To
exploit the high-temperature superinsulation potential of anisotropic
thermal management materials, the incorporation of ceramic aerogel
into the aligned structural networks is indispensable. However, the
long-standing obstacle to exploring ultralight superinsulation ceramic
aerogels is the inaccessibility of its mechanical elasticity, stability,
and anisotropic thermal insulation. In this study, we report a recoverable,
flexible ceramic fiber-aerogel composite with anisotropic lamellar
structure, where the interfacial cross-linking between ceramic fiber
and aerogel is important in its superinsulation performance. The resulting
ultralight aerogel composite exhibits a density of 0.05 g/cm3, large strain recovery (over 50%), and low thermal conductivity
(0.0224 W m–1 K–1), while its
hydrophobicity is achieved by in situ trichlorosilane coating with
the water contact angle of 135°. The hygroscopic tests of such
aerogel composites demonstrate a reversible thermal insulation. The
mechanical elasticity and stability of the anisotropic composites,
with its soundproof performance, shed light on the low-cost superelastic
aerogel manufacturing with scalability for energy saving building
applications.
Silica aerogel gives rise to much attention due to its unique nanoporous network, which consists of nanoscale connective silica particles and high-volume nanoscale pores. This lightweight superinsulation solid material is...
Polymer dielectrics, an insulating material ubiquitous in electrical power systems, must be ultralight, mechanically and dielectrically strong, and very thermally conductive. However, electric and thermal transport parameters are intercorrelated in a way that works against the occurrence of thermally conductive polymer electric insulators. Here, we describe how solution gel-shearing-strained polyethylene yields an electric insulating material with an outstanding in-plane thermal conductivity of 10.74 W m −1 K −1 and an average dielectric constant of 4.1. The dielectric constant and loss of such sheared polymer electric insulators are nearly independent of the frequency and a wide temperature range. The gel-shearing aligns ultrahigh-molecular weight polymer crystalline chains for the formation of separated and aligned nanoscale fibrous arrays. Together with lattice strains and the presence of boron nitride nanosheets, the dielectric polymer shows high current density carrying and high operating temperature, which is attributed to greatly enhanced heat conduction.
Advanced high-temperature materials, metals and ceramics, have been widely sought after for printed flexible electronics under extreme conditions. However, the thermal stability and electronic performance of these materials generally diminish under extreme environments. Additionally, printable electronics typically utilize nanoscale materials, which further exacerbate the problems with oxidation and corrosion at those extreme conditions. Here we report superior thermal and electronic stability of printed copper-flexible ceramic electronics by means of integral hybridization and passivation strategies. High electric conductivity (5.6 MS/m) and thermal stability above 400 °C are achieved in the printed graphene-passivated copper platelet features, while thermal management and stability above 1000 °C of printed electronics can be achieved by using either ultrathin alumina or flexible alumina aerogel sheets. The findings shown here provide a pathway toward printed, extreme electronic applications for harsh service conditions.
Thermal
insulation of solid materials originates from the nanoscale
porous architectures to regulate thermal management in energy-critical
applications from energy-efficient buildings to heat-sensitive energy
devices. Here, we show nanoengineering of porous silica materials
to control the architecture transition from mesoporous to nanocage
networks. A low thermal conductivity of such a porous silica network
is achieved at 0.018 W/(m K) while exhibiting a porosity of 92.05%,
specific surface area of 504 m2/g, and pore volume of 2.37
cm3/g after ambient pressure drying. Meanwhile, the crosslinking
of the porous silica and ceramic fiber frameworks show a tensile Young’s
modulus of 2.8 MPa while maintaining high thermal insulation, which
provides an effective thermal runway mitigation strategy for rechargeable
lithium-ion batteries. The nanoengineering strategy reported here
would shed light on achieving superthermal insulation of nanostructures
for energy-critical applications.
Thermal insulation paint material
is an energy-critical coating
component for thermal management in energy-efficient buildings, vehicles,
electronics, and data centers. Long-standing pursuits for the paint
coating materials are high thermal insulation and light reflectance,
mechanical durability, and wear resistance. Here we describe an aqueous-based
hierarchical coating nanocomposite composed of mesoporous silica aerogel
and titania nanoparticle pigment paint which exhibits a low thermal
conductivity of 0.029 W/m K, a high visible reflectance of 90%, and
a mechanical Young’s modulus of ∼4.86 MPa with a high
abrasion resistance. The hierarchical and hydrophobic nanocomposite
coatings show robust thermal cycling and thermal resistance, resulting
in an equivalent cooling power of 928 W/m2. The design
and manufacturing principle reported here could extend to a variety
of insulation coating materials to achieve energy efficiency and sustainability.
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