Enhanced energy storage and discharge-charge performance by changing glass phase content in potassium sodium niobate glass-ceramics

(1-x) (K2O–Na2O–2Nb2O5)-x (2BaO–Nb2O5–2SiO2) glass-ceramics with x = 0.10, 0.15, 0.20, 0.25 have been successfully prepared by traditional melting method. XRD and microstructure analysis demonstrate that all glass-ceramics are crystallized into uniform Na0.9K0.1NbO3 and K2(NbO)2(Si4O12) ferroelectric crystalline phase. Increasing x promotes the formation of Ba2NaNb5O15 phase with a tungsten bronze structure. Raman and complex impedance data confirmed that Ba2+ is introduced to repair the disruption of the glass network and make carrier migration difficult when x = 0.15. Thus, the x = 0.15 glass-ceramic sample possesses a maximum calculated energy storage density of 2.32 J/cm3 under 820 kV/cm because of a high degree of polymerization (DOP) glass network structure. Moreover, the pulsed discharge-charge tests are carried out to evaluate actual energy storage performance.