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)　and　relatively　low　electric　breakdown　strength　(BDS　−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.　©　2020