Preparation, characterization, and improvement in the energy storage properties of Bi(Li0.5Ta0.5)O3 modified Na0.5K0.5NbO3 ceramic system

•We prepared (1-x)Na0.5K0.5NbO3-xBi (Li0.5Ta0.5) O3 (x = 0, 0.05, 0.10, 0.15, 0.20) ceramics via solid state sintering method.•The dense microstructure is observed for all compositions.•A high energy-storage density of 1.99 J/cm3 at a breakdown electric field of 151.9 kV/cm is achieved for the composition of x = 0.15.•Good temperature stability satisfying the condition of Δεr/εr200 °C ≤±15% in a working temperature range of 30 °C to 371 is observed for x = 0.15.