Balancing Polarization and Breakdown for High Capacitive Energy Storage by Microstructure Design.

Abstract

The compromise of contradictive parameters, polarization and breakdown strength, is necessary to achieve a high energy storage performance. The two can be tuned, regardless of material types, by controlling microstructures: amorphous states possess higher breakdown strength, while crystalline states have larger polarization. However, how to achieve a balance of amorphous and crystalline phases requires systematic and quantitative investigations. Herein, we comprehensively evaluated the trade-off between polarization and breakdown field with the evolution of microstructure, i.e., grain size and crystallinity, by phase-field simulations. The results indicate small grain size (∼10-35nm) with moderate crystallinity (∼60%∼80%) is more beneficial to maintain relatively high polarization and breakdown field simultaneously, consequently contributing to a high overall energy storage performance. Experimentally, we therefore achieved an ultrahigh energy density of 131 J cm-3 with a high efficiency of 81.6% in the microcrystal-amorphous dual-phase Bi3NdTi4O12 films. This work provides a guidance to substantially enhance dielectric energy storage by a simple and effective microstructure design. This article is protected by copyright. All rights reserved.