  The possibility of tuning the vibrational properties and the thermal
conductivity of layered van der Waals materials either chemically or
mechanically paves the way to significant advances in nanoscale heat
management. Using first-principles calculations we investigate the modulation
of heat transport in MoS2 by lithium intercalation and cross-plane strain. We
find that both the in-plane and cross-plane thermal conductivity (kr, kz) of
MoS2 are extremely sensitive to both strain and electrochemical intercalation.
Combining lithium intercalation and strain, the in-plane and cross-plane
thermal conductivity can be tuned over one and two orders of magnitude,
respectively. Furthermore, since kr and kz respond in different ways to
intercalation and strain, the thermal conductivity anisotropy can be modulated
by two orders of magnitude. The underlying mechanisms for such large tunability
of the anisotropic thermal conductivity of \Mos are explored by computing and
analyzing the dispersion relations, group velocities, relaxation times and mean
free paths of phonons. Since both intercalation and strain can be applied
reversibly, their stark effect on thermal conductivity can be exploited to
design novel phononic devices, as well as for thermal management in MoS2-based
electronic and optoelectronic systems.
