Bachelor of Science, Nanjing University (2004)
Master of Science, Nanjing University (2007)
Doctor of Philosophy, University of California Riverside (2012)
Yi Cui, Postdoctoral Faculty Sponsor
In situ observation of divergent phase transformations in individual sulfide nanocrystals.
2015; 15 (2): 1264-1271
Inorganic nanocrystals have attracted widespread attention both for their size-dependent properties and for their potential use as building blocks in an array of applications. A complete understanding of chemical transformations in nanocrystals is important for controlling structure, composition, and electronic properties. Here, we utilize in situ high-resolution transmission electron microscopy to study structural and morphological transformations in individual sulfide nanocrystals (copper sulfide, iron sulfide, and cobalt sulfide) as they react with lithium. The experiments reveal the influence of structure and composition on the transformation pathway (conversion versus displacement reactions), and they provide a high-resolution view of the unique displacement reaction mechanism in copper sulfide in which copper metal is extruded from the crystal. The structural similarity between the initial and final phases, as well as the mobility of ions within the crystal, are seen to exert a controlling influence on the reaction pathway.
View details for DOI 10.1021/nl504436m
View details for PubMedID 25602713
- Ultrathin Two-Dimensional Atomic Crystals as Stable Interfacial Layer for Improvement of Lithium Metal Anode NANO LETTERS 2014; 14 (10): 6016-6022
- Dry-air-stable lithium silicide-lithium oxide core-shell nanoparticles as high-capacity prelithiation reagents NATURE COMMUNICATIONS 2014; 5
- A Three-Dimensionally Interconnected Carbon Nanotube-Conducting Polymer Hydrogel Network for High-Performance Flexible Battery Electrodes ADVANCED ENERGY MATERIALS 2014; 4 (12)
A pomegranate-inspired nanoscale design for large-volume-change lithium battery anodes
2014; 9 (3): 187-192
Silicon is an attractive material for anodes in energy storage devices, because it has ten times the theoretical capacity of its state-of-the-art carbonaceous counterpart. Silicon anodes can be used both in traditional lithium-ion batteries and in more recent Li-O2 and Li-S batteries as a replacement for the dendrite-forming lithium metal anodes. The main challenges associated with silicon anodes are structural degradation and instability of the solid-electrolyte interphase caused by the large volume change (∼300%) during cycling, the occurrence of side reactions with the electrolyte, and the low volumetric capacity when the material size is reduced to a nanometre scale. Here, we propose a hierarchical structured silicon anode that tackles all three of these problems. Our design is inspired by the structure of a pomegranate, where single silicon nanoparticles are encapsulated by a conductive carbon layer that leaves enough room for expansion and contraction following lithiation and delithiation. An ensemble of these hybrid nanoparticles is then encapsulated by a thicker carbon layer in micrometre-size pouches to act as an electrolyte barrier. As a result of this hierarchical arrangement, the solid-electrolyte interphase remains stable and spatially confined, resulting in superior cyclability (97% capacity retention after 1,000 cycles). In addition, the microstructures lower the electrode-electrolyte contact area, resulting in high Coulombic efficiency (99.87%) and volumetric capacity (1,270 mAh cm(-3)), and the cycling remains stable even when the areal capacity is increased to the level of commercial lithium-ion batteries (3.7 mAh cm(-2)).
View details for DOI 10.1038/NNANO.2014.6
View details for Web of Science ID 000332637200011
View details for PubMedID 24531496
Crab shells as sustainable templates from nature for nanostructured battery electrodes.
2013; 13 (7): 3385-3390
Rational nanostructure design has been a promising route to address critical materials issues for enabling next-generation high capacity lithium ion batteries for portable electronics, vehicle electrification, and grid-scale storage. However, synthesis of functional nanostructures often involves expensive starting materials and elaborate processing, both of which present a challenge for successful implementation in low-cost applications. In seeking a sustainable and cost-effective route to prepare nanostructured battery electrode materials, we are inspired by the diversity of natural materials. Here, we show that crab shells with the unique Bouligand structure consisting of highly mineralized chitin-protein fibers can be used as biotemplates to fabricate hollow carbon nanofibers; these fibers can then be used to encapsulate sulfur and silicon to form cathodes and anodes for Li-ion batteries. The resulting nanostructured electrodes show high specific capacities (1230 mAh/g for sulfur and 3060 mAh/g for silicon) and excellent cycling performance (up to 200 cycles with 60% and 95% capacity retention, respectively). Since crab shells are readily available due to the 0.5 million tons produced annually as a byproduct of crab consumption, their use as a sustainable and low-cost nanotemplate represents an exciting direction for nanostructured battery materials.
View details for DOI 10.1021/nl401729r
View details for PubMedID 23758646
- Crab Shells as Sustainable Templates from Nature for Nanostructured Battery Electrodes NANO LETTERS 2013; 13 (7): 3385-3390