Triboelectric nanogenerators with simultaneous outputs in both single-electrode mode and freestanding-triboelectric-layer mode

Triboelectric nanogenerators (TENGs) provide an effective approach for converting mechanical energy into electricity based on the coupling effect of contact electrification and electrostatic induction. The working principle of TENGs is usually based on one of the four basic modes, namely vertical contact-separation mode, contact-sliding mode, single-electrode (SE) mode, and freestanding-triboelectric-layer (FTL) mode. Here we report a dual-mode rotating TENG (DMR-TENG) with simultaneous outputs from both SE and FTL modes. It is found that the energy output of FTL mode can be promoted by turning on the SE-mode output of the DMR-TENG, which may be due to the change in the amount of charges present in the electrodes. When the DMR-TENG is utilized to concurrently charge two capacitors from the FTL- and SE-mode outputs, respectively, the charging rates of both capacitors increase compared to the case when the DMR-TENG works under either FTL or SE mode. The results indicate that the energy utilization efficiency can be improved for TENGs working under dual modes. Charging a LiFePO4/Li battery and a capacitor from the FTL- and SE-mode outputs of the DMR-TENG has also been demonstrated, evidencing the potential of DMR-TENGs for simultaneous charging multiple energy storage devices of different types.