Yangfei Gao

Bio: Yangfei Gao is an academic researcher from Xi'an Jiaotong University. The author has contributed to research in topics: Energy storage & Ceramic. The author has an hindex of 3, co-authored 6 publications receiving 17 citations.

Extraordinary energy storage performance and thermal stability in sodium niobate-based ceramics modified by the ion disorder and stabilized antiferroelectric orthorhombic R phase

Abstract: Developing high-performance dielectric capacitors is essential to meet the growing demands of hybrid electric vehicles and high-power applications. The energy storage efficiency and the temperature-variant energy storage properties should be considered besides the energy density. In this work, we prepared (1 − x)(0.8NaNbO3–0.2SrTiO3) − xBi(Zn0.5Sn0.5)O3 (abbreviated as (1 − x)(NN–ST) − xBZS) lead-free ceramics, where ion disorder is induced in the A–B sites. The experimental results indicate that the antiferroelectric orthorhombic R phase is stabilized, and the breakdown strength is enhanced due to the decreased grain size after BZS modification, which are conducive to optimizing the energy storage performance. The piezoresponse force microscopy (PFM) observation reveals that the incorporated BZS promotes the reversibility of domains, resulting in enhanced energy storage efficiency. Therefore, an energy density of 5.82 J cm−3 and an efficiency of 92.3% are simultaneously obtained in the 0.96(NN–ST) − 0.04BZS composition, and the obtained efficiency in this work reaches a record high in NN-based energy storage ceramics. Especially, the sample displays extraordinary temperature stability, that is, high energy storage density (3.6–4.31 J cm−3) and efficiency (90–95%) are achieved in a wide temperature range from −60 °C to 180 °C. Our work would provide a powerful strategy for designing high-performance energy storage capacitors operating in harsh environments.

Enhanced energy storage properties in lead-free NaNbO3–Sr0.7Bi0.2TiO3–BaSnO3 ternary ceramic

Abstract: The urgent requirement of environment-friendly materials with excellent energy storage performance for pulse power systems has sparked considerable research on lead-free ceramics. In this work, a new lead-free 0.90(0.80NaNbO3–0.20Sr0.7Bi0.2TiO3)–0.10BaSnO3 ceramic with high recoverable energy storage density (Wr = 3.51 J/cm3) and decent energy storage efficiency (η = 70.85%) has been obtained. In particular, these ceramics exhibit an ultrahigh breakdown strength of 402 kV/cm due to the dense microstructure and small grain size. The impedance analysis also reveals that the incorporation of BaSnO3 is conducive to the enhancement of insulation ability and breakdown strength. Additionally, great thermal stability (ΔWr < 10% over 20–120 °C at 200 kV/cm) and fatigue resistance (ΔWr < 1% after 120,000 electrical cycles at 200 kV/cm) are observed, indicating that the 0.90(0.80NaNbO3–0.20Sr0.7Bi0.2TiO3)–0.10BaSnO3 ceramics have promising application prospect for high-temperature energy storage devices in pulse power applications.

Remarkably enhanced energy storage properties of lead-free Ba0.53Sr0.47TiO3 thin films capacitors by optimizing bottom electrode thickness

Abstract: The lead-free Ba0.53Sr0.47TiO3 (BST) thin films buffered with La0.67Sr0.33MnO3 (LSMO) bottom electrode of different thicknesses were fabricated by pulsed laser deposition method on a (001) SrTiO3 substrate. It was found that the roughness of electrode decreases and substrate stress relaxes gradually with the increase of LSMO thickness, which is beneficial for weakening local high electric field and achieving higher Eb. Therefore, the recoverable energy density (Wrec) of BST films can be greatly improved up to 67.3 %, that is, from 30.6 J/cm3 for the LSMO thickness of 30 nm up to 51.2 J/cm3 for the LSMO thickness of 140 nm after optimizing the LSMO thickness. Furthermore, the thin film capacitor with a 140 nm LSMO bottom electrode shows an outstanding thermal stability from 20 °C to 160 °C and superior fatigue resistance after 108 electrical cycles with only a slightly decrease of Wrec below 1.6 % and 3.7 %, respectively. Our work demonstrates that optimizing bottom electrodes thickness is a promising way for enhancing energy storage properties of thin-film capacitors.

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.

Boosting Energy Storage Performance of Lead-Free Ceramics via Layered Structure Optimization Strategy.

Abstract: Owing to the current global scenario of environmental pollution and the energy crisis, the development of new dielectrics using lead-free ceramics for application in advanced electronic and energy storage systems is essential because of the high power density and excellent stability of such ceramics. Unfortunately, most of them have low breakdown strength and/or low maximum polarization, resulting in low energy density and efficiency. To overcome this limitation here, lead-free ceramics comprising a layered structure are designed and fabricated. By optimizing the distribution of the layered structure, a large maximum polarization and high applied electric field (>500 kV cm-1 ) can be achieved; these result in an ultrahigh recoverable energy storage density (≈7 J cm-3 ) and near ideal energy storage efficiency (≈95%). Furthermore, the energy storage performance without obvious deterioration over a broad range of operating frequencies (1-100 Hz), working temperatures (30-160 °C), and fatigue cycles (1-104 ). In addition, the prepared ceramics exhibit extremely high discharge energy density (4.52 J cm-3 ) and power density (405.50 MW cm-3 ). Here, the results demonstrate that the strategy of layered structure design and optimization is promising for enhancing the energy storage performance of lead-free ceramics.