Highly durable direct-current power generation in polarity-controlled and soft-triggered rotational triboelectric nanogenerator

While the sliding-mode triboelectric nanogenerators (TENGs) have demonstrated one of the most efficient rotational energy harvesting devices, alternating-current (AC) generation and wear-off have been a long-standing bottleneck for practical applications. Here, we developed a polarity-controlled and soft-triggered (P-S) TENG for highly efficient and durable direct-current (DC) power generation. The P-S TENG consists of polytetrafluoroethylene (PTFE), nylon, and Cu films for triboelectrification, as well as another Cu film for charge-delivering electrode. The PTFE and nylon films were alternately attached to the outer acrylic cylinder, and four-segmented Cu films were attached to the inner acrylic cylinder. The P-S TENG generated a power-density of 0.32 mW/cm2, which was 4-fold and 32-fold larger than that of paired alternate and single polarity TENG, respectively. Remarkably, the DC output of P-S TENG remained nearly constant, despite 372,000 rotations, which sharply contrasted with the substantial power decrease (47%) in hard-triggered TENG. This work provides an important advancement in a rotational TENG with high DC power generation and long-term durability.