Jian Zeng1,2,Renkun Chen3,Ravi Prasher1,2
Lawrence Berkeley National Laboratory1,University of California, Berkeley2,University of California, San Diego3
Jian Zeng1,2,Renkun Chen3,Ravi Prasher1,2
Lawrence Berkeley National Laboratory1,University of California, Berkeley2,University of California, San Diego3
Electronics will consume ~ 20.9% of global electricity by 2030, all of which will end up as heat. Data center alone requires ~ 2.1×10<sup>11</sup> kWh of cooling load and ~ 1591 billion gallons of water yearly. Passive cooling of high-power electronics with minimum energy and water input is thus critical for the global water-energy nexus but has been challenging due to the large fluctuation in heat loads between the on-/off-peak hours. The thermal fluctuation could be mitigated by latent heat cooling. In this work, we develop a moisture thermal battery (MTB) by coating superabsorbent hydrogel on to a pin fin heat sink with large surface. The MTB leverages large latent heat and high thermal conductance of water evaporation for electronic cooling during on-peak hours and importantly, autonomously harvest atmospheric moisture and store the water during off hours. The MTB provides thermal capacity up to ~ 200 kWh m<sup>-2</sup> for evaporative cooling with a record-high effective heat transfer coefficient up to ~ 1000 W m<sup>-2</sup> K<sup>-1</sup> for a passive device (no external power). The MTB was also demonstrated to suppress temperature fluctuation of a high-power field effect transistor and a computer CPU between the on- and off- peak hours by ~ 15 K, indicating its potential broad applications for autonomous water harvesting and cooling for a wide range of electronic devices with high heat loads.