A convenient, reversible, fast, and wide-range switching
of thermal
conductivity is desired for efficient heat energy management. However,
traditional methods, such as temperature-induced phase transition
and chemical doping, have many limitations, e.g.,
the lack of continuous tunability over a wide temperature range and
low switching speed. In this work, a strategy of electric field-driven
crystal symmetry engineering to efficiently modulate thermal conductivity
is reported with first-principles calculations. By simply changing
the direction of an external electric field loaded in ferroelectric
PbZr0.5Ti0.5O3, near the morphotropic
phase boundary composition, we obtain the largest switching of thermal
conductivity for ferroelectric materials at room temperature based
on the dual-phonon theory, i.e., normal and diffuson-like
phonons, with three different criteria. The calculation results indicate
that with decreasing crystal symmetry, the degeneracy of phonon modes
reduces and the avoid-crossing behavior of phonon branches enhances,
leading to the increase of diffuson-like phonons and weighted phonon–phonon
scattering phase space. A thermal switch prototype based on PbZr0.5Ti0.5O3 is further shown that can
protect the Li-ion battery by modulating its temperature up to 17.5
°C. Our studies would pave the way for designing next-generation
thermal switch with high speed, a wide temperature range, and a large
switching ratio.