The design of high-performance n-type ionic thermoelectric cells (i-TE cells) tailored for harvesting low-grade thermal energy presents significant challenges. In this study, an n-type i-TE cell exhibiting substantial negative thermopower and a high output energy density is developed by leveraging the synergistic interplay between thermal diffusion within an ionic hydrogel electrolyte and redox reactions at the electrode interface. Specifically, a gel network featuring dual positive groups is synthesized by cross-linking quaternized chitosan and guanidine molecules via glutaraldehyde, with thermal diffusion further enhanced by incorporating crown ether for complexation. Additionally, NiCo(CO 3 )(OH) 2 , a material known for its high hydrophilicity, is utilized as the anode to facilitate rapid ion and electron transfer at the electrode interface. The integration of optimized thermal diffusion within polycationic electrolytes with electrode interface-enhanced ion/electron transport mechanisms significantly improves the sustained output performance and thermoelectric conversion efficiency of the i-TE cell. Notably, the thermopower (Seebeck coefficient) of this n-type i-TE cell achieves a value of −26.04 mV K −1 , and its 2 h output energy density reached 1301.61 J m −2 under a temperature difference (ΔT) of 15 K. These findings offer a novel design paradigm for high-performance n-type i-TE cell.
Yuchen Li,Qikai Li,Xinbo Zhang,Biao Deng,Chenggong Han,Weishu Liu
Ionic thermoelectric (i-TE) cells, using ions as energy carriers, have the advantage of achieving a high voltage of 1−5 V at approximately ambient temperature, showing a promise as a technology for powering Internet-of-Things (IoT) sensors. However, the low output power of i-TE cells restricts their applications. Here, a 3D hierarchical structure electrode is designed to enlarge the electroactive surface area, significantly increasing the thermogalvanic reaction sites and decreasing the interface charge transfer resistance. The quasi-solid-state gelatin-KCl-FeCN 4–/3– i-TE cells achieve a record instantaneous output power density (8.9 mW m –2 K –2 ) and an ultrahigh 2 h output energy density ( E 2h ) (80 J m –2 ) under an optimal temperature range. An average E 2h value of 59.4 J m –2 is obtained over the course of a week of operation. A wearable device consisting of 24 i-TE cells can generate a high voltage of 2.8 V and an instantaneous output power of 68 µW by harvesting body heat. A simple and easy-to-operate electrode optimization strategy is provided here to increase the long-term output power performance of i-TE cells. This work represents a promising approach to develop reliable and green power sources for IoT sensors near room temperature.
Harvesting electricity from ubiquitous moisture offers the promise of clean power for self-sustained systems. Despite extensive efforts, achieving high-power electricity generation remains challenging. Existing studies mimicking electric eels’ electrogenesis to enhance their electrical performance focused on the two-membrane structure that linearly adds up the voltage, but their current output was either transient or limited to microamperes, because of the large resistance for ion diffusing across material interfaces. Here, we report an electrocyte-inspired moisture-driven electricity generator (EMEG) made from an interphase-mediated Janus film. The continuous interphase significantly alleviates the ion migration resistance, boosting the current output to 150 µA and sustaining the voltage of 0.8 V continuously for more than 1000 h. We also show that integrated EMEGs were easily assembled to self-powered smart watch for emergency rescue. Furthermore, the integrated EMEGs achieved self-sustained and moisture-powered water splitting with a steady hydrogen production. Our results provide a rational for bio-inspired designs toward green and sustained power generation.
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