Realizing excellent energy storage performances in tetragonal tungsten bronze ceramics via a B-site engineering strategy

The development of dielectric energy storage capacitors has attracted much research interest in recent years. As an important category of dielectric materials, the energy storage potential of the tetragonal tungsten bronze structure ceramic has been underestimated for a long time due to the lower dielectric constant and low breakdown strength. In this work, a series of Sr 0.6 Ba 0.4 Nb 2 O 6 -based tungsten bronze ceramics with excellent energy storage performances was prepared based on a B-site engineering strategy. Enhanced relaxor behavior and improved breakdown strength induced by Ta substitution give rise to a high recoverable energy density of 3.95 J/cm 3 along with superior efficiency of 93.4%. Especially, the capacitor based on the Ta-modified Sr 0.6 Ba 0.4 Nb 2 O 6 ceramics exhibits a large current density of 845 A /cm 2 and a huge power density of 84.5 MW/cm 3 accompanied by a fast discharge time of 75 ns. All these results demonstrate the immense potential of the Ta-modified Sr 0.6 Ba 0.4 Nb 2 O 6 -based tetragonal tungsten bronze ceramics in the high-power energy storage capacitor field. • A novel tetragonal tungsten bronze-based lead-free relaxor ferroelectric system was designed via a B-site engineering strategy for dielectric energy storage applications. • A high W rec of 3.95 J/cm 3 with an excellent η of 93.4% was achieved under an electric field of 360 kV/cm. • Great pulsed charging-discharging capability with a fast-discharging rate (τ 0.9 < 75 ns) and a high P D (~ 84.5 MW/cm 3 ) was obtained.