Design and preparation of lead-free (Bi0.4Na0.2K0.2Ba0.2)TiO3-Sr(Mg1/3Nb2/3)O3 high-entropy relaxor ceramics for dielectric energy storage

• High-entropy BNKBT-SMN ceramics for dielectric energy storage were design and prepared. • A high W rec of 3.37 J/cm 3 and high η of 80% at low electric fields were achieved. • The excellent stability in energy storage has been achieved in 0.88BNKBT-0.12SMN. High-entropy perovskite oxides in (Bi 0.4 Na 0.2 K 0.2 Ba 0.2 )TiO 3 - Sr(Mg 1/3 Nb 2/3 )O 3 system were designed and prepared for dielectric energy storage. The effects of composition and sintering temperature on energy storage performance were investigated. The temperature-and frequency-dependent energy storage performance was characterized. A ceramic with a recoverable energy storage density of 3.37 J/cm 3 and an energy storage efficiency of 80% was obtained at 310 kV/cm. The energy density is one of the best ever reported at low electric fields. The current result provides an idea for developing high-entropy dielectric energy storage ceramics.