Interfacial Polarization Restriction for Ultrahigh Energy‐Storage Density in Lead‐Free Ceramics

Abstract

Dielectric capacitors with high power densities are crucial for pulsed electronic devices and clean energy technologies. However, their breakdown strengths (E b ) strongly limit their power densities. Herein, by modifying the interfacial polarization by adjusting the difference in activation energies (Δφ) between the grain and grain boundary phases, the significant enhancement of E b in the (1-x)(0.94Na 0.5 Bi 0.5 TiO 3 -0.06BaTiO 3 )-xCa 0.7 La 0.2 TiO 3 (NBT-BT-xCLT, x = 0, 0.18, 0.23, 0.28, 0.33, 0.38, and 0.43) ceramics is achieved. The results indicate that adding CLT introduces a super-paraelectric state, refines grain size, and, most importantly, decreases the Δφ value. When Δφ is tuned close to zero in the specific NBT-BT-0.38CLT sample, a significant boost in E b value of 64 kV mm −1 is obtained. As a result, the recoverable energy storage density of the ceramics reaches an unprecedented giant value of 15.1 J cm −3 together with a high efficiency of 82.4%, as well as ultrafast discharge rate of 32 ns, and high thermal and frequency stability. The results demonstrate that interfacial polarization engineering holds huge promise for the development of dielectrics with high-energy-storage performance.

Enhanced Energy Harvesting Performance of Triboelectric Nanogenerators via Dielectric Property Regulation

“…For type 1 samples, the semicircular part of the Nyquist plot can be depressed by the dc bias, while for type 2 samples, the semicircular part of the Nyquist plot can be enhanced with the increase of dc bias. It is well-known that the Maxwell–Wagner relaxation is associated with a Schottky barrier that can be effectively tuned by a dc bias. , The above result firmly indicates that the observed relaxation is a Maxwell–Wagner relaxation, which is caused by space charge at various interfaces.…”

“…It is well-known that the Maxwell−Wagner relaxation is associated with a Schottky barrier that can be effectively tuned by a dc bias. 53,54 The above result firmly indicates that the observed relaxation is a Maxwell−Wagner relaxation, which is caused by space charge at various interfaces.…”

Local Chemical Clustering Enabled Ultrahigh Capacitive Energy Storage in Pb-Free Relaxors

“…Note that it goes far beyond the present performance boundary of high W rec (>10 J cm –3 ) at high η (>90%) in Pb-free bulk ceramics. Accordingly, there are very few systems reported with W rec > 15 J cm –3 , while their corresponding η are only about 80%. − As compared with these highly efficient (η > 90%) dielectric bulk ceramics, BNT-25BT- x NN ( x = 0.12) exhibits much higher W rec . In addition, this performance is superior to the reported multilayer ceramic capacitors, which are typically fabricated with a much smaller thickness (<20 μm). ,,, …”

“…The corresponding capacity density of bulk ceramics has been rapidly improved to 4–8 J cm –3 . Very recently, giant W rec > 15 J cm –3 has been advanced in a few NaNbO 3 (NN)-based , and Bi 0.5 Na 0.5 TiO 3 (BNT)-based ceramics, while their corresponding η is relatively low (∼80%), owing to the open hysteresis loops at high field. High η (>90%) can be obtained in some BaTiO 3 (BT)-based, SrTiO 3 (ST)-based ceramics, but their W rec is typically below 8 J cm –3 , limited by the relatively low intrinsic polarization. − Furthermore, various mesoscopic-structural modulation strategies have been proposed to enhance E B . ,,,− However, owing to the inherent trade-off between P m , H , and E B in dielectrics, achieving “dual high” performance, for example, going beyond the current boundary of W rec > 15 J cm –3 and η > 90% in bulk ceramics, remains a challenge.…”

Outstanding Energy Storage Performance of NBT-Based Ceramics under Moderate Electric Field Achieved via Antiferroelectric Engineering

“…Energy storage dielectrics as key materials for pulsed energy-storage capacitors have become one of the research focuses in recent years. − With the development of energy-storage devices aiming toward miniaturization and integration, higher recoverable energy density ( W rec ) and efficiency (η) as well as comprehensive stability are highly desired. − However, high W rec values (>5 J/cm 3 ) in ceramics are solely obtained under high electric fields (HEFs ≥300 kV/cm). For instance, a high W rec of 8.09 J/cm 3 in K 0.5 Na 0.5 NbO 3 -based ceramics was achieved at an HEF of 870 kV/cm .…”