High‐Performance Ionic Thermoelectric Supercapacitor for Integrated Energy Conversion‐Storage

Abstract

Converting low‐grade waste heat into usable electricity and storing it simultaneously requires a new technology that realize the directional migration of electrons or ions under temperature difference and enrichment on the electrodes. Although the urgent demand of energy conversion‐storage (ECS) has emerged in the field of wearable electronic, achieving the integrated bi‐functional device remains challenge due to the different mechanisms of electrical transportation and storage. Here, we report an ionic thermoelectric supercapacitor that relies on the synergistic functions of thermoelectricity and supercapacitor in the thermoelectric ionogel electrolyte and high‐performance hydrogel electrodes to enhance the ECS performance under a thermal gradient. The thermoelectric electrolyte is composed of polyacrylamide hydrogel and sodium carboxymethyl cellulose (PMSC), possessing cross‐linked network with excellent cation selectivity, while the ionic thermoelectric properties are further improved in the presence of NaCl. The corresponding Seebeck coefficient and ionic conductivity of the NaCl–PMSC electrolyte reach 17.1 mV K−1 and 26.8 mS cm−1, respectively. Owing to good stretchability of both gel‐based electrolyte and electrode, the full‐stretchable integrated ECS device, termed ionic thermoelectric supercapacitor, presents promising thermal‐charge storage capability (~1.3 mC, ΔT ≈ 10 K), thus holds promise for wearable energy harvesting.

Giant and bidirectionally tunable thermopower in nonaqueous ionogels enabled by selective ion doping

“…Over the past few years, giant thermopowers of the order of 10 mV K −1 have been reported frequently in ion conductors (5)(6)(7)(8)(9)(10)(11)(12)(13) or mixed ion-electron conductors (14)(15)(16). The greatly enhanced thermopowers compared with the best electronic thermoelectric materials and reasonable ionic conductivity allow more sensitive thermal sensing, especially for small temperature difference occasions such as the human body thermal monitoring.…”

Advanced Bacterial Cellulose Ionic Conductors with Gigantic Thermopower for Low-Grade Heat Harvesting

“…Therefore, the obtained Seebeck coefficient is basically on the order of mV K –1 , which shows a broad prospect in low-grade heat harvesting . Currently, much research on i-TE systems has been reported based on ionic liquids, − polyelectrolytes, − and inorganic salt–polymers. − Unfortunately, the ionic conductivity of these systems is several orders of magnitude lower than that of normal electronic conductors.…”

Liquid-Free Ion-Conducting Elastomer with Environmental Stability for Soft Sensing and Thermoelectric Generating

“…The ionic thermoelectric capacitor (ITEC) based on LFICE-4 was fabricated for the conversion and store of heat into electricity, , and the schematic diagram of ITEC is shown in Figure a. The voltage variation of ITEC connected with a 1 kΩ external load to Δ T and the operating principle of ITEC are shown in Figure b,c.…”

“…59 Moreover, after 6 months, S i presents no significant change (Figure S13), further indicating that the assembled thermoelectric generator based on LFICE-4 has a long-term stable thermoelectric performance. The ionic thermoelectric capacitor (ITEC) based on LFICE-4 was fabricated for the conversion and store of heat into electricity, 32,58 and the schematic diagram of ITEC is shown in Figure 9a. The voltage variation of ITEC connected with a 1 kΩ external load to ΔT and the operating principle of ITEC are shown in Figure 9b,c.…”