Electrochemically tunable thermal conductivity of lithium cobalt oxide

Abstract

Using time-domain thermoreflectance, the thermal conductivity and elastic properties of a sputter deposited LiCoO 2 film, a common lithium-ion cathode material, are measured as a function of the degree of lithiation. Here we report that via in situ measurements during cycling, the thermal conductivity of a LiCoO 2 cathode reversibly decreases from B5.4 to 3.7 W m À 1 K À 1 , and its elastic modulus decreases from 325 to 225 GPa, as it is delithiated from Li 1.0 CoO 2 to Li 0.6 CoO 2 . The dependence of the thermal conductivity on lithiation appears correlated with the lithiation-dependent phase behaviour. The oxidation-statedependent thermal conductivity of electrolytically active transition metal oxides provides opportunities for dynamic control of thermal conductivity and is important to understand for thermal management in electrochemical energy storage devices.

Light-triggered thermal conductivity switching in azobenzene polymers

“…In conjunction with the structural transition, the polymer exhibits a notable thermal conductivity contrast, r, between the crystal, Λ high and liquid, Λ low states, with r = Λ high /Λ low ∼ 3.5. In comparison, r of a giant-magneto-thermoresistive material is ∼1.8 (15); r of a liquid crystal network switched with a magnetic field is ∼1.5 (16); and r of electrochemically lithiated/delithiated Li x CoO 2 is ∼1.5 (17,18). Our results demonstrate powerful control of the thermophysical properties of polymers by light.…”

Role of Remote Interfacial Phonon (RIP) Scattering in Heat Transport Across Graphene/SiO2 Interfaces

“…25) of monitoring TDTR signals as the applied voltage changes. In conventional TDTR, the accuracy in determining ΔV out (or other TDTR signals) due to the applied voltage depends on the precision of TDTR measurements over time, i.e., the repeatability of TDTR measurements when the same experimental parameters are employed.…”

Evaluating Broader Impacts of Nanoscale Thermal Transport Research

“…Theoretical advances provide hope for much Downloaded by [New York University] at 07: 56 12 June 2015 needed cross-validations between theory and experiment without any free parameters and for problems ranging from thermal phonon coherence to thermal boundary conductance. Nonlinear and actively controlled heat conduction is another opportunity, including thermal diodes and switches [51][52][53][54][55]. Unconventional carrier types such as magnons are also of interest [56][57][58][59][60].…”