A high ionic conductivity cement-based structured electrolyte and preparation method thereof

Abstract

The present invention discloses a method for preparing a high-ionic conductivity cement-based structured electrolyte and the electrolyte, comprising: mixing a polymer solution, cement, and fine sand to obtain a polymer-cement slurry; subjecting the polymer-cement slurry to low-temperature, sealed curing, and then allowing it to stand at room temperature to obtain a cement-based structured electrolyte. The present invention utilizes a controlled phase separation technique to enable elastic phase separation of the polymer network prior to cement hydration. During the hydration process, the cement adaptively forms the backbone of the polymer network, resulting in a good interface between the two, capable of forming continuous, high-conductivity ion channels. The preparation process is simple to operate and highly reproducible.

Description

Technical Field

[0001] The present invention relates to the field of functional composite materials, and in particular to a high-ionic conductivity cement-based structured electrolyte and a preparation method thereof. Background Art

[0002] Advanced building materials of the future should possess multifunctional intelligent properties, such as the ability to collect and store renewable energy sources like solar and wind energy. Using structures and buildings as energy storage devices holds immense innovative significance. Even if the energy storage density per unit volume of new-generation building materials is low due to the large size of buildings, their energy storage potential is considerable. However, cement's low ionic conductivity and high electrical resistance have severely hampered the development of cement-based electrolytes. Existing cement-based electrolytes typically use expensive carbon nanotubes as fillers within the cement to improve its ionic conductivity, but ensuring uniform dispersion of the fillers is difficult. Uneven carbon nanotubes can easily lead to the formation of weak areas within the cement, resulting in a sudden drop in strength. Developing cement-based structural electrolytes that combine high mechanical strength with high ionic conductivity remains challenging. Summary of the Invention

[0003] In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, an object of the present invention is to provide a high ionic conductivity cement-based structured electrolyte and a preparation method thereof.

[0004] The purpose of the present invention is achieved through the following technical solutions:

[0005] A method for preparing a high ionic conductivity cement-based structured electrolyte, comprising:

[0006] Mixing the polymer solution, cement and fine sand to obtain a polymer-cement slurry;

[0007] The polymer solution is obtained by dissolving a polymer and a strong base in water, or by dissolving a polymer, a strong base and a sulfide in water, or by dissolving a polymer, a strong base, an inorganic sulfide and a chemical cross-linking agent in water;

[0008] The polymer-cement slurry is subjected to low-temperature sealed curing and then allowed to stand at room temperature to obtain a cement-based structured electrolyte.

[0009] Furthermore, the polymer is one or more of PVA or PAA; the strong base is one or more of KOH and NaOH; the sulfide is one or more of Na2S or K2S; and the chemical crosslinking agent is one or more of TEAC (tetraethylammonium chloride) and PEGDGE (polyethylene glycol diglycidyl ether).

[0010] Further, the following steps are included:

[0011] Stir the polymer solid, strong base and water at a temperature of 85-95 degrees and a speed of 250-260 r / min for 1.5-2 hours to prepare a uniform polymer solution;

[0012] Mix cement and fine sand at a speed of 60-70 r / min and dry mix for 5-10 minutes at a temperature of 90-95 degrees to obtain a cement-fine sand mixture;

[0013] The polymer solution is mixed with the cement and fine sand mixture at a mixing temperature of 90-95 degrees, so that the polymer solution is evenly dispersed in the cement to obtain a polymer-cement slurry;

[0014] The polymer-cement slurry is then cooled to 2-5 degrees Celsius for 5-10 minutes. During the cooling process, the cement slurry is stirred at a constant speed and 60-80g of deionized water at 2-5 degrees Celsius is slowly added to obtain a cement slurry containing a liquid-solid mixed phase; the slow addition rate refers to an addition rate of 0.3-0.5g / s.

[0015] The cement paste containing the liquid-solid mixed phase is placed in a closed environment for curing to obtain a hardened low-temperature cement-based electrolyte;

[0016] The low-temperature cement-based electrolyte is allowed to stand at room temperature for 12-24 hours to form a fully solid cement-based structured electrolyte.

[0017] Furthermore, the cement slurry is stirred at a constant speed during the cooling process, and the constant stirring speed is the same as the stirring speed in the step of obtaining the polymer-cement slurry.

[0018] Furthermore, the cement slurry containing the liquid-solid mixed phase is placed in a closed environment for curing, the temperature of the closed environment is 0-2 degrees, and the curing time is 6-24 hours.

[0019] Furthermore, the constant stirring time is 15-20 minutes.

[0020] Furthermore, the polymer solution is mixed with the cement and fine sand mixture at a stirring speed of 140±5 r / min for 1 min 30 s to 2 min.

[0021] Furthermore, when the polymer solution contains inorganic sulfide, the inorganic sulfide is added together with the cold water; when the polymer solution contains a chemical crosslinking agent, the chemical crosslinking agent is added together with the cold water;

[0022] The amount of each substance in the polymer solution is calculated by weight:

[0023] 8-10 parts of polymer

[0024] 30-40 parts of strong base

[0025] 190-210 parts water

[0026] When inorganic sulfide is present, the amount of sulfide is 0.5-1 part;

[0027] When a chemical cross-linking agent is contained, the amount of the chemical cross-linking agent is 0.1-0.5 parts;

[0028] When the polymer solution is mixed with cement and fine sand, the cement is 490-510 parts and the fine sand is 140-160 parts.

[0029] A load-bearing and high ion conductivity integrated cement-based structural electrolyte is prepared by the preparation method.

[0030] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0031] The present invention uses a polymer solution, cement and fine sand to be finely mixed under temperature-controlled conditions to obtain a polymer-cement slurry, and utilizes the elastic phase separation characteristics of the polymer in combination with two-stage curing to produce an electrolyte;

[0032] The present invention mixes a polymer solution and a cement sand system at 90-95 degrees, with a rotation speed of 140±5r / min and maintains the mixture for 1 minute 30 seconds to 2 minutes. This process quickly and evenly disperses the polymer solution into the cement. At the same time, due to the 90-95 degree environment, the solubility of the polymer in the solution is relatively high, and the polymer solid phase network will not precipitate early during the mixing process, thereby avoiding the formation of mechanical weak surfaces of the cement. At the same time, the short and continuous stirring prevents the cement from hardening, thereby obtaining a polymer-cement high-temperature mixed slurry with good fluidity and uniformity.

[0033] The present invention cools and stirs the cement slurry. During this process, due to the rapid drop in temperature, the solubility of the polymer in the liquid phase decreases, while the fluidity of the cement does not change significantly. The polymer undergoes elastic phase separation in the completely elastic liquid phase environment of the cement slurry, so that a polymer network of a liquid-solid mixed phase is gradually formed inside the cement. The polymer network serves as an ion channel inside the electrolyte and also as an attachment surface for the nucleation of cement hardening in the subsequent step.

[0034] The present invention utilizes a low-temperature, sealed environment for curing, ensuring humidity levels do not fluctuate suddenly. During this process, the cement begins to transform into a solid phase, hardening and nucleating. In the second step, the liquid phase of the polymer liquid-solid mixed phase network continuously separates from the liquid phase, allowing the complete polymer solid phase network to be continuously distributed in three dimensions. During this process, the liquid cement and liquid polymer simultaneously transform into a solid state, a dual-phase, simultaneous in-situ phase separation. Ultimately, a cement-based structural electrolyte with a stable polymer-cement interface is formed. This well-balanced interface not only avoids mechanical weaknesses caused by dense PVA precipitation but also enhances the synergistic ionic conductivity of the cement-polymer interface. The resulting compressive and flexural strengths are over 80% and 90% of those of a commercial control with the same formulation, respectively, and the ionic conductivity can reach over 300 mS / cm.

[0035] The present invention adopts low-temperature closed environment curing and then allows the cement to stand at room temperature. During this process, as the temperature rises, the intensity of the hydration reaction increases, and the remaining free water in the cement will participate in further hydration, releasing hydration heat, causing the local temperature of the polymer solid phase network to rise. A small part of the polymer solid phase network will redissolve in the free water. As the free water is consumed in the hydration reaction, the polymer dissolved in this process will undergo phase separation again in the post-hydration cement, ultimately forming an all-solid-state cement-based electrolyte with a uniformly distributed polymer network.

[0036] The present invention adopts controlled phase separation technology to enable the elastic phase separation of the polymer network to proceed earlier than the hydration of cement. The cement adaptively becomes the skeleton of the polymer network during the hydration process. The interface between the two is good, and a continuous high-conductivity ion channel can be formed. The preparation process is simple to operate and highly repeatable. The drugs used are all non-toxic and harmless substances, which are environmentally friendly and inexpensive. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1(a)-Figure 1(f) The EIS results of Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2 and Comparative Example 3 are shown respectively;

[0038] Figure 2 Schematic diagram of the LSV window of Comparative Example 3, Comparative Example 1 and Example 1;

[0039] Figure 3 This is a CV test diagram of an embodiment of the present invention;

[0040] Figure 4 CT schematic diagram of the electrolyte of the present invention. DETAILED DESCRIPTION

[0041] The present invention will be further described in detail below with reference to the examples, but the embodiments of the present invention are not limited thereto.

[0042] Example 1

[0043] In this embodiment 1, the polymer solution used is PVA-KOH.

[0044] A method for preparing a high-ionic conductivity cement-based structured electrolyte is described. The preparation process is as follows: 10g of polyvinyl alcohol (PVA) is dissolved in 90g of deionized water, heated in a waterbath at 95°C, and stirred at 250 rpm for 50 minutes. During this stirring period, 30g of solid KOH is dissolved in 110g of water in a separate beaker to obtain a KOH solution. When the PVA solution turns light milky white, the KOH solution is slowly dripped into the PVA solution and heated and stirred for 50 minutes until the mixed solution turns transparent and light yellow, thereby obtaining a PK solution. At 90°C, 490g of cement (PO42.5R) and 140g of fine sand are premixed at 70 rpm for 10 minutes. The cement-fine sand mixture is then added to the PK solution while maintaining the temperature at 90°C. The mixture is stirred at 145 rpm for 2 minutes. After this process, a cooler is turned on and 60g of 2°C deionized water is slowly added to reduce the slurry temperature to 2°C. The slurry is stirred at 145 rpm for 16 minutes to obtain a polymer-cement slurry. The polymer-cement paste was sealed and cured at 2 degrees for 24 hours and then cured at room temperature for 24 hours to obtain a cement-based structural electrolyte.

[0045] Example 2

[0046] In this embodiment 2, the polymer solution used is PVA-PAA-KOH.

[0047] A method for preparing a high-ionic conductivity cement-based structured electrolyte is described as follows: 7.8g PVA and 0.2g PAA are dissolved in 90g deionized water, heated in a waterbath at 85°C, and stirred at 260 rpm for 50 minutes. During this stirring period, 40g of solid KOH is dissolved in 115g of water in a separate beaker to obtain a KOH solution. When the PVA / PAA solution turns light milky white, the KOH solution is slowly dripped into the PVA solution and heated and stirred for 70 minutes until the mixed solution turns transparent and light yellow, thereby obtaining a PKA solution. At 95°C, 510g of cement (PO42.5R) and 160g of fine sand are premixed at 65 rpm for 8 minutes. The cement-fine sand mixture is then added to the PKA solution while maintaining 95°C. The mixture is stirred at 140 rpm for 1 minute and 30 seconds. After this process, a cooler is turned on and 80g of deionized water at 5°C is slowly added to reduce the slurry temperature to 5°C. The slurry is stirred at 140 rpm for 20 minutes to obtain a polymer-cement slurry. The polymer-cement paste was sealed and cured at 0 degrees for 6 hours and then cured at room temperature for 12 hours to obtain a cement-based structured electrolyte.

[0048] Example 3

[0049] In this embodiment 3, the polymer solution used is PVA-KOH-K2S.

[0050] A cement-based structured electrolyte is prepared as follows: 9.8g of PVA is dissolved in 90g of deionized water, heated in a waterbath at 92°C and stirred at 255 rpm for 40 minutes. During this stirring period, 33.6g of KOH solid is dissolved in 110g of water in a separate beaker to obtain a KOH solution. When the PVA solution turns light milky white, the KOH solution is slowly dripped into the PVA solution and heated and stirred for 50 minutes until the mixed solution turns transparent and light yellow, thereby obtaining a PK solution. At 92°C, 500g of cement (PO42.5R) and 150g of fine sand are premixed at 60 rpm for 5 minutes. The cement-fine sand mixture is then added to the PK solution, maintained at 92°C, and stirred at 135 rpm for 1 minute and 45 seconds. After this process, a cooler is turned on and 65g of 3°C deionized water and 0.8g of K2S are slowly added to reduce the slurry temperature to 3°C. The slurry is stirred at 135 rpm for 18 minutes to obtain a polymer-cement slurry. The polymer-cement paste was sealed and cured at 1°C for 21 h and then at room temperature for 18 h to obtain a cement-based structural electrolyte.

[0051] Comparative Example 1

[0052] Compared with Example 1, the polymer solution is PVA-KOH, and there is no cooling process. It is directly mixed and stirred, and then placed in an environment of 2 degrees for curing.

[0053] A cement-based structured electrolyte is prepared as follows: 10g of PVA is dissolved in 90g of deionized water, heated in a waterbath at 95°C and stirred at 250 rpm for 50 minutes. During this stirring period, 33.6g of KOH solid is dissolved in 110g of water in a separate beaker to obtain a KOH solution. When the PVA solution turns light milky white, the KOH solution is slowly dripped into the PVA solution and heated and stirred for 50 minutes until the mixed solution turns transparent and light yellow, thereby obtaining a PK solution. At 90°C, 500g of cement (PO42.5R) and 150g of fine sand are premixed at 70 rpm for 10 minutes. The cement-fine sand mixture and 65g of room-temperature deionized water are added to the PK solution at room temperature, and stirred at 145 rpm for 18 minutes to obtain a polymer-cement slurry. The polymer-cement slurry is sealed and cured at 2°C for 24 hours, followed by curing at room temperature for 24 hours to obtain a cement-based structured electrolyte.

[0054] Comparative Example 2:

[0055] Compared with Example 1, the polymer solution is PVA-KOH, there is a cooling process, and curing is carried out at room temperature.

[0056] A cement-based structured electrolyte is prepared as follows: 10g of polyvinyl alcohol (PVA) is dissolved in 90g of deionized water, heated in a waterbath at 95°C and stirred at 250 rpm for 50 minutes. During this stirring period, 33.6g of KOH solid is dissolved in 110g of water in a separate beaker to obtain a KOH solution. When the PVA solution turns light milky white, the KOH solution is slowly dripped into the PVA solution and heated and stirred for 50 minutes until the mixed solution turns transparent and light yellow, thereby obtaining a PK solution. At 90°C, 500g of cement (PO42.5R) and 150g of fine sand are premixed at 70 rpm for 10 minutes. The cement-fine sand mixture is then added to the PK solution at 95°C and stirred at 145 rpm for 2 minutes. After this process, a cooler is turned on and 65g of 2°C deionized water is slowly added to reduce the slurry temperature to 2°C. The slurry is stirred at 145 rpm for 16 minutes to obtain a polymer-cement slurry. The polymer-cement slurry is sealed and cured at room temperature for 48 hours to obtain a cement-based structured electrolyte.

[0057] Comparative Example 3:

[0058] Compared with Example 1, the polymer solution is PVA-KOH, there is no cooling process, and the curing is carried out at room temperature.

[0059] A cement-based structured electrolyte is prepared as follows: 10g of PVA is dissolved in 90g of deionized water, heated in a waterbath at 95°C and stirred at 250 rpm for 50 minutes. During this stirring period, 33.6g of KOH solid is dissolved in 110g of water in a separate beaker to obtain a KOH solution. When the PVA solution turns light milky white, the KOH solution is slowly dripped into the PVA solution and heated and stirred for 50 minutes until the mixed solution turns transparent and light yellow, thereby obtaining a PK solution. At 90°C, 500g of cement (PO42.5R) and 150g of fine sand are premixed at 70 rpm for 10 minutes. The cement-fine sand mixture and 65g of room-temperature deionized water are added to the PK solution and stirred at 145 rpm for 18 minutes to obtain a polymer-cement slurry. The polymer-cement slurry is sealed and cured at room temperature for 48 hours to obtain a cement-based structured electrolyte.

[0060] Performance testing:

[0061] like Figure 1(a)-Figure 1(f) As shown, it reflects the ionic conductivity of the electrolyte. The higher the ionic conductivity, the better the performance of the electrolyte.

[0062] From the EIS results, it can be seen that the conductivity of Example 1 is 108 mS / cm, the conductivity of Example 2 is 303 mS / cm, the conductivity of Example 3 is 165.6 mS / cm, the conductivity of Comparative Example 1 is 63.3 mS / cm, the conductivity of Comparative Example 2 is 1.926 mS / cm, and the conductivity of Comparative Example 3 is 0.166 mS / cm.

[0063] It can be seen from Examples 1-3 that the ionic conductivity of the cement-based structured electrolyte with cooling stirring and low-temperature curing is on the order of 102 mS / cm.

[0064] From the comparison between Example 1 and Comparative Example 1, it can be seen that the ion conductivity decreased by 41.4% due to the lack of cooling and stirring.

[0065] From the comparison between Example 1 and Comparative Example 2, it can be seen that the ion conductivity decreases by 98.2% due to the lack of low-temperature curing.

[0066] Comparison of Example 1 with Comparative Example 3 shows that the ion conductivity decreased by 99.8% due to the lack of both cooling, stirring, and low-temperature curing. This means that the product formed by directly mixing the polymer solution and cement is not capable of serving as an electrolyte.

[0067] like Figure 2 As shown in the LSV window diagram, the longer the window, the more stable the electrolyte.

[0068] like Figure 2 It can be seen that the electrolyte in Example 1 of the present invention with cooling, stirring and low-temperature curing is the most stable.

[0069] like Figure 3 As shown, the test method is as shown in Examples 1-3 and Comparative Examples 1-3, respectively, using the same nickel-iron pole piece for assembly testing, applying a linearly changing potential (voltage), and monitoring the corresponding current response. Comparative Example 1 (no cooling and stirring, with 2-5 degrees curing) and Comparative Example 3 (no cooling and stirring, no 2-5 degrees curing) do not have the reaction peaks shown in Example 1. The reaction peaks of 0.74V and 1.00V correspond to the reduction reaction of the iron pole, and 1.65V corresponds to the oxidation reaction of the nickel pole. Only in Example 1 (with both cooling and constant speed stirring and 2-5 degrees curing electrolyte) has a complete reaction peak, which proves the feasibility of applying this electrolyte to all-solid-state alkaline batteries. This illustrates the superiority of the temperature-controlled, originally phase-separated cement-based structured electrolyte proposed by the present invention in supporting the electrical reaction of all-solid-state batteries.

[0070] like Figure 4 This is the CT image of the electrolyte prepared by the preparation method of the present invention, which can intuitively show the distribution of the PK network inside the cement.

[0071] Table 1 shows the mechanical properties of the electrolytes prepared in Examples 1 to 3, indicating that the electrolytes have good load-bearing capacity in terms of axial compression and flexural stress.

[0072] Table 1 Mechanical strength

[0073]

[0074] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for preparing a high ionic conductivity cement-based structured electrolyte, characterized in that: include: Mixing the polymer solution, cement and fine sand to obtain a polymer-cement slurry; The polymer solution is obtained by dissolving a polymer and a strong base in water, or by dissolving a polymer, a strong base and an inorganic sulfide in water, or by dissolving a polymer, a strong base, an inorganic sulfide and a chemical cross-linking agent in water; The polymer-cement slurry is subjected to low-temperature sealed curing and then allowed to stand at room temperature to obtain a cement-based structured electrolyte; The specific steps are as follows: The polymer solid, strong base and water are mixed and stirred at a temperature of 85-95°C and a speed of 250-260 r / min for 1.5-2 hours to prepare a uniform polymer solution; when the polymer solution contains inorganic sulfide, the inorganic sulfide is added together with water; when the polymer solution contains a chemical cross-linking agent, the chemical cross-linking agent is added together with water; Mix cement and fine sand at a temperature of 90-95°C, a rotation speed of 60-70 r / min, and dry mix for 5-10 minutes to obtain a cement-fine sand mixture; The polymer solution is mixed with the cement and fine sand mixture at a mixing temperature of 90-95°C to uniformly disperse the polymer solution into the cement to obtain a polymer-cement slurry; The polymer-cement slurry is then cooled to 2-5°C for 5-10 minutes. During the cooling process, the cement slurry is stirred at a constant speed and 60-80 g of water at 2-5°C is slowly added to obtain a cement slurry containing a liquid-solid mixed phase. The cement paste containing the liquid-solid mixed phase is placed in a closed environment for curing to obtain a hardened low-temperature cement-based electrolyte; The low-temperature cement-based electrolyte is allowed to stand at room temperature for 12-24 hours to form a fully solid cement-based structured electrolyte.

2. The preparation method according to claim 1, characterized in that The polymer is one or more of PVA and PAA; the strong base is one or more of KOH and NaOH; the inorganic sulfide is one or more of Na2S and K2S; and the chemical cross-linking agent is one or more of tetraethylammonium chloride and polyethylene glycol diglycidyl ether.

3. The preparation method according to claim 1, characterized in that The cement slurry is stirred at a constant speed during the cooling process, and the constant stirring speed is the same as the stirring speed in the step of obtaining the polymer-cement slurry.

4. The preparation method according to claim 1, characterized in that The cement slurry containing the liquid-solid mixed phase is placed in a closed environment for curing, the temperature of the closed environment is 0-2° C., and the curing time is 6-24 hours.

5. The preparation method according to claim 1, characterized in that The constant speed stirring time is 15-20 minutes.

6. The preparation method according to claim 1, characterized in that The polymer solution is mixed with the cement and fine sand mixture at a stirring speed of 140±5 r / min and a stirring time of 1 min 30 s-2 min.

7. The preparation method according to claim 1, characterized in that The amount of each substance in the polymer solution is calculated by weight: 8-10 parts of polymer; 30-40 parts of strong base; 190-210 parts of water; when containing inorganic sulfide, the amount of inorganic sulfide is 0.5-1 part; when containing chemical crosslinking agent, the amount of chemical crosslinking agent is 0.1-0.5 part; When the polymer solution is mixed with cement and fine sand, cement: 490-510 parts; Fine sand: 140-160 parts.

8. A high ionic conductivity cement-based structured electrolyte, characterized in that: Prepared by the preparation method according to any one of claims 1 to 7.

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