Current Challenges in Materials for Thermal Energy Storage

Neutron News 6 Meeting Report Current Challenges in Materials for Thermal Energy Storage In June 2022, over 40 scientists from 13 countries across four continents came together in stunning Caesar Augusta (Zaragoza, Spain) to participate in a 3-day CECAM Flagship Workshop entitled “Current Challenges in Materials for Thermal Energy Storage.” Originally planned for 2021, the intensity of the COVID pandemic at the time could not guarantee a face-to-face meeting. With the benefit of hindsight, its postponement to 2022 was a gratifying turn of fate, as only a handful of registered participants had to join us online for the event (see Figure 1). The record-high temperatures we all experienced in Zaragoza during the meeting were certainly a vivid reminder of the primary driver behind the workshop, as well as of the challenges associated with securing a sustainable future for all: human activities continue to produce and require vast amounts of energy, and its efficient storage and subsequent use has far-reaching economic and societal impacts. This latter objective drives current efforts in the search for improved Thermal Energy-Storage Materials (TESMs), to store and release energy via sensible heat, adsorption-desorption phenomena or well-defined phase transitions either in the bulk or under confinement. In all cases, the search for improved TESMs has relied primarily on empirical knowledge focused on a handful of observables like the heat capacity, melting/desorption enthalpy & temperature or the thermal conductivity, albeit with quite limited physical insight and success. Motivated by the above, this workshop brought together computational and experimental efforts for their coordinated deployment in order to move beyond the stateof-the-art in the rational design of TESMs. These included ongoing developments of versatile and accurate computer-simulation tools in tandem with increasingly elaborate experimental campaigns, with an emphasis on the exploitation of last-generation radiation-scattering techniques (neutrons and X-rays) and the use of robust methodologies to gain access to much-needed thermophysical data in and out-of equilibrium. During the event, we enjoyed over twenty presentations from leading practitioners across a plethora