10.1021/nn505328j.s001
Minglu Liu
Minglu
Liu
Yuanyu Ma
Yuanyu
Ma
Hsinwei Wu
Hsinwei
Wu
Robert Y. Wang
Robert Y.
Wang
Metal Matrix–Metal Nanoparticle Composites with Tunable Melting Temperature and High Thermal Conductivity for Phase-Change Thermal Storage
American Chemical Society
2015
Ag matrix
equivalent volume fraction
silver matrix
PCM
energy density improvement
nanocomposite formation steps
custom design nanocomposites
management applications
13 nm Bi nanoparticles
nanoparticle volume fractions
nanoparticle coalescence
nanoparticle diameters
medium approximation
volume fraction
nanoparticle diameter
storage materials
Tunable Melting Temperature
nanoparticle volume fraction changes
control nanoparticle size
nanoparticle synthesis
2015-02-24 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Metal_Matrix_Metal_Nanoparticle_Composites_with_Tunable_Melting_Temperature_and_High_Thermal_Conductivity_for_Phase_Change_Thermal_Storage/2193334
Phase-change materials (PCMs) are of broad interest for thermal storage and management applications. For energy-dense storage with fast thermal charging/discharging rates, a PCM should have a suitable melting temperature, large enthalpy of fusion, and high thermal conductivity. To simultaneously accomplish these traits, we custom design nanocomposites consisting of phase-change Bi nanoparticles embedded in an Ag matrix. We precisely control nanoparticle size, shape, and volume fraction in the composite by separating the nanoparticle synthesis and nanocomposite formation steps. We demonstrate a 50–100% thermal energy density improvement relative to common organic PCMs with equivalent volume fraction. We also tune the melting temperature from 236–252 °C by varying nanoparticle diameter from 8.1–14.9 nm. Importantly, the silver matrix successfully prevents nanoparticle coalescence, and no melting changes are observed during 100 melt–freeze cycles. The nanocomposite’s Ag matrix also leads to very high thermal conductivities. For example, the thermal conductivity of a composite with a 10% volume fraction of 13 nm Bi nanoparticles is 128 ± 23 W/m-K, which is several orders of magnitude higher than typical thermal storage materials. We complement these measurements with calculations using a modified effective medium approximation for nanoscale thermal transport. These calculations predict that the thermal conductivity of composites with 13 nm Bi nanoparticles varies from 142 to 47 W/m-K as the nanoparticle volume fraction changes from 10 to 35%. Larger nanoparticle diameters and/or smaller nanoparticle volume fractions lead to larger thermal conductivities.