Van der Waals Epitaxy Enables Rollable Dielectric Superlattice for Record High Overall Energy Density

Abstract

Nanoengineered polar oxide films have attracted much attention for electric energy storage thanks to their high energy density, though they are all deposited on thick and rigid substrates, resulting in inferior overall energy density and poor manufacturability. Herein, an alternative strategy is developed for oxide dielectrics utilizing van der Waals epitaxy on ultrathin and flexible mica substrate, with a dielectric superlattice of Pb 0.92 La 0.08 (Zr 0.95 Ti 0.05 ) O 3 -SrTiO 3 carefully engineered to break its long-range antiferroelectric polar order. An ultrathin flexible capacitor is obtained as a result, with a record high overall energy density of 12.19 J cm −3 and an efficiency of 90.98%, and there is much room for further improvement since mica substrate can approach 2D limit. The superlattice can be easily rolled for large-scale manufacturing, and the energy storage performances are well maintained under large bending deformation as well as extended bending cycling. The study thus establishes a viable route for dielectric oxide films, paving way for their practical applications in high-energy density capacitors.

Improved energy storage performance in flexible (PbLa)ZrO3 thin films via nanocrystalline engineering

“…According to relevant results, low R rms is beneficial to improving the insulation performance of the films. [31][32][33] To further investigate the dielectric properties of (PbLa)ZrO 3 thin films at different annealing temperatures, the temperature dependence of dielectric loss (tan d) and dielectric constant (e r ) is shown in Fig. 4.…”

“…6(e). 22,32,33,[35][36][37][38][39][40] (PbLa)ZrO 3 films exhibit excellent energy storage performance by designing nanocrystalline microstructures. With excellent W rec and Z, as well as a high E b , our results have promising prospects in the field of highperformance dielectric capacitors.…”

“…According to relevant results, low R rms is beneficial to improving the insulation performance of the films. 31–33…”

Remarkable flexibility in freestanding single-crystalline antiferroelectric PbZrO3 membranes

“…They also exhibit a large electric polarization response at the high electric field and weak remnant polarization at the zero field. Those characteristics make them suitable for a wide range of applications in actuation, energy storage [10][11][12] , memory devices 13 , solid-state refrigeration 14 and thermal switches 15 , etc. These extraordinary performances are usually achieved in AFE single-crystals or AFE epitaxial thin films.…”

“…To meet the demand for next-generation flexible electronic devices, it is necessary to manufacture AFE single-crystalline oxides as flexible as metals and polymers. Traditionally, the widely studied flexible AFE oxide thin films are those deposited directly on metal foils 16,17 and mica [11][12][13]18 substrates. However, they either have poor crystallinity or their flexibility is constrained by the substrate, with a maximum bending strain far below 1% 11,16,19 .…”