Ultrahigh dielectric breakdown strength and excellent energy storage performance in lead-free barium titanate-based relaxor ferroelectric ceramics via a combined strategy of composition modification, viscous polymer processing, and liquid-phase sintering

BaTiO3 (BT)-based lead-free ceramics are regarded as one kind of prospective candidates for next generation pulsed power capacitors due to their environmentally friendly and relatively high energy storage properties. Nevertheless, BT-based ceramics are still suffering from their small recoverable energy storage density (Wrec < 3 J cm−3) and relatively low electric breakdown strength (BDS < 350 kV cm−1). Herein, we proposed a combined strategy via composition modification, viscous polymer processing, and liquid-phase sintering into BT-based ceramics to improve their BDS and Wrec. Both an ultrahigh BDS (>410 kV cm−1) and a large Wrec (3.54 J cm−3) are achieved in Sr0.7Bi0.2TiO3 and Li2CO3 modified BT ceramic simultaneously. High Wrec (>2.5 J cm−3 at 300 kV cm−1) with small variation is maintained over a wide temperature range (30–150 °C) and frequency range (0.1–100 Hz), demonstrating very excellent temperature and frequency stability. The recorded ultrahigh BDS with high Wrec achieved in this work indicates that our combined strategy is effective to elevate the electric energy storage performances of BT-based dielectric ceramics and could be further generalized to other ceramic materials for the applications of advanced pulsed power capacitors.