Boosting output charge density is top priority for achieving high-performance triboelectric nanogenerators (TENGs). The charge-excitation strategy is demonstrated to be a superior approach to acquire high output charge density. Meanwhile, the molecular charge behaviors in the dielectric under a strong electric field from high charge density bring new physics that are worth exploring. Here, a rapid self-polarization effect of a polar dielectric material by the superhigh electric field in a charge-excitation TENG is reported, by which the permittivity of the polar dielectric material realizes self-increase to a saturation, and thus enhances the output charge density. Consequently, an ultrahigh charge density of 3.53 mC m −2 is obtained with 7 µm homemade lead zirconate titanate−poly(vinylidene fluoride) composite film in the atmosphere with 5% relative humidity, which is the highest charge density for TENGs with high durability currently. This work provides new guidance for dielectric material optimization under charge excitation to boost the output performance of TENGs toward practical applications.

The triboelectric nanogenerator (TENG) is an emerging technology for ambient mechanical energy harvesting, which provides a possibility to realize wild environment monitoring by self‐powered sensing systems. However, TENGs are limited in some practical applications as a result of their low output performance (low charge density) and mechanical durability (material abrasion). Herein, an ultrarobust and high‐performance rotational TENG enabled by automatic mode switching (contact mode at low speed and noncontact at high speed) and charge excitation is proposed. It displays excellent stability, maintaining 94% electrical output after 72 000 cycles, much higher than that of the normal contact‐mode TENG (30%). Due to its high electrical stability and large electrical output, this TENG powers 944 green light‐emitting diodes to brightness in series. Furthermore, by harvesting water‐flow energy, various commercial capacitors can be charged quickly, and a self‐powered fire alarm and self‐powered temperature and humidity detection are realized. This work provides an ideal scheme for enhancing the mechanical durability, broadening the range of working frequency, and improving the electrical output of TENGs. In addition, the high‐performance hydrodynamic TENG demonstrated in this work will have great applications for Internet of Things in remote areas.

According to the output mode, TENGs can be classified into four categories: i) Mechanical rectification DC TENG (coupling CE and electrostatic induction) [8,9] ; ii) constant DC TENG (Coupling CE and air breakdown) [10,11] ; iii) ordinary AC TENG (coupling CE and electrostatic induction) [12,13] ; iv) inverting AC TENG (Coupling CE with air breakdown). [14] Besides, TENGs can convert ambient mechanical energy from rain, [15,16] wind, [17,18] water flow, [19,20] and body motion [21,22] , etc. into electrical energy at relatively low frequency, so it has superiority to electromagnetic generators in the specific low-frequency mechanical energy harvesting field. [23][24][25] With structure flexibility, TENG can be integrated with other research fields in practical applications, for example, electrocatalysis, [26] biosensing, [27] autoclaving, [28] high-voltage application, [29][30][31][32] artificial intelligence, [3,14] environmental monitoring, [33] which greatly exhibits TENG properties in adjustability, compatibility and high efficiency. [34][35][36][37] The application capability of TENGs is determined by the electric energy output density per cycle, which largely depends on the surface charge density originating from the contact electrification effect. For this reason, many strategies are carried out to boost TENG output charge density, such as vacuum environment, [38] temperature [37] difference, [13] surface modification, [39] and hydrophobic treatment, [40] , etc. Recently, charge excitation methods have achieved a 3.53 mC m −2 output charge density by self-polarization of polar high-k material in charge excitation process. [41] Similarly, the optimal output charge of Miura folding-based TENG has been elevated 4.61 times with the charge excitation strategy. [42] Space-accumulation effect is an effective method for the sliding TENG, which can make 2.3 times improvement compared with the normal sliding TENG in ambient conditions. [43] Nevertheless, the output of TENG based on the coupling of CE and electrostatic induction is still limited by air-breakdown. [35] Solving the problem of air breakdown would be one of the effective ways for TENG to achieve the higher output. After increasing electrodes to 50 units, Wang, et al. achieve an output charge density of 8.80 mC m -2 and an average power density of 0.2 W m -2 for the DC-TENG Triboelectric nanogenerators (TENGs) are regarded as a promising technology to convert ambient low-frequency mechanical energy into electricity for distributed power supply. Although TENGs based on triboelectrification (TE) of metal-dielectric and air breakdown have the advantage of direct current (DC) output, the unidirectional and single-channel output mode limits their energy utilization efficiency. Here, a bidirectional and double-channel (BDC-TENG) based on TE of dielectric-dielectric and local corona discharge is proposed. Different from traditional DC-TENGs, the TE process of the BDC-TENG occurs in two dielectrics, and the double-channel output is generated from simultaneous dis...

An inverting TENG realizes the AC mode based on triboelectrification and air-breakdown by setting alternating polarity distribution areas, and exhibits unique feature in that both the width ratio and amplitude ratio of AC signals can be tuned.

We proposed a universal design strategy of a matched inductor for TENG with parameters studied from both theory and experiments systematically. The results show giant performance improvement for TENG system.