Strategies to Improve the Energy Storage Properties of Perovskite Lead-Free Relaxor Ferroelectrics: A Review

Abstract

Electrical energy storage systems (EESSs) with high energy density and power density are essential for the effective miniaturization of future electronic devices. Among different EESSs available in the market, dielectric capacitors relying on swift electronic and ionic polarization-based mechanisms to store and deliver energy already demonstrate high power densities. However, different intrinsic and extrinsic contributions to energy dissipations prevent ceramic-based dielectric capacitors from reaching high recoverable energy density levels. Interestingly, relaxor ferroelectric-based dielectric capacitors, because of their low remnant polarization, show relatively high energy density and thus display great potential for applications requiring high energy density properties. In this study, some of the main strategies to improve the energy density properties of perovskite lead-free relaxor systems are reviewed, including (i) chemical modification at different crystallographic sites, (ii) chemical additives that do not target lattice sites, and (iii) novel processing approaches dedicated to bulk ceramics, thick and thin films, respectively. Recent advancements are summarized concerning the search for relaxor materials with superior energy density properties and the appropriate choice of both composition and processing routes to match various applications’ needs. Finally, future trends in computationally-aided materials design are presented.

NaNbO3‐(Bi0.5Li0.5)TiO3 Lead‐Free Relaxor Ferroelectric Capacitors with Superior Energy‐Storage Performances via Multiple Synergistic Design

“…[ 7,11–16 ] Owing to the extremely low energy loss, lead‐free relaxor FE ceramics based on BaTiO 3 (BT), (Na 0.5 Bi 0.5 )TiO 3 (BNT), BiFeO 3 (BF), and (K 0.5 Na 0.5 )NbO 3 (KNN), etc., have been actively studied in the last few years. [ 3,8–10,17–29 ] Nevertheless, the obtained W rec values are generally lower than 5 J cm –3 together with η values >80%. The low E B value has been recognized as a very important reason for relaxor FEs.…”

“…Dielectric energy‐storage capacitors have drawn more and more attention in recent years for promising applications in high‐power/pulse‐power systems owing to their high power density, fast charge/discharge rates, and great reliability. [ 1–4 ] However, high recoverable energy‐storage density ( W rec ), high efficiency (η), and their desirable temperature stability are difficult to be achieved simultaneously, which is one of the main challenges for the practical applications of dielectric materials. It is well known that W rec and η values of a dielectric capacitor can be determined according to the polarization–electric field ( P–E ) loop based on the following equations: , , η = W /( W + W loss ), where P max is the maximum polarization, P r is the remnant polarization, and W loss is the area of hysteresis loop.…”

“…[ 6,11,32 ] However, even enough high E B values over 40 kV mm –1 have been realized in some studies, W rec values are still lower than 7 J cm –3 , basically because of relatively low P max values and early polarization saturation. [ 3,8,25,27,29 ] Moreover, a delicate balance between different property parameters in theory obviously limits the development of energy‐storage dielectrics with excellent comprehensive performances. As can be found in Figure 1b, the W rec value of most lead‐free relaxor FE ceramics has an approximately linear relationship with the testable electric field, demonstrating that discovering methods to improve the achievable P max and optimize the shape of the P–E curves is important.…”

Effect of Sintering Temperature on the Physical Properties of Ba0.6Sr0.4TiO3 Prepared by Solid-State Reaction

“…The high sintering temperature to produce pure BST material has prompted various studies to produce pure BST materials at lower sintering temperatures using glass, polymer and inorganic additives [19]. One way to produce BST material at low sintering temperatures is to add Li2O material, as reported by Zhang et al [20].…”

“…However, the XRD test showed two secondary phases as impurities caused by the addition of lithium. Besides, this research method has many limitations when applied to commercial production because it requires a very high cost [19], [21].…”