Temperature-stable dielectric and energy storage properties of La(Ti_0.5Mg_0.5)O₃-doped (Bi_0.5Na_0.5)TiO₃-(Sr_0.7Bi_0.2)TiO₃ lead-free ceramics

A new type of (0.7−x)Bi_0.5Na_0.5TiO₃-0.3Sr_0.7Bi_0.2TiO₃-xLaTi_0.5Mg_0.5O₃ (LTM1000x, x = 0.0, 0.005, 0.01, 0.03, 0.05 wt%) lead-free energy storage ceramic material was prepared by a combining ternary perovskite compounds, and the phase transition, dielectric, and energy storage characteristics were analyzed. It was found that the ceramic materials can achieve a stable dielectric property with a large dielectric constant in a wide temperature range with proper doping. The dielectric constant was stable at 2170 ± 15% in the temperature range of 35-363°C at LTM05. In addition, the storage energy density was greatly improved to 1.32 J/cm³ with a high-energy storage efficiency of 75% at the composition. More importantly, the energy storage density exhibited good temperature stability in the measurement range, which was maintained within 5% in the temperature range of 30-110°C. Particularly, LTM05 show excellent fatigue resistance within 10⁶ fatigue cycles. The results show that the ceramic material is a promising material for temperature-stable energy storage.