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Polymer nanocomposites have higher energy storage density, much lower conductivity, and energy loss than the polymer matrices. The excellent performance may be originated from the deep-level localized states introduced by the interfacial zones between nanofillers and polymer matrices. However, the essential relation between the deep-level localized states and the composition, architecture, and configuration of polymer chains is still not clear. We investigate the temperature dependences of electrical conductivities of three types of energy storage polymer nanocomposites and find that they all obey the Meyer-Neldel (MN) compensation rule and the prefactor has an exponential relationship with the MN energy. It is found that the kinetic energy of electrons in the extended states of nanocomposites is the MN energy, which is related to the excitation of electrons by optical phonons. We propose to redefine the energy of localized states by the energy of optical phonons and the entropy of molecular conformations. It is found that the shape parameter of localized state distribution is related to the optical phonons and controlled by the composition, structure, and configuration of polymer chains, while the density of localized states is determined by the conformation and aggregate structure. We propose an optical phonon and entropy activated charge transport model, and the obtained conductivity equation is consistent with the experimental results. The entropy of molecular conformations can be used as a key factor to tailor the conductivity and energy loss of polymer nanocomposites. It provides a new perspective to study how to improve the energy storage performance of polymer nanocomposites. [ABSTRACT FROM AUTHOR]

The utilization of renewable energy requires power capacitors to maintain low electrical conductivity and high energy storage performance, and it is urgent to develop excellent electrical insulating polymer nanocomposites (PNCs). The improved electrical insulating performance of PNCs originates from the interfacial regions with low conductivity. However, the scale and mesoscopic electrical conduction properties of interfacial regions lack quantitative research. We convert the above questions into an inversion problem of solving the generalized Poisson equation. The Monte Carlo method is used to construct the structure model, and we simulate the distributions of electric fields and the effective electrical conductivity of PNCs via a high-throughput method. Comparing the simulation results and experiments, we obtain that for the polyimide/ γ -Al 2 O 3 , polyimide/HfO 2 , and crosslinked divinyltetramethyldisiloxane-bis(benzocyclobutene)/ γ -Al 2 O 3 PNCs, the maximum thicknesses of interfacial regions can reach 8.2, 6.0, and 2.7 times of the radii of nanofillers respectively, and their conductivities can be up to 934.6, 613.5, and 60.0 times lower than those of polymer matrices, respectively. It is concluded that the ordered and tightly aggregated structure in PNCs induced by the bound effect of nanofillers on molecular chains is the formation mechanism of interfacial regions with low conductivity. [Display omitted] [ABSTRACT FROM AUTHOR]