讲座内容早知道

       Supercapacitors and batteries represent two distinct electrochemical energy storage devices of increasing importance for applications in mobile electronics, electric vehicles, and renewable energy industry. A common feature of these devices involves coupled ion transport (and storage) and electron transport in active electrode materials. Tremendous progress has been made in new electrode materials (e.g., silicon and niobia) that may promise far higher energy or power density than those of today’s batteries. However, these new materials have thus far failed to deliver their promise in practical devices because the exceptional performance is typically only achieved in ultrathin electrodes with very low mass loadings (< 1 mg cm-2) and cannot be easily scaled into devices with practical levels of mass loading (>10 mg cm-2). To sustain the same electrochemical performance in practical electrodes with higher mass loading requires the delivery of proportionally more charge (both electrons and ions) across a proportionally longer distance, which represents a formidable challenge, particularly for new electrode materials with intrinsically higher capacity or rate capability that require the correspondingly higher charge delivery rate. In this talk, I will discuss the critical role of charge transport in electrochemical devices how their performance can be dramatically affected by tailoring the charge transport process. In particular, I will describe the design of a three-dimensional holey graphene framework (3D-HGF) as an ideal conductive scaffold for electrochemical materials. The 3D-HGF features a highly interconnected graphene network for excellent electron transport, a hierarchical porous structure for rapid ion transport, and an ultrahigh high surface area for the efficient loading of electrochemical active nanostructures without sacrificing reaction efficiency. By systematically tailoring the porosity in the holey graphene backbone, we show charge transport in the composite architecture can be optimized to enable a HGF/niobia or HGF/Si composite anode with an unprecedented combination of high areal capacity and high areal current density at practical levels of mass loadings (>10 mg cm-2), marking critical step towards applying high performance electrode materials in practical devices.

       讲座人简介

       段镶锋教授，1997年本科毕业于中国科学技术大学，1999和2002年分别获得美国哈佛大学硕士和博士学位，2008年被聘为美国加州大学洛杉机分校(UCLA)助理教授，2012年晋升为终身副教授，2013年晋升为终身教授。目前兼任Nano Research杂志副主编。2003年被美国 Technology Review 评为当年的―世界百位杰出青年发明家之一。2011 年列入全球领先的专业信息供应商汤森路透集团（Thomson Reuters）发布的2000-2010年全球顶尖一百化学家名人堂榜单全球第 41位，华人第7位。全球顶尖一百材料学家名人堂榜单全球总排名第 20位，华人第7位。1998年获得哈佛大学全额奖学金赴美深造，1999年和2000 年两度获得MRS 全美杰出研究生奖，2001年获得全美发明家竞赛大奖，同年，他和另一位科大学子黄昱合作完成的纳米成果被Science 评为2001年世界十大科技进展，并名列榜首，2002年获得博士学位，2003年他被美国 Technology Review 评为当年的世界百位杰出青年发明家之一。