Conductive carbon fillers were commonly used to mix with polydimethylsiloxane to improve the output performance of polydimethylsiloxane-based triboelectric nanogenerators. In this work, we focused on the mechanism underlying the unpredictable output performance influenced by adding conductive fillers. We selected multiwall carbon nanotubes as conductive fillers and investigated their electronegative performance in triboelectric nanogenerators. An optimized performance was achieved when the weight concentration of carbon nanotubes was about 0.4%. The open-circuit voltage can reach up to 720 V, the short-circuit current was about 18.28 μA, and a power density of 4.65 mW (11.62 W/m2) was obtained at the load resistance of 55.15 MΩ and a stimulus frequency of 2.0 Hz. The attractive performance was attributed to the appropriate balance of the capacitive effect and the leakage effect of carbon nanotubes to triboelectric charges. A model based on alternative current impedance analysis has been proposed, which may be helpful for future triboelectric nanogenerator design and investigation.

Hybrid supercapacitors (HSCs) are attractive in the field of energy storage systems, which can offer higher energy density than capacitors and higher power density than batteries. However, the battery-type electrodes in HSCs often suffer from low rate capability and cycling performance due to their poor electrical conductivity. Here, we demonstrated a positive battery-type electrode by using self-assembled flower-like microspheres (MSs). The MSs were composed of porous ZnO/CoO nanosheets. Compared with pristine CoO and ZnO electrodes, the ZnO/CoO composite electrode shows enhanced electrochemical performance with high specific capacity as well as high rate capability. A high capacity of 85 mAh g −1 (~681 F g −1 ) is achieved at a high current density of 20 A g −1 . Such a favorable performance can be attributed to the ZnO introduction, which improves the electrical conductivity of the electrode, and the porous structure with interconnected pores, which provides fast ion/electron transport. When assembled with activated carbon, the HSCs can deliver high energy density (23.8 Wh kg −1 ) and power density (1.3 kW kg −1 ).

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