Triboelectric nanogenerator (TENG) offers a novel approach for converting high-entropy mechanical energy into electrical energy, yet achieving high charge density remains critical. Optimizations using dielectrics with high specific capacitance have mitigated air breakdown, but charge loss within dielectrics persists as a limiting factor. Here, based on poly(vinylidene fluoride–trifluoroethylene–chlorofluoroethylene) (P(VDF-TrFE-CFE)) with high specific capacitance, (P(VDF-TrFE-CFE)) composites’ trap density and energy are engineered using high-polarity interfaces from barium titanate (BTO) nanoparticles and dense chain segment stacking induced by electrostatic interaction with polyetherimide (PEI) to enhance charge retention capability. With modified high interfacial traps, an ultrahigh charge density of 9.23 mC m−2 is achieved in external charge excitation (ECE) TENG using 0.2 vol% PEI/P(VDF-TrFE-CFE) film, marking the highest charge density reported for single-unit TENGs. This work provides novel material strategies for high-performance TENGs, paving the way for their large-scale practical applications.