Electrostatic dielectric capacitors with ultrafast charging-discharging speed are essential energy-storage components in advanced electronic and electrical power systems, due to their ultrahigh power density, high cycling reliability and good temperature stability compared to electrochemical energy-storage devices such as batteries and supercapacitors. However, the energy density of dielectric capacitors is relatively lower, and thus development of high-performance dielectrics remains a key challenge. Ever-increasing efforts have been made to enhance the energy density and efficiency through optimization of polarization switching hysteresis and breakdown field of nonlinear dielectrics. Recently, we demonstrate further enhancements of energy storage properties in relaxor-ferroelectric films with superparaelectric design. The nanodomains are scaled down to polar clusters of several unit cells so that polarization switching hysteresis is nearly eliminated while relatively high polarization is maintained. We realize an ultrahigh energy density of 152 joules per cubic centimeter with greatly improved efficiency (>90% at an electric field of 3.5 megavolt per centimeter) in optimized superparaelectric Sm-doped BiFeO3-BaTiO3 films.

报告人简介：林元华，清华大学材料学院院长，新型陶瓷与精细工艺国家重点实验室主任。2001年毕业于清华大学大学材料系获博士学位后留校工作，期间2004.11-2006.09日本东京大学物理系博士后(JSPS资助)。主要致力于用于储能的氧化物介质陶瓷及薄膜材料、用于温差发电的高性能氧化物热电材料及器件等方面的研究，在Science、Nat. Commun、Phys. Rev. Lett.、Phys. Rev. B、Adv. Mater.、JACS等期刊上发表SCI论文300余篇，引用超过24000余次，H因子85，获授权发明专利15项，在国内/国际会议上做特邀报告70余次。曾获教育部人才计划、国家人才项目、教育部自然科学一等奖、中国硅酸盐学会青年科学奖等奖励。目前是J. Adv. Ceram.、Rare. Metals、Sci. Rep、Science China Materials等期刊主编/副主编、编委。现任中国材料学会理事、热电材料与应用分会理事、中国硅酸盐学会特陶分会理事等学术职务。