Mechanical energy harvesting in triboelectric nanogenerators (TENGs) addresses the limitations of conventional power supplies, with charge density as a critical parameter for application in distributed energy harvesting. However, conventional triboelectric materials limit further substantial improvement of charge density in TENGs, due to the inevitable air breakdown under high charge density conditions. Here, we demonstrate that a new triboelectric polymer, poly(vinylidene fluoride–trifluoroethylene–chlorofluoroethylene) (P(VDF–TrFE–CFE)), with high dielectric permittivity and thin thickness can effectively suppress the air breakdown in TENGs. Employing the prepared P(VDF–TrFE–CFE) film with low leakage current and low surface roughness to build TENGs, we achieve a record-breaking charge density of ∼8.6 mC m−2 and a milestone energy density of 0.808 J m−2 per cycle with the help of charge excitation technology. This breakthrough significantly enhances the TENGs' performance, paving a new way for high efficiency conversion from mechanical energy to electricity. It has great potential for serving as an energy supply source in the ever-growing internet-of-things devices.