Lead-free Bi0.5(Na,K)0.5TiO3 (BNKT) piezoelectric materials are a good substitution for lead-based piezoelectric materials containing 60 wt. percent of Pb which is poisonous for human and environment. In this study, lead-free Bi0.5(Na0.8-xLixK0.2) Ti0.95Sn0.05O3 piezoelectric ceramics (BNKTS-xLi) with x ranging from 0 to 0.05 were fabricated using a conventional solid state reaction method. The effects of Li concentration (x) on the structure and electrical properties of the ceramics were investigated. The X-ray diffraction patterns revealed the phase transition from pseudocubic to tetragonal with Li concentration being added, leading to a further enhancement of saturation polarization. In addition, a small shift of the hysteresis loops along the electric field axis which known as imprint phenomenon was witnessed on doped specimens. The origin of this displacement is, according to the prediction, derived from an interaction between different ferroelectric states and/or ferroelectric/paraelectric states at grain boundary junction.