Rational Design of Molybdenum Nitride Quantum Dot Engineered by Carbon Framework for Boosted Lithium‐Ion Thermal Charging Cells

Abstract Lithium‐ion thermal charging cell, driven by ion migration and redox reaction, exhibits great potential for harvesting and storing electricity from thermal energy. Combining thermodiffusion and thermogalvanic effects could boost their thermopower, but with limited kinetics for heat‐to‐electric conversion due to the incompatibility between thermodynamical and electrochemical processes. Here, a facile strategy is demonstrated to fully activate the thermoelectrical behavior through simulation‐guided electrode engineering, which is realized by incorporating battery‐type molybdenum nitride quantum dot into carbon matrix. Benefitting to the well‐developed 3D skeleton, abundant electroactive sites, and high conductivity, as‐constructed device can achieve a giant thermopower of 53.6 mV K −1 , normalized power density of 6.83 mW m −2 K −2 , and good durability, which can meet the power demands of wearable sensors and small electronic devices. As a proof‐of‐concept, a flexible quasi‐solid‐state device integrating four units is developed for self‐powered health‐monitoring system by harvesting body heat in daily life. This work provides insights into the effective design of electrodes for high‐performance ionic thermoelectrical systems and the development of multifunctional self‐charging systems with sustainable operation.