Optimized Breakdown Strength and Crystal Structure for Boosting the Energy Storage Performance of Niobate-Based Glass Ceramics via a B-Site Substitution Strategy

Based on the B-site modification strategy, excellent energy storage properties were achieved in this work by substituting Nb with Ta of the same valence in niobate-based glass ceramics. Ta substitution was found to lead to the transformation of crystal structures, and the space point group evolved from the non-centrosymmetric P4bm to the centrosymmetric P4/mbm, resulting in a transition from relaxor ferroelectric to paraelectric glass ceramics. Furthermore, the addition of Ta led to a significant decrease in grain size and interfacial activation energy, as well as an increase in the optical band gap, resulting in a dramatic increase in BDS from 800 kV/cm to 1300 kV/cm. The KBSN-4.0mol%Ta2O5 glass ceramic exhibited optimal energy storage properties, including a discharge energy density of ~5.62 J/cm3 and a superfast discharge rate of ~9.7 ns, resulting in an ultrahigh discharge power density of about ~1296.9 MW/cm3 at 1300 kV/cm. Furthermore, this KBSN-Ta glass ceramic also displayed good thermal stability over a temperature range of 20–120 °C, with the Wd decreasing by 9.0% at 600 kV/cm. B-site modification engineering in glass ceramics has proved to be an important way to effectively optimize energy storage performance.