The　great　potential　of　K1/2Bi1/2TiO3　(KBT)　for　dielectric　energy　storage　ceramics　is　impeded　by　its　low　dielectric　breakdown　strength,　thereby　limiting　its　utilization　of　high　polarization.　This　study　develops　a　novel　composition,　0.83KBT-0.095Na(1/2)Bi(1/2)ZrO(3)-0.075　Bi0.85Nd0.15FeO3　(KNBNTF)　ceramics,　demonstrating　outstanding　energy　storage　performance　under　high　electric　fields　up　to　425　kV　cm(-1):　a　remarkable　recoverable　energy　density　of　7.03　J　cm(-3),　and　a　high　efficiency　of　86.0%.　The　analysis　reveals　that　the　superior　dielectric　breakdown　resistance　arises　from　effective　mitigation　of　space　charge　accumulation　at　the　interface,　influenced　by　differential　dielectric　and　conductance　behaviors　between　grains　and　grain　boundaries.　Electric　impedance　spectra　confirm　the　significant　suppression　of　space　charge　accumulation　in　KNBNTF,　attributable　to　the　co-introduction　of　Na1/2Bi1/2ZrO3　and　Bi0.85Nd0.15FeO3.　Phase-field　simulations　reveal　the　emergence　of　a　trans-granular　breakdown　mode　in　KNBNTF　resulting　from　the　mitigated　interfacial　polarization,　impeding　breakdown　propagation　and　increasing　dielectric　breakdown　resistance.　Furthermore,　KNBNTF　exhibits　a　complex　local　polarization　and　enhances　the　relaxor　features,　facilitating　high　field-induced　polarization　and　establishing　favorable　conditions　for　exceptional　energy　storage　performance.　Therefore,　the　proposed　strategy　is　a　promising　design　pathway　for　tailoring　dielectric　ceramics　in　energy　storage　applications.　[GRAPHICS]　.