The present work introduces the design and fabrication of a strongly coupled piezoelectric vibration energy harvester dedicated to resonant frequency tuning by electrical methods. The electromechanical coupling coefficient of the harvester is maximized thanks to an analytical model and 3D FEM simulations in order to extend the frequency tuning bandwidth. Moreover, losses of candidate substrates are analyzed in order to maximize the mechanical quality factor of the harvester. A PZN-5.5PT and aluminum based cantilever is proposed and experimentally validated with resistive output loads. Among state-of-the-art solutions, the proposed prototype exhibits one of the best coupling coefficient (k²=41%) and normalized power density (115 kg.s.m-3).