Zesheng Li

Controlled synthesis of SnO2@carbon core-shell nanochains as high-performance anodes for lithium-ion batteries

A new low-flow-rate inert atmosphere strategy has been demonstrated for the synthesis of perfect SnO2@carbon core-shell nanochains (SCNCs) by carbonization of an SnO2@carbonaceous polysaccharide (CPS) precursor at a relatively high temperature. This strategy results in the thorough carbonization of CPS whilst avoiding the carbothermal reduction of SnO2 at 700 °C. It has been investigated that a moderate carbon content contributes to the 1-D growth of SCNCs, and the thickness of the carbon shell can be easily manipulated by varying the hydrothermal treatment time in the precursor process. Such a unique nanochain architecture could afford a very high lithium storage capacity as well as resulting in a desirable cycling performance. SCNCs with about 8 nm carbon shell synthesized by optimized routes were demonstrated for optimal electrochemical performances. More than 760 mAh g¬1 of reversible discharge capacity was achieved at a current density of 300 mA g−1, and above 85% retention can be obtained after 100 charge-discharge cycles. TEM analysis of electrochemically-cycled electrodes indicates that the structural integrity of the SnO2@carbon core-shell nanostructure is retained during electrochemical cycling, contributing to the good cycleability demonstrated by the robust carbon shell.

Close-packed mesoporous carbon polyhedrons derived from colloidal carbon microspheres for electrochemical energy storage applications

A new class of mesoporous carbon polyhedrons (MCPs) with a facet-to-facet close-packed model are presented for the first time as electrode materials for electrochemical capacitors (ECs). These MCPs are evolved directly from the colloidal carbon microspheres (CCMs) by a new silica-free approach, the top-down carbonate (Li2CO3) site-occupying strategy. The obtained polyhedral materials consist of a desirable mesoporous structure with mesopores with a mean size of about 30 nm. The unique structures of the large-size mesopores in a close-packed combination are considered to provide a more favourable pathway for electrolyte penetration and transportation, as well as good electronic conductivity for electrochemical energy storage applications. Accordingly, the resultant mesoporous materials show great promise for high performance EC applications, of which high energy and high power properties are desirable.

Bimetallic carbide of Co3W3C enhanced non-noble-metal catalysts with high activity and stability for acidic oxygen reduction reaction

A bimetallic carbide enhanced nitrogen/phosphor co-doped graphite nanocomposite (Co3W3C/NPG) is proposed for the first time as a highly active and stable non-noble-metal catalyst for the oxygen reduction reaction (ORR). The newly multi-component Co3W3C/NPG catalysts presented a high on-set potential of 0.92 V and little decreased half-wave potential of 5 mV after 8000 cycles in the O2-saturated 0.1 M HClO4 electrolyte. The electron transfer number was calculated to be above 3.9 before and after 8000 cycles, indicating that the Co3W3C/NPG catalyst behaves as a steady 4e oxygen reductant in acidic medium.