An impact-based piezoelectric and triboelectric energy harvester with elastic double-side stoppers for wideband operation and efficient energy capture is proposed. The coupled nonlinear governing equations of the energy harvesting system are derived based on Hertz's contact model. The dynamic behavior of the energy harvester is enriched from linear to nonlinear regime by introducing stoppers to broaden the energy harvesting frequency range. The dynamic mechanism and energy harvesting performance of the harvester are explored through frequency sweeps, which identify comprehensive dynamic states and evaluate the energy harvesting performance. The time history diagram, phase diagram, Poincaré mapping and bifurcation diagram are used to discuss the single-period, double-period, multi-period and chaotic period vibrations of the energy harvester. Detailed parametric studies investigate the effects of the initial gap, mass ratio, stopper stiffness and excitation amplitude on the voltage and power output. Four models with different stoppers are compared to identify the best energy harvesting performance. Results show that compared with the cantilever without stopper, the proposed model with elastic double-side stoppers significantly broadens the resonance frequency region by 172.5%, and increases the output cumulative voltage by 0.89 V. A maximum voltage of 1.2 V with a 0.6-V-bandwidth of 6.9 Hz is achieved when the energy harvester is actuated at 0.8 g acceleration. The RMS voltage of triboelectric nanogenerator is highest at 25 Hz, reaching 1.99 V, and the peak-to-peak output voltage reaches 15.59 V.