Temperature negative self-feedback preventing thermal runaway in lead-free energy-storage ceramics

Abstract

Lead-free multilayer ceramic capacitors (MLCC) have received unprecedented attention for energy storage in constantly lightweighted and miniaturized electronic and electrical systems. However, their popularized application is still bottlenecked by the thermal runaway issues of energy-storage ceramics because of the common nature of temperature positive self-feedback characteristics that are reflected by continuously increasing power loss with elevated temperatures. In this work, temperature negative self-feedback that prevents thermal runaway is realized in NaNbO3 modified 0.87BaTiO3-0.13Bi[Zn2/3(Nb0.85Ta0.15)1/3]O3 (NN0, NN0.05, NN0.10, NN0.15, NN0.20) lead-free energy-storage ceramics as a demonstration, based on a strategy of peak shifting and loss suppression. Negative self-feedback at weak and strong electric fields was attained by the temperature dependent power loss extracted from dielectric-temperature curves and polarization–electric field loops, respectively, in which NN0.05 is the optimal selection because of the largest negative self-feedback range from 25 to 150 °C and minimally declined energy-storage performance compared to the pristine NN0. Thermal field simulation of single ceramic layers indicates that NN0.05 achieves faster thermal stabilization with lower than NN0. Based on the Monte Carlo method, MLCC consisting of 20 ceramic layers with different defect levels were created, and evenly distributed temperature was confirmed for NN0.05 with prevented thermal runaway. General applicability and advantages of temperature negative self-feedback preventing thermal runaway in energy-storage ceramics were verified by three artificial types of MLCC. This work offers a solution to the critical thermal runaway issues of lead-free energy-storage ceramics, facilitating their wide application in MLCC toward lightweighted and miniaturized electronic and electrical systems.