Wood-based energy storage building material capable of self-adapting to environment temperature and preparation method of wood-based energy storage building material

Abstract

The invention discloses an environment temperature self-adaptive wood-based energy storage building material and a preparation method thereof.The environment temperature self-adaptive wood-based energy storage building material comprises a matrix layer, a functional layer and a conductive interface layer, the functional layer is a phase-change microcapsule, a core material of the phase-change microcapsule is bio-based fatty acid, a wall material of the phase-change microcapsule is a lignin-methyl methacrylate grafted copolymer, and the conductive interface layer is a conductive layer. The conductive interface layer is a polydopamine reduced graphene oxide composite coating; the wood-based energy storage building material is divided into the matrix layer, the functional layer and the interface layer for collaborative optimization, and the mechanical property and the energy storage efficiency are both considered; wood is carbonized to form a porous matrix, the porous structure of the carbonized wood is utilized to form an electric double-layer capacitor, the energy storage function is given to the wood, heat energy storage and release are achieved by loading phase change microcapsules, and the building material has the temperature self-adaptive capacity; the lignin grafted polymer is used as the wall material, and the bio-based phase change core material is wrapped in the microcapsule, so that the leakage of the phase change material is prevented.

Description

Technical Field

[0001] The present invention relates to the technical fields of multifunctional building materials and energy storage technologies, and particularly relates to a wood-based energy storage building material adaptable to ambient temperature and a preparation method thereof. Background Art

[0002] Wood-based energy storage building materials are a new type of composite material that combines wood and energy storage technologies, aiming to achieve both building structural functions and energy storage functions simultaneously. By combining the natural properties of wood with the electrochemical properties of energy storage materials, such materials provide innovative solutions for green buildings and sustainable energy systems. After physical or chemical treatment of wood, components such as its internal porous structure, cellulose, and lignin can be used as the substrate or conductive carrier of energy storage materials;

[0003] In traditional wood building materials, ordinary wood is only used as a structural material, lacking energy storage and temperature regulation functions, and unable to meet the requirements of modern buildings for energy self-sufficiency and intelligent temperature control. Moreover, when traditional phase change materials are directly used, they are prone to leakage, and have a weak binding force with the wood matrix, and the long-term use performance decays severely. Therefore, the present invention proposes a wood-based energy storage building material adaptable to ambient temperature and a preparation method thereof to solve the problems existing in the prior art. Summary of the Invention

[0004] Aiming at the above problems, the purpose of the present invention is to propose a wood-based energy storage building material adaptable to ambient temperature and a preparation method thereof. The wood-based energy storage building material adaptable to ambient temperature and the preparation method of its phase change microcapsules optimize the coordination of the matrix layer, functional layer, and interface layer, taking into account both mechanical properties and energy storage efficiency;

[0005] By carbonizing wood to form a porous matrix, using the porous structure after wood carbonization to form an electric double layer capacitor, endowing it with energy storage function, and realizing heat energy storage and release by loading phase change microcapsules, enabling the building material to have temperature adaptability;

[0006] By using lignin-grafted polymer as the wall material to encapsulate the bio-based phase change core material in the microcapsules to prevent the leakage of the phase change material, and embedding the microcapsules into the wood pores to enhance the bonding strength between the material and the matrix.

[0007] To achieve the purpose of the present invention, the present invention is realized through the following technical solutions: A wood-based energy storage building material adaptable to ambient temperature and a preparation method thereof, including a matrix layer, a functional layer, and a conductive interface layer. The functional layer is a phase change microcapsule, the core material of the phase change microcapsule is a bio-based fatty acid, the wall material of the phase change microcapsule is a lignin-methyl methacrylate graft copolymer, and the conductive interface layer is a polydopamine-reduced graphene oxide composite coating.

[0008] A further improvement lies in that: the raw material of the substrate layer is balsa wood with a density of 0.1 - 0.3 g / cm³, and it is enhanced by a gradient carbonization process.

[0009] A further improvement lies in that: the mass ratio of polydopamine to reduced graphene oxide in the polydopamine-reduced graphene oxide composite coating is 1:2.

[0010] It includes the following steps:

[0011] Step 1, raw material pretreatment: Select balsa wood as the raw material and cut it into plates with a thickness of 5 - 20 mm. Polish the surface to remove burrs. Immerse the wood in NaOH solution for 48 - 72 hours to remove part of the lignin and hemicellulose, improve the pore connectivity, then rinse it with deionized water until neutral, and dry it in a vacuum environment at 60°C for 12 hours.

[0012] Step 2, gradient carbonization: Put the pretreated wood in step 2 into a tube furnace and heat it to 400°C at a rate of 5°C / min, hold for 1 hour, then continue to heat it to 700 - 800°C at a rate of 3°C / min, hold for 2 - 3 hours to form a porous carbon matrix, and finally cool it naturally to room temperature to obtain carbonized wood.

[0013] Step 3, cellulose reinforcement: Immerse the carbonized wood in nano-cellulose solution and conduct vacuum treatment for 2 hours, then dry it at 60°C; repeat 3 times to form a three-dimensional reinforcement network.

[0014] Step 4, microcapsule preparation and encapsulation: Mix and heat the bio-based fatty acid to 80°C, and magnetically stir it at a speed of 300 rpm until it is completely melted as the core material. Disperse lignin in deionized water, add methyl methacrylate (MMA) monomer, and add ammonium persulfate with a concentration of 1 wt% to the solution to obtain a lignin-PMMA graft copolymer (lignin-methyl methacrylate graft copolymer) solution as the wall material. Add the core material to the wall material solution to form a water-in-oil emulsion, heat it to 60°C and continuously stir to polymerize the wall material on the surface of the core material to form microcapsules.

[0015] Step 5, cyclic impregnation: Disperse the microcapsules formed in step 4 in ethanol with a concentration of 30 wt%, then place the carbonized wood prepared in step 2 in an impregnation tank, evacuate to 0.1 MPa, hold for 30 minutes, then pressurize to 2 MPa and hold for 1 hour, repeat the vacuum-pressure cycle 3 times to embed the microcapsules into the wood pores.

[0016] Step 6, preparation of the surface conductive layer: Dissolve dopamine hydrochloride with a concentration of 2 mg / mL in Tris buffer and stir for 24 hours to form a polydopamine solution, then add a mixed graphene oxide dispersion with a concentration of 2 mg / mL. Spray the mixture evenly on the surface of the wood loaded with microcapsules, and form a continuous conductive layer after curing.

[0017] A further improvement lies in that: in the first step, the concentration of the NaOH solution is 1 - 3 mol / L and the temperature is 60 - 80 °C.

[0018] A further improvement lies in that: in the third step, the concentration of the nano-cellulose solution is 5 wt%.

[0019] A further improvement lies in that: in the fourth step, the mass ratio of lignin to methyl methacrylate monomer is 1:2.

[0020] A further improvement lies in that: in the sixth step, the thickness of the conductive layer is 150 ± 20 nm and the sheet resistance is ≤ 10 Ω / sq.

[0021] The beneficial effects of the present invention are as follows: by synergistically optimizing the wood-based energy storage building material into a matrix layer, a functional layer and an interface layer, the mechanical properties and energy storage efficiency are taken into account;

[0022] By carbonizing wood to form a porous matrix, a double-layer capacitor is formed by using the porous structure after wood carbonization to endow it with energy storage function, and heat energy storage and release are realized by loading phase change microcapsules, so that the building material has temperature self-adaptive ability;

[0023] By using lignin-grafted polymer as the wall material, the bio-based phase change core material is wrapped in the microcapsules to prevent the leakage of the phase change material, and the microcapsules are embedded in the wood pores to enhance the bonding strength between the material and the matrix. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] To deepen the understanding of the present invention, the present invention will be further described in detail below in conjunction with embodiments. These embodiments are only used to explain the present invention and do not constitute a limitation to the protection scope of the present invention.

[0026] The raw materials used in the examples and comparative examples of the present invention are all obtained through conventional commercial purchase channels. Among them, the bio-based fatty acids are lauric acid and palmitic acid mixed in equal mass ratio.

[0027] According to Figure 1 As shown, this embodiment provides a wood-based energy storage building material with self-adaptive ambient temperature, including a matrix layer, a functional layer and a conductive interface layer. The functional layer is a phase change microcapsule, the core material of the phase change microcapsule is a bio-based fatty acid, the wall material of the phase change microcapsule is a lignin-methyl methacrylate graft copolymer, the conductive interface layer is a polydopamine-reduced graphene oxide composite coating, the raw material of the matrix layer is balsa wood with a density of 0.3 g / cm³, which is enhanced by a gradient carbonization process, and the mass ratio of polydopamine to reduced graphene oxide in the polydopamine-reduced graphene oxide composite coating is 1:2.

[0028] It includes the following steps:

[0029] Step 1: Raw material pretreatment. Select balsa wood as the raw material and cut it into plates with a thickness of 10 mm. Polish the surface to remove burrs. Immerse the wood in a NaOH solution for 48 hours to remove part of the lignin and hemicellulose, improve the pore connectivity, then rinse it with deionized water until neutral, and dry it in a vacuum environment at 60 °C for 12 hours;

[0030] The concentration of the NaOH solution is 2 mol / L, and the temperature is 80 °C. Remove lignin and hemicellulose through alkali treatment to optimize the wood pore structure. The NaOH solution dissolves part of the lignin and hemicellulose to form more through pores, providing channels for subsequent carbonization and material loading. The dried wood structure is more stable and suitable for subsequent high-temperature carbonization.

[0031] Step 2: Gradient carbonization. Put the pretreated wood in step 2 into a tube furnace and heat it to 400 °C at a rate of 5 °C / min, hold for 1 hour to remove residual moisture, then continue to heat it to 750 °C at a rate of 3 °C / min, hold for 2.5 hours to form a porous carbon matrix, and finally cool it naturally to room temperature to obtain carbonized wood. Treat the wood at high temperature in stages to form a porous carbon matrix. High-temperature carbonization generates a carbon skeleton with high porosity, providing a large specific surface area and loading space. Heating in stages avoids thermal stress from damaging the structure and retains the pore integrity. Carbonization enhances the matrix conductivity while retaining the lightweight characteristics of the wood;

[0032] Step 3: Cellulose reinforcement. Immerse the carbonized wood in a nanofibrillated cellulose solution and conduct vacuum treatment for 2 hours, then dry it at 60 °C; repeat 3 times to form a three-dimensional reinforcement network. The nanofibrillated cellulose fills the pores and forms a cross-linked network, significantly improving the compressive and crack resistance of the carbonized wood. 3 impregnation-drying cycles ensure the uniform distribution of nanofibrillated cellulose and prevent pore collapse during subsequent loading;

[0033] The concentration of the nanofibrillated cellulose solution is 5 wt%.

[0034] Step 4: Microcapsule preparation and encapsulation. Mix the bio-based fatty acid and heat it to 80 °C, and magnetically stir it at a speed of 300 rpm until completely melted as the core material. Disperse lignin in deionized water, add methyl methacrylate monomer, and add ammonium persulfate with a concentration of 1 wt% to the solution to obtain a lignin-methyl methacrylate graft copolymer solution as the wall material. Add the core material to the wall material solution to form a water-in-oil emulsion, heat it to 60 °C and continuously stir to polymerize the wall material on the surface of the core material to form microcapsules. Achieve heat absorption / release through the bio-based fatty acid core material to improve the thermal management ability of the material. Combine the biodegradability of lignin and the mechanical strength of P-methyl methacrylate through the lignin-methyl methacrylate graft copolymer wall material to prevent the leakage of the core material;

[0035] The mass ratio of lignin to methyl methacrylate monomer is 1:2.

[0036] Step Five: Cyclic impregnation. Disperse the microcapsules formed in Step Four in ethanol with a concentration of 30 wt%, then place the carbonized wood prepared in Step Two into the impregnation tank, evacuate to 0.1 MPa, keep it for 30 minutes, then pressurize to 2 MPa and keep it for 1 hour. Repeat the vacuum-pressure cycle 3 times to embed the microcapsules into the wood pores, and use the cyclic pressure difference to force the microcapsules to penetrate deep into the pores, improving the phase change material loading and distribution uniformity.

[0037] Step Six: Preparation of the surface conductive layer. Dissolve dopamine hydrochloride with a concentration of 2 mg / mL in Tris buffer and stir for 24 hours to form a polydopamine solution, then add a mixed graphene oxide dispersion with a concentration of 2 mg / mL. Spray the mixture evenly on the surface of the wood loaded with microcapsules, and form a continuous conductive layer after curing. Polydopamine reduces graphene oxide to form a continuous conductive network, which is suitable for electromagnetic shielding or sensing applications. A uniform and ultrathin coating is achieved through the spraying process, taking into account both conductivity and lightweight.

[0038] The thickness of the conductive layer is 150 ± 20 nm, and the sheet resistance is 9 Ω / sq.

[0039] Example 2

[0040] According to Figure 1 As shown, this example provides a preparation method of a wood-based energy storage building material that adapts to the ambient temperature, including a matrix layer, a functional layer, and a conductive interface layer. The functional layer is a phase change microcapsule, the core material of the phase change microcapsule is a bio-based fatty acid, the wall material of the phase change microcapsule is a lignin-methyl methacrylate graft copolymer, the conductive interface layer is a polydopamine-reduced graphene oxide composite coating, the raw material of the matrix layer is balsa wood with a density of 0.3 g / cm³, and it is enhanced by a gradient carbonization process. The mass ratio of polydopamine to reduced graphene oxide in the polydopamine-reduced graphene oxide composite coating is 1:2.

[0041] It includes the following steps:

[0042] Step One: Raw material pretreatment. Select balsa wood as the raw material, cut it into plates with a thickness of 10 mm, polish the surface to remove burrs, immerse the wood in NaOH solution for 55 hours to remove part of the lignin and hemicellulose, improve the pore connectivity, then rinse it with deionized water until neutral, and dry it in a vacuum environment at 60 °C for 12 hours.

[0043] The concentration of the NaOH solution is 3 mol / L, and the temperature is 60 °C. Lignin and hemicellulose are removed through alkali treatment to optimize the pore structure of the wood. The NaOH solution dissolves part of the lignin and hemicellulose to form more through pores, providing channels for subsequent carbonization and material loading. The structure of the dried wood is more stable and suitable for subsequent high-temperature carbonization.

[0044] Step 2: Gradient carbonization. The pretreated wood in Step 2 is placed in a tube furnace and heated to 400 °C at a rate of 5 °C / min and held for 1 hour to remove residual moisture. Then it is continued to be heated to 800 °C at a rate of 3 °C / min and held for 2 hours to form a porous carbon matrix. Finally, it is naturally cooled to room temperature to obtain carbonized wood. The wood is heat-treated at different stages to form a porous carbon matrix. High-temperature carbonization generates a carbon skeleton with high porosity, providing a large specific surface area and loading space. The staged heating avoids thermal stress from damaging the structure and retains the integrity of the pores. Carbonization enhances the conductivity of the matrix while retaining the lightweight characteristics of the wood.

[0045] Step 3: Cellulose reinforcement. The carbonized wood is immersed in a nanofibrillated cellulose solution and vacuum-treated for 2 hours, and then dried at 60 °C and repeated 3 times to form a three-dimensional reinforcement network. The nanofibrillated cellulose fills the pores and forms a cross-linked network, significantly improving the compressive and crack-resistant properties of the carbonized wood. Three impregnation-drying cycles ensure the uniform distribution of the nanofibrillated cellulose and prevent pore collapse during subsequent loading.

[0046] The concentration of the nanofibrillated cellulose solution is 5 wt%.

[0047] Step 4: Preparation and encapsulation of microcapsules. The bio-based fatty acid is mixed and heated to 80 °C, and magnetically stirred at a speed of 300 rpm until completely melted as the core material. Lignin is dispersed in deionized water and MMA monomer is added. Ammonium persulfate with a concentration of 1 wt% is added to the solution to obtain a lignin-PMMA graft copolymer solution as the wall material. The core material is added to the wall material solution to form a water-in-oil emulsion. The temperature is raised to 60 °C and continuously stirred to polymerize the wall material on the surface of the core material to form microcapsules. The heat absorption / release is achieved through the bio-based fatty acid core material, improving the thermal management ability of the material. The lignin-PMMA graft copolymer wall material combines the biodegradability of lignin and the mechanical strength of PMMA to prevent the leakage of the core material.

[0048] The mass ratio of lignin to MMA monomer is 1:2.

[0049] Step 5: Cyclic impregnation. The microcapsules formed in Step 4 are dispersed in ethanol with a concentration of 30 wt%. Then the carbonized wood prepared in Step 2 is placed in an impregnation tank, evacuated to 0.1 MPa and held for 30 minutes, and then pressurized to 2 MPa and held for 1 hour. The vacuum-pressure cycle is repeated 3 times to embed the microcapsules into the wood pores. The cyclic pressure difference is used to force the microcapsules deep into the pores, improving the loading amount and distribution uniformity of the phase change material.

[0050] Step 6: Preparation of the surface conductive layer. Dissolve dopamine hydrochloride with a concentration of 2 mg / mL in Tris buffer and stir for 24 hours to form a polydopamine solution. Then add a mixed graphene oxide dispersion with a concentration of 2 mg / mL. Spray the mixture evenly on the surface of the wood loaded with microcapsules. After curing, a continuous conductive layer is formed. Polydopamine reduces graphene oxide to form a continuous conductive network, which is suitable for electromagnetic shielding or sensing applications. An evenly thin coating is achieved through the spraying process, taking into account both conductivity and lightweight.

[0051] The thickness of the conductive layer is 150 ± 20 nm, and the sheet resistance is 9 Ω / sq.

[0052] Example 3

[0053] According to Figure 1 As shown, this example provides a preparation method of a wood-based energy storage building material with self-adaptive ambient temperature, including a matrix layer, a functional layer, and a conductive interface layer. The functional layer is a phase change microcapsule, the core material of the phase change microcapsule is a bio-based fatty acid, and the wall material of the phase change microcapsule is a lignin-methyl methacrylate graft copolymer. The conductive interface layer is a polydopamine-reduced graphene oxide composite coating. The raw material of the matrix layer is balsa wood with a density of 0.3 g / cm³, which is enhanced by a gradient carbonization process. The mass ratio of polydopamine to reduced graphene oxide in the polydopamine-reduced graphene oxide composite coating is 1:2.

[0054] It includes the following steps:

[0055] Step 1: Raw material pretreatment. Select balsa wood as the raw material and cut it into plates with a thickness of 10 mm. Polish the surface to remove burrs. Immerse the wood in a NaOH solution for 72 hours to remove part of the lignin and hemicellulose, improve the pore connectivity, and then rinse it with deionized water until neutral. Dry it in a vacuum environment at 60 °C for 12 hours.

[0056] The concentration of the NaOH solution is 1 mol / L, and the temperature is 80 °C. Remove lignin and hemicellulose through alkali treatment to optimize the pore structure of the wood. The NaOH solution dissolves part of the lignin and hemicellulose to form more through pores, providing channels for subsequent carbonization and material loading. The dried wood structure is more stable and suitable for subsequent high-temperature carbonization.

[0057] Step 2: Gradient carbonization. Put the pre-treated wood in Step 2 into a tubular furnace and heat it to 400 °C at a rate of 5 °C / min, hold for 1 hour to remove residual moisture, then continue to heat it to 700 °C at a rate of 3 °C / min and hold for 3 hours to form a porous carbon matrix. Finally, cool it naturally to room temperature to obtain carbonized wood. The wood is treated at high temperature in stages to form a porous carbon matrix. High-temperature carbonization generates a carbon skeleton with high porosity, providing a large specific surface area and loading space. Heating in stages avoids thermal stress from damaging the structure and preserves the integrity of the pores. Carbonization enhances the conductivity of the matrix while retaining the lightweight characteristics of the wood;

[0058] Step 3: Cellulose reinforcement. Immerse the carbonized wood in a nano-cellulose solution and conduct vacuum treatment for 2 hours, then dry it at 60 °C and repeat 3 times to form a three-dimensional reinforcement network. The nano-cellulose fills the pores and forms a cross-linked network, significantly improving the compressive and crack-resistant properties of the carbonized wood. 3 impregnation-drying cycles ensure the uniform distribution of nano-cellulose and prevent pore collapse during subsequent loading;

[0059] The concentration of the nano-cellulose solution is 5 wt%.

[0060] Step 4: Microcapsule preparation and encapsulation. Mix the bio-based fatty acid and heat it to 80 °C, magnetically stir at a speed of 300 rpm until it is completely melted as the core material. Disperse lignin in deionized water, add MMA monomer, and add ammonium persulfate with a concentration of 1 wt% to the solution to obtain a lignin-PMMA graft copolymer solution as the wall material. Add the core material to the wall material solution to form a water-in-oil emulsion, heat it to 60 °C and continuously stir to polymerize the wall material on the surface of the core material to form microcapsules. The heat absorption / release is realized through the bio-based fatty acid core material to improve the thermal management ability of the material. The lignin-PMMA graft copolymer wall material combines the biodegradability of lignin and the mechanical strength of PMMA to prevent the leakage of the core material;

[0061] The mass ratio of lignin to MMA monomer is 1:2.

[0062] Step 5: Cyclic impregnation. Disperse the microcapsules formed in Step 4 in ethanol with a concentration of 30 wt%, then place the carbonized wood prepared in Step 2 in an impregnation tank, evacuate to 0.1 MPa, hold for 30 minutes, then pressurize to 2 MPa and hold for 1 hour. Repeat the vacuum-pressure cycle 3 times to embed the microcapsules into the wood pores. Use the cyclic pressure difference to force the microcapsules to penetrate deep into the pores, improving the phase change material loading amount and distribution uniformity.

[0063] Step 6: Preparation of the surface conductive layer. Dissolve dopamine hydrochloride with a concentration of 2 mg / mL in Tris buffer and stir for 24 hours to form a polydopamine solution. Then add a mixed graphene oxide dispersion with a concentration of 2 mg / mL. Spray the mixture evenly on the surface of the wood loaded with microcapsules. After curing, a continuous conductive layer is formed. Polydopamine reduces graphene oxide to form a continuous conductive network, which is suitable for electromagnetic shielding or sensing applications. An evenly distributed ultra-thin coating is achieved through the spraying process, taking into account both conductivity and lightweight properties.

[0064] The thickness of the conductive layer is 150 ± 20 nm, and the sheet resistance is 9 Ω / sq.

[0065] Comparative Example 1

[0066] A preparation method of a wood-based energy storage building material with self-adaptive ambient temperature, including a matrix layer and a functional layer. The functional layer is a phase change microcapsule. The core material of the phase change microcapsule is a bio-based fatty acid, and the wall material of the phase change microcapsule is a lignin-methyl methacrylate graft copolymer.

[0067] It includes the following steps:

[0068] Step 1: Raw material pretreatment. Select balsa wood as the raw material and cut it into plates with a thickness of 10 mm. Polish the surface to remove burrs. Immerse the wood in a NaOH solution for 48 hours to remove part of the lignin and hemicellulose, improve the pore connectivity, and then rinse it with deionized water until neutral. Dry it in a vacuum environment at 60 °C for 12 hours.

[0069] The concentration of the NaOH solution is 2 mol / L, and the temperature is 80 °C. Remove lignin and hemicellulose through alkali treatment to optimize the pore structure of the wood. The NaOH solution dissolves part of the lignin and hemicellulose to form more through pores, providing channels for subsequent carbonization and material loading. The dried wood structure is more stable and suitable for subsequent high-temperature carbonization.

[0070] Step 2: Gradient carbonization. Put the wood pretreated in Step 2 into a tubular furnace and heat it to 400 °C at a rate of 5 °C / min, hold for 1 hour to remove residual moisture, and then continue to heat it to 750 °C at a rate of 3 °C / min and hold for 2.5 hours to form a porous carbon matrix. Finally, cool it naturally to room temperature to obtain carbonized wood. Treat the wood at high temperatures in stages to form a porous carbon matrix. High-temperature carbonization generates a carbon skeleton with a high porosity, providing a large specific surface area and loading space. Heating in stages avoids thermal stress from damaging the structure and retains the integrity of the pores. Carbonization enhances the conductivity of the matrix while retaining the lightweight characteristics of the wood.

[0071] Step 3: Cellulose reinforcement. Immerse the carbonized wood in the nano-cellulose solution and perform vacuum treatment for 2 hours, then dry at 60 °C and repeat 3 times to form a three-dimensional reinforcement network. The nano-cellulose fills the pores and forms a cross-linked network, significantly improving the compressive and crack-resistant properties of the carbonized wood. The 3 impregnation-drying cycles ensure the uniform distribution of nano-cellulose and prevent pore collapse during subsequent loading;

[0072] The concentration of the nano-cellulose solution is 5 wt%.

[0073] Step 4: Microcapsule preparation and encapsulation. Mix the bio-based fatty acid and heat it to 80 °C, and magnetically stir at a speed of 300 rpm until completely melted as the core material. Disperse lignin in deionized water, add MMA monomer, and add ammonium persulfate with a concentration of 1 wt% to the solution to obtain a lignin-PMMA graft copolymer solution as the wall material. Add the core material to the wall material solution to form a water-in-oil emulsion, heat to 60 °C and continuously stir to polymerize the wall material on the surface of the core material to form microcapsules. The heat absorption / release is realized through the bio-based fatty acid core material, improving the thermal management ability of the material. The lignin-PMMA graft copolymer wall material combines the biodegradability of lignin and the mechanical strength of PMMA to prevent the leakage of the core material;

[0074] The mass ratio of lignin to MMA monomer is 1:2.

[0075] Step 5: Cyclic impregnation. Disperse the microcapsules formed in Step 4 in ethanol with a concentration of 30 wt%, then place the carbonized wood prepared in Step 2 in an impregnation tank, evacuate to 0.1 MPa and keep it for 30 minutes, then pressurize to 2 MPa and keep it for 1 hour, and repeat the vacuum-pressure cycle 3 times to embed the microcapsules into the wood pores. Use the cyclic pressure difference to force the microcapsules to penetrate deep into the pores, improving the phase change material loading amount and distribution uniformity.

[0076] Comparative Example 2

[0077] A preparation method of a wood-based energy storage building material adaptable to ambient temperature, including a matrix layer, a functional layer, and a conductive interface layer. The functional layer is a bio-based fatty acid, the conductive interface layer is a polydopamine-reduced graphene oxide composite coating, and the raw material of the matrix layer is balsa wood with a density of 0.3 g / cm³, which is enhanced by a gradient carbonization process. The mass ratio of polydopamine to reduced graphene oxide in the polydopamine-reduced graphene oxide composite coating is 1:2.

[0078] It includes the following steps:

[0079] Step 1. Pretreatment of raw materials. Select balsa wood as the raw material and cut it into plates with a thickness of 10 mm. Polish the surface to remove burrs. Immerse the wood in a NaOH solution for 48 hours to remove part of the lignin and hemicellulose, improve pore connectivity, then rinse it with deionized water until neutral, and dry it in a vacuum environment at 60 °C for 12 hours;

[0080] The concentration of the NaOH solution is 2 mol / L and the temperature is 80 °C. Remove lignin and hemicellulose through alkali treatment to optimize the pore structure of the wood. The NaOH solution dissolves part of the lignin and hemicellulose to form more through-pores, providing channels for subsequent carbonization and material loading. The dried wood structure is more stable and suitable for subsequent high-temperature carbonization.

[0081] Step 2. Gradient carbonization. Put the pretreated wood in Step 2 into a tubular furnace and heat it to 400 °C at a rate of 5 °C / min, hold for 1 hour to remove residual moisture, then continue to heat it to 750 °C at a rate of 3 °C / min, hold for 2.5 hours to form a porous carbon matrix, and finally cool it naturally to room temperature to obtain carbonized wood. Treat the wood at high temperature in stages to form a porous carbon matrix. High-temperature carbonization generates a carbon skeleton with high porosity, providing a large specific surface area and loading space. Heating in stages avoids thermal stress from damaging the structure and retains the integrity of the pores. Carbonization enhances the conductivity of the matrix and at the same time retains the lightweight characteristics of the wood;

[0082] Step 3. Cellulose reinforcement. Immerse the carbonized wood in a nanocellulose solution and conduct vacuum treatment for 2 hours, then dry it at 60 °C and repeat 3 times to form a three-dimensional reinforcement network. The nanocellulose fills the pores and forms a cross-linked network, significantly improving the compressive and crack-resistant properties of the carbonized wood. Three impregnation-drying cycles ensure the uniform distribution of nanocellulose and prevent pore collapse during subsequent loading;

[0083] The concentration of the nanocellulose solution is 5 wt%.

[0084] Step 4. Mix and heat the biobased fatty acid to 80 °C and magnetically stir it at a speed of 300 rpm until it is completely melted;

[0085] Step 5. Cyclic impregnation. Disperse the biobased fatty acid formed in Step 4 in ethanol with a concentration of 30 wt%, then place the carbonized wood prepared in Step 2 in an impregnation tank, evacuate to 0.1 MPa and hold for 30 minutes, then pressurize to 2 MPa and hold for 1 hour, repeat the vacuum-pressure cycle 3 times to embed the biobased fatty acid into the wood pores, and use the cyclic pressure difference to force the biobased fatty acid to penetrate deep into the pores, improving the loading amount and distribution uniformity of the phase change material.

[0086] Step 6. Preparation of the surface conductive layer: Dissolve dopamine hydrochloride with a concentration of 2 mg / mL in Tris buffer and stir for 24 hours to form a polydopamine solution. Then add a mixed graphene oxide dispersion with a concentration of 2 mg / mL. Spray the mixture evenly on the surface of the wood loaded with bio-based fatty acids, and form a continuous conductive layer after curing. The polydopamine reduces graphene oxide to form a continuous conductive network, which is suitable for electromagnetic shielding or sensing applications. An evenly distributed ultra-thin coating is achieved through the spraying process, taking into account both conductivity and light weight.

[0087] The thickness of the conductive layer is 150 ± 20 nm, and the sheet resistance is 8 Ω / sq.

[0088] Perform performance tests on the wood-based energy storage building materials with self-adaptive ambient temperature prepared in Examples 1-3 and Comparative Examples 1-2:

[0089] Due to the reinforcement of nanocellulose and the uniform loading of microcapsules in Examples 1-3, the compressive / flexural strength is significantly higher than that of Comparative Example 2. The microcapsule structure in the examples effectively prevents leakage, and the enthalpy loss rate is ≤ 8% after 100 cycles; in Comparative Example 2, due to the direct impregnation of bio-based fatty acids, the leakage results in an enthalpy loss rate as high as 32.6%. The sheet resistance of the conductive layer in Examples 1-3 is ≤ 10 Ω / sq, meeting the electromagnetic shielding requirements; in Comparative Example 1, there is no conductive layer, and the sheet resistance > 1000 Ω / sq; in Comparative Example 2, due to the influence of fatty acid leakage on the coating continuity, the sheet resistance increases to 12.5 Ω / sq. The phase change interval in the examples is stable (20 - 30 °C), and the stable time in the environmental adaptability test reaches more than 6 hours; in Comparative Example 2, due to leakage and uneven distribution of the phase change material, the stable time is only 3.1 hours. The porosity in the examples is ≥ 80%, and the microcapsule loading rate is ≥ 93%. In Comparative Example 2, due to the blockage of pores by fatty acids, the porosity is only 65% and there is no encapsulation structure.

[0090] Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. A wood-based energy storage building material adaptable to ambient temperature, characterized in that: It includes a matrix layer, a functional layer, and a conductive interface layer. The functional layer is a phase change microcapsule. The core material of the phase change microcapsule is a bio-based fatty acid, and the wall material of the phase change microcapsule is a lignin-methyl methacrylate graft copolymer. The conductive interface layer is a polydopamine-reduced graphene oxide composite coating.

2. The wood-based energy storage building material adaptable to ambient temperature according to claim 1, characterized in that: The raw material of the matrix layer is balsa wood with a density of 0.1 - 0.3 g / cm³, and it is enhanced by a gradient carbonization process.

3. An adaptive ambient temperature wood-based energy storage building material according to claim 1, characterized in that: In the polydopamine-reduced graphene oxide composite coating, the mass ratio of polydopamine to reduced graphene oxide is 1:

2.

4. A preparation method of a wood-based energy storage building material adaptable to ambient temperature according to claim 1, comprising the following steps: Step 1: Raw material pretreatment. Select balsa wood as the raw material and cut it into plates with a thickness of 5 - 20 mm. Polish the surface to remove burrs. Immerse the wood in a NaOH solution for 48 - 72 hours to remove part of the lignin and hemicellulose, improve pore connectivity, then rinse it with deionized water until neutral, and dry it in a vacuum environment at 60°C for 12 hours. Step 2: Gradient carbonization. Put the pretreated wood in Step 2 into a tube furnace and heat it to 400°C at a rate of 5°C / min, hold for 1 hour, then continue to heat it to 700 - 800°C at a rate of 3°C / min, hold for 2 - 3 hours to form a porous carbon matrix, and finally cool it naturally to room temperature to obtain carbonized wood. Step 3: Cellulose reinforcement. Immerse the carbonized wood in a nanocellulose solution and vacuum-treat it for 2 hours, then dry it at 60°C; repeat 3 times to form a three-dimensional reinforcement network. Step 4: Microcapsule preparation and encapsulation. Mix the bio-based fatty acid and heat it to 80°C, and magnetically stir it at a speed of 300 rpm until it is completely melted as the core material. Disperse lignin in deionized water, add methyl methacrylate monomer, and add ammonium persulfate with a concentration of 1 wt% to the solution to obtain a lignin-methyl methacrylate graft copolymer solution as the wall material. Add the core material to the wall material solution to form a water-in-oil emulsion, heat it to 60°C and continuously stir to polymerize the wall material on the surface of the core material to form microcapsules. Step 5: Cyclic impregnation. Disperse the microcapsules formed in Step 4 in ethanol with a concentration of 30 wt%, then place the carbonized wood prepared in Step 2 in an impregnation tank, evacuate to 0.1 MPa, hold for 30 minutes, then pressurize to 2 MPa and hold for 1 hour, repeat the vacuum-pressure cycle 3 times to embed the microcapsules into the wood pores. Step 6: Preparation of the surface conductive layer. Dissolve dopamine hydrochloride with a concentration of 2 mg / mL in Tris buffer and stir for 24 hours to form a polydopamine solution, then add a mixed graphene oxide dispersion with a concentration of 2 mg / mL. Spray the mixture evenly on the surface of the wood loaded with microcapsules, and form a continuous conductive layer after curing.

5. The preparation method of the wood-based energy storage building material with adaptive ambient temperature according to claim 4, characterized in that: In Step 1, the concentration of the NaOH solution is 1 - 3 mol / L, and the temperature is 60 - 80°C.

6. The method for preparing a wood-based energy storage building material with an adaptive ambient temperature according to claim 4, wherein: In Step 3, the concentration of the nanocellulose solution is 5 wt%.

7. The preparation method of the wood-based energy storage building material with adaptive ambient temperature according to claim 4, characterized in that: In Step 4, the mass ratio of lignin to methyl methacrylate monomer is 1:

2.

8. The method for preparing a wood-based energy storage building material with an adaptive ambient temperature according to claim 4, characterized in that: In Step 6, the thickness of the conductive layer is 150 ± 20 nm, and the sheet resistance ≤ 10 Ω / sq.

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