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An effective strategy to employ the synthetic Cu 1.5 Mn 1.5 O 4 spinel-type PTC materials for constructing the STEG device series integrated supercapacitor to achieve the conversion and storage of solar-thermal energy to electrical energy. [Display omitted] • Cu 1.5 Mn 1.5 O 4 spinel-type PTC materials to design and construct the STEG device. • Employing synthetic C 4 ImBF 4 ionic liquid electrolyte to construct supercapacitor. • Coupling the STEG device with supercapacitor to convert and store solar-thermal energy into electrical energy. • Inspiring new insight to design and construct novel energy conversion and storage devices. Thermoelectric generators (TEGs), which harness and convert solar-thermal energy into electrical energy, possess immense potential within the field of photothermal conversion (PTC). However, the widespread adoption of conventional TEGs in PTC domain has encountered some obstacles, which represent that TEGs have poor inherent PTC performance, resulting in low solar-thermoelectric conversion efficiency, and this solar-thermal-electric conversion method lacks the capability of electrical energy storage. Hence, an urgent imperative exists to develop integrated and synergistic energy technologies that can respond to these underlying challenges. Herein, we reported a novel strategy for employing spinel-type Cu 1.5 Mn 1.5 O 4 PTC coating to adorn conventional TEG to construct the solar-thermoelectric generator (STEG) which exhibited excellent solar-thermoelectric conversion capability, and then integrating the STEG in series with a supercapacitor composed of synthetic ionic liquid electrolytes and carbon electrodes to fulfill the conversion and storage of solar-thermal energy into electrical energy. The results indicated that, when compared to a conventional TEG, the STEG attained a drastically elevated internal temperature difference due to the excellent PTC capability of spinel-type coating. As a result, remarkable enhancements were observed in both the steady-state voltages (V oc) and maximum output power density (P max) of the STEG, exceeding a 6-fold and 40-fold increase, respectively. Furthermore, we conducted experimental validation to ascertain the viability of the solar-driven STEG to charge a supercapacitor, thereby achieving the conversion and storage of solar-thermal energy into electrical energy, and the working mechanism of this integrated system has been revealed. This study offers invaluable insights into the development of highly efficient solar-thermal energy conversion and storage methods. [ABSTRACT FROM AUTHOR]

Electrochemical quartz crystal microbalance (EQCM) can be used to study the charge storage mechanisms of supercapacitors because of its excellent accuracy in mass change, and a homogeneous and ultrathin sample coating is strongly required for accurate measurement. However, it is difficult to obtain such a coating by the frequently used methods. Here a vacuum filtration‐and‐transfer (VFT) technique is reported to achieve this target. To prove the universality of this method, six materials with different dimensions are selected as research objects, and they are prepared into test films on quartz by VFT method and well‐used spray method for EQCM measurements, respectively. The results show that the VFT method can eliminate the influence caused by inhomogeneity of the films, which is beneficial for clearly distinguishing the rigid model from the viscoelastic model. This method helps EQCM to reflect more precise quality change as well as deformation of the material itself. Consequently, it makes EQCM more reliable to describe the energy storage mechanisms of various electrode materials. [ABSTRACT FROM AUTHOR]