Effective energy manipulation inside vibrating structures is essential for numerous engineering application such as vibration mitigation and energy harvesting. In this regard, wave retarding structures, exemplified by acoustic black hole (ABH) structures, offer a promising solution. ABH features remarkable slow wave effects inside a structure whose thickness is tailored to a reducing power-law profile. As such, flexural vibration energy can be trapped, before further dissipated or harvested. This property has been well demonstrated in linear systems through either stand-alone or periodic ABH designs. ABH effects, however, are limited to high frequency regime, typically above the so-called cut-on frequency. Therefore, for low frequency applications, exorbitantly large  structural size is needed. To tackle this problem, this talk discusses the option of introducing intentional electromechanical coupling into an ABH beam through surface-coated PZT patches with nonlinear electrical shunts. The targeted outcome is to create effective electro-mechanical coupling and the cross-frequency energy transfer, to boost up the low frequency ABH benefits. Numerical modelling, salient nonlinear phenomena, and the potential of the technique for both vibration mitigation and energy harvesting is discussed using a beam example.