A ferromagnetic tribo-cilia enhanced triboelectric-electromagnetic hybrid generator with superior performance in contact-noncontact sliding motion

Abstract

One of the most challenging problems of sliding mode triboelectric nanogenerators (TEGs) is the mechanical wear occurring at the surface of triboelectric layers. Compromising by enlarging the frictional distance to reduce this wear conversely deteriorates the output performance of TEGs. This work presents a strategic path for addressing this problem by incorporating the ferromagnetic tribo-medium into a flexible cilium structure. Based on a rotational freestanding sliding mode, we have developed a highly integrated triboelectric-electromagnetic hybrid generator (TEHG) that combines a ferromagnetic cilia based TEG (FC-TEG) and a printed multi-layer winding based electromagnetic generator (PMW-EMG). Interestingly, contrary to the conventional notion that the outstanding performance of TEGs is usually performed under compressed friction, the FC-TEG achieved its highest output at the critical contact/noncontact state (0 mm clearance). Compared to the ordinary flat film without doping ferromagnetic material, the FC-TEG at 500 rpm exhibited increments of 71.9 %, 100 %, and 87.4 % in open-circuit voltage, short-circuit current, and transferred charge, respectively, while accompanied with a resistance torque of only 20.8 % of the former. Further experimental findings have demonstrated that TEG and EMG exhibit a mutually complementary relationship in coordinating motion frequency and electrical output across varying rotational speed conditions. Under laboratory testing conditions, the output power and power density of the FC-TEG reached 442.5 μW and 41.2 mW/m2, respectively, while those of the PMW-EMG achieved 3.0 W and 17.5 mW/cm3. With this TEHG, we successfully drove a variety of sensors for monitoring information in agricultural environment and machinery. This study provides new insights and solutions for using ferromagnetic materials to address mechanical wear problems with enhanced performance in sliding TEGs.