Form-stable phase change materials enhanced photothermic conversion and thermal conductivity by Ag-expanded graphite

Zou

ACS Appl. Mater. Interfaces

et al. 2022

Self Cite

In the field of thermal energy storage, organic phase change materials (PCMs) are widely used as functional materials to boost thermal applications. However, there is often a tradeoff between constructing shape-stable composite PCMs with high enthalpy value and those with low leakage rates. Here, we proposed a promising scheme to address this issue. A novel hydrogel consisting of reduced graphene oxide (rGO) and covalent organic framework (COF) was prepared via hydrothermal methods, and the rGO–COF ultralight aerogel with a hierarchical porous structure was formed after freeze-drying. The rGO–COF aerogel shows excellent absorption ability and affinity for organic solvents. It can sufficiently adsorb the molten organic PCMs, such as polyethylene glycol (PEG), and synthesize shape-stable composite PCMs with excellent leak resistance. The COF grown on the surface of rGO has a superior affinity for PEG, so rGO–COF aerogel shows an outstanding PEG loading rate of up to 96.1 wt %, which is 1.7 wt % higher than that of rGO aerogel. In addition, the COF effectively reduces the subcooling of PEG/rGO–COF with 20.3%, compared to PEG/rGO. Meanwhile, the prepared PEG/rGO–COF exhibits extremely high enthalpy and relative enthalpy efficiency (164.6 J/g, 97.4%). This demonstrates that a promising direction was highlighte for the preparation of high-enthalpy shape-stable composite organic PCMs in this work.

Section: Resultsmentioning

confidence: 99%

Lipophilic Modified Hierarchical Multiporous rGO Aerogel-Based Organic Phase Change Materials for Effective Thermal Energy Storage

Zou

ACS Appl. Mater. Interfaces

et al. 2022

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J of Applied Polymer Sci

“…As shown in Figure 6a, pristine EG had a smooth surface. In contrast, Si@EG exhibited microsized particles on the EG surface, 24 as shown in Figure 6b. and 0.5 keV in Figure 7a can be attributed to carbon and oxygen, respectively.…”

Section: Si@eg Characterizationmentioning

confidence: 95%

“…EG maintains a layered structure similar to that of natural flake graphite, which has very high thermal and electrical conductivities. [22][23][24][25][26] However, EG tends to aggregate in epoxy resins because of its poor compatibility with the epoxy matrix, which deteriorates the performance of the resulting composites. Therefore, the EG surface is modified using several methods, such as coupling agent modification, surface coating, silver plating, and plasma treatment, to improve the interfacial interactions between EG and epoxy matrix.…”

Section: Introductionmentioning

confidence: 99%

Improved thermal conductivity of epoxy resins using silane coupling agent‐modified expanded graphite

Jiang

Chu

Zhang

et al. 2022

A silane coupling agent was used to modify the surface of expanded graphite (EG), which was subsequently used as a thermally conductive filler to fabricate diglycidylether of bisphenol-A (DGEBA)/EG composites with high thermal conductivity via hot blending and compression-curing processes. The surface characteristics of silane coupling agent-modified EG (Si@EG) were characterized by a variety of analytical techniques. The effects of the Si@EG content on the thermal conductivity, thermal stability, impact strength, and morphology of the DGEBA/Si@EG composites were investigated. The results revealed that the addition of 80 wt.% Si@EG increased the thermal conductivity of the composites from 0.17 to 10.56 W/m K, which was 61.1 times higher than that of pristine DGEBA. The initial decomposition temperature of the composite containing 80 wt.% Si@EG was 60.6 C higher than that of pristine DGEBA. The impact strength of the composites decreased from 2.0 to 0.87 kJ/m 2 when the Si@EG content increased from 0 to 80 wt.%. The scanning electron microscopy images of the fractured surfaces revealed that the EG sheets in the DGEBA matrix formed a continuous thermally conductive path at high Si@EG contents.

ACS Sustainable Chem. Eng.

“…PCM is a kind of thermal storage material that stores and releases latent heat by changing the physical state, which is extensively employed in the fields of construction energy saving, solar thermal utilization, , and thermal management of electronic devices . Organic PCMs such as paraffin wax (PW), , polyethylene glycol (PEG), ,, lauric acid, and so forth are widely used because of their high latent heat, inexpensive price, moderate phase change temperature, low supercooling, and stable physical and chemical characteristics.…”

Section: Introductionmentioning

confidence: 99%

A Novel Room-Temperature Flexible Phase Change Material for Solar Energy Photothermal Conversion and Battery Thermal Management

Huang,

Zou,

Chen

et al. 2024

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In recognition of their excellent capacity for regulating thermal energy storage and release, phase change materials (PCMs) have been rediscovered and received growing significance in advanced solar energy storage and battery thermal management (BTM). Nevertheless, their insufficient thermal conductivity, poor shape stabilization, and high rigidity hinder their application in BTM systems. Herein, we reported a novel stable ordinary temperature flexible phase change material (FPCM) basis of paraffin wax (PW), polyolefin elastomer (POE), and expanded graphite (EG), which efficiently solves the aforementioned problem. And then, through flexibility, the FPCM was smartly mounted on the power batteries by overfilling, making the components compact and efficient. Thermal contact resistance (TCR) while operating the battery pack could be decreased by the flexible wrapping of the FPCM. Results show that the above BTM assembly effectively reduced the TCR to 0.28 °C/W. This FPCM-based reactive cooling BTM ensures that the temperature of the battery pack is kept under a safe temperature (55 °C) at all times. With the effect of EG, the prepared FPCM exhibits a substantial improvement in thermal conductivity, achieving 1.929 W/mK, as well as a prominent photothermal efficiency of conversion (91.2%). Notably, its ultraflexibility, high thermal conductivity, and excellent latent heat provide a convenient way for the thermal management packaging of complex and multimodel electronic devices.