Annular cement-based supercapacitor and preparation method and application thereof

Abstract

The invention relates to an annular cement-based supercapacitor and a preparation method and application thereof. The supercapacitor comprises a first circular electrode layer, an annular electrolyte layer and a second annular electrode layer which are sequentially arranged from inside to outside. The first circular electrode layer and the second annular electrode layer are composed of the following components in parts by weight: 100-900 parts of a cementing material, 8-95 parts of a conductive material, 1-50 parts of a water reducing agent, 10-60 parts of an early strength agent and 200-800 parts of water; the annular electrolyte layer comprises the following components in parts by weight: 30-400 parts of a cementing material, 0.05-4 parts of a water reducing agent, 1-20 parts of an early strength agent and 10-200 parts of water; and the three layers all contain inorganic metal ions. The defects of a traditional cement-based super capacitor are structurally improved, the electrode / electrolyte contact area, the ion transmission efficiency and the mass capacitance of the capacitor are obviously improved, and meanwhile the capacitor has the excellent mechanical property.

Description

Technical Field

[0001] The present invention specifically relates to an annular cement-based supercapacitor and a preparation method and application thereof. Background Art

[0002] The rapid iteration of the industrial energy industry has given rise to people's demand for diversified and multifunctional energy storage systems. Cement-based supercapacitors, as a structural energy storage device with cement as the main raw material, have both load-bearing and energy storage functions. They have the advantages of abundant raw material reserves, low cost, safety and environmental protection, and are expected to achieve large-scale energy storage. However, the research on cement-based supercapacitors is still in its infancy and faces many challenges. Traditional cement-based supercapacitors are mostly sandwich structures. The spacing of electrode materials is restricted by the thickness of cement electrolytes, and the area of ​​electrode materials is limited to the cross-sectional area of ​​the electrolyte. As a result, traditional cement-based supercapacitors have shortcomings such as low electrode / electrolyte contact area, large ion migration distance, and device performance bound to device thickness, showing low coulomb efficiency and poor electrochemical performance. Traditional research improves the electrochemical performance of cement-based supercapacitors by introducing polymers (polyacrylic acid, polyacrylamide, etc.), pore-forming agents (sodium bicarbonate, hemp fiber, etc.) and optimizing electrode materials (pseudocapacitive electrode materials), but they face problems such as complex preparation processes, deteriorated mechanical properties and high costs, which are not conducive to large-scale application of energy storage. In addition, the traditional method maintains the sandwich structure architecture, and the optimization effect of the device has reached saturation.

[0003] How to further improve the electrode / electrolyte contact area, ion transfer efficiency and mass capacitance of cement-based supercapacitors is a difficult problem in this field. Summary of the invention

[0004] In view of the deficiencies in the prior art, one of the objects of the present invention is to provide an improved annular cement-based supercapacitor having a new structural framework, and having significantly improved electrode / electrolyte contact area, ion transfer efficiency and mass capacitance, while having excellent mechanical properties.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A ring-shaped cement-based supercapacitor, comprising a first circular electrode layer, a ring-shaped electrolyte layer and a second ring-shaped electrode layer arranged in sequence from inside to outside;

[0007] The first circular electrode layer and the second annular electrode layer include the following components in total, in parts by weight: 100-900 parts of gelling material, 8-95 parts of conductive material, 1-50 parts of water reducing agent, 10-60 parts of early strength agent and 200-800 parts of water.

[0008] The annular electrolyte layer comprises the following components in parts by weight: 30-400 parts of a gelling material, 0.05-4 parts of a water reducing agent, 1-20 parts of an early strength agent and 10-200 parts of water;

[0009] The first circular electrode layer, the annular electrolyte layer and the second annular electrode layer all contain inorganic metal ions.

[0010] The first circular electrode layer and the second annular electrode layer both contain conductive materials and serve as electrode layers, while the annular electrolyte layer between the two does not contain conductive materials and serves as an electrolyte layer. The three-layer structure can form a capacitor.

[0011] In some specific embodiments, the first circular electrode layer and the second annular electrode layer together include the following components: 250-700 parts of gelling material, 15-50 parts of conductive material, 1-18 parts of water reducing agent, 14-40 parts of early strength agent and 300-595 parts of water.

[0012] In some specific embodiments, the first circular electrode layer, the annular electrolyte layer and the second annular electrode layer are arranged concentrically.

[0013] In some specific embodiments, the composition ratio of the first circular electrode layer and the second annular electrode layer is exactly the same.

[0014] In some specific embodiments, the inorganic metal ions are selected from a combination of one or more of potassium ions, sodium ions, and lithium ions. The inorganic metal ions are used to allow the electrolyte to be transported in the cement pores to achieve the energy storage function of the capacitor.

[0015] In some specific embodiments, the inorganic metal ions are obtained by soaking in a mixed solution of an inorganic metal salt and an inorganic metal hydroxide.

[0016] In some embodiments, the radius a of the first circular electrode layer is 2 5-30mm.

[0017] In some embodiments, the width a of the annular electrolyte layer is 1 5-30mm.

[0018] In some embodiments, the width a of the second annular electrode layer is 0 5-30mm.

[0019] In some specific embodiments, the height h of the annular cement-based supercapacitor is 10-100 mm.

[0020] In some embodiments, the width a of the second annular electrode layer is 0 , the width of the annular electrolyte layer a 1, the radius a of the first circular electrode layer 2 The ratio of the height h of the annular cement-based supercapacitor is 1-6: 1-6: 1-6: 2-20, preferably 1-6: 1-3: 1-4: 8-20. By adjusting the ratio of the four, the electrical performance of the supercapacitor can be adjusted.

[0021] In some specific embodiments, the cementitious material is selected from any one or more combinations of Portland cement, fly ash, and blast furnace slag.

[0022] Preferably, the cementitious material is a mixture of Portland cement, fly ash and blast furnace slag; more preferably, in the mixture, the mass ratio of Portland cement, fly ash and blast furnace slag is 60-80:10-20:10-20.

[0023] In some specific embodiments, the conductive material is selected from one or both of activated carbon and carbon black conductive agent.

[0024] Preferably, the conductive material is a mixture of activated carbon and carbon black conductive agent; more preferably, in the mixture, the mass ratio of the activated carbon to the carbon black conductive agent is 70-95:5-30.

[0025] In some specific embodiments, the water reducer is any one or more combinations of polycarboxylate water reducer and lignin sulfonate.

[0026] In some specific embodiments, the early strength agent is selected from any one or more combinations of sodium carbonate, gypsum, and water glass.

[0027] Preferably, the early strength agent is a mixture of sodium carbonate, gypsum and water glass. More preferably, in the mixture, the mass ratio of sodium carbonate, gypsum and water glass is 30-50:20-40:20-40.

[0028] In some specific embodiments, the compressive strength of the annular cement-based supercapacitor is 28-40 MPa, the porosity is 38%-60%, and the contact area between the cement electrode and the cement electrolyte is 2800-7000 mm 2 The mass capacitance is 3.0-15.0 mF / g. The annular cement-based supercapacitor of the present invention has excellent mechanical properties and electrical properties.

[0029] The present invention also provides a method for preparing the aforementioned annular cement-based supercapacitor, the method using a mold, the mold comprising, arranged from inside to outside, an inner annular cavity corresponding to the first circular electrode layer, a middle annular cavity corresponding to the annular electrolyte layer, and an outer annular cavity corresponding to the second annular electrode layer; a detachable stainless steel ring is arranged between the inner annular cavity and the middle annular cavity, and between the middle annular cavity and the outer annular cavity;

[0030] The preparation method comprises the following steps:

[0031] 1) mixing the components of the first circular electrode layer evenly to obtain a first cement electrode precursor slurry; mixing the components of the second annular electrode layer evenly to obtain a second cement electrode precursor slurry; mixing the components of the annular electrolyte layer evenly to obtain a cement electrolyte precursor slurry;

[0032] 2) placing the mold in a liquid nitrogen environment, pouring the second cement electrode precursor slurry into the outer ring cavity of the mold, pouring the cement electrolyte precursor slurry into the middle ring cavity of the mold when the second cement electrode precursor slurry is not completely frozen, and taking out the detachable stainless steel ring between the outer ring cavity and the middle ring cavity; pouring the first cement electrode precursor slurry into the inner ring cavity of the mold when the cement electrolyte precursor slurry is not completely frozen, and taking out the detachable stainless steel ring between the middle ring cavity and the inner ring cavity; after the column is completely frozen, take it out together with the mold to obtain a solidified column;

[0033] 3) thawing the solidified column, removing the mold to obtain a block, and performing cement curing on the block to obtain a cement-based material with an integrated directional pore structure;

[0034] 4) Soaking the cement-based material in a mixed solution of an inorganic metal salt and an inorganic metal hydroxide, and taking it out to obtain a ring-shaped cement-based supercapacitor.

[0035] In step 2), when the slurry is poured twice, the previous slurry cannot be completely solidified to ensure that the interface is in liquid contact. When the slurry is poured before it is completely solidified, the liquid contact helps the two phases blend and maximizes the contact between the two phases, thereby further improving the mechanical and electrochemical properties of the final capacitor.

[0036] In step 4), soaking can allow the cement electrolyte to absorb the electrolyte so as to achieve the transmission of the electrolyte in the cement pores, thereby realizing the energy storage function of the cement-based supercapacitor.

[0037] The outer annular cavity eventually forms the second annular electrode layer of the capacitor, the middle annular cavity eventually forms the annular electrolyte layer of the capacitor, and the inner annular cavity eventually forms the first circular electrode layer of the capacitor.

[0038] In some specific embodiments, the size of the removable stainless steel ring can be adjusted so that the size of the outer ring cavity, the middle ring cavity or the inner ring cavity can be adjusted. The main parameters of the mold are the ring spacing a 0 , a 1 , a 2 And height h, all four can be adjusted. Adjusting the first three can realize the regulation of the proportion of each annular component, and then adjust the composition of the electrode layer and the electrolyte layer, and finally adjust the electrical performance.

[0039] In some specific embodiments, the material of the bottom of the mold is polytetrafluoroethylene thermal insulation material.

[0040] In some specific embodiments, the outer ring of the mold is made of a heat-conducting metal ring, preferably a copper ring.

[0041] In some specific embodiments, in step 2), only the outer ring material of the mold contacts the liquid nitrogen, and the bottom material of the mold does not contact the liquid nitrogen. Contacting only the annular outer ring with liquid nitrogen can maintain radial supercooling, which helps to construct a radial directional transmission channel.

[0042] In some specific embodiments, in step 3), the thawing process is performed at 0-4°C. Slow thawing can be achieved at this temperature. The thawing process is a process in which the ice sheet layer melts and the frozen cement particles gradually hydrate. Due to low-temperature freezing, most of the cement particles are not hydrated, and their hydration rate at low temperatures is also slow, and the strength is generated slowly. Therefore, it is necessary to control the thawing rate to ensure that the ice layer melts slowly to adapt to the strengthening process of the cement skeleton at low temperatures, so as to ensure that the frozen cast structure can be retained.

[0043] In some specific embodiments, the thawing time is 1-4 days.

[0044] In some specific embodiments, the cement curing is performed in a cement standard curing box.

[0045] In some specific embodiments, the cement curing time is 20-30 days.

[0046] In some specific embodiments, the inorganic metal salt is selected from a combination of one or more of potassium chloride, sodium chloride and lithium chloride.

[0047] In some specific embodiments, the inorganic metal hydroxide is selected from a combination of one or more of potassium hydroxide and sodium hydroxide.

[0048] In some specific embodiments, the molar concentration of the inorganic metal salt is 0.5-2M.

[0049] In some specific embodiments, the molar concentration of the inorganic metal hydroxide is 0.5-2M.

[0050] In some specific embodiments, the soaking time is 1-4 days.

[0051] In some specific embodiments, the block is placed in a cement curing box for 28 days.

[0052] In some specific embodiments, the soaking is soaking in 1M KOH+1M KCl solution for 2 days.

[0053] The present invention also provides a use of the aforementioned annular cement-based supercapacitor as a functional device in a road, a building or a bridge.

[0054] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0055] Compared with the traditional sandwich-structured cement-based supercapacitor, the annular cement-based supercapacitor prepared by the present invention has a larger electrode / electrolyte contact area, and the ion transmission distance is not affected by the aspect ratio. The present invention helps to improve the comprehensive performance of cement-based supercapacitors, such as mechanical properties, power density, and mass specific capacity, and broaden the construction method and application scenarios of cement-based supercapacitors, which can not only enrich the energy storage form, but also has positive significance for promoting the development of green, low-carbon and energy-saving buildings.

[0056] The present invention creates a ring-shaped cement-based supercapacitor with a completely new structure, which can significantly improve the electrical performance while ensuring excellent mechanical properties.

[0057] The present invention attempts to improve the shortcomings of traditional cement-based supercapacitors from a structural design perspective. Based on this, the present invention innovatively proposes a ring frame structure and designs a corresponding preparation mold. Through the ring structure design, the contact area of ​​the electrode / electrolyte is greatly increased, the ion transmission is improved, and the mass capacitance of the cement-based supercapacitor is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 It is a mold for preparing the annular cement-based supercapacitor of the present invention.

[0059] Figure 2 It is a schematic diagram of the freeze casting preparation method of the present invention.

[0060] Figure 3 This is a photo of the annular cement-based supercapacitor prepared in the present invention.

[0061] Figure 4 Figure 2 is the contact area diagram between cement electrode and cement electrolyte of each sample.

[0062] Figure 5 is the mass capacitance diagram of each sample.

[0063] Among them, 1-outer ring cavity; 2-middle ring cavity; 3-inner ring cavity; 4-detachable stainless steel ring; 5-outer ring; a 2 - the radius of the first circular electrode layer; a 1 - the width of the annular electrolyte layer; a 0 - The width of the second annular electrode layer. DETAILED DESCRIPTION

[0064] The sandwich structure of traditional cement-based supercapacitors (i.e., the layered structure of electrode-cement electrolyte-electrode) has the disadvantages of low effective contact area, large spacing between electrode materials, and contradiction between device performance and thickness. The present invention attempts to improve the disadvantages of traditional cement-based supercapacitors from the perspective of structural design, and innovatively proposes a ring-shaped cement-based supercapacitor structure and designs a matching mold. The present invention prepares a ring-shaped cement-based supercapacitor by optimizing key components, optimizing the preparation process, and combining the freeze casting method. Through the ring structure design, the contact area of ​​the electrode / electrolyte is greatly improved, the ion transmission is improved, and the mass capacitance of the cement-based supercapacitor is significantly improved.

[0065] The advantage of the annular electrode design of the present invention is that the annular arrangement of the components avoids direct force on the cement-based composite electrode and optimizes the mechanical properties; the annular structure combined with the radial freezing strategy increases the contact area of ​​the electrode material while creating a rapid ion transmission channel, thereby improving the ion transmission efficiency; thanks to this, per unit volume, the capacity of the cement-based capacitor with an annular design is greater than that of the traditional sandwich-type supercapacitor.

[0066] The present invention proposes a capacitor with an annular structure frame. Through the construction of the annular structure, the contradiction between the performance of the sandwich-type cement supercapacitor and the thickness of the device is alleviated. The annular distribution of the electrode material significantly increases the electrode / electrolyte contact area, provides more energy storage sites, and improves the mass specific capacitance of the cement-based supercapacitor; at the same time, the electrode spacing is greatly shortened and is not affected by the thickness of the device, the ion transmission distance is significantly reduced, and the ion conductivity and power density of the device are greatly improved; in addition, the annular design improves the radial force of the device, avoids the damage of the weak phase of mechanical properties-cement electrode, and improves the mechanical properties of the overall device. The annular cement-based supercapacitor prepared by the present invention has excellent comprehensive performance.

[0067] In order to prepare the annular supercapacitor, the present invention also specially designs a mold and innovatively develops a freeze casting method to prepare the capacitor. The present invention prepares an annular cement-based supercapacitor by freeze casting, and can control the proportion of each component of the cement-based supercapacitor by controlling the diameter of the detachable stainless steel ring in the preparation mold, and has the advantages of low cost, simple operation process, good stability, and easy processing. At the same time, the freeze casting technology constructs an oriented channel between the electrode and the electrolyte, which is beneficial to the ion transmission inside the device.

[0068] The present invention prepares a ring-shaped cement-based supercapacitor by freeze casting. On the basis of maintaining the structural performance of cement-based materials, it expands the application in electrochemical energy storage, which is conducive to reducing the dependence on rare metals in traditional energy storage systems. The ring-shaped cement-based supercapacitor designed by this patent is expected to be widely promoted and applied in future green buildings, which is of great significance to the in-depth promotion of the "dual carbon" strategy.

[0069] In the present invention, the structure of the mold for preparing the supercapacitor is as follows Figure 1 As shown. Among them, the mold includes an inner ring cavity 3 corresponding to the first circular electrode layer of the final capacitor, a middle ring cavity 2 corresponding to the annular electrolyte layer of the final capacitor, and an outer ring cavity 1 corresponding to the second annular electrode layer of the final capacitor, which are arranged in sequence from the inside to the outside; a removable stainless steel ring 4 is arranged between the inner ring cavity and the middle ring cavity, and between the middle ring cavity and the outer ring cavity. When the capacitor is prepared by the freeze casting method, the corresponding slurry is first poured into the outer ring cavity 1, and when it is not completely frozen, the corresponding slurry is poured into the middle ring cavity 2, and the removable stainless steel ring 4 between the two is immediately taken out, so that the interface between the two interacts in liquid form. Then, when the slurry in the middle ring cavity 2 is not completely frozen, the corresponding slurry is poured into the inner ring cavity 3, and the removable stainless steel ring 4 between the two is immediately taken out, so that the interface between the two interacts in liquid form. After freezing, thawing, demolding, cement curing and salt solution immersion, the final supercapacitor is prepared. The width of the inner ring cavity 3 corresponds to the radius a of the first circular electrode layer 2 The width of the middle ring cavity 2 corresponds to the width a of the annular electrolyte layer. 1 The width of the outer ring cavity 1 corresponds to the width a of the second ring electrode layer. 0 .

[0070] Furthermore, the size of the detachable stainless steel ring can be adjusted so that the size of the outer ring cavity, the middle ring cavity or the inner ring cavity can be adjusted.

[0071] Furthermore, the material of the bottom of the mold is polytetrafluoroethylene thermal insulation material.

[0072] Furthermore, the outer ring 5 of the mold is made of a heat-conducting metal ring, preferably a copper ring.

[0073] The technical solution of the present invention is described in detail below in conjunction with specific embodiments so that those skilled in the art can better understand and implement the technical solution of the present invention, but the present invention is not limited to the scope of the examples.

[0074] In the following examples and comparative examples, unless otherwise specified, raw materials or processing techniques are conventional commercially available raw materials or conventional processing techniques in the art.

[0075] Example 1

[0076] This embodiment provides a ring-shaped cement-based supercapacitor, and the preparation method thereof is as follows:

[0077] 1) Prepare the raw material components as follows:

[0078]

[0079]

[0080] Mould parameters: a 0 :a 1 :a 2 :h=1:1:2:8,where a 0 is 10mm, a 1 is 10mm, a 2 is 20mm and h is 80mm.

[0081] The cementitious material is a mixture of 70% silicate cement, 15% fly ash and 15% blast furnace slag in mass percentage; the conductive material is a mixture of 90% activated carbon and 10% carbon black conductive agent in mass percentage; the water reducer is a polycarboxylic acid water reducer; the early strength agent is a mixture of 40% sodium carbonate, 30% gypsum and 30% water glass in mass percentage.

[0082] 2) The above raw material components are separated into component A and component B, wherein component B includes a conductive material, and component A does not contain a conductive material.

[0083] First, 150 parts of cementitious material, 0.375 parts of water reducing agent, 7.5 parts of early strength agent and 105 parts of water were placed in a stirring pot and mixed evenly to obtain cement electrolyte precursor slurry A; then 450 parts of cementitious material, 39 parts of conductive material, 1.125 parts of water reducing agent, 22.5 parts of early strength agent and 315 parts of water were placed in a stirring pot and mixed evenly to obtain cement electrode precursor slurry B; the above mold was placed in liquid nitrogen for precooling for 5s, and in a liquid nitrogen environment (only the outer ring material of the mold was in contact with liquid nitrogen, and the bottom material of the mold was not in contact with liquid nitrogen), from outside to inside (outside The mold is made in the order of (ring-middle ring-inner ring), first pour slurry B into the outer ring cavity of the mold, and when slurry B is not completely frozen, pour slurry A into the middle ring cavity, then take out the stainless steel ring between the two, and then pour slurry B into the inner ring cavity, and then take out the stainless steel ring between the two, wait for the column to be completely frozen, and take it out together with the mold to obtain a solidified column C; the solidified column C is placed in an environment of 0-4℃ to slowly thaw, and a block D is obtained after demolding, and then the block D is placed in a cement standard curing box for curing for 28 days to obtain a ring-shaped cement-based material D with an integrated directional pore structure. The cement-based material D is placed in a 1M KOH+1M KCl solution and soaked for 2 days, and a ring-shaped cement-based supercapacitor is obtained after taking it out.

[0084] Example 2

[0085] This embodiment provides a ring-shaped cement-based supercapacitor, and its preparation method is basically the same as that of embodiment 1, except that: the mold parameters used are different, specifically, a 0 :a 1 :a 2 :h=1:2:1:8,where a 0 is 10mm, a 1 is 20mm, a 2 is 10mm and h is 80mm.

[0086] Example 3

[0087] This embodiment provides a ring-shaped cement-based supercapacitor, and its preparation method is basically the same as that of embodiment 1, except that: the mold parameters used are different, specifically, a 0 :a 1 :a 2 :h=2:1:1:8,where a 0 is 20mm, a 1 is 10mm, a 2 is 10mm and h is 80mm.

[0088] Example 4

[0089] This embodiment provides a ring-shaped cement-based supercapacitor, and the preparation method thereof is as follows:

[0090] 1) Prepare the raw material components as follows:

[0091]

[0092] Mould parameters: a 0 :a 1 :a 2 :h=3:3:3:20,where a 0 is 15mm, a 1 is 15mm, a 2 is 15mm and h is 100mm.

[0093] The cementitious material is a mixture of 60% silicate cement, 25% fly ash and 15% blast furnace slag in mass percentage; the conductive material is a mixture of 80% activated carbon and 20% carbon black conductive agent in mass percentage; the water reducer is a polycarboxylic acid water reducer; the early strength agent is a mixture of 20% sodium carbonate, 40% gypsum and 40% water glass in mass percentage.

[0094] 2) The above raw material components are separated into component A and component B, wherein component B includes a conductive material, and component A does not contain a conductive material.

[0095] First, 300 parts of cementitious material, 2 parts of water reducing agent, 10 parts of early strength agent and 105 parts of water were placed in a stirring pot and mixed evenly to obtain cement electrolyte precursor slurry A; then 700 parts of cementitious material, 20 parts of conductive material, 18 parts of water reducing agent, 40 parts of early strength agent and 595 parts of water were placed in a stirring pot and mixed evenly to obtain cement electrode precursor slurry B; the above mold was placed in liquid nitrogen for precooling for 5s, and in a liquid nitrogen environment (only the outer ring material of the mold was in contact with liquid nitrogen, and the bottom material of the mold was not in contact with liquid nitrogen), from outside to inside (outer ring-middle ring- In the order of the inner ring, first pour slurry B into the outer ring cavity of the mold, when slurry B is not completely frozen, pour slurry A into the middle ring cavity, then take out the stainless steel ring between the two, pour slurry B into the inner ring cavity, then take out the stainless steel ring between the two, wait for the column to be completely frozen, take out together with the mold, and obtain a solidified column C; place the solidified column C in an environment of 0-4℃ to slowly thaw, and obtain block D after demolding, and then place block D in a cement standard curing box for curing for 28 days to obtain an annular cement-based material D with an integrated directional pore structure. Cement-based material D is soaked in 1M KOH+1M KCl solution for 2 days, and an annular cement-based supercapacitor is obtained after taking it out.

[0096] Example 5

[0097] This embodiment provides a ring-shaped cement-based supercapacitor, and the preparation method thereof is as follows:

[0098] 1) Prepare the raw material components as follows:

[0099]

[0100] Mould parameters: a 0 :a 1 :a 2 :h=6:1:4:10,where a 0 is 30mm, a 1 5mm, a 2 is 20mm, h is 50mm.

[0101] The cementitious material is a mixture of 80% silicate cement, 10% fly ash and 10% blast furnace slag in mass percentage; the conductive material is a mixture of 70% activated carbon and 30% carbon black conductive agent in mass percentage; the water reducer is a polycarboxylic acid water reducer; the early strength agent is a mixture of 40% sodium carbonate, 30% gypsum and 30% water glass in mass percentage.

[0102] 2) The above raw material components are separated into component A and component B, wherein component B includes a conductive material, and component A does not contain a conductive material.

[0103] First, 150 parts of cementitious material, 2 parts of water reducing agent, 6 parts of early strength agent and 100 parts of water are placed in a stirring pot and mixed evenly to obtain cement electrolyte precursor slurry A; then 250 parts of cementitious material, 40 parts of conductive material, 8 parts of water reducing agent, 14 parts of early strength agent and 300 parts of water are placed in a stirring pot and mixed evenly to obtain cement electrode precursor slurry B; the above mold is placed in liquid nitrogen for precooling for 5s, and in a liquid nitrogen environment (only the outer ring material of the mold is in contact with liquid nitrogen, and the bottom material of the mold is not in contact with liquid nitrogen), from outside to inside (outer ring-middle ring-inner ring The mold is made of a mold, and the slurry B is first poured into the outer ring cavity of the mold. When the slurry B is not completely frozen, the slurry A is poured into the middle ring cavity, and then the stainless steel ring between the two is taken out. Then the slurry B is poured into the inner ring cavity, and then the stainless steel ring between the two is taken out. The column is completely frozen and taken out together with the mold to obtain a solidified column C; the solidified column C is slowly thawed in an environment of 0-4°C, and a block D is obtained after demolding, and then the block D is placed in a cement standard curing box for curing for 28 days to obtain an annular cement-based material D with an integrated directional pore structure. The cement-based material D is soaked in a 1M KOH+1M KCl solution for 2 days, and an annular cement-based supercapacitor is obtained after being taken out.

[0104] Comparative Example 1

[0105] This comparative example provides a cement-based supercapacitor with a conventional sandwich structure. During its preparation, the annular freezing casting step of Example 1 is not adopted, but layered radial casting at room temperature is adopted, and the volume of the three-layer slurry remains the same as that of Example 1.

[0106] 1) Prepare raw material components:

[0107]

[0108] Mold parameters: a cylindrical mold with the same diameter as the outermost ring of the annular mold in Example 1;

[0109] The compositions of the cementitious material, the conductive material, the water reducing agent and the early strength agent are the same as those in Example 1.

[0110] 150 parts of cementitious material, 0.375 parts of water reducer, 7.5 parts of early strength agent and 105 parts of water are placed in a stirring pot and mixed evenly to obtain cement electrolyte precursor slurry A; then 450 parts of cementitious material, 39 parts of conductive material, 1.125 parts of water reducer, 22.5 parts of early strength agent and 315 parts of water are placed in a stirring pot and mixed evenly to obtain cement electrode precursor slurry B; referring to the volume ratio of each layer of slurry in Example 1, in the order of slurry A, slurry B, slurry A, layered cement test block C is cast at room temperature. Cement test block C is placed in a cement standard curing box and cured for 28 days to obtain layered cement-based material D. Cement-based material D is placed in a 1M KOH+1M KCl solution and soaked for 2 days, and a layered cement-based supercapacitor is obtained after taking it out.

[0111] Comparative Example 2

[0112] The method is basically the same as Example 1, except that the amount of the conductive material is replaced with 6 parts, and all of them are used in the cement electrode precursor slurry B.

[0113] Comparative Example 3

[0114] The method is basically the same as Example 1, except that the amount of the conductive material is replaced with 100 parts, and all of it is used in the cement electrode precursor slurry B.

[0115] The compression test was performed on the cylindrical cement-based supercapacitor samples of Φ20mm×h 20mm prepared in the above embodiments and comparative examples according to the national standard "Test Method for Cement Mortar Strength (ISO Method)" (GB / T17671-2021). The testing instrument is a universal testing machine. The porosity test adopts GB / T 50081-2002 "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete", using the mercury penetration method. The results are shown in Table 1-2.

[0116] Table 1 Physical properties of cement-based supercapacitors in various embodiments and comparative examples

[0117]

[0118] Table 1 shows the physical properties of cement-based supercapacitors with different structures. Examples 1-5 are all annular cement-based supercapacitors, among which Examples 1-3 respectively changed the proportion of the annular electrode and electrolyte, Examples 4 and 5 adjusted the size of the test block, and Comparative Example 1 is a layered cement-based supercapacitor cast at room temperature. The results show that with the increase of the cement electrolyte ratio of the annular cement-based supercapacitor, the porosity of the block decreases and the compressive strength increases; the radial mechanical properties of the layered cement-based supercapacitor are poor. The cement electrode component is considered to be a weak phase in mechanical properties due to the doping of activated carbon, and the annular structure design can effectively contain the cement electrode; on the contrary, the cement electrode of the layered structure specimen is directly stressed in the radial direction, and the weak phase is easy to become a stress concentration point, showing poor mechanical properties.

[0119] Table 2 Physical properties of cement-based supercapacitors in Example 1 and Comparative Examples 2-3

[0120]

[0121] Table 2 shows the effect of cement electrode components on device performance. The results show that as the amount of activated carbon in the cement electrode increases, the porosity increases and the compressive strength decreases.

[0122] Figure 4 The contact area between the cement electrode and the cement electrolyte in Examples 1-3 and Comparative Example 1. As shown in the figure, in cement-based supercapacitors of equal volume (diameter 80 mm, height 80 mm), the design of the ring structure significantly increases the contact area between the cement electrode and the cement electrolyte. 0 :a 1 :a 2 =1:1:2 component ratio, the contact area can reach up to 6280mm 2 The electrodes are no longer limited to lamellar shapes. The ring design is conducive to making the most of the test block characteristics. Moreover, the design is not affected by the aspect ratio. The transmission distance between electrodes is only affected by a 0 , a 1 , a 2 Influence.

[0123] Figure 5 The mass capacitance of the cement-based supercapacitors in Examples 1-3 and Comparative Example 1 is shown in the figure. The ring structure design helps to improve the mass density of the cement-based supercapacitor. 0 :a 1 :a 2 =1:1:2 component ratio, the mass capacitance can reach up to 13.2mF / g. This is due to the larger contact area of ​​the electrodes, and the ring structure design avoids the ion transmission distance being affected by the height of the specimen; on the other hand, the freeze casting technology constructs an oriented channel, which is conducive to improving the transmission of ions between electrodes.

[0124] The electrical properties of Example 2-3 are as follows:

[0125] Table 2 Mass specific capacity data of Example 2 and Example 3

[0126] Example 4 Example 5 Comparative Example 2 Comparative Example 3 Mass specific capacity F / g 19.1 9.6 0.5 24.9

[0127] Example 4 and Example 5 are annular cement-based supercapacitors of different sizes, respectively. The results show that by modifying mold parameters and other indicators, large-scale products can be prepared, which are suitable for the application scenarios where cement-based materials are large in quantity and wide in scope. Comparative Example 2 reduced the amount of conductive material, and Comparative Example 3 added too much conductive material. The results show that too low a conductive material dosage will result in a lower mass specific capacity, which is caused by poor conductive paths and excessive internal resistance. Excessive conductive material dosage will lead to a significant degradation of mechanical properties, while the improvement in mass specific capacity is limited. This is because too much conductive material will aggravate the agglomeration phenomenon and the actual energy storage area will decrease.

[0128] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

[0129] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

Claims

1. A ring-shaped cement-based supercapacitor, characterized in that: The annular cement-based supercapacitor comprises a first circular electrode layer, an annular electrolyte layer and a second annular electrode layer arranged in sequence from the inside to the outside; The first circular electrode layer and the second annular electrode layer include the following components in total, in parts by weight: 100-900 parts of gelling material, 8-95 parts of conductive material, 1-50 parts of water reducing agent, 10-60 parts of early strength agent and 200-800 parts of water; The annular electrolyte layer comprises the following components in parts by weight: 30-400 parts of a gelling material, 0.05-4 parts of a water reducing agent, 1-20 parts of an early strength agent and 10-200 parts of water; The first circular electrode layer, the annular electrolyte layer and the second annular electrode layer all contain inorganic metal ions.

2. The annular cement-based supercapacitor according to claim 1, characterized in that: The first circular electrode layer, the annular electrolyte layer and the second annular electrode layer are arranged concentrically; and / or, the composition ratio of the first circular electrode layer and the second annular electrode layer is completely the same.

3. The annular cement-based supercapacitor according to claim 1, characterized in that: The inorganic metal ions are selected from potassium ions, sodium ions, lithium ions, or a combination of one or more thereof.

4. The annular cement-based supercapacitor according to claim 3, characterized in that: The inorganic metal ions are obtained by soaking in a mixed solution of an inorganic metal salt and an inorganic metal hydroxide.

5. The annular cement-based supercapacitor according to claim 1, characterized in that: The radius a2 of the first circular electrode layer is 5-30 mm; and / or, the width a1 of the annular electrolyte layer is 5-30 mm; and / or, the width a0 of the second annular electrode layer is 5-30 mm; and / or, the height h of the annular cement-based supercapacitor is 10-100 mm.

6. The annular cement-based supercapacitor according to claim 1, characterized in that: The ratio of the width a0 of the second annular electrode layer, the width a1 of the annular electrolyte layer, the radius a2 of the first circular electrode layer and the height h of the annular cement-based supercapacitor is 1-6:1-6:1-6:2-20.

7. The annular cement-based supercapacitor according to claim 1, characterized in that: The cementitious material is selected from any one or more combinations of Portland cement, fly ash, and blast furnace slag; preferably, the cementitious material is a mixture of Portland cement, fly ash, and blast furnace slag; more preferably, in the mixture, the mass ratio of the Portland cement, fly ash, and blast furnace slag is 60-80:10-20:10-20.

8. The annular cement-based supercapacitor according to claim 1, characterized in that: The conductive material is selected from one or both of activated carbon and carbon black conductive agent; preferably, the conductive material is a mixture of activated carbon and carbon black conductive agent; more preferably, in the mixture, the mass ratio of the activated carbon to the carbon black conductive agent is 70-95:5-30.

9. The annular cement-based supercapacitor according to claim 1, characterized in that: The water reducer is any one or more of a polycarboxylate water reducer and a lignin sulfonate; and / or the early strength agent is any one or more of a sodium carbonate, gypsum, and water glass; preferably, the early strength agent is a mixture of sodium carbonate, gypsum, and water glass. In the mixture, the mass ratio of sodium carbonate, gypsum, and water glass is 30-50:20-40:20-40.

10. The annular cement-based supercapacitor according to claim 1, characterized in that: The annular cement-based supercapacitor has a compressive strength of 28-40 MPa, a porosity of 38%-60%, and a contact area between the cement electrode and the cement electrolyte of 2800-7000 mm 2 , mass capacitance is 3.0-15.0mF / g.

11. A method for preparing the annular cement-based supercapacitor according to any one of claims 1 to 10, characterized in that: The preparation method uses a mold, which includes, arranged from inside to outside, an inner ring cavity corresponding to the first circular electrode layer, a middle ring cavity corresponding to the annular electrolyte layer, and an outer ring cavity corresponding to the second annular electrode layer; a detachable stainless steel ring is arranged between the inner ring cavity and the middle ring cavity, and between the middle ring cavity and the outer ring cavity; The preparation method comprises the following steps: 1) mixing the components of the first circular electrode layer evenly to obtain a first cement electrode precursor slurry; mixing the components of the second annular electrode layer evenly to obtain a second cement electrode precursor slurry; mixing the components of the annular electrolyte layer evenly to obtain a cement electrolyte precursor slurry; 2) placing the mold in a liquid nitrogen environment, pouring the second cement electrode precursor slurry into the outer ring cavity of the mold, pouring the cement electrolyte precursor slurry into the middle ring cavity of the mold when the second cement electrode precursor slurry is not completely frozen, and taking out the detachable stainless steel ring between the outer ring cavity and the middle ring cavity; pouring the first cement electrode precursor slurry into the inner ring cavity of the mold when the cement electrolyte precursor slurry is not completely frozen, and taking out the detachable stainless steel ring between the middle ring cavity and the inner ring cavity; after the column is completely frozen, take it out together with the mold to obtain a solidified column; 3) thawing the solidified column, removing the mold to obtain a block, and performing cement curing on the block to obtain a cement-based material with an integrated directional pore structure; 4) Soaking the cement-based material in a mixed solution of an inorganic metal salt and an inorganic metal hydroxide, and taking it out to obtain a ring-shaped cement-based supercapacitor.

12. The method for preparing the annular cement-based supercapacitor according to claim 11, characterized in that: The size of the removable stainless steel ring can be adjusted so that the size of the outer ring cavity, the middle ring cavity or the inner ring cavity can be adjusted; and / or, the material of the bottom of the mold is polytetrafluoroethylene insulation material; and / or, the material of the outer ring of the mold is a heat-conducting metal ring, preferably a copper ring.

13. The method for preparing the annular cement-based supercapacitor according to claim 11, characterized in that: In step 2), only the outer ring material of the mold is in contact with the liquid nitrogen, and the bottom material of the mold is not in contact with the liquid nitrogen.

14. The method for preparing the annular cement-based supercapacitor according to claim 11, characterized in that: In step 3), the thawing treatment is carried out at 0-4°C; and / or, the thawing treatment time is 1-4 days; and / or, the cement curing is carried out in a cement standard curing box; and / or, the cement curing time is 20-30 days; and / or, the inorganic metal salt is selected from a combination of one or more of potassium chloride, sodium chloride, and lithium chloride; and / or, the inorganic metal hydroxide is selected from a combination of one or more of potassium hydroxide and sodium hydroxide; and / or, the molar concentration of the inorganic metal salt is 0.5-2M; and / or, the molar concentration of the inorganic metal hydroxide is 0.5-2M; and / or, the immersion time is 1-4 days.

15. Use of the annular cement-based supercapacitor according to any one of claims 1 to 10 as a functional device in roads, buildings or bridges.

Images