“…Although modulating phonon transport poses greater challenges compared with electron transport, thanks to the conceptualization of phononic devices ( 6 ), active and reversible control of phonon transport to mitigate heat-related concerns has stimulated broad research interest ( 5 , 10 , 11 ). Until now, active and reversible control of phonon transport or thermal conductivity k (i.e., thermal switching) has been explored by many different methods: strain engineering ( 10 , 12 ), light-triggered alignment of molecular chains ( 13 , 14 ), electrochemical-controlled phase transition ( 15 ) or ion intercalation ( 16 – 18 ), temperature-triggered phase transition ( 19 , 20 ), and electric field–driven domain wall density change ( 21 – 23 ), etc. For practical applications, high-performance thermal switching should meet three crucial conditions: (i) high switching ratio, (ii) large number of switching cycles, and (iii) short switching time.…”