Winding type cement-based battery and preparation method thereof

Abstract

The invention provides a coiled cement-based battery which is composed of a positive electrode, a negative electrode and a cement-based electrolyte, the negative electrode is coiled and adhered to the inner wall of the battery, the positive electrode is coiled and arranged in the center of a battery shell, the cement-based electrolyte is arranged between the positive electrode and the negative electrode, and the mass ratio of the positive electrode to the negative electrode to the electrolyte is (1.5-1.7): 1: 10. The invention also provides a preparation method of the coiled cement-based battery. The coiled cement-based battery disclosed by the invention has proper mechanical properties and high mechanical strength, and compared with a common layered cement-based battery, the coiled cement-based battery also shows relatively high energy density and more excellent cycle stability.

Description

Technical Field

[0001] The invention relates to a wound cement-based battery. Background Art

[0002] As an important building material, cement consumes a lot of energy in both its production and use. As a traditional energy-intensive industry, the construction industry accounts for about 40% of total energy consumption, 40% of atmospheric emissions, 30% of raw material consumption, and 25% of water consumption. Due to their huge size, buildings often have a large amount of exterior wall surface area directly exposed to natural resources such as wind energy and solar energy, which also provides good conditions for the large-scale development of the current building photovoltaic industry. However, these clean energy sources cannot stably output electricity due to weather and other reasons. Therefore, the development of energy storage devices is an important factor in the development and use of clean energy.

[0003] As an ion conductor, cement has good electronic insulation and can be used as an electrolyte material. On this basis, the development and application of rechargeable cement-based batteries become possible. At present, relevant reports have made progress in cement-based electrochemical performance. If this concept is further developed and commercialized, this concept of using and building as a battery may be revolutionary because it can provide an alternative solution to the energy crisis by providing a large amount of energy storage. However, in addition to being non-conductive, the electrolyte material also needs to have a certain porosity to facilitate the free transmission of ions. Considering that in traditional engineering applications, the strength of cement is an important parameter that directly determines the quality and life of the building. Therefore, cement-based electrolytes are also required to have high mechanical properties such as compressive strength. However, more porosity in cement is conducive to the transmission of ions but not conducive to the improvement of mechanical properties. Although less porosity improves the mechanical properties, it limits the transport capacity of ions. From this perspective, the pore structure of cement directly affects the ionic conductivity of cement, but it is difficult for cement as an electrolyte to have good mechanical properties and ionic conductivity at the same time.

[0004] There are two types of rechargeable cement-based batteries that have been reported so far: layered structure and probe structure ( Figure 1), and each has its own characteristics. In traditional layered-structured cement-based batteries, metal powder is mixed with cement mortar as the positive and negative electrode layers. During the charge and discharge process, the electron transfer resistance is relatively large, resulting in poor battery performance. It is difficult for metal powder to be evenly dispersed in the cement matrix and may form defect points, leading to a rapid decrease in cement strength. In probe-structured cement-based batteries, the positive and negative electrodes are embedded to achieve full contact between the electrodes and the conductive cement mortar electrolyte. However, this structure consumes more positive and negative electrode materials, and the electrochemical performance of the battery is also not ideal (Research on the Preparation and Electrochemical Performance of New Cement-Based Batteries, Bulletin of the Chinese Ceramic Society; Cement-Based Structural Batteries: Mechanisms, Influencing Factors and Applications, DOI: 10.13801 / j.cnki.fhclxb.20240205.003). Summary of the Invention

[0005] The technical solution of the present invention provides a wound cement-based battery. The present invention also provides a preparation method for this cement-based battery.

[0006] The present invention provides a wound cement-based battery, which is composed of a positive electrode, a negative electrode, and a cement-based electrolyte. The negative electrode is wound and adhered to the inner wall of the battery, the positive electrode is wound and placed in the center of the battery case, and the cement-based electrolyte is in the middle of the positive electrode and the negative electrode. The mass ratio of the positive electrode, the negative electrode, and the electrolyte is: 1.5 - 1.7:1:10.

[0007] Among them, the mass ratio of the positive electrode, the negative electrode, and the electrolyte is: 1.7:1:10.

[0008] Among them, the formula of the positive electrode is:

[0009] 4 parts of Ni(OH)2, 1 part of PVDF, 0.1 part of polyvinyl alcohol, 4.9 parts of water (water in the PVA solution);

[0010] The formula of the negative electrode is:

[0011] 8 parts of iron powder, 1 part of graphite, 1 part of PVDF, 0.2 part of polyvinyl alcohol, 4.8 parts of water;

[0012] The formula of the electrolyte is:

[0013] 50 parts of cement, 1 part of polyvinyl alcohol, 0.5 part of water reducing agent, 0.25 - 0.1 part of ionic additive, 20 parts of water.

[0014] Among them, the ionic additive is one or a mixture of two or more of CaCl2, MgCl2, AlCl3, and FeCl3.

[0015] The present invention also provides a preparation method for the wound cement-based battery, including the following steps:

[0016] a. Preparation of the positive electrode: Cement, Ni(OH)2, PVDF, and a 2% polyvinyl alcohol (PVA) solution were taken and ground and thoroughly mixed in an agate mortar to obtain a uniform positive electrode paste. This paste was coated onto carbon cloth and placed in an oven, dried at 60 °C for 12 h to obtain the battery positive electrode;

[0017] b. Preparation of the negative electrode: A water pool, Fe powder, graphite, and PVDF were taken, and a PVA solution with a mass fraction of 4% was added and ground into a uniform paste in an agate mortar and coated on copper foil. This negative electrode was placed in an oven at 60 °C and dried for 12 h to obtain the battery negative electrode;

[0018] c. Preparation of the cement-based electrolyte: Cement, polyvinyl alcohol, water reducer, and ionic additive were placed in a ceramic bowl and mixed evenly; water was added and stirred;

[0019] d. Battery preparation:

[0020] The negative electrode was wound and adhered to the inner wall of the battery case, and at the same time, the positive electrode was wound and placed in the center of the battery case. Then, the uniformly mixed cement-based electrolyte was poured in, and the cement-based material in the battery case was shaken; the battery was placed in a wet box with a relative humidity of 100% for curing, and after curing was completed, the battery case was sealed.

[0021] On the basis of ensuring that the cement-based electrolyte has basic strength, the present invention controls the water-cement ratio to regulate the porosity in the cement-based electrolyte to improve the ionic conductivity of the cement-based material. At the same time, an ionic additive is added to the cement mortar, and an ionic migration network is formed in the cement by the ionic solution. There are many capillary pores in the mortar, and the concentration of ions in the mortar capillary and gel increases. Under the action of voltage, the rate of electrolytic migration of ions increases, thereby improving the ionic conductivity of the cement-based electrolyte and achieving good electrochemical performance of the cement-based battery. The electrode active materials are respectively coated on carbon cloth and copper foil. On the one hand, this method reduces the resistance between the electrode and the cement contact interface, so that the positive and negative electrode plates have stable and good conductivity. In addition, carbon cloth and copper foil as current collectors can improve the electrochemistry reaction efficiency. The improvement of the electronic conductivity of the positive and negative electrodes and the ionic conductivity of the cement-based electrolyte synergistically improve the electrochemical performance of the cement-based battery. Therefore, the wound cement-based battery has appropriate mechanical properties and high mechanical strength. Compared with general layered cement-based batteries, the wound battery also exhibits higher energy density and more excellent cycle stability. Brief Description of the Drawings

[0022] Figure 1 . Schematic diagrams of the structures of (a) layered structure and (b) probe-type structure cement-based batteries;

[0023] Figure 2 . Energy density of cement-based batteries with different positive and negative electrode mass ratios after cycling to the 10th time;

[0024] Figure 3 . Schematic diagram of the structure of a wound cement battery;

[0025] Figure 4 . Influence of the water - cement ratio of the cement - based electrolyte on the porosity;

[0026] Figure 5 . Circuit diagram for resistivity measurement;

[0027] Figure 6 . Influence of the type of ionic additive on the resistivity of the cement - based electrolyte (addition amount is 1%, water - cement ratio is 0.5);

[0028] Figure 7 . Influence of the dosage of ionic additive on the resistivity of the cement - based electrolyte (water - cement ratio is 0.5, cured for 7 days);

[0029] Figure 8 . Electrochemical impedance spectra of wound cement - based batteries 1 - 3;

[0030] Figure 9 . Electrochemical impedance spectra of layered cement - based batteries 4 - 6;

[0031] Figure 10 . Cyclic test curves of battery 2 and battery 4. Detailed implementation manners

[0032] Example 1 Preparation of the wound cement - based battery of the present invention

[0033] 1. Preparation of the positive electrode: In this study, Ni(OH)₂ was selected as the positive electrode active material. An appropriate amount of Ni(OH)₂ and PVDF were mixed in a ratio of 4:1, and a 2% (by mass) polyvinyl alcohol (PVA) solution was added and ground in an agate mortar and mixed thoroughly to obtain a uniform positive electrode paste. This paste was coated on carbon cloth and placed in an oven, dried at 60 °C for 12 h to obtain the battery positive electrode.

[0034] 2. Preparation of the negative electrode: The negative electrode active material is Fe. Fe powder, graphite and PVDF were mixed in a ratio of 8:1:1, and a 2% (by mass) PVA solution was added and ground into a uniform paste in an agate mortar and coated on copper foil. This negative electrode was placed in an oven at 60 °C and dried for 12 h to obtain the battery negative electrode. According to the electrode reactions (Equations 1 and 2), the mass ratio of the positive and negative electrode active materials is about 1.7, that is, m Ni(OH)2 : m Fe= 1.7. However, after the cement solidifies, the pore structure affects ion transport, and the actual effective capacity of the positive and negative active materials may be lower than the theoretical value. In addition, the electrolyte in the cement pores participates in the reaction, and its indirect contribution to the capacity needs to be considered. Therefore, generally, the negative electrode needs to be in excess to compensate for the polarization loss caused by the low ionic conductivity of the cement matrix and prevent the negative electrode from being exhausted prematurely due to ion transport delay. On this basis, cement-based batteries with different positive and negative mass ratios (the same process and formula) are prepared, and the optimal mass ratio of Ni(OH)2 positive electrode and Fe negative electrode in this wound cement-based battery is screened according to the energy density test results.

[0035] Fe(OH) 2(s) + 2e - → Fe (s) + 2OH - (aq) Formula 1

[0036] Ni(OH)2 + 2OH - → NiOOH + 2H2O + 2e - Formula 2

[0037] The battery reaches a stable state basically after cycling 10 times. Therefore, the energy density data of the battery when cycling the 10th time at different positive and negative active material ratios are selected for comparison ( Figure 2 ). From Figure 2 it is obtained that when the mass ratio of the positive and negative active materials is relatively high, that is, when the positive electrode is in excess, the battery shows a lower energy density; as the ratio decreases, the energy density increases. When the positive and negative mass ratio is between 1.5 and 1.7, the battery has a higher energy density, that is, the negative electrode needs to be slightly in excess, and the utilization rate of the electrode materials is higher in this interval. However, when the negative electrode is in excess too much (1.3), due to the increase in the ineffective mass of the negative electrode, the energy density of the battery is reduced instead. Therefore, the optimal positive and negative mass ratio is between 1.5 and 1.7.

[0038] Preparation of cement-based electrolyte: Weigh the cement, polyvinyl alcohol, water reducing agent and ionic additives (CaCl2, MgCl2, AlCl3, FeCl3, dosage 0.5%-2%) and put them into a ceramic bowl, and mix them evenly. Add an appropriate amount of water and stir.

[0039] 3. Battery preparation: Wind and adhere the negative electrode to the inner wall of the battery case, and at the same time wind and place the positive electrode in the center of the battery case. Then pour in the evenly mixed cement-based electrolyte and shake the cement-based material in the battery case. By controlling the positive and negative paste ratios and the positive and negative coating thicknesses, the mass ratio of the positive and negative active materials is controlled to be 1.7 according to the size of the electrodes in the battery case. Place the battery in a wet box with a relative humidity of 100% for curing, and encapsulate the battery case after curing is completed (see Figure 3 ).

[0040] Example 2: Mechanical and Electrochemical Property Tests of the Wound Cement Battery of the Present Invention

[0041] In order to compare the advantages of the wound cement-based battery and the conventional layered cement-based battery in terms of mechanical and electrochemical properties, layered cement-based electrolytes and positive and negative electrodes were prepared as comparative sample materials with similar formulations and processes.

[0042] The specific formulation is as follows:

[0043] Table 1. Formulation of the Layered Cement-Based Battery

[0044]

[0045]

[0046] In order to maintain the consistency of the electrolyte and electrodes in the comparative samples and the wound battery as much as possible, the positive electrode of the comparative sample was loaded on a carbon fiber mesh and cast in cement mortar; the negative electrode was also loaded on a copper foil and cast in cement mortar. In the subsequent mechanical and electrochemical tests, the preparation conditions (including water-cement ratio, specimen size, type and addition amount of ionic additives) of the comparative samples were the same as those of the wound cement-based battery.

[0047] 1. Screening Test of the Water-Cement Ratio of the Electrolyte

[0048] The pore structure of cement directly affects the ionic conductivity of cement, and the water-cement ratio is an important factor affecting the pore structure of cement. Therefore, four electrolyte samples were prepared with the water-cement ratio as a variable to explore the effects of different water-cement ratios on porosity and mechanical properties (water-cement ratio range: 0.3 - 0.6); the water-cement ratio refers to the mass ratio of water to cement.

[0049] Table 2. Electrolyte Formulation of the Wound Cement-Based Battery

[0050]

[0051] The methanol method was used to measure the porosity. This method can quickly and simply measure the connected porosity of the mortar specimens. First, the cement mortar specimens were left standing in a methanol solution containing molecular sieves for 5 days for dehydration. The mass W1 of each specimen suspended in anhydrous methanol (absorbing water with molecular sieves) and the mass W2 of each specimen when it was surface-dry and dull were measured first. Then, each specimen was placed in a vacuum drying oven to evacuate methanol, and weighed every 1 - 2 hours until the mass of the specimen no longer changed, obtaining W3. The measured porosity e of the specimen was calculated according to Equation 3 (where ρ in the equation is the specific gravity of methanol, ρ = 0.7918):

[0052]

[0053] The compressive strength test method of mortar specimens refers to GB / T 17671-1999, and the size of the specimens is 40mm×40mm×40mm.

[0054] Cement mortar itself is a porous material, and the porosity is generally between 10% and 15%. In cement-based batteries, ions are exchanged through the pore water in the cement matrix to realize the occurrence of electrode reactions and the charge and discharge process of the battery. Therefore, most current cement-based batteries need to pay attention to water treatment during the test to prevent the rapid decay of battery performance due to water loss of the cement-based electrolyte. Therefore, from the perspective of electrochemistry, an increase in the porosity of the cement matrix is beneficial to the electrochemical performance of the battery, but as a structural material, the strength of cement will decrease significantly with the increase in porosity. Specifically, the pores in the mortar are generally divided into two categories: connected pores and closed pores. Connected pores are the spaces left by the mixing water. Generally speaking, the larger the water-cement ratio, the more mixing water there is. When this mixing water is lost, more pores are formed, and finally the porosity of the specimen will be greater. However, when the water-cement ratio is too large, the fluidity of the mortar increases, and it becomes easier for small air bubbles to merge into large air bubbles and escape, which will directly lead to a decrease in porosity. Figure 4 As shown in the figure of the influence of the water-cement ratio on the porosity of the cement-based electrolyte, with the increase of the water-cement ratio, the porosity of the final cement matrix increases. For the cement matrix, an increase in porosity means that the strength of the cement may decrease. Table 3 further shows the relationship between the water-cement ratio, the porosity of the cement matrix, and the compressive strength. Different from the porosity, with the increase of the water-cement ratio, the compressive strength of the cement matrix continuously decreases.

[0055] Table 3. Relationship between water-cement ratio, porosity, and compressive strength of cement matrix electrolyte

[0056]

[0057] Since the cement matrix of the wound cement-based battery mainly exists in the electrolyte, the above mechanical property tests focus on the cement-based electrolyte. However, for the layered cement-based battery, both the positive and negative electrodes are made of cement. Compared with the cement-based electrolyte, the cement-based electrodes have a more significant impact on the mechanical properties of the battery. In addition, the electrolyte formulations and processes of the layered cement-based battery and the wound cement-based battery are basically the same. Therefore, the relationships between the mechanical properties, water-cement ratio, and porosity of the positive and negative electrode specimens in Table 1 were tested respectively, as shown in Table 4. The compressive strengths of both the positive and negative electrodes of the layered cement-based battery are lower than those of the electrolyte of the wound cement-based battery. This may be related to the addition of positive and negative active materials, indicating that when assembled into a cement-based battery, the overall mechanical properties of the layered cement-based battery will be inferior to those of the wound cement-based battery. Compared with the layered cement-based battery, the wound cement-based battery shows better mechanical stability.

[0058] Table 4. Relationship between water-cement ratio, porosity and compressive strength of the positive and negative electrodes of the layered cement-based battery

[0059]

[0060]

[0061] For cement-based electrolytes, ionic conductivity is the key to determining the electrochemical performance of the battery. There are a large number of connected or unconnected capillary pores in the concrete structure. The capillary pores contain a large amount of pore solution, and the pore solution is a saturated electrolyte solution. The resistance theory of concrete is based on the transport of ions in the concrete structure. Ions in the electrolyte solution move directionally under the action of voltage, thus generating current. Incorporating ionic conductive substances into the concrete electrolyte can maintain the stability of the resistivity of ionic conductive concrete and improve the ionic conductivity of the cement-based electrolyte. Therefore, further tests were carried out on the effects of ionic additives (CaCl2, MgCl2, AlCl3, FeCl3) and their addition amounts on the conductive performance of the cement-based electrolyte. The resistivity of the cement-based electrolyte samples was measured by the voltammetry method according to Figure 5 the circuit shown. The test was carried out at room temperature of 25 °C, and alternating current was selected with the voltage set at 10 V. To ensure accurate data, the corresponding voltage value and current value were read after 2 min of power-on, and the final resistivity value was calculated by Equation 4. In the formula, R is the resistance of the specimen, with the unit of Ω; S is the cross-sectional area of the specimen, with the unit of m 2 ; L is the distance between the two electrode plates of the specimen, with the unit of m; ρ is the resistivity, with the unit of Ω·m.

[0062]

[0063] When the water-cement ratio of the cement-based electrolyte is 0.5 and the dosage of ionic additives is 1% for all, the types of ionic additives on the resistivity of the cement-based electrolyte are as Figure 6 shown. Compared with the blank sample, the incorporation of ionic additives significantly reduces the resistivity of the cement electrolyte, and the reduction of resistivity is related to the types of ionic additives. Further, the relationship between the resistivity of the cement-based electrolyte samples cured for 7 days with a water-cement ratio of 0.5 and the dosage of ionic additives is as Figure 7 shown. As the dosage of the electrolyte increases, the resistivity of the electrolyte concrete gradually decreases. When the dosage of the electrolyte is from 0 to 1%, the reduction of resistivity is relatively large, and the resistivity further decreases when the dosage is 1.5%. As the dosage continues to increase, the resistivity tends to be stable. This is mainly because the number of particles in the concrete increases after the dosage is increased, making the conductive ability of the concrete enhanced. When the ion concentration reaches saturation, the resistivity tends to be stable.

[0064] 2. Comparative test on the effects of the layered cement-based battery and the wound cement-based battery

[0065] A wound cement - based battery is made of a cement - based electrolyte doped with an ionic additive, a positive electrode and a negative electrode. The electrolyte formulations of the batteries are shown in Table 5.

[0066] Table 5. Electrolyte formulations of the tested batteries

[0067]

[0068] Assemble the above three kinds of batteries according to the formulation and conduct electrochemical tests. In order to compare the electrochemical performance of the wound cement - based battery with that of the conventional layered cement - based battery, a layered cement - based battery was also prepared and assembled simultaneously. The amounts of positive and negative electrode active materials, the water - cement ratio, the types and addition amounts of ionic additives of the comparative samples are all the same as those of the wound cement - based battery (as shown in Table 5), and are denoted as Battery 4, Battery 5, and Battery 6 respectively. That is, Battery 1 - 3 are wound cement - based batteries based on the formulation in Table 5; Battery 4 - 6 are layered cement - based batteries based on the formulation in Table 5.

[0069] For the electrochemical impedance test (EIS), a CHI660E electrochemical workstation was used to test the battery impedance, and the scanning frequency range was 1 mHz - 1 MHz. As Figure 8 shown by the measured EIS spectra of the batteries, the ionic conductivity of the cement - based electrolyte can be calculated by Equation 3:

[0070] σ = d / (s×R b ) Equation 5

[0071] where σ is the ionic conductivity, d is the thickness of the cement - based electrolyte, and R b is the bulk resistivity, that is, the measured value of the EIS spectrum. Combining the EIS test and the formula calculation, the ionic conductivities of Battery 1, Battery 2, and Battery 3 are 4.8×10 3 S / cm, 3.6×10 3 S / cm, and 4.2×10 3 S / cm respectively. While the corresponding layered cement - based batteries show a significantly increased resistivity ( Figure 9 ), which is mainly because the structure of the wound cement - based battery reduces the resistance between the positive and negative electrodes and the contact interface of the cement electrolyte, thus enabling the positive and negative electrodes to have stable and good electrical conductivity.

[0072] For the battery charge - discharge test, first charge at a constant current of 10 mA for 10 h, and then discharge at a constant current of 3 mA. Set the discharge cut - off voltage to 0.5 V. During the whole charging process, the average charging and discharging cycle is extended by about 12 hours. The electrochemical test results of the wound cement - based battery are as Figure 10As shown (Battery 2), at the initial stage of cycling, the energy densities of the layered cement-based battery and the wound cement-based battery are basically the same. However, after several cycles, the energy density of the layered cement-based battery drops rapidly, while the wound cement-based battery remains in a relatively stable state after 50 cycles. This is mainly due to the structure of the wound cement-based battery. The positive and negative electrodes are in direct contact with the cement-based electrolyte, reducing the interfacial resistance. At the same time, the electrode reaction kinetics is accelerated, the electrochemical efficiency of the positive and negative active materials increases, and finally, it shows a higher energy density and better electrochemical performance.

[0073] In summary, due to the small interfacial resistance between the positive and negative electrodes and the electrolyte, high ion diffusion and electron transfer kinetics, the wound cement-based battery promotes the participation of positive and negative active substances in the electrochemical reaction, and has a high utilization rate of positive and negative electrodes. Compared with the layered cement-based battery, the wound battery shows a higher energy density and more excellent cycle stability. In addition, even using the same process and formula, the mechanical properties of the cement-based positive electrode and the cement-based negative electrode of the layered battery are lower than those of the cement-based electrolyte. For the mechanical properties of the battery, its overall mechanical properties often depend on the poorer components. Therefore, compared with the layered cement-based battery, due to its special structure, the positive and negative electrodes of the wound cement-based battery are not cast in the cement matrix but are in direct contact with the cement-based electrolyte, thus showing better mechanical properties. At the same time, the ionic conductivity of the cement-based electrolyte is the key to directly affecting the mechanical properties and electrochemical performance of the cement-based battery. By controlling the water-cement ratio of the cement matrix, selecting appropriate ionic additives and their addition concentrations, and regulating the porosity and conductivity of the cement matrix, a wound cement-based battery with good mechanical properties and stable electrochemical performance can be obtained.

Claims

1. A wound cement-based battery, characterized in that: It consists of a positive electrode, a negative electrode, and a cement-based electrolyte. The negative electrode is wound and adhered to the inner wall of the battery, the positive electrode is wound and placed in the center of the battery case, and the cement-based electrolyte is in the middle of the positive electrode and the negative electrode. The mass ratio of the positive electrode, the negative electrode, and the electrolyte is: 1.5 - 1.7:1:

10.

2. The wound cement-based battery according to claim 1, wherein: The mass ratio of the positive electrode, the negative electrode, and the electrolyte is: 1.7:1:

10.

3. The wound cement-based battery according to claim 1 or 2, characterized in that: The formula of the positive electrode is: 4 parts of Ni(OH)2, 1 part of PVDF, 0.1 part of polyvinyl alcohol, 4.9 parts of water (water in the PVA solution); The formula of the negative electrode is: 8 parts of iron powder, 1 part of graphite, 1 part of PVDF, 0.2 part of polyvinyl alcohol, 4.8 parts of water; The formula of the electrolyte is: 50 parts of cement, 1 part of polyvinyl alcohol, 0.5 part of water reducing agent, 0.25 - 0.1 part of ionic additive, 20 parts of water.

4. The wound cement-based battery according to claim 3, wherein: The ionic additive is one or a mixture of two or more of CaCl2, MgCl2, AlCl3, and FeCl3.

5. The preparation method of the wound cement-based battery according to any one of claims 1-4, characterized in that: It includes the following steps: a. Preparation of the positive electrode: Take cement, Ni(OH)2, PVDF, and 2% polyvinyl alcohol (PVA) solution and grind and mix them well in an agate mortar to obtain a uniform positive electrode slurry. Coat this slurry on carbon cloth and put it in an oven to dry at 60°C for 12 hours to obtain the battery positive electrode; b. Preparation of the negative electrode: Take water pool, Fe powder, graphite, PVDF, add a PVA solution with a mass fraction of 4% and grind it into a uniform slurry in an agate mortar and coat it on copper foil. Place this negative electrode in an oven at 60°C and dry it for 12 hours to obtain the battery negative electrode; c. Preparation of the cement-based electrolyte: Put cement, polyvinyl alcohol, water reducing agent, and ionic additive into a ceramic bowl and mix them evenly; add water and stir; d. Battery preparation: Wind and adhere the negative electrode to the inner wall of the battery case, and at the same time wind and place the positive electrode in the center of the battery case. Then pour in the evenly mixed cement-based electrolyte and vibrate the cement-based material in the battery case; Place the battery in a humidity box with a relative humidity of 100% for curing, and after curing is completed, seal the battery case.

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