Zhilun Lu

Bio: Zhilun Lu is an academic researcher from University of Sheffield. The author has contributed to research in topics: Ceramic & Dielectric. The author has an hindex of 18, co-authored 46 publications receiving 1420 citations. Previous affiliations of Zhilun Lu include Central South University & Henry Royce Institute.

Author Correction: The nature of spin excitations in the one-third magnetization plateau phase of Ba3CoSb2O9.

Abstract: The original version of this Article omitted the following from the Acknowledgements: ‘J. Ma’s primary affiliation is Shanghai Jiao Tong University.’ This has been corrected in both the PDF and HTML versions of the Article.

Electroceramics for High-Energy Density Capacitors: Current Status and Future Perspectives

Abstract: Materials exhibiting high energy/power density are currently needed to meet the growing demand of portable electronics, electric vehicles and large-scale energy storage devices. The highest energy densities are achieved for fuel cells, batteries, and supercapacitors, but conventional dielectric capacitors are receiving increased attention for pulsed power applications due to their high power density and their fast charge-discharge speed. The key to high energy density in dielectric capacitors is a large maximum but small remanent (zero in the case of linear dielectrics) polarization and a high electric breakdown strength. Polymer dielectric capacitors offer high power/energy density for applications at room temperature, but above 100 °C they are unreliable and suffer from dielectric breakdown. For high-temperature applications, therefore, dielectric ceramics are the only feasible alternative. Lead-based ceramics such as La-doped lead zirconate titanate exhibit good energy storage properties, but their toxicity raises concern over their use in consumer applications, where capacitors are exclusively lead free. Lead-free compositions with superior power density are thus required. In this paper, we introduce the fundamental principles of energy storage in dielectrics. We discuss key factors to improve energy storage properties such as the control of local structure, phase assemblage, dielectric layer thickness, microstructure, conductivity, and electrical homogeneity through the choice of base systems, dopants, and alloying additions, followed by a comprehensive review of the state-of-the-art. Finally, we comment on the future requirements for new materials in high power/energy density capacitor applications.

Superior energy density through tailored dopant strategies in multilayer ceramic capacitors

Abstract: The Gerson–Marshall (1959) relationship predicts an increase in dielectric breakdown strength (BDS) and therefore, recoverable energy density (Wrec) with decreasing dielectric layer thickness. This relationship only operates however, if the total resistivity of the dielectric is sufficiently high and the electrical microstructure is homogeneous (no short circuit diffusion paths). BiFeO3–SrTiO3 (BF–ST) is a promising base for developing high energy density capacitors but Bi-rich compositions which have the highest polarisability per unit volume are ferroelectric rather than relaxor and are electrically too conductive. Here, we present a systematic strategy to optimise BDS and maximum polarisation via: (i) Nb-doping to increase resistivity by eliminating hole conduction and promoting electrical homogeneity and (ii) alloying with a third perovskite end-member, BiMg2/3Nb1/3O3 (BMN), to reduce long range polar coupling without decreasing the average ionic polarisability. These strategies result in an increase in BDS to give Wrec = 8.2 J cm−3 at 460 kV cm−1 for BF–ST–0.03Nb–0.1BMN ceramics, which when incorporated in a multilayer capacitor with dielectric layers of 8 μm thickness gives BDS > 1000 kV cm−1 and Wrec = 15.8 J cm−3.

High-Figure-of-Merit Thermoelectric La-Doped A-Site-Deficient SrTiO3 Ceramics

Abstract: The structure and thermoelectric (TE) properties of La-doped, A-site-deficient SrTiO3 (Sr1–3x/2LaxTiO3) ceramics sintered in air and N2/5% H2 have been investigated. Air-sintered ceramics with 0.10 ≤ x 0.50 are orthorhombic with an a–a–c+ tilt system and long-range VA ordering. x = 0.15 sintered in N2/5% H2 shows the largest dimensionless TE figure-of-merit ZT = 0.41 at 973 K reported for n-type SrTiO3-based ceramics, suggesting that the accommodation of La throu...

Electroceramics for High-Energy Density Capacitors: Current Status and Future Perspectives

Abstract: Materials exhibiting high energy/power density are currently needed to meet the growing demand of portable electronics, electric vehicles and large-scale energy storage devices. The highest energy densities are achieved for fuel cells, batteries, and supercapacitors, but conventional dielectric capacitors are receiving increased attention for pulsed power applications due to their high power density and their fast charge-discharge speed. The key to high energy density in dielectric capacitors is a large maximum but small remanent (zero in the case of linear dielectrics) polarization and a high electric breakdown strength. Polymer dielectric capacitors offer high power/energy density for applications at room temperature, but above 100 °C they are unreliable and suffer from dielectric breakdown. For high-temperature applications, therefore, dielectric ceramics are the only feasible alternative. Lead-based ceramics such as La-doped lead zirconate titanate exhibit good energy storage properties, but their toxicity raises concern over their use in consumer applications, where capacitors are exclusively lead free. Lead-free compositions with superior power density are thus required. In this paper, we introduce the fundamental principles of energy storage in dielectrics. We discuss key factors to improve energy storage properties such as the control of local structure, phase assemblage, dielectric layer thickness, microstructure, conductivity, and electrical homogeneity through the choice of base systems, dopants, and alloying additions, followed by a comprehensive review of the state-of-the-art. Finally, we comment on the future requirements for new materials in high power/energy density capacitor applications.