In　this　study,　we　developed　a　novel　(Sr1/3Nb2/3)4+　complex　ion　dopant　to　tailor　the　electrostrain　and　energy-storage　properties　of　(Bi0.5Na0.5)TiO3　(BNT)-based　ferroelectric　ceramics.　The　chemical　formula　of　the　investigated　system　is　[0.93(Bi0.51Na0.5)0.07Ba)]Ti1-x(Sr1/3Nb2/3)xO3,　where　x　=　0.0025,　0.005,　0.0075,　and　0.01.　The　crystal　structures,　microstructures,　and　dielectric/ferroelectric/electrostrictive/energy-storage　properties　of　the　ceramics　synthesized　by　a　solid-state　reaction　method　were　thoroughly　investigated.　For　the　x　=　0.01　composition,　an　ultrahigh　electrostrain　of　0.59　%　was　achieved　under　an　electric　field　of　130　kV/cm.　The　strain　response　of　this　composition　increased　progressively　with　increasing　temperature　from　30　to　150　°C　while　maintaining　good　symmetry.　Interestingly,　the　electrostrictive　coefficient　Q33　was　shown　to　be　strongly　temperature-sensitive.　The　Q33　value　was　0.018　m4/C2　at　30　°C　and　increased　dramatically　as　the　temperature　increased,　reaching　a　maximum　value　of　0.0378　m4/C2　at　150　°C.　Furthermore,　under　a　relatively　modest　electric　field　of　100　kV/cm,　a　high　recoverable　energy-storage　density　of　1.36　J/cm3　was　obtained　for　the　x　=　0.0075　composition.　These　findings　demonstrate　that　the　addition　of　(Sr1/3Nb2/3)4+　complex　ions　can　effectively　tailor　the　electrostrain　and　energy　storage　properties　of　BNT-based　ceramics.　Moreover,　the　doping　ion　design　principle　can　be　applied　to　other　BNT-based　ferroelectrics,　with　potential　for　dramatic　improvements　in　electrostrain　and　energy　storage　properties.　©　2022　Elsevier　Ltd　and　Techna　Group　S.r.l.