Cellulose-based electrode and preparation method and application thereof

Abstract

The invention discloses a cellulose-based electrode and a preparation method and application thereof. The method comprises the following steps: firstly, dispersing an active electrode material in a binder aqueous solution to obtain a mixed system A; dispersing a conductive agent and cellulose in deionized water to obtain a mixed system B; uniformly mixing the mixed system A and the mixed system B to obtain a mixed system C, and performing coating forming to obtain a coating type cellulose-based electrode; or the paper-based cellulose-based electrode is prepared through paper-based forming. The cellulose-based electrode prepared by the invention still has excellent mechanical strength and flexibility under the condition of high-activity substance loading capacity; the battery prepared on the basis of the cellulose-based electrode can keep excellent electrochemical performance while giving consideration to the loading capacity of high-activity substances. The preparation process is simple and convenient, the cost is low, and large-scale production can be realized.

Description

A cellulose-based electrode, its preparation method and application Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, specifically to a cellulose-based electrode, its preparation method, and its application. Background Technology

[0002] With the booming development of new energy vehicles, smart grids, and 3C electronics, traditional lithium-ion batteries face severe challenges in terms of energy density, rate performance, and cost control. Increasing the active material loading has become an effective way to increase energy density, but increasing electrode thickness will cause a series of problems. Increased electrode thickness leads to deterioration of mechanical stability, lengthening of ion / electron transport paths, and intensification of interface polarization. It is difficult to balance high mechanical stability and rapid ion transport kinetics under ultra-high active material loading.

[0003] Existing solutions to this technical problem mainly fall into two categories: traditional coated cellulose-based electrode technology, which prepares electrodes through coating to increase the active material loading; and emerging dry electrode technology, which relies on dry processes to increase the active material loading. Traditional coated cellulose-based electrodes, while significantly increasing the loading, are limited by the adhesive's bonding ability, easily leading to coating cracking, powdering, and detachment from the current collector due to increased internal stress. Furthermore, electron / ion transport within the thick electrode is severely hindered. While emerging dry electrodes can effectively increase the active material loading, their mechanical strength and rate performance often fail to meet application requirements. Existing technologies all exhibit significant bottlenecks in high-load applications. Therefore, developing a thick electrode preparation technology that can maintain high mechanical stability and rapid ion transport kinetics even with ultra-high active material loading (>93%) is of significant scientific and practical value for realizing the application of next-generation high-energy-density lithium-ion batteries. Summary of the Invention

[0004] To address the problems of the prior art, this invention provides a high-load cellulose-based electrode and its preparation method. By introducing cellulose, this invention effectively overcomes the defects of traditional coated cellulose-based electrodes, such as cracking and peeling, under high loads, while significantly improving electrochemical performance. This method is applicable to various electrode preparation processes. The introduction of cellulose balances the electrode's mechanical strength, flexibility, conductivity, and electrochemical kinetics, and possesses excellent process versatility, adapting to both slurry coating and wet paper-based processes. The prepared coated and paper-based cellulose-based electrodes exhibit excellent overall performance and hold promise for large-scale industrial production.

[0005] To achieve the above objectives, the present invention provides the following technical solution: The present invention provides a method for preparing a cellulose-based electrode, comprising the following steps: dispersing an active electrode material in a binder aqueous solution to obtain a mixed system A; dispersing a conductive agent and cellulose in deionized water to obtain a mixed system B; mixing mixed system A and mixed system B uniformly to obtain a mixed system C, and molding it by any of the following methods: coating molding: adding a binder to mixed system C to obtain a coating slurry, coating the coating slurry onto a current collector and drying it to obtain a coated cellulose-based electrode; paper-based molding: adding cellulose to mixed system C to obtain a paper-based slurry, vacuum filtering the paper-based slurry, and then dehydrating it by vacuum hot pressing to obtain a paper-based cellulose-based electrode.

[0006] Furthermore, the active electrode material is a positive electrode active material or a negative electrode active material; the positive electrode active material includes one or more of lithium iron phosphate, lithium manganese iron phosphate, nickel cobalt manganese ternary materials, or lithium cobalt oxide; the negative electrode active material includes one or more of graphite, lithium titanate, or silicon carbon.

[0007] Furthermore, the adhesive includes one or more of carboxymethyl cellulose, sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, sodium alginate, styrene-butadiene rubber, or acrylonitrile copolymer.

[0008] Furthermore, the cellulose includes one or more of lithium cellulose nanocrystals, carboxylated cellulose nanofibers, bacterial nanocellulose, filamentous cellulose fibers, or coniferous wood fibers; wherein the beating degree of the coniferous wood fibers is not less than 90°RS.

[0009] Furthermore, the conductive agent is one or both of multi-walled carbon nanotubes or single-walled carbon nanotubes.

[0010] Furthermore, in preparing the coated cellulose-based electrode, the mass ratio of the active electrode material, binder, conductive agent, and cellulose is (0.93–0.97): (0.015–0.035): (0.005–0.02): (0.001–0.015); the overall solid content of the coating slurry is 30.0%–60.0%.

[0011] Furthermore, when preparing the paper-based cellulose-based electrode, the mass ratio of the active electrode material, binder, conductive agent and cellulose is (0.93~0.97):(0.001~0.01):(0.001~0.02):(0.02~0.05); the overall solid content of the paper-based pulp is 1.0%~20.0%.

[0012] Furthermore, when preparing the paper-based cellulose-based electrode, the temperature of the vacuum hot pressing is 60℃~120℃, and the vacuum degree is -0.05~-0.1 MPa.

[0013] The present invention also provides a cellulose-based electrode obtained by the above-described method for preparing a cellulose-based electrode.

[0014] The present invention also provides the application of the above-described cellulose-based electrode in lithium-ion batteries.

[0015] Compared with existing technologies, the advantages of this invention are as follows: This invention uses cellulose as a base support framework, uniformly dispersing active materials, conductive agents, and binders within the support framework. Combined with traditional papermaking or coating processes, it produces cellulose-based electrodes with high loading capacity and excellent electrical properties. Introducing specific polymeric binders into the slurry system allows for a tighter gradient network connection between cellulose and carbon nanotubes. This network structure also facilitates the dispersion and encapsulation of the active material microparticles, thereby improving the loading capacity and dispersion uniformity of the active material in the electrode. Furthermore, the interaction between the binder and cellulose effectively enhances the mechanical strength and flexibility of the electrode under high active material loading. The active material loading of the coated or paper-based cellulose-based electrode prepared by this method can reach 93.0%~97.0%, and the areal capacity can reach 2 mAh cm⁻¹. -2 ~20 mAh cm -2 The mechanical strength is >2 MPa. The cellulose-based electrode prepared in this invention can be applied to lithium-ion batteries, and high-capacity, high-energy-density, high-rate soft-pack batteries can be assembled by winding or stacking. Full batteries assembled from this type of cellulose-based electrode exhibit cycle performance greater than 1000 cycles and excellent rate performance. Lithium-ion batteries based on cellulose-based electrodes can ensure good electrochemical performance while maintaining a high loading of active materials, and the overall preparation process is simple, low-cost, and can be mass-produced. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the examples of the present invention or the prior art, the drawings used in the description of the examples or the prior art will be briefly introduced below. Obviously, the drawings described below are some examples of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 shows the SEM images of the cellulose-based electrodes prepared in Examples 5 and 6; Figure 2 shows the physical images of the cellulose-based electrodes prepared in Examples 5 and 6; Figure 3 shows the first-cycle constant current charge-discharge (GCD) curves of the half-cells and full-cells prepared in Examples 1-7 of this invention; Figure 4 shows the rate performance test graphs of the half-cells and full-cells prepared in Examples 1-7 of this invention; Figure 5 shows the long-cycle performance curves of the half-cells and full-cells prepared in Examples 1-7 of this invention at different rates; Figure 6 shows the comparison graphs of the AC impedance spectra (EIS) of the batteries prepared in Examples 5, 6 and 7 of this invention. Detailed Implementation

[0018] To make the technical problem to be solved, the technical solution, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0019] In this invention, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0020] In this invention, "at least one" refers to one or more items, and "more than one" refers to two or more items. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c," or "at least one of a, b, and c," can both represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can each be single or multiple.

[0021] It should be understood that in various embodiments of the present invention, the order of the above-mentioned processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0022] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0023] The weights of the relevant components mentioned in the embodiments of this invention can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this invention is within the scope disclosed in the embodiments of this invention. Specifically, the mass described in the embodiments of this invention can be a mass unit known in the chemical industry, such as μg, mg, g, or kg.

[0024] The present invention discloses a method for preparing a cellulose-based electrode, comprising the following steps: dispersing an active electrode material in an aqueous binder solution to obtain a mixed system A; dispersing a conductive agent and cellulose in deionized water to obtain a mixed system B; mixing mixed system A and mixed system B uniformly to obtain a mixed system C, which is then formed by any of the following methods: (a) coating forming: adding a binder to mixed system C to obtain a coating slurry, coating the coating slurry onto a current collector and drying it to obtain a coated cellulose-based electrode (referred to as a type I electrode); (b) paper-based forming: adding cellulose to mixed system C to obtain a paper-based slurry, mixing the paper-based slurry uniformly and then vacuum filtering it, followed by vacuum hot pressing dehydration to obtain a paper-based cellulose-based electrode (referred to as a type II electrode).

[0025] In some specific embodiments, the active electrode material is either a positive electrode active material or a negative electrode active material; the positive electrode active material includes one or more of lithium iron phosphate, lithium manganese iron phosphate, nickel-cobalt-manganese ternary materials, or lithium cobalt oxide; the negative electrode active material includes one or more of graphite, lithium titanate, or silicon-carbon. These Mars electrode materials can be selected according to the actual needs of the battery, achieving both high energy density and ensuring excellent electrochemical performance such as long cycle life and good rate performance.

[0026] In some specific embodiments, the positive electrode paper-based cellulose-based electrode comprises: positive electrode active electrode material, binder, conductive agent and cellulose; the negative electrode paper-based cellulose-based electrode comprises: negative electrode active electrode material, binder, conductive agent and cellulose.

[0027] In some specific embodiments, the binder is one or more of carboxymethyl cellulose (CMC), sodium carboxymethyl cellulose (CMC-Na), lithium carboxymethyl cellulose (CMC-Li), sodium alginate, styrene-butadiene rubber (SBR), and acrylonitrile copolymer.

[0028] In some specific embodiments, cellulose includes one or more of lithium-ion cellulose nanocrystals, carboxylated cellulose nanofibers, bacterial cellulose nanoparticles, filamentous cellulose fibers, or coniferous fibers. These celluloses can serve as the basic supporting framework for the electrode, constructing a dense three-dimensional network structure that efficiently disperses and immobilizes active materials and conductive components, improving the loading capacity and dispersion uniformity of active materials, and ensuring high loading characteristics of the electrode. Simultaneously, the structural properties of cellulose can enhance the interaction between the electrode and the binder, significantly improving the mechanical strength and flexibility of the electrode, reducing structural damage during charging and discharging, and thus maintaining excellent and stable electrochemical performance of the electrode. Among them are lithium-ionized cellulose nanocrystals (CNC-Li) with a diameter of 5–20 nm, a length of 100–500 nm, and a lithium content of 0.05 mmol / g–0.5 mmol / g; carboxylated cellulose nanofibers (CNF) with a diameter of 4–10 nm and a length of 1–3 μm; bacterial nanocellulose (BC) with a diameter of 50–100 nm and a length of approximately 20–100 μm; filamentous cellulose fibers (CF) with a diameter of several hundred nanometers to 3 μm and a length of 100 μm to 1 mm; and coniferous wood fibers (CWFs) with a diameter of 20–50 μm and a length of 500 μm to 2 mm; wherein the beating degree of the coniferous wood fibers is not less than 90°RS.

[0029] In some specific embodiments, when preparing type II paper-based cellulose-based electrodes, a mixture of coniferous wood fiber, carboxylated cellulose nanofiber, filamentous cellulose fiber and bacterial nanocellulose can be used; wherein, the mixing ratio of coniferous wood fiber, carboxylated cellulose nanofiber, filamentous cellulose fiber and bacterial nanocellulose is (6-8):(0-1):(0-1):(0-1).

[0030] In some specific embodiments, the conductive agent includes one or both of multi-walled carbon nanotubes and single-walled carbon nanotubes; the conductive agent used can construct a continuous and efficient conductive network in the electrode, greatly improving the electron and ion conduction efficiency and improving the electrode rate performance. The conductive agent is composed of a dispersion of multi-walled carbon nanotubes with a diameter of 8-15 nm and a length of 30-50 μm, mixed with any of the following carbon nanotube powders: (1) single-walled carbon nanotube powder with a diameter of <2 nm and a length of 5-30 μm; (2) multi-walled carbon nanotube powder with a diameter of 8-15 nm and a length of about 50 μm; the mass ratio of multi-walled carbon nanotubes to carbon nanotube powder in the multi-walled carbon nanotube dispersion is 1: (1-5).

[0031] In some specific embodiments, when preparing coated cellulose-based electrodes, the mass ratio of active electrode material, binder, conductive agent, and cellulose is (0.93–0.97):(0.015–0.035):(0.005–0.02):(0.001–0.015); the overall solid content of the coating slurry is 30.0%–60.0%. In this mass ratio, the high proportion of active electrode material ensures the electrochemical performance of the electrode; the ratio of binder to conductive agent balances the adhesion of the electrode structure with electronic conduction efficiency; a small amount of cellulose constructs a stable supporting framework and optimizes the dispersibility of each component. The slurry solid content of 30.0%–60.0% is suitable for the coating process, ensuring the coating formability of the slurry while improving the electrode density. The synergistic effect of each dosage parameter achieves the characteristics of high loading capacity, excellent conductivity, and strong structure of the electrode, significantly improving its electrochemical performance and cycle stability.

[0032] In some specific embodiments, when preparing paper-based cellulose-based electrodes, the mass ratio of active electrode material, binder, conductive agent, and cellulose is (0.93–0.97):(0.001–0.01):(0.001–0.02):(0.02–0.05); the overall solid content of the paper pulp is 1.0%–20.0%. This ratio is suitable for the preparation requirements of paper-based cellulose-based electrodes. The high proportion of active electrode material ensures the electrochemical performance of the electrode, the high proportion of cellulose can construct a stable three-dimensional network support framework, and the appropriate amount of binder and conductive agent not only enhances the stability of the electrode structure and the electronic conduction efficiency, but also optimizes the dispersion uniformity of each component. The 1.0%–20.0% pulp solid content is suitable for the papermaking process, helping to form a dense and porous electrode structure. All parameters synergistically improve the electrode's load capacity, mechanical properties, and electrochemical cycle stability.

[0033] When preparing paper-based cellulose-based electrodes, the vacuum hot pressing temperature is 60℃~120℃, and the vacuum degree is -0.05~-0.1 MPa.

[0034] The cellulose-based electrodes prepared by the above method can achieve an active material loading of 93.0%~97.0% for coated or paper-based cellulose-based electrodes; the areal capacity is 2 mAh cm⁻¹. -2 ~12 mAh cm -2 .

[0035] The active electrode of this invention includes a positive active material or a negative active material; the positive active material is lithium iron phosphate or lithium manganese iron phosphate, and the negative active material is graphite or lithium titanate, etc.

[0036] In some specific embodiments, when the positive electrode material of the active electrode is lithium iron phosphate, the components of the type I electrode include: lithium iron phosphate, a conductive agent (a mixture of multi-walled carbon nanotube dispersion and single-walled carbon nanotube powder), sodium carboxymethyl cellulose, styrene-butadiene rubber, and cellulose (lithium-modified nanocellulose crystals). The mass ratio of lithium iron phosphate, binder, multi-walled carbon nanotubes + single-walled carbon nanotubes, and lithium-modified nanocellulose crystals is (15-25):(0.30-0.70):(0.15-0.25):(0.10-0.25).

[0037] In some specific embodiments, when the positive electrode material of the active electrode is lithium iron phosphate, the components of the type II electrode include: lithium iron phosphate, binder, cellulose, and conductive agent (a mixture of multi-walled carbon nanotube dispersion and single-walled carbon nanotube powder). The mass ratio of lithium iron phosphate, binder, cellulose, multi-walled carbon nanotubes, and single-walled carbon nanotubes is: (13-26): (0.05-0.1): (0.3546-0.7092): (0.0339-0.0677): (0.1015-0.2031).

[0038] In some specific embodiments, when the positive electrode material of the active electrode is lithium manganese iron phosphate, the components of the type I electrode include: lithium manganese iron phosphate, a conductive agent (a mixture of multi-walled carbon nanotube dispersion and single-walled carbon nanotube powder), a binder (sodium carboxymethyl cellulose and styrene-butadiene rubber), and lithium-ionized cellulose nanocrystals. The mass ratio of lithium manganese iron phosphate, binder, multi-walled carbon nanotubes + single-walled carbon nanotubes, and lithium-ionized cellulose nanocrystals is (15-25):(0.30-0.70):(0.15-0.50):(0.10-0.25).

[0039] In some specific embodiments, when the positive electrode material of the active electrode is lithium manganese iron phosphate, the components of the type II electrode include: lithium manganese iron phosphate, binder, coniferous wood fiber, conductive agent (a mixture of multi-walled carbon nanotube dispersion and single-walled carbon nanotube powder), carboxylated cellulose nanofibers, and bacterial nanocellulose. The mass ratio of lithium manganese iron phosphate, binder, coniferous wood fiber, multi-walled carbon nanotubes + single-walled carbon nanotubes, carboxylated cellulose nanofibers, and bacterial nanocellulose is (6.618~26.472):(0.025~0.1):(0.162~0.648):(0.069~0.276):(0.0005~0.002):(0.0015~0.006).

[0040] When the negative electrode material of the active electrode is graphite, the components of the type I electrode include: graphite, conductive agent (a mixture of multi-walled carbon nanotube dispersion and single-walled carbon nanotube powder), sodium carboxymethyl cellulose, styrene-butadiene rubber, and lithium-ionized cellulose nanocrystals. The mass ratio of graphite, binder (sodium carboxymethyl cellulose + styrene-butadiene rubber), multi-walled carbon nanotubes + single-walled carbon nanotubes, and lithium-ionized cellulose nanocrystals is (14.4~24):(0.30~0.70):(0.30~0.50):(0.075~0.125).

[0041] When the negative electrode material of the active electrode is graphite, the components of the type II electrode include: graphite, binder, coniferous wood fiber, filamentous cellulose fiber, and conductive agent (a mixture of multi-walled carbon nanotube dispersion and single-walled carbon nanotube powder). The mass ratio of graphite, binder, coniferous wood fiber, filamentous cellulose fiber, and multi-walled carbon nanotube + single-walled carbon nanotube is (5.92~11.85):(0.08~0.2):(0.25~0.45):(0.25~0.45):(0.03~0.08).

[0042] When the negative electrode material of the active electrode is lithium titanate, the components of the type I electrode include: lithium titanate, conductive agent (a mixture of multi-walled carbon nanotube dispersion and single-walled carbon nanotube powder), sodium carboxymethyl cellulose, styrene-butadiene rubber, and lithium-ionized cellulose nanocrystals. The mass ratio of lithium titanate, binder (sodium carboxymethyl cellulose + styrene-butadiene rubber), multi-walled carbon nanotubes + single-walled carbon nanotubes, and lithium-ionized cellulose nanocrystals is (14.4~24):(0.30~0.70):(0.30~0.50):(0.075~0.125).

[0043] When the active electrode negative electrode material is lithium titanate, the components of the type II electrode include: lithium titanate, binder, coniferous wood fiber, carboxylated cellulose nanofibers, and bacterial cellulose. The mass ratio of lithium titanate, binder, coniferous wood fiber, multi-walled carbon nanotubes + single-walled carbon nanotubes, carboxylated cellulose nanofibers, and bacterial cellulose is (5.89~23.56):(0.025~0.1):(0.139~0.556):(0.061~0.244):(0.0005~0.002):(0.0015~0.006).

[0044] The binder is preferably sodium carboxymethyl cellulose, sodium alginate, or a mixture thereof.

[0045] When the active electrode material is lithium manganese iron phosphate and lithium iron phosphate, the preparation method of the electrode includes: (1) Preparation step of coating type cellulose-based electrode (Type I): Disperse positive electrode active material powder (LMFP or LFP) in binder aqueous solution, and obtain mixed system A after uniform dispersion.

[0046] Step (2): Disperse the multi-walled carbon nanotube dispersion and multi-walled carbon nanotube powder (the mass ratio of multi-walled carbon nanotubes and multi-arm carbon nanotube powder in the multi-walled carbon nanotube dispersion is 1:3) in deionized water. After uniform dispersion, add lithium cellulose nanocrystals (or carboxylated cellulose nanofibers) and disperse uniformly to obtain mixed system B.

[0047] Step (3): Mix system A and system B evenly to obtain system C. Add styrene-butadiene rubber (SBR) emulsion to system C and stir evenly to obtain coating slurry.

[0048] Step (4): Coat the current collector (such as aluminum foil) with the coating slurry and dry it in a vacuum drying oven at 100°C for 12 hours to obtain the coated cellulose-based positive electrode.

[0049] (2) Preparation steps of paper-based cellulose-based electrode (Type II): Disperse the positive electrode active material powder (LMFP or LFP) in the binder aqueous solution, and obtain the mixed system A after uniform dispersion.

[0050] When the positive electrode active material powder is LMFP: Step (2): Disperse the multi-walled carbon nanotube dispersion and multi-walled carbon nanotube powder (the mass ratio of multi-walled carbon nanotubes and multi-arm carbon nanotube powder in the multi-walled carbon nanotube dispersion is 1:3) in deionized water. After uniform dispersion, add carboxylated cellulose nanofibers and bacterial nanocellulose (the dry weight mass ratio of the two is 1:3). After uniform dispersion, obtain the mixed system B.

[0051] When the positive electrode active material powder is LFP: Step (2): Disperse the multi-walled carbon nanotube dispersion and the single-walled carbon nanotube powder (the mass ratio of multi-walled carbon nanotubes and single-walled carbon nanotube powder in the multi-walled carbon nanotube dispersion is 1:3) in deionized water, and obtain the mixed system B after uniform dispersion.

[0052] Step (3): Mix system A and system B evenly to obtain system C. Add softwood fiber pulp to system C and disperse evenly to obtain paper base pulp.

[0053] Step (4): The paper-based pulp is vacuum filtered and then dehydrated by vacuum hot pressing to obtain a high-capacity lithium-ion flexible paper-based cellulose-based cathode.

[0054] When the active electrode material is lithium titanate or graphite, the preparation method of the electrode includes: (1) Preparation steps of coated cellulose-based electrode (Type I): Disperse the negative electrode active material powder (LTO or graphite) in the binder aqueous solution, and obtain a mixed system A after uniform dispersion.

[0055] Step (2): Disperse the conductive agent (multi-walled carbon nanotube dispersion, or a combination of it and single-walled carbon nanotubes) and lithium cellulose nanocrystals in deionized water, and obtain mixed system B after uniform dispersion.

[0056] Step (3): Mix system A and system B evenly to obtain system C. Add styrene-butadiene rubber (SBR) emulsion to system C and stir evenly to obtain coating slurry.

[0057] Step (4): Coating slurry onto a current collector (such as copper foil) and drying it in a vacuum drying oven at 100 ℃ for 12 hours to obtain a coated cellulose-based negative electrode.

[0058] (2) Preparation steps of paper-based cellulose-based electrode (Type II): Disperse the negative electrode active material powder (LTO or graphite) in the binder aqueous solution, and obtain the mixed system A after uniform dispersion.

[0059] Step (2): When the active material is lithium titanate: disperse multi-walled carbon nanotube dispersion and single-walled carbon nanotube powder (the mass ratio of multi-walled carbon nanotubes to single-walled carbon nanotube powder in the multi-walled carbon nanotube dispersion is 1:3) in deionized water, add carboxylated cellulose nanofiber slurry and bacterial nanocellulose slurry (the mass ratio of carboxylated cellulose nanofibers to bacterial nanocellulose is 1:3), and disperse evenly to obtain system B.

[0060] When the active material is graphite: no conductive agent; Step (3): Mix system A and mixed system B evenly to obtain mixed system C, add softwood fiber pulp to mixed system C and disperse evenly to obtain paper base pulp.

[0061] Step (4): The paper-based pulp is vacuum filtered and then dehydrated by vacuum hot pressing to obtain a high-capacity lithium-ion flexible paper-based cellulose-based anode.

[0062] Dispersion Process: In the above steps, the dispersion method is a combination of mechanical stirring and ultrasonic dispersion. The mechanical stirring speed is 500~800 r / min. -1 The ultrasonic power was 80%, and the ultrasonic time was controlled at 20-30 minutes.

[0063] Hot pressing process: The vacuum hot pressing temperature of the paper-based cellulose-based electrode (Type II) is 60~120 ℃, and the vacuum degree is -0.05~-0.1 MPa.

[0064] The cellulose-based electrode prepared by the above method has an active material content that can be controlled at 93%–97% and an areal capacity that can be controlled at 2 mAh cm⁻¹. -2 ~12mAh cm -2 .

[0065] This invention also discloses the application of the high-capacity cellulose-based electrode in lithium-ion batteries. The cellulose electrode is directly used as the positive electrode of the battery, placed inside the battery casing, with a lithium sheet as the counter electrode and a polyethylene membrane as the separator. The resulting lithium-ion battery exhibits superior electrochemical performance. Alternatively, a cellulose-based full cell can be assembled, using a porous polyethylene membrane as the separator to obtain a lithium-ion full cell.

[0066] The technical means disclosed in this invention are not limited to the active electrode materials selected in the above-described embodiments, but can also be applied to paper-based lithium-ion batteries prepared from NCM ternary materials and other active electrode materials such as silicon-carbon.

[0067] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading this description, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0068] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under standard conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications in the art, unless otherwise stated.

[0069] In Example 1, step (1) is to prepare an aqueous solution of sodium carboxymethyl cellulose (CMC-Na) with a concentration of about 0.4 wt% (10.8 mg CMC-Na is added to 2.6 g of deionized water and stirred for 5 min at 50 °C and 500 r / min until completely dissolved). 1.0 g of lithium iron phosphate (LFP) powder is added to the CMC-Na aqueous solution and dispersed evenly to obtain mixed system A.

[0070] Step (2): Take 10.8 mg of conductive agent (135 mg, 2.0 wt% multi-walled carbon nanotube (MWCNT) dispersion (the mass of multi-walled carbon nanotubes is 2.7 mg) and mix with 8.1 mg of single-walled carbon nanotube (SWCNT) powder. Treat with an ultrasonic cell disruptor (power 80%) for 5 min, repeat 3 to 5 times; then add 102.8 mg, 10.5 wt% lithium cellulose nanocrystal slurry (the content of lithium cellulose nanocrystals is 10.8 mg), and continue to sonicate for 5 min to obtain mixed system B.

[0071] Step (3): Mix system A and system B, and stir continuously at 700 r / min for 6 h until the slurry is uniform to obtain system C. Add 44.3 mg of 48.5 wt% styrene-butadiene rubber (SBR) emulsion (of which the mass of styrene-butadiene rubber is 21.5 mg) to system C, and stir at a low speed of 300 r / min for 15 min to obtain coating slurry.

[0072] Step (4): Use a doctor blade coater to evenly coat the coating slurry onto a carbon-coated aluminum foil with a length of 26 mm and a width of 7.5 mm, and control the wet film thickness at 500 μm. Transfer the coated electrode to a vacuum drying oven and dry it at 100°C and a vacuum of -0.1 MPa for 12 hours to obtain a lithium iron phosphate coated cellulose-based electrode.

[0073] The areal capacity of the lithium iron phosphate coated cellulose-based electrode prepared in this embodiment is 2 mAh cm⁻¹. -2 The mass percentage of the electrode active material is 95%.

[0074] Cut lithium iron phosphate coated cellulose-based electrodes were used as the positive electrode material for lithium-ion batteries and placed inside a CR2016 battery casing. Lithium foil was used as the counter electrode, polyethylene film as the separator, and 1M LiTFSI + 0.4M LiNO3 in DOL was used as the electrolyte to assemble the battery. The tested constant current charging cutoff voltage was 3.7V, the constant voltage charging current cutoff was 0.1C, and the constant current discharging cutoff voltage was 2.5V. The discharge was carried out at 0.1C (1C = 145 mAh g⁻¹). -1 Three charge-discharge activation cycles were performed, and charge-discharge rate tests were conducted at 0.3 C, 0.5 C, 1 C, 2 C, 3 C, 4 C, and 0.5 C. A charge-discharge cycle test was conducted at 4 C.

[0075] In Example 2, step (1) is to prepare a CMC-Na aqueous solution with a concentration of approximately 0.2 wt% (4.5 mg of CMC-Na is added to 2.6 g of deionized water and stirred for 5 min at 50℃ and 500 r / min until completely dissolved); 857.0 mg of lithium iron phosphate powder is added to the CMC-Na aqueous solution and dispersed evenly to obtain mixed system A.

[0076] Step (2): Take 8.3 mg of conductive agent (105 mg, 2.0 wt% multi-walled carbon nanotube (MWCNT) dispersion (MWCNT mass is 2.1 mg) and mix with 6.2 mg of single-walled carbon nanotube (SWCNT) powder, and treat with an ultrasonic cell disruptor (power 80%) for 5 min, repeat 3-5 times). Then add 42.9 mg, 10.5 wt% lithium cellulose nanocrystal slurry (of which the lithium cellulose nanocrystal content is 4.5 mg), and continue to sonicate for 5 min to obtain mixed system B.

[0077] Step (3): Mix system A and mix system B, and stir continuously at 700 r / min for 6 h until the slurry is uniform to obtain mix system C. Add 18.4 mg of 48.5 wt% styrene-butadiene rubber (SBR) emulsion (of which the mass of styrene-butadiene rubber is 8.9 mg) to mix system C, and stir at a low speed of 300 r / min for 15 min to obtain coating slurry.

[0078] Step (4) is the same as step 4 in Example 1. A lithium iron phosphate coated cellulose-based electrode is obtained.

[0079] The areal capacity of the lithium iron phosphate coated cellulose-based electrode prepared in this embodiment is 2 mAh cm⁻¹. -2 The mass percentage of the electrode active material is 97%.

[0080] Cut lithium iron phosphate coated cellulose-based electrodes were used as the positive electrode material for lithium-ion batteries and placed inside a CR2016 battery casing. Lithium foil was used as the counter electrode, polyethylene film as the separator, and 1M LiTFSI + 0.4M LiNO3 in DOL was used as the electrolyte to assemble the battery. The tested constant current charging cutoff voltage was 3.7V, the constant voltage charging current cutoff was 0.1C, and the constant current discharging cutoff voltage was 2.5V. The discharge was carried out at 0.1C (1C = 145 mAh g⁻¹). -1 Three charge-discharge activation cycles were performed, and charge-discharge rate tests were conducted at 0.3 C, 0.5 C, 1 C, 2 C, 3 C, 4 C, and 0.5 C, as well as a charge-discharge cycle test at 1 C.

[0081] Example 3 Positive electrode (lithium iron phosphate paper-based cellulose-based electrode, areal capacity 6 mAh cm⁻¹) -2 Step (1): Prepare an aqueous solution of sodium carboxymethyl cellulose (CMC-Na) with a concentration of approximately 0.2 wt% (50.0 mg CMC-Na dissolved in 30.0 mL deionized water, placed on a magnetic stirrer and stirred at 40℃ and 500 r min). -1Stir at a certain speed for 5 minutes); add 13.0 g of lithium iron phosphate powder to the CMC-Na aqueous solution and disperse evenly to obtain mixed system A.

[0082] Step (2): Take 135.5 mg of conductive agent (1695 mg, 2.0 wt% multi-walled carbon nanotube (MWCNT) dispersion (the mass of multi-walled carbon nanotubes is 33.9 mg) and 101.6 mg of single-walled carbon nanotube (SWCNT) powder and add them to 80.0 mL of deionized water. Treat in an ultrasonic cell disruptor (power 80%) for 5 min and repeat 3 to 5 times under ice bath conditions. This is the mixed system B.

[0083] Step (3): Mix system A and system B evenly to obtain system C. Add 1981.1 mg of 18.0 wt% softwood fiber pulp (softwood fiber mass is 356.6 mg, freeness 90°RS) to system C at 500 rpm. -1 Stir for about 10 minutes until the mixture is uniform to obtain paper-based pulp.

[0084] Step (4): The obtained paper-based pulp is filtered through a 0.45 μm filter membrane, and then... Under a vacuum pressing environment of 0.09 MPa, the paper-based cellulose electrode was dried at 105℃ for 10 min and then at 120℃ for 10 h to obtain a lithium iron phosphate paper-based cellulose electrode.

[0085] The areal capacity of the lithium iron phosphate paper-based cellulose electrode prepared in this embodiment is 6 mAh cm⁻¹. -2 The mass percentage of the electrode active material is 96%.

[0086] Negative electrode (graphite paper-based cellulose-based electrode, areal capacity 6 mAh cm⁻¹) -2 Step (1): Prepare a CMC-Na aqueous solution with a concentration of approximately 0.2 wt% (50.0 mg CMC-Na dissolved in 30.0 mL of deionized water, placed on a magnetic stirrer and heated at 40 °C and 500 r / min). -1 Stirring at a certain speed for 5 min), add 5.9 g of graphite powder to the CMC-Na aqueous solution and disperse evenly to obtain mixed system A.

[0087] Step (2): Take 12.3 mg of conductive agent (154.3 mg, 2.0 wt% multi-walled carbon nanotube (MWCNT) dispersion (MWCNT mass is 3.1 mg) and 9.2 mg single-walled carbon nanotube (SWCNT) powder are added to 80.0 mL of deionized water, treated in an ultrasonic cell disruptor (power 80%) for 5 min, and repeated 3 to 5 times under ice bath conditions), add 4545.5 mg, 2.2 wt% filamentous cellulose fiber slurry (filamentous cellulose fiber mass is 100.0 mg), and stir at 500 r / min to obtain mixed system B.

[0088] Step (3): Mix system A and system B evenly to obtain system C. Add 555.6 mg of 18.0 wt% softwood fiber pulp (softwood fiber mass is 100.0 mg, freeness 90°RS) to system C at 500 rpm. -1 Stir for about 10 minutes until the mixture is uniform to obtain paper-based pulp.

[0089] Step (4) is the same as step (4) of the positive electrode in Example 3, to obtain a graphite paper-based cellulose-based electrode.

[0090] The areal capacity of the graphite paper-based cellulose-based electrode prepared in this embodiment is 6 mAh cm-2, and the mass ratio of the electrode active material is 96%.

[0091] Lithium iron phosphate (LFP) paper-based cellulose electrodes and graphite paper-based cellulose electrodes were cut into 12mm diameter sheets. Using a CR2016 battery case and a polyethylene film separator, LFP / / Gr full cells were assembled with 2M LiTFSI + 0.4M LiNO3inDOL as the electrolyte. The assembled LFP / / Gr full cells were tested, and the constant current charging cutoff voltage was 3.7V, the constant voltage charging current cutoff was 0.1C, and the constant current discharging cutoff voltage was 2.5V. The discharge was carried out at 0.1C (1C = 145 mAh g⁻¹). -1 It was activated by three charge-discharge cycles, and then subjected to charge-discharge cycle tests and rate tests at 1C.

[0092] Example 4 Positive electrode (lithium iron phosphate paper-based cellulose-based electrode, areal capacity 12 mAh cm⁻¹) -2 Step (1): Prepare an aqueous solution of CMC-Na with a concentration of approximately 0.2 wt% (100.0 mg CMC-Na dissolved in 60.0 mL of deionized water, placed on a magnetic stirrer and stirred at 40℃ and 500 r min). -1 Stir at a certain speed for 5 min); add 26 g of lithium iron phosphate powder to the CMC-Na aqueous solution and disperse evenly to obtain mixed system A.

[0093] Step (2): Take 271 mg of conductive agent (3390 mg, 2.0 wt% multi-walled carbon nanotube (MWCNT) dispersion (the mass of multi-walled carbon nanotubes is 67.8 mg) and 203.2 mg single-walled carbon nanotube (SWCNT) powder and add them to 80.0 mL of deionized water. Treat with an ultrasonic cell disruptor (power 80%) for 5 min and repeat 3 to 5 times under ice bath conditions. This is the mixed system B.

[0094] Step (3): Mix system A and system B evenly to obtain system C. Add 3962.2 mg of 18.0 wt% softwood fiber pulp (softwood fiber mass is 713.2 mg, freeness 90°RS) to system C at 500 rpm. -1 Stir for about 10 minutes until the mixture is uniform to obtain paper-based pulp.

[0095] Step (4): The same positive electrode step (4) of Example 3 is used to obtain the lithium iron phosphate paper-based cellulose electrode.

[0096] The areal capacity of the lithium iron phosphate paper-based cellulose electrode prepared in this embodiment is 12 mAh·cm⁻¹. -2 The mass percentage of the electrode active material is 96%.

[0097] Negative electrode (graphite paper-based cellulose-based electrode, areal capacity 12 mAh cm⁻¹) -2 Step (1): Prepare a CMC-Na aqueous solution with a concentration of approximately 0.2 wt% (100.0 mg CMC-Na dissolved in 60.0 mL of deionized water, stirred on a magnetic stirrer at 40℃ and 500 r / min for 5 min). Add 11.9 g of graphite powder to the CMC-Na aqueous solution and disperse evenly to obtain mixed system A.

[0098] Step (2): Take 24.6 mg of conductive agent (308.6 mg, 2.0 wt% multi-walled carbon nanotube (MWCNT) dispersion (MWCNT mass is 6.2 mg) and 18.4 mg single-walled carbon nanotube (SWCNT) powder and add them to 80.0 mL of deionized water. Treat with an ultrasonic cell disruptor (power 80%) for 5 min and repeat 3-5 times under ice bath conditions. Add 9091 mg of 2.2 wt% filamentous cellulose fiber slurry (filamentous cellulose fiber mass is 200.0 mg) and stir at 500 r / min to obtain mixed system B.

[0099] Step (3): Mix system A and system B evenly to obtain system C. Add 1111.2 mg of 18.0 wt% softwood fiber pulp (softwood fiber mass is 200.0 mg, freeness 90°RS) to system C and spray at 500 rpm. -1 Stir for about 10 minutes until the mixture is uniform to obtain paper-based pulp C.

[0100] Step (4): The same positive electrode step (4) of Example 3 is used to obtain the graphite paper-based cellulose-based electrode.

[0101] Electrodes prepared from lithium iron phosphate paper-based cellulose electrodes and graphite paper-based cellulose electrodes were cut into 12mm diameter plates. Using a CR2016 battery case and a polyethylene film as the separator, LFP / / Gr full cells were assembled using 2M LiTFSI + 0.4M LiNO3in DOL as the electrolyte.

[0102] The assembled LFP / / Gr full cell was tested with a constant current charging cutoff voltage of 3.7V, a constant voltage charging current cutoff of 0.1C, and a constant current discharging cutoff voltage of 2.5V, at 0.1C (1C = 145 mAhg). -1 It was activated by three charge-discharge cycles, followed by 0.5C and 1C discharge cycle tests and rate tests.

[0103] Example 5, step (1): Prepare an aqueous solution of CMC-Na with a concentration of approximately 0.2 wt% (25.0 mg CMC-Na dissolved in 15.0 mL of deionized water, placed on a magnetic stirrer and stirred at 40°C and 500 r / min). -1 Stirring at a certain speed for 5 min); Add 6.6 g of lithium manganese iron phosphate (LMFP) powder to the CMC-Na aqueous solution, and stir at a magnetic stirrer at 500 r / min, 50℃, for 5 min to obtain mixed system A.

[0104] Step (2): Take 69 mg of conductive agent (add 865 mg of 2.0 wt% multi-walled carbon nanotube (MWCNT) dispersion (MWCNT mass is 17.3 mg) and 51.7 mg of single-walled carbon nanotube (SWCNT) powder to 60.0 mL of deionized water, and treat in an ultrasonic cell disruptor (power 80%) for 5 min, repeat 3-5 times), add 500 mg of 1 wt% carboxylated cellulose nanofiber slurry (of which carboxylated cellulose nanofiber mass is 5 mg) and 10 mL of deionized water and continue ultrasonic disruption for 5 min, then add 1875 mg of 0.8 wt% bacterial nanocellulose slurry (bacterial nanofiber mass is 15 mg) and add deionized water to 90.0 mL, and ultrasonic disruption for 5 min to obtain mixed system B.

[0105] Step (3): Mix system A and system B evenly to obtain system C. Add 898.9 mg of 18.0 wt% softwood fiber pulp (softwood fiber mass is 161.8 mg, freeness 90°RS) to system C at 500 rpm. -1 Stir for about 10 minutes until the mixture is uniform to obtain paper-based pulp.

[0106] Step (4) is the same as the positive electrode step (4) in Example 3 to obtain the lithium manganese iron phosphate paper-based cellulose-based electrode.

[0107] The areal capacities of the lithium manganese iron phosphate paper-based cellulose electrodes prepared in this embodiment are 3 mAh·cm⁻¹. -2 The mass percentage of the electrode active material is 96%.

[0108] Cut lithium manganese iron phosphate paper-based cellulose-based electrodes were used as the positive electrode material for lithium-ion batteries and placed inside a CR2016 battery casing. Lithium foil was used as the counter electrode, polyethylene film as the separator, and 1M LiTFSI + DOL / DME (v / v = 1 / 1) was used as the electrolyte to assemble the battery. The tested constant current charging cutoff voltage was 4.5V, the constant voltage charging current cutoff was 0.1C, and the constant current discharging cutoff voltage was 2.5V. The discharge was carried out at 0.1C (1C = 150 mAh·g⁻¹). -1 Three charge-discharge activation cycles were performed, followed by a charge-discharge cycle test at 0.5 C.

[0109] Example 6, step (1): Prepare a CMC-Na aqueous solution with a concentration of approximately 0.2 wt% (25.0 mg CMC-Na dissolved in 15.0 mL of deionized water, stirred on a magnetic stirrer at a speed of 500 r / min). -1 5.89 g of lithium titanate powder was added to CMC-Na aqueous solution at 50℃ for 5 min and dispersed evenly to obtain mixed system A.

[0110] Step (2): Take 61.4 mg of conductive agent (767 mg, 2.0 wt% multi-walled carbon nanotube (MWCNT) dispersion (of which the mass of multi-walled carbon nanotubes is 15.3 mg) and 46.1 mg single-walled carbon nanotube (SWCNT) powder and add them to 60.0 mL of deionized water. Process in an ultrasonic cell disruptor (power 80%) for 5 min, repeat 3 to 5 times. Add 500 mg, 1 wt% carboxylated cellulose nanofiber slurry (the mass of carboxylated cellulose nanofibers is 5 mg) and 10 mL of deionized water and continue ultrasonic disruption for 5 min. Then add 1875 mg, 0.8 wt% bacterial nanocellulose slurry (the mass of bacterial nanofibers is 15 mg) and add deionized water to 90.0 mL. Sonicate for 5 min to obtain mixed system B.

[0111] Step (3): Mix system A and system B evenly to obtain system C. Add 775.6 mg of 18.0 wt% softwood fiber pulp (softwood fiber mass is 139.6 mg, freeness 90°RS) to system C at 500 rmin. -1 Stir for about 10 minutes until the mixture is uniform to obtain paper-based pulp.

[0112] Step (4) is the same as the positive electrode step (4) in Example 3, to obtain a lithium titanate paper-based cellulose electrode.

[0113] The areal capacities of the lithium titanate paper-based cellulose-based electrodes prepared in this embodiment are 3 mAh / cm². -2 The mass percentage of the electrode active material is 96%.

[0114] Cut lithium titanate paper-based cellulose-based electrodes were used as the negative electrode material for lithium-ion batteries and placed inside a CR2016 battery casing. Lithium foil was used as the counter electrode, polyethylene film as the separator, and 1M LiTFSI + DOL / DME (v / v = 1 / 1) was used as the electrolyte to assemble the battery. The tested constant current discharge cutoff voltage was 1 V, and the constant current charging cutoff voltage was 2.5 V, at 0.1 C (1C = 160 mAh·g). -1 Three charge-discharge activation cycles were performed, followed by a charge-discharge cycle test at 0.5 C.

[0115] In Example 7, the cellulose-based electrodes prepared in Examples 5 and 6 were cut into 12 mm diameter plates. Using a CR2016 battery case, a polyethylene film as the separator, and 1 M LiTFSI + DOL / DME (v / v = 1 / 1) as the electrolyte, an LMFP / / LTO full cell was assembled.

[0116] The assembled LMFP / / LTO full cell was tested with a constant current charging cutoff voltage of 3V, a constant voltage charging current cutoff of 0.1C, and a constant current discharging cutoff voltage of 1V, at a rate of 0.1C (1C = 150 mAh·g). -1 Three charge-discharge activation cycles were performed, followed by charge-discharge cycle tests at 0.5C, 1C, and 2C, and rate tests were conducted.

[0117] Figures 1 and 2 show the SEM images and physical images of the samples prepared in Examples 5 and 6. In Figures 1 and 2a, the SEM image and physical image of Example 5 are shown; in Figures 1 and 2b, the SEM image and physical image of Example 6 are shown. As can be seen from the figures, cellulose and carbon nanotubes are the main mechanical support and conductive framework of the paper-based cellulose electrode, and the active material is uniformly distributed within the paper-based cellulose electrode. The paper-based cellulose electrode contains a rich porous structure and maintains a certain degree of flexibility.

[0118] Figure 3 shows the first-cycle constant-current charge-discharge curves of half-cells and full cells prepared according to different examples of the present invention. The results show that the electrodes prepared according to the present invention exhibit excellent and versatile electrochemical performance. Whether it is the coated LFP electrode or the paper-based graphite, LMFP, or LTO electrode, they all exhibit a flat voltage plateau and a specific capacity close to the theoretical value (approximately 160 mAh g⁻¹ for LFP). -1 Graphite approximately 350 mAh g -1 The high first-cycle coulombic efficiency demonstrates that cellulose-based conductive networks can effectively adapt to various positive and negative electrode materials; especially when the areal capacity of LFP paper-based cellulose-based electrodes increases from 6 mAh cm⁻¹ -2 Doubled to 12 mAh cm -2 When using ultra-thick electrodes, polarization only increases slightly without significant capacity decay. This is attributed to the unique porous structure and three-dimensional conductive network of the paper-based material, which greatly improves electrolyte wettability and electron / ion transport efficiency, successfully overcoming the kinetic limitations of traditional thick electrodes. In addition, the LMFP / / LTO full cell operates stably, further verifying the application potential of this technology in practical high-energy-density flexible batteries.

[0119] Figure 4 illustrates the excellent rate performance of the electrodes of this invention. The coated cellulose-based electrodes (Examples 1 and 2) retain approximately 130 mAh g⁻¹ even at current densities up to 4C. -1 and 155 mAh g -1 The reversible capacity demonstrates the enhancing effect of lithium-ionized cellulose nanocrystals on high-rate conductive networks; paper-based cellulose-based electrodes (Examples 3-6) also exhibit stability over a wide rate range, especially high-load electrodes (Example 4, 12 mAh cm⁻¹). -2The rapid capacity recovery after a high current impact confirms that the porous cellulose framework effectively alleviates the polarization and mass transfer limitations of thick electrodes; the excellent rate response of the full cell (Example 7) further verifies the practical value of this technology in balancing high energy density and high power output.

[0120] Figure 5 shows the long-term cycling performance of the half-cell and full-cell prepared by this invention at different rates. The test results show that the coated cellulose-based electrodes (Examples 1 and 2) exhibit stable cycling curves at high rates (4C / 1C) with almost no capacity decay; especially the paper-based cellulose-based electrode (Example 4) shows excellent cycling performance at ultra-high loading rates (12 mAh cm⁻¹). -2 The capacity retention rate was 68% after 1000 cycles at 0.5C; the LMFP / / LTO full cell also achieved stable cycling for thousands of cycles at rates from 0.5C to 2C. This excellent cycling stability is mainly attributed to the introduction of lithium-ionized cellulose nanocrystals, which significantly enhances the mechanical strength and interfacial adhesion of the binder network, effectively suppressing the shedding of active materials under high-rate impact; at the same time, the unique dense cellulose / carbon nanotube porous framework of the paper-based material provides a strong mechanical interlocking effect and efficient ion transport channels, successfully overcoming the technical bottleneck of traditional high-load thick electrodes that are prone to pulverization failure due to intensified polarization and volume expansion.

[0121] Figure 6 shows the AC impedance spectra of Example 5 (LMFP half-cell), Example 6 (LTO half-cell), and Example 7 (full cell). The curves all exhibit typical high-frequency semicircles (representing charge transfer impedance) and low-frequency slopes (representing ion diffusion impedance). Notably, Example 7 exhibits a smaller semicircle diameter and a steeper low-frequency slope, indicating that the full-cell system possesses extremely low interfacial charge transfer resistance and excellent solid-state diffusion kinetics. This superior low impedance characteristic is mainly attributed to the unique porous structure and three-dimensional conductive network of the cellulose paper-based cellulose electrode. The former significantly improves the electrolyte wetting efficiency and shortens the ion transport path, while the latter ensures rapid electron conduction between the active particles and the current collector, thereby effectively reducing battery polarization and providing a solid kinetic foundation for achieving high-rate output and long cycle life.

[0122] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values; these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. In the following, various technical solutions can, in principle, be combined with each other to obtain new technical solutions, which should also be considered as specifically disclosed herein.

[0123] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still make modifications or equivalent substitutions to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the protection scope of the claims of the present invention pending approval.

Claims

1. A method for preparing a cellulose-based electrode, characterized in that, The process includes the following steps: dispersing the active electrode material in an aqueous binder solution to obtain a mixed system A; dispersing the conductive agent and cellulose in deionized water to obtain a mixed system B; mixing mixed system A and mixed system B uniformly to obtain a mixed system C, which is then formed by any of the following methods: coating forming: adding a binder to mixed system C to obtain a coating slurry, coating the coating slurry onto a current collector and drying it to obtain a coated cellulose-based electrode; paper-based forming: adding cellulose to mixed system C to obtain a paper-based slurry, vacuum filtering the paper-based slurry, and then dehydrating it by vacuum hot pressing to obtain a paper-based cellulose-based electrode.

2. The method for preparing the cellulose-based electrode according to claim 1, characterized in that, The active electrode material is a positive electrode active material or a negative electrode active material; the positive electrode active material includes one or more of lithium iron phosphate, lithium manganese iron phosphate, nickel cobalt manganese ternary materials or lithium cobalt oxide; the negative electrode active material includes one or more of graphite, lithium titanate or silicon carbon.

3. The method for preparing the cellulose-based electrode according to claim 1, characterized in that, The adhesive includes one or more of carboxymethyl cellulose, sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, sodium alginate, styrene-butadiene rubber, or acrylonitrile copolymer.

4. The method for preparing the cellulose-based electrode according to claim 1, characterized in that, The cellulose includes one or more of lithium cellulose nanocrystals, carboxylated cellulose nanofibers, bacterial nanocellulose, filamentous cellulose fibers, or coniferous wood fibers; wherein the beating degree of the coniferous wood fibers is not less than 90°RS.

5. The method for preparing the cellulose-based electrode according to claim 1, characterized in that, The conductive agent is one or both of multi-walled carbon nanotubes and single-walled carbon nanotubes.

6. The method for preparing a cellulose-based electrode according to claim 1, characterized in that, When preparing the coated cellulose-based electrode, the mass ratio of the active electrode material, binder, conductive agent and cellulose is (0.93~0.97):(0.015~0.035):(0.005~0.02):(0.001~0.015); the overall solid content of the coating slurry is 30.0%~60.0%.

7. The method for preparing the cellulose-based electrode according to claim 1, characterized in that, When preparing the paper-based cellulose-based electrode, the mass ratio of the active electrode material, binder, conductive agent and cellulose is (0.93~0.97):(0.001~0.01):(0.001~0.02):(0.02~0.05); the overall solid content of the paper-based pulp is 1.0%~20.0%.

8. The method for preparing the cellulose-based electrode according to claim 1, characterized in that, When preparing the paper-based cellulose-based electrode, the temperature of the vacuum hot pressing is 60℃~120℃, and the vacuum degree is -0.05~-0.1 MPa.

9. According to claim 1 The cellulose-based electrode obtained by the method for preparing the cellulose-based electrode according to any one of the claims 8.

10. The application of the cellulose-based electrode according to claim 9 in a lithium-ion battery.

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