Fig. 1: Concept for the spontaneously established reverse electric field to restrict the side-discharge problem and its characteristics.

a 1. With the SCD increases from 0 to σ₁, the electric field strength increases from 0 to E_B1. E_B1 is the threshold of electrostatic breakdown at air. σ₁ is the corresponding maximum SCD. 2. For the special atmosphere condition (such as SF₆ and N₂, etc.), the electric field strength can increase from E_B1 to E_B2, and the corresponding maximum SCD is σ₂. 3. The SEREF on insulator can increase with the SCD, which can maintain the electric field strength of electrode edge around E_B1 and avoid the recurrence of electrostatic breakdown. b Schematic diagram of electrode <i> without the insulator (w/o insulator) and <ii> with the insulator (w/ insulator). c The SCD of insulator’s side surface rapidly accumulates and reaches to 1 mC m⁻² when the moving distance is 10 cm. This box plot presents the distribution of five sets of data, with the whiskers indicating the most extreme values while excluding outliers. d, e The simulated electric field around the edge of electrode (SCD of the triboelectric layer is −50 μC m⁻².). <i> w/o insulator; the electric field at electrode edge is over E_B1 (E_B1 = 3 MV m⁻¹). <ii> w/ insulator; the electric field at electrode edge is also over E_B1. <iii> w/ insulator and SCD of the insulator is only −50 μC m⁻²; the electric field around the edge of electrode is below E_B1. The data in e is taken from the electric field intensity at 5 μm above the triboelectric layer in d. f The Q-V curve represents the output charge (Q(V)) when the output voltage is V. 1. The black line is the Q-V curve of TENG in air. 2. The purple line is the Q-V curve of TENG in special atmosphere, which increases the performance of TENG from two aspects: Q_SC and V_OC. 3. The orange line is the Q-V curve of TENG with insulator. The SEREF on the insulator can improve the performance of TENG from three aspects: Q_SC, V_OC, and η(V). Source data are provided as a Source data file.