Solid-solid phase change composite energy storage patch with self-supporting heat conduction channel and preparation method thereof

Abstract

The application discloses a solid-solid phase change composite energy storage patch with a self-supporting heat conduction channel, which comprises a self-supporting three-dimensional topological heat conduction channel framework and a solid-solid phase change energy storage matrix filled in the gap of the heat conduction channel framework. The application also discloses a preparation method of the solid-solid phase change composite energy storage patch, specifically: preparation of the self-supporting three-dimensional topological heat conduction channel framework, and surface activation treatment of the heat conduction channel framework; solid-solid phase change energy storage matrix raw materials are uniformly filled into the gap of the activated heat conduction channel framework, and solidified to obtain the solid-solid phase change composite energy storage patch. The solid-solid phase change composite energy storage patch has high heat conduction channels which form a three-dimensional directional rapid heat conduction channel in space, and heat from a heat source is quickly conducted into the whole phase change matrix, thereby fundamentally solving the technical problems of low intrinsic thermal conductivity of the solid-solid phase change material, slow internal heat conduction and asynchronous internal and external phase change.

Description

Technical Field

[0001] This invention belongs to the field of energy storage patch manufacturing technology, specifically relating to a solid-solid phase change composite energy storage patch with a self-supporting thermal conductive path, and also relating to a method for manufacturing a solid-solid phase change composite energy storage patch with a self-supporting thermal conductive path. Background Technology

[0002] Solid-solid phase change materials (SCTs) are widely used in passive thermal management of precision electronics and new energy equipment due to their advantages such as no liquid phase leakage, small volume deformation, and excellent chemical stability. Currently, most mainstream solid-solid phase change temperature control patches on the market adopt a structure of pure phase change material directly pressed into a sheet. The heat transfer relies entirely on the phase change material itself, and the heat can only be slowly conducted through the material itself. The heat transfer path is single and the internal heat transfer efficiency is extremely low.

[0003] Current modification routes for phase change heat management materials (such as graphite surface reinforcement, powder blending, metal mesh composites, porous substrates and 3D printed skeleton composites, etc.) all have inherent defects, making it difficult to simultaneously achieve high thermal conductivity, long-term interface stability, ultra-thin flexibility and synchronous phase change across the entire domain. Specifically, the following issues are observed: pure substrate tablets have extremely low intrinsic thermal conductivity (0.1–0.8 W / (m·K)), resulting in a lag in phase change response and an inability to rapidly store energy at high power; surface graphite reinforcement only achieves surface heat dissipation, lacks three-dimensional pathways, has internal thermal conductivity blind spots, and has limited temperature suppression capabilities; powder blending results in disordered doping, and high filling amounts lead to a loss of flexibility, making it unsuitable for assembling ultra-thin curved surfaces of 0.1–2.0 mm; conventional woven mesh / flat laminated skeletons have a single topology, small contact area, and rely on simple physical composites, lacking interface anchoring, and are prone to delamination and a surge in thermal resistance after prolonged thermal shock; porous foam and existing 3D printed skeleton structures are uncontrollable, resulting in thick and rigid products, and often employ open-top potting and solid-liquid phase change systems, posing a risk of leakage; the lack of vacuum impregnation-hot pressing integrated process makes it impossible to achieve effective compatibility between ultra-thin flexible molding and cross-linked solid-solid phase change. Therefore, there is an urgent need to design a solid-solid phase change composite energy storage patch with a built-in self-supporting three-dimensional topological heat conduction path. By drawing on the fiber-reinforced resin composite mechanism, an optimal three-dimensional directional heat conduction path is constructed from the inside. This maximizes the contact area between the phase change material and the heat conduction path within a limited volume ratio, thus solving the technical problems of slow phase change response, internal heat conduction bottleneck, limited contact interface, poor structural stability, and inability to be ultra-thin and flexible in existing technologies. Summary of the Invention

[0004] The purpose of this invention is to provide a solid-solid phase change composite energy storage patch with a self-supporting heat conduction path, which solves the problems of inefficient internal heat transfer and poor temperature uniformity and control of existing solid-solid phase change patches.

[0005] Another objective of this invention is to provide a method for preparing a solid-solid phase change composite energy storage patch with a self-supporting thermally conductive path.

[0006] The technical solution adopted in this invention is a solid-solid phase change composite energy storage patch with a self-supporting thermally conductive path, comprising a self-supporting three-dimensional topological thermally conductive path framework and a solid-solid phase change energy storage substrate filling the gaps in the thermally conductive path framework; the volume of the thermally conductive path framework accounts for 8% to 35% of the total volume of the solid-solid phase change composite energy storage patch. The self-supporting three-dimensional topological thermally conductive path framework can be any one of laminated copper mesh, thermally conductive fiber woven mesh, graphite fiber array, graphene foam, porous carbon felt, micro heat pipe array, or 3D printed integrated porous metal network. The solid-solid phase change energy storage substrate uses polyol, polyurethane, or cross-linked polyethylene glycol polymer-based solid-solid phase change material as the continuous phase substrate, and the substrate is doped with 0-45% by mass of thermally conductive filler, which is selected from one or more of boron nitride, alumina, silicon carbide, and graphite powder. The thickness of the solid-solid phase change composite energy storage patch is 0.1-2.0 mm. Another technical solution adopted in this invention is a method for preparing a solid-solid phase change composite energy storage patch with a self-supporting thermal conductive path, which is specifically implemented according to the following steps: Step 1: Fabrication of a self-supporting three-dimensional topological thermal conductive pathway framework, followed by surface activation treatment of the thermal conductive pathway framework. Step 2: The solid-solid phase change energy storage substrate material is uniformly filled into the gaps of the activated thermal conductive path skeleton, and then solidified to obtain a solid-solid phase change composite energy storage patch with a self-supporting thermal conductive path.

[0007] The invention is further characterized in that, In step 1, the thermal conductive path framework is subjected to surface activation treatment, which is plasma activation, with a treatment power of 200-800W, a gas flow rate of 10-50sccm, and a treatment time of 30-180s; the process gas introduced is any one or more of Ar, N2, and O2.

[0008] In step 2, if a thermally softening solid-solid phase change energy storage matrix is ​​used, the specific steps are as follows: weigh the solid-solid phase change matrix raw materials according to the formula, heat them to 70-130℃ for thermal softening, viscosity reduction and plasticization, the stirring rate is 300-800 r / min, and the stirring time is 15-60 min; add 0-45% by mass of thermally conductive filler as needed, and continue to keep warm and stir for 20-90 min to obtain a phase change fluidized mixture; The activated thermally conductive pathway framework is placed in a vacuum impregnation tank, with the vacuum level controlled at -0.06 to -0.10 MPa and the tank temperature maintained at 65 to 125°C. The phase change fluidized bed mixture is slowly injected into the impregnation tank and impregnated for 10 to 60 minutes to form a composite blank. The impregnated composite blank is then sent to a precision hot press for hot pressing at a temperature of 60 to 140°C, with a vertical pressure of 0.2 to 2.5 MPa applied. The temperature is held constant for 5 to 45 minutes, and a programmed gradient cooling is used with a cooling rate controlled at 2 to 10°C / min. After cooling to room temperature, the pressure is released to obtain a solid-solid phase change composite energy storage patch.

[0009] In step 2, if a phase change microcapsule-type solid-solid phase change energy storage matrix is ​​used, the specific steps are as follows: Solid-solid phase change microcapsules are mixed with binder and matrix resin, stirred evenly, and 0-30% thermally conductive filler is added as needed by mass. The mixture is stirred to obtain a solid-solid phase change microcapsule composite slurry. The solid-solid phase change microcapsule composite slurry is then uniformly filled into the gaps of the activated thermally conductive pathway framework using coating, rolling, or layering methods to complete the pre-composite molding. Curing is performed using hot pressing, with the temperature controlled at 40-80℃, a pressure of 0.2-2.5MPa applied, and maintained for 30-120 minutes. A programmed gradient cooling process is then used, with the cooling rate controlled at 2-10℃ / min. After cooling to room temperature, the pressure is released to obtain a solid-solid phase change composite energy storage patch.

[0010] The beneficial effects of this invention are: 1) This invention abandons the traditional two-dimensional planar heat conduction and surface heat dissipation mode, and constructs a three-dimensional topological self-supporting heat conduction path inside the phase change matrix. Under the same heat conduction unit volume ratio constraint, the three-dimensional coating contact area between the phase change material and the heat conduction path is increased by 18% to 60% compared with the conventional flat arrangement. It breaks through the technical bottleneck of traditional contact boundary limitation. Heat can be quickly penetrated to the entire material through the three-dimensional path, and the phase change response speed is increased by 35% to 60%, realizing synchronous phase change heat absorption throughout the entire domain. 2) The three-dimensional thermal conduction path itself has self-supporting mechanical properties, eliminating the need for additional surface reinforcement substrates or adhesive layers, simplifying the multi-layer composite structure, eliminating additional interfacial thermal resistance between layers, and improving the overall equivalent thermal conductivity by 40% to 90%. Under high-power pulse conditions, the chip peak temperature drop can reach 10 to 15°C. 3) The vacuum impregnation and low-temperature hot pressing integrated composite process is adopted, and the phase change material is tightly anchored to the micropores of the heat conduction channel. After 1000 cycles of high and low temperature thermal shock from -40℃ to 120℃, there are no bubbles, delamination and debonding phenomena. The phase change enthalpy decay rate is less than 2%, the thermal conductivity change rate is less than 3%, and the long-term service stability is excellent. Attached Figure Description

[0011] Figure 1 is a schematic cross-sectional view of the solid-solid phase change composite energy storage patch with a self-supporting thermal conductive path according to the present invention. Figure 2 is a schematic diagram of the self-supporting three-dimensional heat conduction pathway interlayer staggered close-packed planar distribution structure of the present invention; Figure 3 is a comparison curve of the temperature rise control effect between the composite patch of the present invention and the existing pure phase change patch; Figure 4 is a schematic diagram of the arrangement structure of the self-supporting three-dimensional heat conduction path of the present invention (I); Figure 5 is a schematic diagram of the arrangement structure of the self-supporting three-dimensional heat conduction path of the present invention (II). Detailed Implementation

[0012] The present invention will now be described in detail with reference to specific embodiments and accompanying drawings.

[0013] This invention relates to a solid-solid phase change composite energy storage patch with a self-supporting thermally conductive path, such as... Figure 1 As shown, it includes a self-supporting three-dimensional topological heat-conducting pathway framework and a solid-solid phase change energy storage matrix filled and encapsulated in the gaps of the heat-conducting pathway framework. The thickness of the solid-solid phase change composite energy storage patch is 0.1–2.0 mm, and it is a substrate-free, self-supporting, independent flexible sheet; the axial thermal conductivity of the heat conduction path framework is ≥800 W / (m²). K); The volume of the thermal conductive pathway framework accounts for 8% to 35% of the total volume of the solid-solid phase change composite energy storage patch. The self-supporting three-dimensional topology thermal conductive pathway framework is a metal-based or carbon-based three-dimensional thermal conductive framework, selected from one or more combinations of laminated copper mesh, thermally conductive fiber braided mesh, graphite fiber array, graphene foam, porous carbon felt, micro heat pipe array, and 3D printed integrated porous metal network; The three-dimensional thermal conductivity pathway framework adopts a three-dimensional topological structure with interlayer staggered close packing and / or micro-folds; the solid-solid phase change energy storage matrix uses polyol, polyurethane, or cross-linked polyethylene glycol polymer-based solid-solid phase change materials as the continuous phase matrix, and the matrix is ​​doped with 0-45% by mass of thermally conductive filler, which is selected from one or more of boron nitride, alumina, silicon carbide, and graphite powder. A high thermal conductivity graphite insulating protective layer with a thickness of 0.01 to 0.15 mm is added to the outer surface of the heat conduction path skeleton for insulation protection and surface temperature uniformity.

[0014] Figure 2 is a schematic diagram of the planar distribution structure of the self-supporting three-dimensional heat conduction pathway with interlayer staggered close arrangement. In the figure, the grid lines represent the three-dimensional heat conduction pathway, and the white area is the solid-solid phase change energy storage substrate encapsulated in the gaps of the heat conduction pathway. The cross-section of the heat conduction pathway intuitively shows the rhomboid three-dimensional conductive network formed by the interlayer staggered close arrangement, as well as its structural relationship with the phase change substrate.

[0015] The present invention discloses a method for preparing a solid-solid phase change composite energy storage patch with a self-supporting thermally conductive path, which is implemented according to the following steps: Step 1: Fabrication and surface activation of a self-supporting three-dimensional topological thermal conductive pathway framework; A self-supporting three-dimensional topological thermally conductive skeleton can be prepared by any of the following methods: weaving, lamination, template method, or metal 3D printing. When using 3D printing, a staggered, densely packed, micro-folded three-dimensional topology is preset through three-dimensional modeling. The entire three-dimensional metal network is directly and integrally formed through SLM selective laser melting, eliminating the need for subsequent bending, stacking, and shaping processes. The feature size of the thermal skeleton unit is 20-500μm, and it is cut and shaped according to the design size. The thermal skeleton can be pre-processed with micro-folding forming and interlayer staggered arrangement.

[0016] The process of preparing a 3D-printed integrated porous metal network using SLM (Selective Laser Melting) involves: selecting high-purity copper-based spherical powder (particle size 15–45 μm); constructing a TPMS (Temporally Transparent Surface Motion) implicit porous structure model using 3D modeling software, with a preset porosity of 40%–60% and an interconnected open structure; importing the model slices into an SLM equipment; introducing high-purity argon gas into the forming chamber to prevent oxidation; and laying 30 μm thick metal powder layers on a powder-laying roller; using a fiber laser with a laser power of 180–240 W and a scanning rate of 800–1200 mm / s, melting the powder point by point according to the slice outline; solidifying the molten pool to achieve interlayer metallurgical bonding; and stacking layers until a complete integrated green body is formed; cooling to room temperature in the furnace after forming; removing excess powder from the substrate; and obtaining a seamless, continuously interconnected 3D porous metal thermally conductive network. The pore cavities are used for impregnation and filling of a solid-solid phase change matrix.

[0017] The hot-pressing lamination process is used to prepare laminated copper mesh. Specifically, copper woven mesh with a aperture of 0.2–0.5 mm is selected, and single-layer copper meshes of different mesh counts are stacked in a staggered manner for 3–8 layers, with staggered seams between layers forming three-dimensional interconnected pores. The stacked blank is placed inside the mold of a flat hot press, preheated to 180–220 ℃, and subjected to a constant pressure of 5–8 MPa for 20–35 min. Solid-phase pressing and bonding of the mesh wire contact interface is achieved by relying on the slight plastic deformation of the copper surface. After cooling and depressurization, a multi-layered solidified laminated copper mesh skeleton is obtained, with multi-dimensional heat conduction channels and material storage cavities formed within and between layers.

[0018] Graphene foam was prepared by a foaming crosslinking method, specifically as follows: A 3–5 wt% graphene oxide aqueous dispersion was prepared, and ammonium bicarbonate physical foaming agent and polyethyleneimine crosslinking agent were added under stirring conditions. The amount of foaming agent added was 8%–12% of the slurry mass. The dispersion of the foaming agent was uniformly dispersed by high-speed stirring at room temperature for 30 min, and then sealed and allowed to stand for 1 h for pre-foaming. The foamed slurry was injected into a molding mold and cured and crosslinked in a low-temperature oven at 60 ℃ for 4 h. The foaming agent decomposed upon heating, releasing gas that formed continuous open pores inside the matrix. Finally, the slurry was thoroughly dried at 120 ℃ to remove residual solvents and small molecule additives, obtaining a three-dimensional open-cell network graphene foam framework.

[0019] The preparation of upright graphite fiber arrays by wet spinning and directional arrangement involves: preparing a graphite precursor spinning solution with a concentration of 18–22 wt%, and continuously extruding the solution through a screw extruder from a spinneret with an orifice diameter of 0.1–0.3 mm; The thermal conductive path framework is subjected to surface activation treatment, which can be any one of plasma activation, corona activation, or chemical etching, preferably argon-oxygen-nitrogen mixed plasma activation.

[0020] Process parameters for plasma activation: processing power 200-800W, gas flow rate 10-50sccm, processing time 30-180s; the process gas introduced is any one or more of Ar, N2, and O2. By controlling the contact angle of the thermal conductive pathway skeleton surface to below 40°, the wetting, spreading, and interfacial anchoring properties with the phase change substrate are improved.

[0021] Step 2: The thermally conductive pathway framework and the solid-solid phase change energy storage substrate are integrally molded. If a thermally softening solid-solid phase change energy storage substrate is used, the solid-solid phase change energy storage layer substrate is based on a solid-solid phase change material. The solid-solid phase change material is selected from polyols, polyurethane-based solid-solid phase change materials, polymer-based solid-solid phase change materials prepared by cross-linked polyethylene glycol, and solid-solid phase change energy storage layer substrates prepared by phase change microencapsulation.

[0022] Specifically, the solid-solid phase change matrix raw materials are weighed according to the formula, heated to 70-130℃ for thermal softening, viscosity reduction and plasticization, with a stirring rate of 300-800 r / min and a stirring time of 15-60 min; 0-45% by mass of thermally conductive filler is added as needed, and the mixture is kept at the temperature and stirred for 20-90 min to obtain a uniform, non-agglomerated, and fluidized phase change fluidized mixture; The raw materials for the polyethylene glycol crosslinked solid-solid phase change matrix are: polyethylene glycol PEG6000: 75-90 parts, diphenylmethane diisocyanate MDI: 8-20 parts, catalyst stannous octoate: 0.1-0.5 parts, and anhydrous deoxygenating solvent N,N-dimethylformamide DMF: 30-60 parts; The raw materials for polyurethane-based / polyol solid-solid phase change matrix are: polyol monomer: 75-90 parts, diphenylmethane diisocyanate (MDI): 10-22 parts, catalyst stannous octoate: 0.1-0.5 parts, and N,N-dimethylformamide (DMF): 30-60 parts. The activated heat-conducting pathway framework is placed in a vacuum impregnation tank, with the vacuum level controlled at -0.06 to -0.10 MPa and the tank temperature maintained at 65 to 125°C. The phase change fluidized mixture is slowly injected into the impregnation tank and kept at the temperature for 10 to 60 minutes to fully wet and fill all gaps and micropores inside the heat-conducting framework, forming a composite blank. The impregnated composite blank is fed into a precision hot press for hot pressing at a temperature of 60–140°C, and the hot pressing temperature is controlled to be 5–10°C lower than the peak phase change temperature of the phase change material. A vertical pressure of 0.2–2.5 MPa is applied and the temperature is kept constant for 5–45 minutes to ensure that the phase change matrix and the heat conduction path are tightly anchored and fused together, eliminating internal micro-voids and interface gaps. A programmed gradient cooling method is used, with the cooling rate controlled at 2–10°C / min, and the material is slowly cooled to room temperature of 25°C before the pressure is released. After precise edge cutting and surface insulating coating or adhesive bonding, a solid-solid phase change composite energy storage patch with a substrate-free, bendable, self-supporting heat conduction path is obtained. If a phase change microcapsule-type solid-solid phase change energy storage substrate is used, the specific details are as follows: Using solid-solid phase change microcapsules as the main functional component, they are mixed with polymer binders and matrix resins in a certain proportion and stirred at low speed and uniformly. 0-30% by mass of thermally conductive filler is added as needed, and the mixture is stirred at room temperature or low temperature and low speed to prepare a phase change microcapsule composite slurry that can be coated and pressed and filled. The system temperature is controlled to not exceed 80℃ throughout the process to avoid heat damage to the microcapsule shell and loss of effectiveness. The activated thermally conductive skeleton is coated, rolled, or layered to allow the phase change microcapsule composite slurry to be uniformly filled and penetrated into the gaps of the thermally conductive pathway grid, thus completing the pre-composite molding. Curing is achieved through hot pressing, with the temperature controlled at 40–80℃ and the pressure applied at 0.2–2.5 MPa. The temperature is maintained for 30–120 minutes to allow the adhesive to cure and cross-link, ensuring a strong bond between the microcapsules, fillers, and the three-dimensional thermally conductive pathway interface, preventing microcapsule cracking and core leakage due to high temperatures. A programmed gradient cooling method is used, with a cooling rate controlled at 2–10℃ / min, slowly cooling to room temperature (25℃) before depressurization. After precise edge trimming and surface insulating coating or adhesive bonding, a substrate-free, bendable, self-supporting thermally conductive solid-solid phase change composite energy storage patch is obtained. A protective layer with a thickness of 0.01–0.15 mm is prepared using a dry hot-pressing lamination process. First, an insulating and thermally conductive graphite film is pre-made using a scraping process, combined with graphite, insulating ceramic powder, and PET release film. Then, the film is laminated by low-temperature and low-pressure hot pressing for 30 seconds at 70°C and 1 MPa. The release substrate can then be removed. The finished coating has a uniform and controllable thickness, and the coating adheres firmly to the phase change substrate.

[0023] The method of this invention abandons the traditional single-layer surface heat conduction and flat two-dimensional grid composite mode. It prefabricates a self-supporting three-dimensional heat conduction path with interlayer misalignment and micro-fold topology inside the phase change material. The high thermal conductivity path forms a three-dimensional directional rapid heat transfer channel in space, which can quickly introduce heat from the heat source into the entire interior of the phase change matrix. This fundamentally solves the technical pain points of low intrinsic thermal conductivity, slow internal heat transfer, and asynchronous internal and external phase changes in solid-solid phase change materials. This invention employs vacuum impregnation and low-temperature hot pressing processes, in which the phase change polymer in a thermally softened state fully wets the surface of the thermally conductive pathway and micropores. After cooling and solidification, it forms a molecular chain segment-level anchoring bond with high interfacial bonding strength, no liquid phase leakage, and no significant volume deformation. The solid-solid phase change composite energy storage patch with self-supporting thermal conductive path of the present invention is used as an example. A composite phase change patch with a single-layer graphite layer on the surface is used as comparative example 1, and an ordinary pure phase change patch without thermal conductive path is used as comparative example 2. The steady-state and pulse temperature rise of the chip are compared.

[0024] Test conditions: ambient temperature 25℃, heating power 20W pulsed operation, test duration 0~600s, continuous recording of chip surface temperature change pattern; Test results: During the initial 0-30s rapid heating phase, the heating slope of this embodiment is significantly lower than that of the two comparative groups, and the instantaneous heat conduction response of the three-dimensional continuous heat conduction path is faster, which can quickly dissipate the concentrated heat source. The embodiment forms a wide-range stable phase change temperature control platform in the 65-75℃ range, and the constant temperature holding time is extended by 50%-60% compared with Comparative Example 1, and the temperature control stability is significantly improved. Under high-power pulse thermal shock conditions, the peak temperature of the embodiment is reduced by more than 12°C compared with Comparative Example 1 and by more than 8°C compared with Comparative Example 2, demonstrating a significant advantage in uniform temperature dissipation. After undergoing alternating high and low temperatures of -40℃ to 120℃ and 1000 cycles of thermal shock, the patch in the embodiment showed no delamination, bubbling, or cracking; the phase change enthalpy decay rate was <2%, and the equivalent thermal conductivity decay rate was <3%. The overall structural integrity and thermal performance stability are far superior to existing conventional surface composite and simple stacked phase change structures.

[0025] This invention employs a three-dimensional self-supporting heat conduction path with interlayer staggered close-packing and micro-folded three-dimensional topology. Compared with the traditional flat stacked and planar bonded heat conduction grid structure, under the premise of the same heat conduction unit volume ratio, simulation and actual measurement statistics of cross-sectional contact area are carried out: 1) The three-dimensional topology structure and the three-dimensional coating contact area of ​​the phase change matrix are increased by 18% to 60% compared with the conventional flat arrangement. The heat conduction path and the phase change matrix are upgraded from line contact and local surface contact to full-domain three-dimensional embedded coating contact, which completely solves the problem of limited effective contact area and interface heat transfer hindrance of traditional structures; 2) Actual comparison of phase change response rate: With a 20W pulse heat source as the test condition, the phase change start-up time of the composite patch of this invention is shortened by 35% to 60% compared with ordinary pure phase change patches, realizing synchronous phase change heat absorption in the thickness direction and in-plane direction, eliminating the asynchronous defects of surface phase change and internal lag in traditional patches.

[0026] Two sets of comparative samples were set up: the embodiment (the solid-solid phase change composite energy storage patch of the present invention) and the comparative example (pure solid-solid phase change patch without thermally conductive filler). Tests were conducted at 25℃ ambient temperature, under steady-state thermal conductivity, and under 20W pulsed thermal shock conditions: 1) Equivalent thermal conductivity: The overall equivalent thermal conductivity of the solid-solid phase change composite energy storage patch of the present invention is 40%–90% higher than that of the pure phase change patch, and the axial thermal conductivity of the three-dimensional self-supporting pathway is ≥800W / (m²). K), constructing a through-type rapid heat transfer channel, breaking through the intrinsic thermal conductivity of solid-solid phase change materials of 0.1~0.8W / (m). 1) Natural bottleneck of K); 2) Peak temperature suppression effect: Under high power pulse conditions, the peak temperature of the chip surface in the embodiment of the present invention is reduced by more than 20°C compared with the comparative example; within the test duration of 0-600s, the temperature of ordinary pure phase change patch continues to rise to above 95°C, while the present invention can stably maintain a wide phase change temperature control platform of 65-75°C, the temperature control platform range is significantly widened, and the constant temperature holding time is extended by 50%-60% compared with the surface graphite-reinforced structure. As shown in Figure 3, the heating rate of the embodiment of the present invention is significantly lower than that of the comparative example in the early stage of the test, and enters the wide phase change temperature control platform of 65-75°C after about 100s, and the temperature curve tends to flatten out, while the ordinary pure phase change patch has no obvious temperature control platform and the temperature continues to rise rapidly; at the end of the test, the surface temperature of the chip in the embodiment is about 74°C, while the temperature of the comparative example exceeds 95°C, and the temperature difference is greater than 20°C, which verifies the excellent temperature control and heat dissipation effect of the present invention.

[0027] The embodiments of the present invention and existing conventional laminated composite patches were subjected to high and low temperature alternating thermal shock cycles of -40℃ to 120℃. After 1000 cycles, dissection observation and performance retesting were performed, as shown in Table 1: 1) Structural morphology: The composite patch of the present invention has no bubble generation, no interlayer delamination, and no edge debonding or cracking. The thermal conduction path and phase change matrix still maintain an integrated anchored composite structure; conventional laminated composite samples all showed varying degrees of interface debonding, local delamination, and micropore bubbling defects; 2) Thermal performance degradation: The phase change enthalpy decay rate of the present invention is less than 2%, and the equivalent thermal conductivity change rate is less than 3%, with no significant degradation in thermal management performance during long-term service; conventional surface-reinforced and simple blended samples showed phase change enthalpy decay exceeding 8% and thermal conductivity decay exceeding 12%, with significant differences in long-term stability; 3) Interface bonding characteristics: After surface activation, vacuum impregnation and low-temperature hot pressing, the thermally conductive path and the phase change matrix form a molecular chain segment-level anchor bond, with no liquid phase leakage and a volume deformation rate of less than 1% under normal and high temperature conditions, completely avoiding the drawbacks of easy leakage and deformation after solid-solid phase change material composite.

[0028] Table 1 - Results of samples tested before and after 1000 thermal shock cycles at 40℃~120℃

[0029] Example 1 This embodiment prepares an ultrathin solid-solid phase change composite patch with a thickness of 0.1 mm. A multilayered copper micromesh is used as a three-dimensional heat-conducting pathway, and a cross-linked polyethylene glycol-based thermally softening solid-solid phase change material is selected as the matrix. No additional thermally conductive fillers are added to the matrix. The specific preparation process is as follows: First, copper micromesh with a wire diameter of 20 μm and a pore size of 50 μm is selected. Multiple sets of copper micromesh are pretreated using an interlayer staggered arrangement. The overall volume ratio of the heat-conducting pathway after pretreatment is controlled to be 8%. Subsequently, the pretreated copper micromesh framework is subjected to plasma surface activation treatment. The equipment power is set to 200W, argon gas is introduced as the treatment gas, the gas flow rate is maintained at 10 sccm, and the activation treatment is continued for 30 seconds. Plasma bombardment improves the surface roughness of the metal framework and enhances the interfacial bonding ability between the framework and the phase change matrix. Next, the phase change matrix slurry was prepared. Cross-linked polyethylene glycol-based solid phase change raw materials were placed in a stirring device, and the thermal softening and viscosity reduction temperature was set to 70℃. The mixture was stirred at a constant temperature for 15 minutes at a stirring rate of 300 r / min to obtain a pure phase change matrix slurry. The activated copper micromesh thermally conductive skeleton was placed inside a vacuum impregnation device with a vacuum degree of -0.06 MPa and a constant temperature of 65℃. This vacuum impregnation state was maintained for 10 minutes, allowing the liquid phase change slurry to fully impregnate and fill the pore structure of the copper micromesh, achieving preliminary composite of the matrix and the thermally conductive pathway. After impregnation, the composite preform was removed and transferred to a low-temperature hot-pressing and shaping device. The hot-pressing temperature was 60℃, the molding pressure was 0.2 MPa, and the temperature and pressure were maintained for 5 minutes to complete the densification and shaping. The material was then cooled at a rate of 2℃ / min to obtain an ultra-thin phase change composite patch with uniform thickness and a dense structure.

[0030] Performance test results of this embodiment: The prepared 0.1mm ultrathin composite patch structure is lightweight, flexible, and has good in-plane thermal uniformity; after 1000 cycles of high and low temperature thermal shock at -40℃ to 120℃, the patch showed no bubbles, no interlayer delamination, and no edge debonding or cracking, and the thermal conductivity path maintained an integrated anchoring structure with the phase change matrix; the phase change enthalpy decay rate was 1.2%, the equivalent thermal conductivity change rate was 2.1%, the volume deformation rate was <1% under all temperature range conditions, there was no leakage, and the thermal management stability was excellent under ultrathin size, making it suitable for heat dissipation scenarios of precision microelectronic devices.

[0031] Example 2 This embodiment prepares a 1.0 mm thick solid-solid phase change composite patch, using a carbon fiber woven mesh as a three-dimensional thermal conductive pathway. A polyurethane-based thermally softening solid-solid phase change material is selected as the matrix, and 22% by mass of boron nitride thermally conductive filler is added to improve overall thermal conductivity. The specific preparation process is as follows: First, a carbon fiber woven mesh with a 50 μm filament diameter and 250 μm pore size is selected. The mesh is then subjected to surface micro-pleating treatment. Simultaneously, a multi-layer thermal conductive pathway pretreatment is completed using a staggered, densely packed interlayer arrangement, effectively increasing the contact area between the thermal conductive framework and the phase change matrix. After pretreatment, the volume ratio of the thermal conductive pathway is controlled to 20%. Subsequently, a corona discharge and chemical etching composite process is used to activate the carbon fiber thermal conductive framework. The equipment power is set to 500 W, oxygen is introduced as the process gas at a flow rate of 30 sccm, and the activation treatment is continued for 100 seconds to improve surface wettability and interfacial bonding strength. Next, polyurethane-based solid-state phase change material was mixed with 22% by mass of boron nitride thermally conductive filler and placed in a constant-temperature stirring device. The thermal softening and viscosity reduction temperature was set to 100℃, and the mixture was stirred at a stirring rate of 500 r / min for 40 min to ensure uniform dispersion of the boron nitride filler in the phase change matrix, resulting in a highly uniform composite phase change slurry. The activated carbon fiber thermally conductive skeleton was placed in a vacuum impregnation device with a vacuum degree of -0.08 MPa and a constant temperature of 90℃ for 35 min to ensure complete penetration of the composite phase change slurry into the micropores of the carbon fiber woven mesh, achieving seamless filling. After impregnation, the preform was removed and sent to a hot-pressing and shaping device. The hot-pressing temperature was set to 100℃, the molding pressure to 1.2 MPa, and the temperature and pressure were held constant for 25 min to complete the densification and interfacial anchoring of the preform. The preform was then gradually cooled at a rate of 6℃ / min to obtain a high-performance phase change composite patch.

[0032] Performance test results of this embodiment: The prepared 1.0mm composite patch has excellent thermal conductivity, high structural strength, and good flatness; after 1000 cycles of high and low temperature thermal shock, the sample structure is intact, without delamination, bubbling, or cracking defects, and the interface is tightly and stably bonded; the phase change enthalpy decay rate is 1.5%, the equivalent thermal conductivity change rate is 2.4%, there is no material leakage problem under high and low temperature environments, and the volume deformation rate is <1%. Compared with traditional composite patches, the long-term thermal stability and structural reliability are greatly improved, making it suitable for thermal management scenarios of conventional high-power electronic devices.

[0033] Example 3 This embodiment prepares a 2.0 mm thick solid-solid phase change composite patch, using a copper mesh and graphite fiber composite laminate structure as a three-dimensional heat conduction pathway. A polyol-based thermally softening solid-solid phase change material is selected as the matrix, and silicon carbide and graphite powder are doped with a composite thermally conductive filler, with a total mass fraction of 45%. The specific preparation process is as follows: First, high-toughness copper mesh and high-thermal-conductivity graphite fibers are alternately laminated to construct a three-dimensional heat conduction network. The skeleton wire diameter is controlled at 100 μm and the pore size at 500 μm, precisely controlling the overall heat conduction pathway volume ratio to 35%, forming a highly permeable heat conduction channel. Subsequently, the composite thermally conductive framework underwent plasma-enhanced activation treatment. The equipment power was set to 800W, and nitrogen gas was introduced as a protective and activating gas at a flow rate of 50 sccm for 180 seconds. The polyol-based solid-solid phase change material was then thoroughly mixed with a composite thermally conductive filler containing 45% silicon carbide and graphite powder. This mixture was placed in a high-temperature stirring device, with a thermal softening and viscosity reduction temperature set at 130℃, and stirred at a high speed of 800 r / min for 60 minutes to obtain a stable phase change slurry with high solid content and high thermal conductivity. The activated composite thermally conductive framework was then placed in a vacuum impregnation device at a vacuum degree of -0.10 MPa and a constant temperature of 125℃ for 60 minutes to ensure the high-viscosity composite slurry fully impregnates and fills the pores of the entire three-dimensional thermally conductive network. After impregnation and molding, the preform is sent to a high-temperature hot press. The hot pressing temperature is set at 140℃ and the molding pressure is 2.5MPa. The temperature is kept constant for 45 minutes to complete the high-pressure densification and shaping. Finally, the temperature is gradually reduced to room temperature at a rate of 10℃ / min to obtain a thick phase change composite patch with high filling and high stability.

[0034] Performance test results of this embodiment: The prepared 2.0mm thick composite patch has both high heat storage capacity and ultra-high thermal conductivity, and excellent thermal conductivity pathway. After 1000 cycles of high and low temperature thermal shock, the sample showed no structural failure defects, and the thermal skeleton and substrate anchoring structure remained intact. The phase change enthalpy decay rate was 1.8%, the equivalent thermal conductivity change rate was 2.8%, the high filler filling system showed no filler shedding or substrate leakage, and the volume deformation rate was <1% under extreme temperature change conditions. It can be stably adapted to the continuous heat dissipation scenarios of high-power, high-heat-generating equipment for a long time.

[0035] Example 4 This embodiment is adapted to phase change microcapsule systems that are not resistant to high temperatures. A flexible, leak-proof phase change composite patch with a thickness of 1.5 mm is prepared. A graphene foam composite porous carbon felt self-supporting structure is used as a three-dimensional heat conduction pathway, combined with melamine resin shell phase change microcapsules and an aqueous polymer binder for composite molding, avoiding microcapsule damage caused by high-temperature preparation. The specific preparation process is as follows: First, a self-supporting three-dimensional heat conduction pathway is prepared by combining graphene foam and porous carbon felt. The heat conduction pathway is pretreated using an interlayer staggered arrangement to optimize the internal heat conduction channel distribution, controlling the overall volume ratio of the heat conduction pathway to 25%, ensuring pathway continuity and structural flexibility. Subsequently, the heat conduction framework is subjected to corona activation treatment. The equipment power is set to 400W, and a mixed process gas of oxygen and nitrogen is introduced at a total flow rate of 20 sccm for 60 seconds of continuous activation treatment. Next, the microcapsule composite slurry was prepared, with the system temperature strictly controlled below 80℃ throughout the process. Melamine resin shell phase change microcapsules were used as the core heat storage substrate, mixed uniformly with a water-based polymer binder, and 15% by mass of alumina thermally conductive filler was added. The mixture was thoroughly mixed to obtain a uniformly dispersed composite slurry. A roll coating method was used for composite molding, uniformly coating the microcapsule composite slurry onto the surface of a graphene foam / carbon felt thermally conductive framework. Roll coating allowed the slurry to fully penetrate and fill the pores of the thermal conductive pathways, achieving a tight bond between the slurry and the framework. After coating and lamination, the preform was placed in a low-temperature curing hot press at 65℃ and 1.0 MPa, and cured under constant temperature and pressure for 60 minutes. Finally, it was uniformly cooled to room temperature at a gradient cooling rate of 5℃ / min, resulting in a highly flexible, zero-leakage microcapsule-based phase change composite patch.

[0036] Performance test results of this embodiment: The prepared 1.5mm microcapsule-based composite patch has excellent flexibility and can be bent at will without powder shedding or matrix leakage. After 1000 cycles of high and low temperature thermal shock, the sample structure is intact, the microcapsules are undamaged, and the thermal conductivity pathways are uniformly distributed. The phase change enthalpy decay rate is 1.3%, and the equivalent thermal conductivity change rate is 2.2%. The structure and thermal performance stability under high and low temperature cycling are excellent, making it suitable for various heat dissipation applications that are not resistant to high temperatures and require flexible adaptation. This makes up for the technical shortcomings of traditional high-temperature preparation processes that cannot be adapted to microcapsule systems.

[0037] Example 5 In this embodiment, a high-precision three-dimensional network phase change composite patch with a thickness of 1.2 mm was prepared. An integrated pure copper porous metal network was fabricated using SLM (Selective Laser Melting) 3D printing technology as a three-dimensional heat conduction pathway. The specific fabrication process is as follows: A pure copper porous metal heat conduction network was integrally formed using SLM 3D printing technology. A three-dimensional topology design with interlayer misalignment and honeycomb structure was adopted, controlling the thickness of the network ribs to 80 μm and the mesh diameter to 300 μm. The overall volume ratio of the heat conduction pathway was kept stable at 22%. Subsequently, the 3D-printed pure copper heat conduction network was subjected to plasma activation modification. The equipment power was set to 550W, and a mixture of argon and nitrogen gas was introduced at a total gas flow rate of 35 sccm. The activation treatment was carried out continuously for 120 seconds, and the contact angle of the skeleton surface was precisely controlled to below 40°. Using polyurethane-based thermally softening solid-solid phase change material as the matrix, a composite thermally conductive filler of alumina and graphite was doped, with a total filler mass fraction of 28%. The raw materials were mixed and placed in a constant-temperature stirring device. The thermal softening and viscosity reduction temperature was set at 105℃, and the mixture was stirred at a stirring rate of 550 r / min for 45 min to ensure uniform dispersion of the composite filler, resulting in a composite phase change slurry. The activated and modified 3D-printed integrated copper network skeleton was placed in a vacuum impregnation device with a vacuum degree of -0.09 MPa and a constant temperature of 95℃ for 40 min to ensure the phase change slurry fully penetrated and filled the three-dimensional honeycomb pore structure. After impregnation, the preform was removed and hot-pressed for shaping. The hot-pressing temperature was set at 105℃ and the molding pressure at 1.5 MPa, and the temperature and pressure were held constant for 30 min to achieve molecular-level anchoring of the matrix and the three-dimensional metal network. Finally, the preform was uniformly cooled to room temperature at a gradient cooling rate of 5.5℃ / min to obtain a high-precision, high-stability three-dimensional network phase change composite patch.

[0038] Performance test results of this embodiment: The prepared 1.2mm composite patch thermal conductive network has strong integration, high structural precision, and excellent thermal conductivity uniformity; after 1000 cycles of high and low temperature thermal shock, the sample showed no delamination, cracking, or bubbling defects, and the interface bonding strength was extremely high; the phase change enthalpy decay rate was 1.6%, the equivalent thermal conductivity change rate was 2.5%, and the volumetric deformation rate over the entire temperature range was <1%, making it suitable for high-precision and high-stability thermal management scenarios in high-end electronic devices.

[0039] Example 6 Figure 4 and Figure 5 The diagram shows the arrangement of the self-supporting three-dimensional heat conduction pathway of the present invention, which are biomimetic fractal tree-like arrangement structure and honeycomb regular hexagonal arrangement structure. The above complex topological structures can be fabricated by 3D printing metal network in one piece, breaking through the processing limitations of traditional weaving and stamping that cannot produce complex hollow three-dimensional skeletons. They can be selected or combined according to different heat dissipation requirements.

Claims

1. A solid-solid phase change composite energy storage patch with a self-supporting thermally conductive path, characterized in that, The device includes a self-supporting three-dimensional topology heat-conducting pathway framework and a solid-solid phase change energy storage substrate that fills and covers the gaps in the heat-conducting pathway framework; the volume of the heat-conducting pathway framework accounts for 8% to 35% of the total volume of the solid-solid phase change composite energy storage patch.

2. The solid-solid phase change composite energy storage patch with a self-supporting thermally conductive path as described in claim 1, characterized in that, The self-supporting three-dimensional topology's heat conduction pathway framework can be any one of the following: laminated copper mesh, thermally conductive fiber braided mesh, graphite fiber array, graphene foam, porous carbon felt, micro heat pipe array, or 3D printed integrated porous metal network.

3. The solid-solid phase change composite energy storage patch with a self-supporting thermally conductive path as described in claim 1, characterized in that, The solid-solid phase change energy storage matrix uses polyol, polyurethane, or cross-linked polyethylene glycol polymer-based solid-solid phase change materials as the continuous phase matrix. The matrix is ​​doped with 0-45% by mass of thermally conductive filler, which is selected from one or more of boron nitride, alumina, silicon carbide, and graphite powder.

4. The solid-solid phase change composite energy storage patch with a self-supporting thermally conductive path as described in claim 1, characterized in that, The thickness of the solid-solid phase change composite energy storage patch is 0.1–2.0 mm.

5. The method for preparing a solid-solid phase change composite energy storage patch with a self-supporting thermally conductive path as described in any one of claims 1-4, characterized in that, The specific steps are as follows: Step 1: Fabrication of a self-supporting three-dimensional topological thermal conductive pathway framework, followed by surface activation treatment of the thermal conductive pathway framework. Step 2: The solid-solid phase change energy storage substrate material is uniformly filled into the gaps of the activated thermal conductive path skeleton, and then solidified to obtain a solid-solid phase change composite energy storage patch with a self-supporting thermal conductive path.

6. The method for preparing a solid-solid phase change composite energy storage patch with a self-supporting thermally conductive path as described in claim 5, characterized in that, In step 1, the thermal conductive path framework is subjected to surface activation treatment, which is plasma activation, with a treatment power of 200-800W, a gas flow rate of 10-50sccm, and a treatment time of 30-180s; the process gas introduced is any one or more of Ar, N2, and O2.

7. The method for preparing a solid-solid phase change composite energy storage patch with a self-supporting thermally conductive path as described in claim 5, characterized in that, In step 2, if a thermally softening solid-solid phase change energy storage matrix is ​​used, the specific steps are as follows: weigh the solid-solid phase change matrix raw materials according to the formula, heat them to 70-130℃ for thermal softening, viscosity reduction and plasticization, the stirring rate is 300-800 r / min, and the stirring time is 15-60 min; add 0-45% by mass of thermally conductive filler as needed, and continue to keep warm and stir for 20-90 min to obtain a phase change fluidized mixture; The activated thermally conductive pathway framework is placed in a vacuum impregnation tank, with the vacuum level controlled at -0.06 to -0.10 MPa and the tank temperature maintained at 65 to 125°C. The phase change fluidized bed mixture is slowly injected into the impregnation tank and impregnated for 10 to 60 minutes to form a composite blank. The impregnated composite blank is then sent to a precision hot press for hot pressing at a temperature of 60 to 140°C, with a vertical pressure of 0.2 to 2.5 MPa applied. The temperature is held constant for 5 to 45 minutes, and a programmed gradient cooling is used with a cooling rate controlled at 2 to 10°C / min. After cooling to room temperature, the pressure is released to obtain a solid-solid phase change composite energy storage patch.

8. The method for preparing a solid-solid phase change composite energy storage patch with a self-supporting thermally conductive path as described in claim 5, characterized in that, In step 2, if a phase change microcapsule-type solid-solid phase change energy storage matrix is ​​used, the specific steps are as follows: the solid-solid phase change microcapsules are mixed with binder and matrix resin, stirred evenly, and 0-30% thermally conductive filler is added as needed by mass fraction. The mixture is stirred to obtain a solid-solid phase change microcapsule composite slurry. The solid-solid phase change microcapsule composite slurry is uniformly filled into the gaps of the activated thermally conductive pathway skeleton by coating, rolling or layering methods to complete the pre-composite molding. Curing is performed by hot pressing, with the temperature controlled at 40-80℃, the pressure applied at 0.2-2.5MPa, and held for 30-120 minutes. A programmed gradient cooling method is used, with the cooling rate controlled at 2-10℃ / min. After cooling to room temperature, the pressure is released to obtain a solid-solid phase change composite energy storage patch.

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