[en] In recent years, piezoelectric energy harvesting has attracted growing attention due to its great potential in the application of Internet of Things. However, traditional linear harvesters have limited operation bandwidth, resulting into the sharp decline of the output power when the excitation frequency shifts from the resonance thus a low efficiency for stochastic excitations in the ambient environment. In order to overcome these issues, this paper analyzes the performance of an impact-bistable piezoelectric energy harvester. Influence of critical parameters including the clearance between two collision parts of the harvester, and external excitation frequencies and amplitudes upon the harvester performance are theoretically studied using the dimensionless model. Phase portraits, time histories, bifurcation diagrams and 0-1 test are employed to analyze the characteristics of the harvesting system. The results show that by choosing appropriate physical parameters, the proposed energy harvester could exhibit high-energy interwell motion with an 80% frequency bandwidth under both the harmonic excitation and broadband random excitation.