pH values ​​for 14 days.

[0021] Figure 4 Graphs showing the cycle performance test results of symmetrical batteries assembled using the GF membrane, the AD membrane, and the CSC membrane in Example 1, respectively.

[0022] Figure 5SEM images of the zinc electrode surface at different magnifications after cycling of zinc symmetric batteries assembled with different separators, where (a) is CSC separator, magnification of 1k; (b) CSC separator, magnification of 5k; (c) CSC separator, magnification of 10k; (d) GF separator, magnification of 1k; (e) GF separator, magnification of 5k; (f) GF separator, magnification of 10k; (g) AD separator, magnification of 1k; (h) AD separator, magnification of 5k, and (I) AD separator, magnification of 5k.

[0023] Figure 6 Graph showing the zinc desolvation activation energy test results of symmetrical batteries assembled using GF membrane, AD membrane, and the CSC membrane in Example 1.

[0024] Figure 7 The Zn content of the symmetrical cells assembled with the GF membrane, the AD membrane, and the CSC membrane in Example 1 is 2+ Transfer constant test results graph.

[0025] Figure 8 This is a graph showing the cycling performance test results of a Zn / / CSC / / MnO2 full battery assembled using the CSC separator in Example 1. DETAILED DESCRIPTION

[0026] The present invention provides a composite cellulose battery separator and its preparation method and application. To make the objectives, technical solutions, and effects of the present invention more clear and explicit, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only for the purpose of explaining the present invention and are not intended to limit the present invention.

[0027] Unless otherwise defined, all technical terms and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0028] If there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features.

[0029] The embodiment of the present invention provides a method for preparing a composite cellulose battery separator, wherein, Figure 1 As shown, the following steps are included: S1, mixing carboxylated sisal fiber, sulfonated cotton fiber and water, placing the mixture in a film mold, and drying the mixture to obtain a primary composite fiber membrane; S2. placing the primary composite fiber membrane in a solution containing a cross-linking agent and soaking it for a preset time to obtain the composite cellulose battery separator.

[0030] In an embodiment of the present invention, a primary composite cellulose membrane is constructed by self-assembly of carboxylated sisal fibers and sulfonated cotton fibers. This membrane is then chemically crosslinked with a crosslinker to produce a bio-based composite cellulose battery separator suitable for aqueous zinc-ion batteries. This invention employs a double crosslinking strategy to form a dense chemical crosslinking network, enhancing the intermolecular forces of the cellulose molecules and effectively inhibiting water-induced swelling and deformation of the cellulose membrane.

[0031] In addition, the molecular chains of carboxylated sisal fiber and sulfonated cotton fiber contain a large number of hydrophilic and zinc-philic groups. Therefore, the composite cellulose battery separator prepared by the preparation method provided by the present invention has abundant hydrophilic and zinc-philic groups. The hydrophilic groups can form hydrogen bonds with free water, weakening the activity of free water (or effectively inhibiting the activity of water), thereby inhibiting the side reactions caused by free water; the zinc-philic groups can accelerate the desolvation of hydrated zinc (or accelerate the desolvation of hydrated zinc), thereby accelerating the desorption of Zn 2+ Transport, and regulate the deposition direction of zinc, thereby inhibiting the growth of zinc dendrites on the surface of the zinc electrode. In addition, the composite cellulose battery separator exhibits excellent mechanical properties (such as high mechanical strength) and acid and alkali corrosion resistance (such as corrosion passivation blocking) in terms of physical properties. The high mechanical strength composite cellulose battery separator can inhibit the growth of zinc dendrites in the vertical direction, and further inhibit the growth of zinc dendrites on the surface of the zinc electrode. Therefore, the composite cellulose battery separator can effectively solve the problem of zinc dendrite growth on the surface of the zinc electrode through a physical and chemical synergistic mechanism, improve the cycle life of aqueous zinc ion batteries, and has broad prospects in the application of aqueous zinc ion batteries.

[0032] The preparation method provided by the present invention is simple, uses a wide range of raw materials, is environmentally friendly, and is suitable for large-scale industrial production. The prepared composite cellulose battery separator has excellent mechanical properties and chemical stability (such as acid and alkali corrosion resistance), is not prone to water-induced swelling and deformation, and can accelerate the Zn 2+ transport, inhibiting the growth of zinc dendrites on the surface of the zinc electrode.

[0033] Specifically, since carboxylated sisal fiber has excellent film-forming properties and mechanical properties, it can promote film formation and improve mechanical properties; on the other hand, the molecular chain of carboxylated sisal fiber contains a large number of hydrophilic and zinc-philic groups (-OH, -COO - ), can form hydrogen bonds with free water, reduce the activity of free water and inhibit the side reactions caused by free water, promote the desolvation of hydrated zinc, accelerate the Zn 2+ transport, regulate the deposition direction of zinc and inhibit the growth of dendrites on the surface of zinc electrode.

[0034] The abundant hydrophilic and zinc-philic groups (-SO3 - ), further promoting the desolvation of hydrated zinc and accelerating the 2+ transport, regulate the deposition direction of zinc and inhibit the growth of dendrites on the surface of zinc electrode.

[0035] In step S1, in some implementation methods, the mass ratio of the carboxylated sisal fiber to the sulfonated cotton fiber is (10-1):(1-5), for example, 10:1, 10:3, 10:5, 5:1, 5:3, 1:1, 1:3, or 1:5.

[0036] In step S1, the carboxylated sisal fiber, the sulfonated cotton fiber, and water may be mixed; or the carboxylated sisal fiber and the sulfonated cotton fiber may be dispersed in water separately, and then the carboxylated sisal fiber aqueous dispersion and the sulfonated cotton fiber aqueous dispersion are mixed. Therefore, in some embodiments, the step of mixing the carboxylated sisal fiber, the sulfonated cotton fiber, and water specifically includes: mixing a carboxylated sisal fiber aqueous dispersion and a sulfonated cotton fiber aqueous dispersion; Among them, in the carboxylated sisal fiber aqueous dispersion, the mass content of the carboxylated sisal fiber is 0.5% to 5% (that is, the solid content of the carboxylated sisal fiber aqueous dispersion is 0.5% to 5%, for example, it can be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%, etc.); in the sulfonated cotton fiber aqueous dispersion, the mass content of the sulfonated cotton fiber is 1% to 10% (that is, the solid content of the sulfonated cotton fiber aqueous dispersion is 1% to 10%, for example, it can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%, etc.).

[0037] In some embodiments, the method for preparing the carboxylated sisal fiber aqueous dispersion comprises the following steps: S11, alkali boiling, bleaching, and grafting carboxyl groups onto sisal fibers (e.g., carboxylation using chloroacetic acid) to obtain carboxylated sisal fibers; S12, adding the carboxylated sisal fiber into water, and mechanically crushing and dispersing the fiber to obtain the carboxylated sisal fiber aqueous dispersion.

[0038] In this embodiment, alkaline boiling removes non-cellulose impurities, activating the fiber microstructure and providing more sites for subsequent carboxyl grafting. This also improves surface wettability, ensuring uniform penetration of the carboxylating agent (such as chloroacetic acid), resulting in more uniform grafting of carboxyl groups. Furthermore, bleaching can render the composite cellulose battery separator bright and transparent, facilitating symmetrical battery assembly and improving battery performance.

[0039] In step S2, the primary composite fiber membrane is placed in a solution containing a cross-linking agent, so that the solution containing the cross-linking agent covers the primary composite fiber membrane.

[0040] In step S2, in some embodiments, the crosslinking agent includes at least one of, but is not limited to, citric acid, malic acid, tartaric acid, oxalic acid, succinic acid, and fumaric acid. Using these organic acids as crosslinking agents ensures effective crosslinking and effectively suppresses deformation caused by water swelling. Taking citric acid as an example, during the crosslinking process, the citric acid first dehydrates to form a cyclic anhydride, which then undergoes an esterification reaction with the hydroxyl groups in the primary composite fiber membrane to achieve crosslinking.

[0041] In some implementation methods, the mass percentage of the cross-linking agent in the solution containing the cross-linking agent is 1-20%, for example, it can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%, etc.

[0042] In some implementations, the preset soaking time is 1 to 60 minutes. This soaking time allows for sufficient crosslinking of the carboxylated sisal fiber and the sulfonated cotton fiber. For example, the preset soaking time can be 1 minute, 2 minutes, 5 minutes, 8 minutes, 10 minutes, 12 minutes, 15 minutes, 18 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, or 60 minutes.

[0043] An embodiment of the present invention further provides a composite cellulose battery separator, which is prepared using the above-mentioned method for preparing the composite cellulose battery separator of the present invention.

[0044] An embodiment of the present invention further provides a use of the composite cellulose battery separator as described above in an aqueous zinc ion battery.

[0045] An embodiment of the present invention further provides an aqueous zinc-ion battery comprising a positive electrode, a negative electrode, and a separator positioned between the positive electrode and the negative electrode, wherein the separator comprises the composite cellulose battery separator described above. In this embodiment, the aqueous zinc-ion battery exhibits excellent cycling performance, with a cycle life of up to 10,000 cycles.

[0046] In some embodiments, the negative electrode includes metallic zinc, the positive electrode includes manganese dioxide, and the aqueous zinc ion battery further includes an electrolyte, and the electrolyte includes a ZnSO4 aqueous solution.

[0047] The present invention will be further described below with reference to specific examples.

[0048] Unless otherwise specified in the following examples, the raw materials, equipment, etc. used are all commercially available products. For example, the wall breaking machine used in the following examples was purchased from Zhongshan Feiyue Electric Co., Ltd., model FY-1055.

[0049] Example 1 This embodiment provides a method for preparing a composite cellulose battery separator, comprising the following steps: 22 g of natural sisal plant fiber, 16 g of NaOH, 16 g of Na2SO4 and 200 mL of deionized water were mixed and alkalized at 100 °C for 24 h (i.e., alkali boiling treatment). The mixture was then cooled to 75 °C and reacted with 13 g of NaClO2 and 8 mL of CH3COOH for 2 h (i.e., bleaching). The mixture was then washed and dried to obtain sisal fiber. 7 g of the sisal fiber prepared above, 3.5 g of NaOH and 15 mL of deionized water were taken and alkalized at room temperature for 30 min. Then, 5 g of ClCH2COOH and 200 mL of anhydrous ethanol were added and the temperature was raised to 70 °C for reaction for 8 h (i.e., carboxyl groups were grafted). Finally, the reaction solution was washed to neutrality, deionized water was added, and high-speed shearing was performed by a wall breaking machine (speed of 35000 rpm, 5 min each time, for a total of 30 times) to obtain a carboxylated sisal fiber aqueous solution with a solid content of 1%; 50 g of 1% solid content carboxylated sisal fiber aqueous dispersion and 37.5 g of 4% solid content sulfonated cotton fiber aqueous dispersion (purchased from Guilin Qihong Technology Co., Ltd., model CNC-C) were taken and then heated at 1000 r·min. -1 The mixture was mechanically stirred at a high speed for 6 h to mix (i.e., the mass ratio of carboxylated sisal fiber to sulfonated cotton fiber was 1:3), transferred into a film mold (e.g., a flat-bottomed container capable of holding the solution), and vacuum dried at 60 °C for 6 h to obtain a primary composite fiber membrane.

[0050] The primary composite fiber membrane prepared above was immersed in 60 mL of citric acid aqueous solution (the mass content of citric acid was 10%, and the citric acid aqueous solution covered the primary composite fiber membrane) for 5 min to obtain a composite cellulose battery separator (diameter 140 mm, thickness 38 μm).

[0051] The mechanical properties of the primary composite fiber membrane (CS membrane), composite cellulose battery separator (CSC membrane), glass fiber (GF membrane) and aqueous acid and alkali resistant membrane (AD membrane) in Example 1 were tested. The results are as follows: Figure 2 As shown, Figure 2 a in the figure is the dry tensile stress-strain curve. Figure 2Figure (b) shows the wet tensile stress-strain curve. The results show that the CSC separator achieves tensile strengths of 131.74 MPa and 28.31 MPa in the dry and wet states, respectively, which is much higher than that of the CS membrane.

[0052] The acid and alkali corrosion resistance of the CSC membrane prepared in Example 1 was tested. Specifically, the CSC membrane was immersed in different pH solutions for different days and the average wet tensile stress was tested. The results are as follows: Figure 3 When the CSC diaphragm was immersed in acid and alkali solutions with a pH range of 3 to 9 for 14 days, the average wet tensile strength of the CSC diaphragm remained almost unchanged, indicating that the CSC diaphragm has good acid and alkali resistance and can effectively achieve corrosion passivation and blocking.

[0053] The CSC separator prepared in Example 1 was used to assemble a zinc symmetric battery (i.e., a Zn / / Zn symmetric battery). Specifically, metallic zinc was used as the positive and negative electrodes of the zinc symmetric battery, a 2 M ZnSO4 aqueous solution was used as the electrolyte, and a CSC separator (cut into a 17 mm diameter disc) was used as the separator. It was placed between the positive and negative electrodes and encapsulated in a 2032 button battery shell. Following the same scheme, zinc symmetric batteries were assembled using GF separators and AD separators. The zinc symmetric battery was then placed in a 25°C incubator and charged at 2 mA·cm -2 The constant current charge and discharge cycle test was carried out at a current density of Figure 4 As shown in the figure, it can be seen that the zinc symmetric battery assembled with CSC separator has a high -2 It has an excellent cycle life of up to 3600 h at a current density of 1.5 GHz, which is much higher than that of commercial battery separators (GF membrane and AD membrane).

[0054] After 100 cycles, the zinc symmetric batteries prepared with CSC, GF and AD membranes were disassembled and the zinc electrodes were tested by scanning electron microscopy (SEM). The results are as follows: Figure 5 As shown, it can be seen that Figure 5 As shown in (a), (b) and (c) in the figure, after cycling of the symmetrical battery prepared with the CSC separator, the deposited Zn preferentially grows parallel to the surface of the zinc electrode; Figure 5 As shown in (d), (e), (f), (g), (h), and (I), after cycling in a symmetrical zinc battery prepared using GF and AD separators, deposited Zn grows perpendicular to the zinc electrode surface, forming zinc dendrites. This demonstrates that the composite cellulose battery separator provided by the present invention can effectively inhibit the growth of zinc dendrites on the zinc electrode surface.

[0055] The zinc desolvation activation energy of zinc symmetric batteries prepared using CSC membrane, GF membrane and AD membrane was tested respectively. The results are as follows: Figure 6As shown in Figure 2, the activation energy of zinc desolvation in the zinc symmetric battery prepared using the CSC separator is Ea = 18.60 ± 3.08 kJ·mol -1 The activation energy of zinc desolvation in the zinc symmetric battery prepared with GF membrane is Ea=31.69±3.49 kJ·mol -1 The activation energy of zinc desolvation in the zinc symmetric battery prepared with AD separator is Ea=26.62±3.99 kJ·mol -1 This indicates that the composite cellulose battery separator provided by the present invention has a low zinc desolvation activation energy and can promote the desolvation of hydrated zinc.

[0056] The zinc symmetric batteries prepared with CSC membrane, GF membrane and AD membrane were tested respectively. 2+ Transfer constant test, the results are as follows Figure 7 As shown. It can be seen that the Zn 2+ The transfer constant is 0.70, and the Zn 2+ The transfer constant is 0.38, and the Zn 2+ The transfer constant is 0.50. This shows that the composite cellulose battery separator provided by the present invention has a high Zn 2+ transfer constant, which can accelerate the Zn 2+ transport, thereby effectively inhibiting the formation of zinc dendrites.

[0057] A full cell (referred to as a Zn / / CSC / / MnO2 full cell) was assembled using the CSC separator prepared in Example 1. Specifically, zinc metal served as the negative electrode, manganese dioxide served as the positive electrode, a 2 M ZnSO4 aqueous solution served as the electrolyte, and a CSC separator (cut into 17 mm diameter discs) was placed between the positive and negative electrodes. The cells were then encapsulated in a 2032 button-type battery case. Using the same method, full cells were assembled using GF and AD separators, respectively. The resulting full cells are referred to as Zn / / GF / / MnO2 full cells and Zn / / AD / / MnO2 full cells, respectively.

[0058] The Zn / / CSC / / MnO2 full cell, Zn / / GF / / MnO2 full cell and Zn / / AD / / MnO2 full cell were placed in a 25℃ constant temperature box at 1A·g -1 The constant current charge and discharge cycle test was carried out at a current density of Figure 8 As shown. Figure 8 It can be seen that the Zn / / CSC / / MnO2 full battery assembled with CSC separator has a high -1It has an excellent cycle life of up to 10,000 times at the current density, and a capacity retention rate of 71.13%, which is much higher than the full battery cycle performance assembled with commercial GF membrane (capacity retention rate of 53.13%) and AD membrane (1947 failures).

[0059] Example 2 This embodiment provides a method for preparing a composite cellulose battery separator. The only difference from Example 1 is that 50 g of a 1% solid content carboxylated sisal fiber aqueous solution and 62.5 g of a 4% solid content sulfonated cotton fiber aqueous solution are mixed at 1000 r·min. -1 The mixture was mechanically stirred at a high speed for 6 h (i.e., the mass ratio of carboxylated sisal fiber to sulfonated cotton fiber was 1:5); The primary composite fiber membrane was immersed in 60 mL of a succinic acid aqueous solution (with a succinic acid content of 1% by mass) for 60 min to obtain a composite cellulose battery separator.

[0060] Example 3 This embodiment provides a method for preparing a composite cellulose battery separator. The only difference from Example 1 is that 150 g of a 1% solid content carboxylated sisal fiber aqueous solution and 37.5 g of a 4% solid content sulfonated cotton fiber aqueous solution are mixed at 1000 r·min. -1 The mixture was mechanically stirred at a high speed for 6 h (i.e., the mass ratio of carboxylated sisal fiber to sulfonated cotton fiber was 1:1); The primary composite fiber membrane was immersed in 60 mL of malic acid aqueous solution (mass content of malic acid was 20%) for 35 min to obtain a composite cellulose battery separator.

[0061] Example 4 This embodiment provides a method for preparing a composite cellulose battery separator. The only difference from Example 1 is that 300 g of a 1% solid content carboxylated sisal fiber aqueous solution and 37.5 g of a 4% solid content sulfonated cotton fiber aqueous solution are mixed at 1000 r·min. -1 The mixture was mechanically stirred at a high speed for 6 h (i.e., the mass ratio of carboxylated sisal fiber to sulfonated cotton fiber was 2:1); The primary composite fiber membrane was immersed in 60 mL of tartaric acid aqueous solution (the mass content of tartaric acid was 20%) for 25 min to obtain a composite cellulose battery separator.

[0062] Example 5 This embodiment provides a method for preparing a composite cellulose battery separator. The only difference from Example 1 is that 50 g of a 1% solid content carboxylated sisal fiber aqueous solution and 1.25 g of a 4% solid content sulfonated cotton fiber aqueous solution are mixed at 1000 r·min. -1The mixture was mechanically stirred at a high speed for 6 h (i.e., the mass ratio of carboxylated sisal fiber to sulfonated cotton fiber was 10:1); The primary composite fiber membrane was immersed in 60 mL of an oxalic acid aqueous solution (the mass percentage of oxalic acid was 5%) for 10 minutes to obtain a composite cellulose battery separator.

[0063] The composite cellulose battery separators prepared in Examples 2 to 5 have similar properties to the composite cellulose battery separator in Example 1. The prepared Zn / / CSC / / MnO2 full battery has a high conductivity at 1 A·g -1 It has an excellent cycle life of up to 10,000 times at the same current density.

[0064] It should be understood that the application of the present invention is not limited to the above examples. For those skilled in the art, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for preparing a composite cellulose battery separator, characterized in that: The steps include: Carboxylated sisal fiber, sulfonated cotton fiber and water are mixed, placed in a film mold, and dried to obtain a primary composite fiber membrane; The primary composite fiber membrane is placed in a solution containing a cross-linking agent and soaked for a preset time to obtain the composite cellulose battery separator.

2. The preparation method according to claim 1, characterized in that The mass ratio of the carboxylated sisal fiber to the sulfonated cotton fiber is (10-1): (1-5).

3. The preparation method according to claim 1, characterized in that The cross-linking agent includes at least one of citric acid, malic acid, tartaric acid, oxalic acid, succinic acid and fumaric acid.

4. The preparation method according to claim 1, characterized in that In the solution containing the cross-linking agent, the mass percentage of the cross-linking agent is 1% to 20%.

5. The preparation method according to claim 1, characterized in that The preset time is 1 to 60 minutes.

6. The preparation method according to claim 1, characterized in that The step of mixing carboxylated sisal fiber, sulfonated cotton fiber and water specifically comprises: mixing a carboxylated sisal fiber aqueous dispersion and a sulfonated cotton fiber aqueous dispersion; Wherein, the mass content of the carboxylated sisal fiber in the carboxylated sisal fiber aqueous dispersion is 0.5% to 5%; the mass content of the sulfonated cotton fiber in the sulfonated cotton fiber aqueous dispersion is 1% to 10%.

7. The preparation method according to claim 6, characterized in that The preparation method of the carboxylated sisal fiber aqueous dispersion comprises the following steps: The sisal fiber is subjected to alkali boiling, bleaching, and carboxyl grafting to obtain carboxylated sisal fiber; The carboxylated sisal fibers are added into water, and mechanically crushed and dispersed to obtain the carboxylated sisal fiber aqueous dispersion.

8. A composite cellulose battery separator, characterized in that: The preparation method is described in any one of claims 1 to 7.

9. Use of the composite cellulose battery separator according to claim 8 in an aqueous zinc ion battery.

10. An aqueous zinc ion battery, characterized in that: The battery comprises a positive electrode, a negative electrode, and a separator located between the positive electrode and the negative electrode, wherein the separator comprises the composite cellulose battery separator according to claim 8.

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