Through years of development, the triboelectric nanogenerator (TENG) has been demonstrated as a burgeoning efficient energy harvester. Plenty of efforts have been devoted to further improving the electric output performance through material/surface optimization, ion implantation or the external electric circuit. However, all these methods cannot break through the fundamental limitation brought by the inevitable electrical breakdown effect, and thus the output energy density is restricted. Here, a method for enhancing the threshold output energy density of TENGs is proposed by suppressing the breakdown effects in the high‐pressure gas environment. With that, the output energy density of the contact‐separation mode TENG can be increased by over 25 times in 10 atm than that in the atmosphere, and that of the freestanding sliding TENG can also achieve over 5 times increase in 6 atm. This research demonstrates the excellent suppression effect of the electric breakdown brought by the high‐pressure gas environment, which may provide a practical and effective technological route to promote the output performance of TENGs.

An investigation of the relationship between the microstructure parameters and thermomechanical properties of epoxy resin can provide a scientific basis for the optimization of epoxy systems. In this paper, the thermomechanical properties of diglycidyl ether of bisphenol A (DGEBA)/methyl tetrahydrophthalic anhydride (MTHPA) and DGEBA/nadic anhydride (NA) were calculated and tested by the method of molecular dynamics (MD) simulation combined with experimental verification. The effects of anhydride curing agents on the thermomechanical properties of epoxy resin were investigated. The results of the simulation and experiment showed that the thermomechanical parameters (glass transition temperature (T_g) and Young’s modulus) of the DGEBA/NA system were higher than those of the DGEBA/MTHPA system. The simulation results had a good agreement with the experimental data, which verified the accuracy of the crosslinking model of epoxy resin cured with anhydride curing agents. The microstructure parameters of the anhydride-epoxy system were analyzed by MD simulation, including bond-length distribution, synergy rotational energy barrier, cohesive energy density (CED) and fraction free volume (FFV). The results indicated that the bond-length distribution of the MTHPA and NA was the same except for C–C bonds. Compared with the DGEBA/MTHPA system, the DGEBA/NA system had a higher synergy rotational energy barrier and CED, and lower FFV. It can be seen that the slight change of curing agent structure has a significant effect on the synergy rotational energy barrier, CED and FFV, thus affecting the T_g and modulus of the system.

Investigating the relationship between microstructure and macroscopic properties of epoxy resin (EP) materials for high-voltage insulation at the molecular level can provide theoretical guidance for the synthetic design of EP. Here, using diglycidyl ether (DGEBA) as the resin matrix and methyl tetrahydrophthalic anhydride (MTHPA) as the curing agent, a set of crosslinked EP molecular models at different curing stages were constructed based on the proposed crosslinking method. We studied the influences of crosslinking density on micro-parameters and macro-properties employing molecular dynamics (MD) simulations. The results indicate that crosslinking of DGEBA/MTHPA is a contraction and exothermic process. The structural parameters and macroscopic properties are closely related to the degree of crosslinking. With the increase of crosslinking density, the mean square displacement (MSD) of the system decreases, and the segment motion in the models is weakened gradually, while, the fractional free volume (FFV) first decreases and then increases. In addition, the thermal and mechanical properties of DGEBA/MTHPA have a significant dependence on the crosslinking density. Increasing crosslinking density can improve the glass transition temperature (T_g), reduce the coefficient of thermal expansion (CTE), and enhances the static mechanical properties of DGEBA/MTHPA system. Furthermore, the relationship between microparameters and properties has been fully investigated. Free volume is an important factor that causes thermal expansion of DGEBA/MTHPA. Moreover, there is a negative correlation between MSD and mechanical moduli. By elevating temperature, the decline in mechanical moduli may be due to the exacerbated thermal motion of the molecules and the increasing MSD values.