The enhancement of energy storage performance of BaTiO₃–Bi(Mg_0·5Ti_0.5)O₃ Pb-free ceramics via an optimized viscous polymer process route

In this study, the viscous polymer processing (VPP) technique is implemented to optimize the characteristics of bulk (1-x)BaTiO₃-xBi(Mg_0·5Ti_0.5)O₃ (BT-xBMT) lead-free relaxor ferroelectric ceramics, with a focus on enhancing the recoverable energy storage density (W_rec), improving breakdown strength resistance (E_b), and increasing storage efficiency (η). The influence of polyvinyl alcohol (PVA) inclusion in the VPP process on the resulting dielectric ceramics is thoroughly investigated, covering rheological, dielectric, and ferroelectric properties. The results reveal that a gradual increase in PVA quantity during the VPP process effectively improves the density of ceramic blanks. However, an excess of PVA leads to void formation in the ceramic blanks post-debinding, hindering the achievement of a dense structure in the final ceramics and causing performance degradation. The resulting BT-0.405BMT-40 wt% PVA ceramic showed excellent storage performance, with W_rec, η, and E_b of 6.55 J/cm³ 81.45 %, and 480 kV/cm, respectively. In comparison to bulk BT-0.405BMT ceramics, there is a notable 2.47-fold increase in W_rec and a 1.92-fold increase in E_b, accompanied by a substantial improvement in η. Moreover, the BT-BMT-40 wt% PVA ceramic exhibits favorable temperature stability (30–150 °C), frequency stability (1–50 Hz), and commendable charge/discharge performance.