<p>Electro ceramic materials with formula Bi_0.5(Na_1-xLi_x)_0.5TiO₃ (0 ≤ x ≤ 0.2) (Li-NBT) were synthesized via solid state route. X-ray diffraction, Scanning electron microscopy and Raman spectroscopy analysis confirmed the formation of a single phase material and implied that Li was diffused into NBT lattice. The influence of sintering temperature and Lithium contents in these compositions is interpreted also by impedance spectroscopy. The dielectrical properties’ thermal and frequency evolutions were discussed in terms of classical versus relaxor ferroelectric behavior. Particularly, the evolution of ɛ = f(T) revealed that at sintered temperature lower than 1190&#xa0;°C these ferroelectric not exhibit any relaxor-like behavior. Only when sintering temperature exceeds 1190&#xa0;°C the relaxor behaviour became more pronounced and persisted. More importantly, the presence of Lithium, even at low rates, leads also to a remarkable increase in the Curie temperature and the maximum temperature of ɛ’r. A Lorentzan fitting of Raman spectra is used to discuss the second-order phase transition and to confirm the increase of the Curie temperature by the introduction of Lithium in NBT lattice. Independently of the sintering temperature, Lithium-doped NBT ceramics exhibit relatively high piezoelectric coefficients [d₃₃ = 102 pC/N et d₃₃ = 86 pC/N for Na_0.4Li_0.1Bi_0.5TiO₃ et Na_0.45Li_0.05Bi_0.5TiO₃ ceramics respectively], compared to pure material [d₃₃ = 15.2 pC/N]. This significant improvement, due to the presence of Lithium, makes these NBT-based materials excellent promising candidates for the fabrication of high-performance piezoelectric devices. Having a lead-free relaxor material with a high maximum temperature of ɛ’r is a very interesting result in itself, as the number of these types of materials is very limited. So, the presence of Lithium in the crystal lattice, even at low rates, has highlighted encouraging dielectric, ferroelectric and piezoelectric performances.</p>