Comprehensive output performance optimization of ternary constant DC triboelectric nanogenerators via dual-phase symmetric step-down conversion

Abstract

Achieving high and stable output performance remains a critical challenge for the practical application of constant direct current triboelectric nanogenerators (C-DC-TENGs). While ternary DC-TENGs (T-DC-TENGs) outperform other C-DC-TENGs, they face significant limitations including output charge thresholds, high internal impedance, and uncontrollable high voltages. To address these, we present a novel power management circuit (PMC) based on a dual-phase symmetric step-down converter (DSSC) with collaborative switches, termed a DSSC-TENG. For rotating T-DC-TENGs at 120 rpm, this approach yields remarkable improvements: a 6.6-fold increase in output charge density (4.8 mC m⁻² per cycle), a 1.7-fold enhancement in average power density (4.94 W m⁻² Hz⁻¹), and a reduction in output impedance to 10 MΩ, setting a benchmark among ternary-structure-based TENGs. The PMC reduces output voltage by 54.7% while improving output stability, as confirmed by Fourier analysis showing that the AC/DC component ratio decreased from 0.6% to 0.05%. The demonstrated DSSC-TENG directly powers electronic devices including a calculator, a watch, 2400 LEDs, and parallel 10 W lamps without pre-charging capacitors, and achieves a 67.2% increase in a methyl orange degradation rate compared to the case without a DSSC. This work introduces the first PMC specifically designed for C-DC-TENGs, substantially advancing their potential for real-world implementation in self-powered systems.