Cement-based electrode, preparation method and cement-based battery

Abstract

The invention discloses a cement-based electrode and a preparation method thereof, and a cement-based battery, and the preparation method comprises the following steps: respectively preparing positive and negative cement-based slurries through deposition of magnetic particles on the surface of carbon fiber and dispersion of hydrogel: mixing a graphite plate, cement, Ni deposited carbon fiber, Ni-doped hydrogel, Ni (OH) and a water reducing agent, and stirring to obtain a mixture; the preparation method comprises the following steps: preparing a cement-based positive electrode by adjusting and controlling the orientation of fibers and hydrogel to be perpendicular to an electrode plane, mixing a graphite plate, cement, FeO deposited carbon fibers, FeO-doped hydrogel, FeO and a water reducing agent, injecting slurry into a mold with a pre-embedded wire, placing the mold in a numerical control magnetic field system, and adjusting and controlling the orientation of the fibers and hydrogel to be perpendicular to the electrode plane to obtain a cement-based negative electrode. Therefore, by doping the magnetic carbon fibers and the magnetic hydrogel and inducing the morphology of the directionally arranged carbon fibers and the hydrogel through the magnetic field, the key problem that the electronic conductivity and the ionic conductivity of the cement-based electrode are low is solved, and the storage capacity and the mechanical property of the rechargeable cement-based battery are improved through the cooperation of the magnetic carbon fibers and the magnetic hydrogel.

Description

Technical Field

[0001] The present invention relates to the field of cement-based batteries, in particular to electrodes of cement-based batteries. Background Art

[0002] Under the guidance of the "dual carbon" strategy, new energy has become a social hotspot. With the rapid development of new energy industries such as photovoltaics and wind power, and the need to improve energy efficiency, "energy storage," as a key link in the new energy industry chain, has attracted considerable attention. Existing lithium battery energy storage technology and equipment suffer from high costs, poor safety, and high pollution levels. The emergence of new energy storage technologies will undoubtedly stimulate the restructuring of power and energy infrastructure.

[0003] Integrated structural energy storage composite materials offer an effective solution. By integrating structural and energy storage functions, these materials achieve a dual breakthrough: While simultaneously fulfilling structural functions and possessing energy storage properties, they effectively enhance overall system performance, achieving quality optimization and intensive spatial utilization. Currently, two main technical approaches exist. While the embedded integration approach allows for functional integration through built-in energy storage devices, weak structural interfaces restrict mechanical performance. The intrinsic fusion approach, based on multifunctional materials, simultaneously enhances energy storage efficiency and structural load-bearing capacity through the design of continuous phases and dense interfaces within the material, demonstrating a more significant technological advantage. This material system not only promotes the transformation of building structures from "energy consumers" to "energy suppliers," but also lays the foundation for the development of cutting-edge technologies such as rechargeable cement-based batteries, providing key technical support for the construction of zero-carbon buildings and low-carbon cities.

[0004] At present, the application of rechargeable cement-based batteries is limited by problems such as low energy density, short service life, and high electron ion transfer resistance, making it difficult to break through the kinetic bottleneck of traditional cement-based electrodes. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a method for preparing a cement-based electrode.

[0006] A method for preparing a cement-based electrode according to an embodiment of the present invention comprises: S1, depositing magnetic particles Fe3O4 and metal Ni on the surface of carbon fibers respectively to obtain fibers oriented by magnetic field control; The Fe3O4 deposition method involves dissolving 0.01 mol Fe2+ and 0.02 mol Fe3+ ions in deionized water in an N2 atmosphere. The carbon fibers are then dispersed in the deionized water and heated with continuous stirring. NaOH is added to the solution to control the pH to >10, depositing Fe3O4 nanoparticles on the carbon fibers. Finally, after filtration and freeze-drying, the magnetic field-controlled oriented fibers, Fe3O4 / CF, are obtained. The metallic nickel deposition method involves applying an external current to reduce and deposit nickel ions onto the surface of conductive carbon fibers. The carbon fibers are electroplated in a Watts bath containing nickel sulfate (250-300 g / L), nickel chloride (30-60 g / L), and boric acid (pH 3-4) at a current density of 1-5 A / dm² and 50-60°C for 10-30 minutes. Finally, the coating is washed, dried, or annealed to obtain a nickel coating with strong adhesion and controllable thickness. The carbon fibers are straight and ≤5 mm in length. The mass ratio of Fe₃O₄ / Ni to carbon fibers is 20%-60% Fe₃O₄ / CFs.

[0007] The carbon fiber is straight and its length is ≤5mm; The mass ratio of Fe3O4 to carbon fiber is 20%~60%, and the mass ratio of Ni to carbon fiber is 20%~60%; S2, ultrasonically dispersing Fe3O4 and metallic Ni powder respectively, adding them into the hydrogel and mixing; wherein the hydrogel is one or more of polyacrylamide (PAM), alginate, polyvinyl alcohol (PVA), and polyacrylic acid (PAA), and the ultrasonic dispersion time is 20-60 min; S3, mixing the graphite plate, cement, Ni-deposited carbon fiber, Ni-doped hydrogel, Ni(OH)2, and water reducer with the dry mixture at a certain water-cement ratio to obtain a positive electrode cement-based slurry; S4, mixing the graphite plate, cement, Fe3O4 deposited carbon fiber, Fe3O4-doped hydrogel, Fe3O4, and a water reducer with the dry mixture at a certain water-cement ratio to obtain a negative electrode cement-based slurry; Specifically, the graphite plates are flake particles or flakes of graphite, with a transverse dimension of ≥20 μm; the graphite plates account for 0.1% to 0.3% of the mass of the cement; and the magnetic carbon fibers account for 0.3% to 0.5% of the mass of the cement; The cement is one or more selected from the group consisting of Portland cement, ordinary Portland cement, slag Portland cement, pozzolanic Portland cement, fly ash Portland cement, composite Portland cement, medium-heat Portland cement, low-heat slag Portland cement, and white Portland cement; The water reducer is a naphthalene-based high-efficiency water reducer; the water-cement ratio is 0.6-0.8, the mass of the water reducer accounts for 0.2%-0.4% of the mass of water; the stirring time is 20-25 minutes; S5. Pour the positive and negative electrode cement-based slurries into the mold for pre-embedded conductors and place them in a CNC coil magnetic field generating system. Regulate the arrangement of the carbon fibers and hydrogel to be perpendicular to the plane of the cement-based electrodes. The magnetic field frequency is <100 Hz. S6. Inserting a Ni mesh and an iron mesh into the positive and negative electrode cement-based slurry molds respectively, and curing after molding to obtain the cement-based positive and negative electrodes, wherein the curing temperature is 20±2° C. and the relative humidity is controlled at above 95%.

[0008] Specifically, in the above steps, the present invention realizes directional arrangement of magnetic carbon fibers perpendicular to the electrode plates to construct a linear conductive network. At the same time, in order to solve the problem of insufficient connection points between the magnetic carbon fibers, larger-sized graphite sheets are introduced as planar connection media, thereby forming a composite conductive system of "fiber-oriented conductive path + graphite transverse bridging", wherein the carbon fibers are like longitudinal "wires" to enhance the conductive efficiency in the thickness direction, and the graphite sheets are like transverse "connector plates" to fill the fiber gaps. The two work together to construct a three-dimensional conductive framework, which is conducive to breaking through the bottleneck problem of conductive efficiency attenuation of thick electrode plates.

[0009] In addition, since carbon fiber is expensive and has poor dispersibility, and although graphite is cheap and easy to incorporate, it requires a high dosage to form a conductive network, which can easily lead to increased porosity and decreased strength. Therefore, the present invention constructs a conductive frame through magnetic carbon fiber, and then forms a conductive network structure through bridging of graphite sheets. It can not only utilize the synergistic effect of magnetic carbon fiber and graphite to improve conductivity, but also reduce the amount of carbon fiber while ensuring conductivity. This avoids the high cost and difficult dispersion problems of single carbon fiber, and circumvents the degradation of mechanical properties caused by graphite, thereby achieving a balanced optimization between conductivity and mechanical properties.

[0010] Furthermore, since ion transport efficiency depends on the connectivity of the pore structure, an unobstructed pore network facilitates the rapid migration of ions such as hydroxide ions, thereby promoting ion transport. Conversely, if the pore tortuosity is too high or closed pores are formed, the ion transport polarization will be significantly increased, resulting in power density attenuation.

[0011] Therefore, the present invention utilizes the action of a magnetic field to magnetize ferroferric oxide nanoparticles and metallic Ni powder, generating magnetic dipole interactions and forming chain-like or fibrous arrangements along the direction of the magnetic field. This arrangement overcomes the local elastic resistance of the hydrogel network, driving the overall deformation of the hydrogel to form a fibrous morphology extending along the direction of the magnetic field. As the hydration reaction proceeds, the CSH gel gradually wraps around the oriented structure and solidifies it into a permanent microstructure.

[0012] At this time, the hydrophilic groups of the hydrogel along the direction of the magnetic field adsorb free water molecules to form a hydration layer, providing a channel for ion migration. The tortuosity of the pores formed in this way is significantly reduced, and the constructed three-dimensional connected network reduces "dead-end pores", improves the efficiency of ion diffusion, thereby forming a "dual-channel" ion transmission, overcoming the problem of low ionic conductivity of cement-based materials.

[0013] At the same time, the active groups on the surface of the hydrogel combine with the cement hydration products through hydrogen bonds or ionic bonds, enhancing the interfacial bonding force, while the directionally arranged hydrogel is embedded in the cement pores, producing a mechanical anchoring effect, further improving the integrity of the structure.

[0014] Preferably, in the design of electrode materials, Fe3O4 introduced into the negative electrode and metal Ni introduced into the positive electrode both have the functions of magnetizing hydrogel and enhancing conductivity, effectively constructing a three-dimensional electronic conduction network.

[0015] Among them, for the negative electrode, Fe3O4 not only participates in the reversible reaction of Fe3O4+2OH⁻↔3FeO(OH)+e⁻ as an active substance, but also improves the electrode kinetics through the redox process; For the positive electrode, metallic Ni enhances the charge transfer efficiency through the in-situ generated Ni(OH)2 / NiOOH redox couple (Ni(OH)2↔NiOOH+H⁺+e⁻) on the surface under alkaline conditions. The Ni(OH)2 formed by its partial oxidation can also directly contribute to the electrochemical capacity, thereby achieving dual-electrode synergistic efficiency and comprehensively improving the overall performance of the battery.

[0016] According to a second aspect of an embodiment of the present invention, a cement-based electrode is prepared by the above-mentioned method for preparing a cement-based electrode.

[0017] According to a third aspect of the present invention, a cement-based battery employs the aforementioned cement-based electrodes. Specifically, a Ni mesh and an iron mesh are inserted into a mold for the positive and negative cement-based slurries, respectively. After forming and curing, the cement-based positive and negative electrodes are bonded together with an alkali separation layer to produce a rechargeable battery based on the cement-based electrodes. The alkali separation layer is prepared by weighing cement, sand (passing 200 mesh), and anion exchange resin, mixing them thoroughly to a mass ratio of 4:2:1 and a water-cement ratio of 0.5 to 0.8. The mixture is then mixed with 20% to 40% of a 10 mol / L to 20 mol / L alkaline solution in a blender, and stirred thoroughly to produce the alkali separation layer material.

[0018] Beneficial effects

[0019] The present invention deposits magnetic particles on the surface of carbon fiber and combines them with magnetic hydrogel for dispersion. After using numerically controlled magnetic fields to directionally control the arrangement of carbon fiber and hydrogel perpendicular to the electrode plane, ferroferric oxide and metallic Ni magnetic components are introduced. The magnetic field is then used to coordinate the carbon fiber magnetic particles to enhance the interface bonding. The network structure not only embeds carbon fiber and graphite plates to improve the dispersion uniformity, but also wraps the graphite sheets to optimize the matrix distribution. Finally, a three-dimensional conductive-ionic dual network of "fiber conductive path + graphite lateral bridging + hydrogel ion channel" is formed, realizing the parallel construction of ion / electron transmission channels on a microscopic scale, thereby breaking through the kinetic bottleneck of traditional cement-based electrodes and facilitating the improvement of the overall energy storage efficiency of cement-based batteries. DETAILED DESCRIPTION

[0020] The embodiments of the present invention are described in detail below.

[0021] Example 1

[0022] In this embodiment, cement-based electrodes and batteries are prepared according to the following steps: Fe3O4 and Ni were deposited on the surface of carbon fibers to form magnetic field-responsive fibers, and the corresponding electrode slurries (0.3% Ni fiber / 4% Ni(OH)2 hydrogel / 20% Ni(OH)2 for the positive electrode and 0.3% Fe3O4 fiber / 4% Fe3O4 hydrogel / 20% ferroferric oxide for the negative electrode) were added according to the mass of cement. The mixture was stirred with 0.3% graphite plate and a water reducer (0.4% water mass) at a water-cement ratio of 0.6 for 25 minutes. The slurry was injected into a mold and placed in a 100Hz magnetic field to align the fibers vertically. After forming, a Ni / iron current collector was inserted, and the positive and negative electrodes were bonded through an alkaline separation layer (cement: sand: resin = 4:2:1, containing 40% 15 mol / L alkaline solution, water-cement ratio 0.7), finally forming a rechargeable battery.

[0023] Example 2

[0024] In this embodiment, cement-based electrodes and batteries are prepared according to the following steps: Fe3O4 and Ni were deposited on the surface of carbon fibers to form magnetic field-responsive fibers. The corresponding electrode slurry (0.5% Ni fiber / 2% Ni(OH)2 hydrogel / 40% Ni(OH)2 for the positive electrode and 0.5% Fe3O4 fiber / 2% Fe3O4 hydrogel / 40% ferroferric oxide for the negative electrode) was added according to the mass of cement. The mixture was stirred with 0.1% graphite plate and water reducer (0.2% water mass) at a water-cement ratio of 0.8 for 20 minutes. The slurry was injected into a mold and placed in an 80Hz magnetic field to align the fibers vertically. After forming, a Ni / iron current collector was inserted and the positive and negative electrodes were bonded through an alkaline separation layer (cement: sand: resin = 4:2:1, containing 40% 15mol / L alkaline solution, water-cement ratio 0.7), finally forming a rechargeable battery.

[0025] Example 3

[0026] In this embodiment, cement-based electrodes and batteries are prepared according to the following steps: Fe3O4 and Ni were deposited on the surface of carbon fibers to form magnetic field-responsive fibers. The corresponding electrode slurry (0.4% Ni fiber / 3% Ni(OH)2 hydrogel / 30% Ni(OH)2 for the positive electrode and 0.4% Fe3O4 fiber / 3% Fe3O4 hydrogel / 30% ferroferric oxide for the negative electrode) was added according to the mass of cement. The mixture was stirred with 0.2% graphite plate and a water reducer (0.3% water mass) at a water-cement ratio of 0.7 for 22 minutes. The slurry was injected into a mold and placed in a 50Hz magnetic field to align the fibers vertically. After forming, a Ni / iron current collector was inserted, and the positive and negative electrodes were bonded through an alkaline separation layer (cement: sand: resin = 4:2:1, containing 40% 15mol / L alkaline solution, water-cement ratio 0.7), finally forming a rechargeable battery.

[0027] Comparative Example 1: In this example, cement-based electrodes and batteries were prepared according to the following steps. In this comparative example, the graphite sheets in Example 1 were replaced with carbon fibers of the same mass.

[0028] Fe3O4 and Ni were deposited on the surface of carbon fibers to form magnetic field-responsive fibers, and the corresponding electrode slurries (0.6% Ni fiber / 4% Ni(OH)2 hydrogel / 20% Ni(OH)2 for the positive electrode and 0.6% Fe3O4 fiber / 4% Fe3O4 hydrogel / 20% ferroferric oxide for the negative electrode) were added according to the mass of cement and stirred with a water reducer (0.4% water mass) at a water-cement ratio of 0.6 for 25 minutes. The slurry was injected into a mold and placed in a 100Hz magnetic field to align the fibers vertically. After forming, a Ni / iron current collector was inserted, and the positive and negative electrodes were bonded through an alkaline separation layer (cement: sand: resin = 4:2:1, containing 40% 15 mol / L alkaline solution, water-cement ratio 0.7), finally forming a rechargeable battery.

[0029] Comparative Example 2: In this example, a cement-based electrode and a battery were prepared according to the following steps. In this comparative example 2, 0.4% of carbon fiber was added to that in comparative example 1.

[0030] Fe3O4 and Ni were deposited on the surface of carbon fibers to form magnetic field-responsive fibers. The corresponding electrode slurry (the positive electrode contained 1% Ni fiber / 3% Ni(OH)2 hydrogel / 20% Ni(OH)2, and the negative electrode contained 1% Fe3O4 fiber / 3% Fe3O4 hydrogel / 20% ferroferric oxide) was added according to the mass of cement and stirred with a water reducer (0.4% water mass) at a water-cement ratio of 0.6 for 25 minutes. The slurry was injected into a mold and placed in a 100Hz magnetic field to align the fibers vertically. After forming, a Ni / iron current collector was inserted, and the positive and negative electrodes were bonded through an alkaline separation layer (cement: sand: resin = 4:2:1, containing 40% 15 mol / L alkaline solution, water-cement ratio 0.7), finally forming a rechargeable battery.

[0031] Comparative Example 3: In this example, cement-based electrodes and batteries were prepared according to the following steps. In this comparative example, the graphite sheets in Example 2 were replaced with carbon fibers of the same mass.

[0032] 0.6% graphite plate was added to the corresponding electrode slurry (positive electrode 2% Ni(OH)2 hydrogel / 40% Ni(OH)2, negative electrode containing 2% Fe3O4 hydrogel / 40% ferrosoferric oxide), and stirred with a water reducer (0.2% water mass) at a water-cement ratio of 0.8 for 20 minutes; the slurry was injected into the mold and placed in an 80Hz magnetic field to align the fibers vertically. After molding, a Ni / iron current collector was inserted, and the positive and negative electrodes were bonded through an alkaline separation layer (cement: sand: resin = 4:2:1, containing 40% 15mol / L alkaline solution, water-cement ratio 0.7), finally forming a rechargeable battery.

[0033] Comparative Example 4: In this embodiment, cement-based electrodes and batteries were prepared according to the following steps. In this comparative example, 10 times more graphite sheets were added than in comparative example 3.

[0034] 6% graphite plates were added to the corresponding electrode slurry (the positive electrode contained 2% Ni(OH)2 hydrogel / 40% Ni(OH)2, and the negative electrode contained 2% Fe3O4 hydrogel / 40% ferroferric oxide), and stirred with a water reducer (0.2% water mass) at a water-cement ratio of 0.8 for 20 minutes; the slurry was injected into the mold and placed in an 80Hz magnetic field to align the fibers vertically. After molding, a Ni / iron current collector was inserted, and the positive and negative electrodes were bonded through an alkaline separation layer (cement: sand: resin = 4:2:1, containing 40% 15mol / L alkaline solution, water-cement ratio 0.7), finally forming a rechargeable battery.

[0035] Comparative Example 5: In this example, cement-based electrodes and batteries were prepared according to the following steps, wherein no magnetic material was added to the hydrogel in this comparative example.

[0036] Fe3O4 and Ni were deposited on the surface of carbon fibers to form magnetic field-responsive fibers, and the corresponding electrode slurries (0.4% Ni fiber / 3% Ni(OH)2 hydrogel / 30% Ni(OH)2 for the positive electrode and 0.4% Fe3O4 fiber / 3% Fe3O4 hydrogel / 30% ferroferric oxide for the negative electrode) were added according to the mass of cement. The mixture was stirred with 0.2% graphite plate and a water reducer (0.3% water mass) at a water-cement ratio of 0.7 for 22 minutes. The slurry was injected into a mold and placed in a 50Hz magnetic field to align the fibers vertically. After forming, a Ni / iron current collector was inserted, and the positive and negative electrodes were bonded through an alkaline separation layer (cement: sand: resin = 4:2:1, containing 40% 15mol / L alkaline solution, water-cement ratio 0.7), finally forming a rechargeable battery.

[0037] The compressive and flexural strengths were measured according to GB / T 5348, and the 28-day strength was recorded.

[0038] A uniform electrode slurry was poured into a 1 cm³ cubic mold, and two copper plates were inserted into the mold's two edges to test the ionic and electronic conductivity of the cement-based electrode. Constant current charge and constant resistance discharge tests were performed on the cement-based battery using a Xinwei battery tester. The charge current was 50 mA, the charge time was 30 min, the discharge load was 100 Ω, and the discharge cutoff current was 1 mA. The energy density and capacity decay rate after 10 cycles were calculated.

[0039] ; According to the data of Example 1, Comparative Example 1 and Comparative Example 2 in the above table, it can be seen that when the graphite sheets in the electrode material are replaced with carbon fibers of equal mass using the preparation process of this patent, the electronic conductivity can be increased by 47.08%. Further comparison shows that in order to achieve the synergistic effect of the composite incorporation of graphite sheets and carbon fibers, it is necessary to add additional carbon fibers equivalent to 0.4% of the mass of cement for compensation. This fully proves that graphite sheets play a key role in magnetic field-oriented electrode systems: their unique two-dimensional structure effectively compensates for the node connection defects caused by the parallel orientation of carbon fibers, and by constructing a three-dimensional conductive network, the amount of carbon fibers used is significantly reduced, thereby optimizing material costs while improving conductive properties.

[0040] According to the data of Example 2, Comparative Example 3 and Comparative Example 4 in the above table, it can be seen that: the experimental data show that when the carbon fiber in the electrode is replaced with graphite sheets of equal mass using the preparation process of the present invention, the electronic conductivity is improved by two to three orders of magnitude compared with the single-doped graphite sheet system. Further comparison reveals that if the conductive performance of the multi-doped system is achieved by doping only a single graphite sheet, ten times the amount of graphite sheets needs to be added and the mechanical properties will be significantly deteriorated at the same time. The experimental results show that carbon fiber plays a key bridging role in the composite electrode: its unique one-dimensional structure effectively makes up for the conductive network defects of the graphite sheet dispersion system, and simultaneously improves the conductive efficiency and mechanical strength by constructing a long-range conductive channel, achieving a breakthrough optimization of the comprehensive performance of the material.

[0041] According to the data in Example 3 and Comparative Example 5 in the above table, compared with the unoriented system, its ionic conductivity is improved by 1-2 orders of magnitude, while the energy density is significantly improved and the capacity decay rate is effectively suppressed. This performance leap is due to the precise control of the microstructure by magnetic field orientation technology. By eliminating the pore dispersion and gel island phenomenon commonly found in traditional hydrogels, a three-dimensional through-hole network is successfully constructed, which greatly reduces the ion transmission resistance and optimizes the charge transport path, ultimately achieving a synergistic improvement in ion transmission efficiency and electrochemical stability.

[0042] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "example," "specific example," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0043] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A method for preparing a cement-based electrode, characterized in that: The preparation method comprises the following steps: The ferroferric oxide and metallic Ni powder are deposited on the surface of carbon fibers to obtain ferroferric oxide deposited carbon fibers and Ni deposited carbon fibers respectively. Ferroferric oxide and metallic Ni powder were ultrasonically dispersed and added into the hydrogel to obtain ferroferric oxide-doped hydrogel and Ni-doped hydrogel. The graphite plate, cement, the Ni-deposited carbon fiber, the Ni-doped hydrogel, Ni(OH)2, and a water reducer are mixed and stirred to obtain a positive electrode cement-based slurry; Mixing and stirring the graphite plate, cement, the ferroferric oxide-deposited carbon fiber, the ferroferric oxide-doped hydrogel, ferroferric oxide, and a water reducer to obtain a negative electrode cement-based slurry; The positive electrode cement-based slurry and the negative electrode cement-based slurry are respectively poured into the mold of the pre-embedded wire, and then placed in a CNC coil magnetic field generating system to regulate the arrangement direction of the Ni-deposited carbon fiber and the Ni-doped hydrogel to be perpendicular to the plane of the cement-based electrode. After the cement-based slurry is formed, a positive electrode cement-based electrode is obtained; and the arrangement direction of the ferroferric oxide-deposited carbon fiber and the ferroferric oxide-doped hydrogel is regulated to be perpendicular to the plane of the cement-based electrode. After the cement-based slurry is formed, a negative electrode cement-based electrode is obtained.

2. The method for preparing a cement-based electrode according to claim 1, characterized in that: The preparation method of depositing ferroferric oxide on the surface of carbon fiber comprises the following steps: In a nitrogen atmosphere, 0.01 mol Fe2+ and 0.02 mol Fe3+ ions were dissolved in deionized water, and then carbon fibers were dispersed in the deionized water and stirred continuously under heating conditions. After adding NaOH to the solution to control the solution pH>10, filtering and freeze-drying were performed to obtain ferroferric oxide deposited carbon fibers with orientation regulated by a magnetic field.

3. The method for preparing a cement-based electrode according to claim 1 or 2, characterized in that: The preparation method of depositing metallic Ni powder on the surface of carbon fiber comprises the following steps: reducing and depositing Ni ions on the surface of conductive carbon fiber by applying an external current, electroplating the carbon fiber in a Watt bath containing Ni sulfate, Ni chloride and boric acid at a current density of 1-5 A / dm² and 50-60°C for 10-30 minutes, and finally washing, drying or annealing to obtain a Ni coating.

4. The method for preparing a cement-based electrode according to claim 1, wherein: The cement is a combination of one or more of Portland cement, ordinary Portland cement, slag Portland cement, pozzolanic Portland cement, fly ash Portland cement, composite Portland cement, medium-heat Portland cement, low-heat slag Portland cement, and white Portland cement.

5. The method for preparing a cement-based electrode according to claim 1, characterized in that: The graphite plates are flake-shaped particles or flakes of graphite, and have a transverse extension size of ≥20 microns.

6. The method for preparing a cement-based electrode according to claim 1 or 5, characterized in that: The graphite plate accounts for 0.1% to 0.3% of the mass of the cement, the ferroferric oxide deposited carbon fiber accounts for 0.3% to 0.5% of the mass of the cement, the Ni deposited carbon fiber accounts for 0.3% to 0.5% of the mass of the cement, the ferroferric oxide accounts for 20% to 40% of the mass of the cement, and the Ni(OH)2 accounts for 20% to 40% of the mass of the cement.

7. The method for preparing a cement-based electrode according to claim 1, wherein: The hydrogel is a combination of one or more of polyacrylamide, alginate, polyvinyl alcohol, and polyacrylic acid, and the mass of the hydrogel accounts for 2% to 4% of the mass of the cement.

8. The method for preparing a cement-based electrode according to claim 1, characterized in that: The water reducer is a naphthalene-based high-efficiency water reducer, and the mass of the water reducer accounts for 0.2% to 0.4% of the mass of water.

9. A cement-based electrode, characterized in that: A cement-based electrode prepared by the method for preparing a cement-based electrode according to any one of claims 1 to 8.

10. A cement-based battery, characterized in that: A cement-based electrode as claimed in claim 9 is used.