To overcome the lithium storage barriers of current lithium-ion batteries, it is imperative that conventional low capacity graphite anodes be replaced with other higher capacity anode materials. Silicon is a promising alternative anode material due to its huge energy densities; however, its lithiumconcentration-dependent volumetric changes can induce severely adverse effects that lead to drastic degradations in capacity during cycling. The dealloying of Si-metal alloys is recently suggested as a scalable approach to fabricate high-performance porous Si anode materials. Herein, a microstructure controlled porous Si is developed by the dealloying in conjunction with wet alkaline chemical etching. The resulting 3D networked structure enables enhancement in lithium storage properties when the Si-based material is applied not only as a single active material but also in a graphite-blended electrode.

Real time dilation behaviors of a Si-Ti-Fe-Al alloy electrode adopting a poly (amide-imide) binder were investigated to understand the effects of thermal treatment temperature for PAI binder on the electrochemical performance of the Si-alloy electrode using an in-situ electrochemical dilatometer. In situ measurement of the electrode thickness showed that the changes in the volume of the Si electrode was suppressed by heat treatment greater than 300 C, which well agreed with the improved cycle performance of the Sialloy electrode thermally treated at the same temperature. Differential dilation plots of the Si-alloy electrodes were found to reveal more detailed changes in the volume of the Si-alloy electrode, thus showing that the enhanced mechanical strength of thermally treated PAI effectively could control the expansion and contraction of the Si-alloy electrode and ensuring a more stable cycle performance of the Si-alloy electrode.

Artificially grown superstructures from small building blocks is an intriguing subject in 'bottom-up' molecular science and nanotechnology. Although discrete nanoparticles with different morphologies and physicochemical properties are readily produced, assembly them into higher-order structure amenable to practical applications is still a considerable challenge. This report introduces a stepwise heterogeneous approach for coupling colloidal quantum dots (QDs) synthesis with self-organization to directly generate quantum chains (QCs). By using vulcanized sulfur precursors, QDs are interdigitated into microscale chainlike supracrystals associated with oleylamine and oleic acid as structure directing agents. The cooperative nature of the QD growth and assembly have been extended to fabricate binary (PbS) and ternary metal

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We report foamed Si particles as a high-performance lithium storage material prepared by a milling-assisted alkaline etching process. The resulting foamed Si electrode showed excellent cycling performance of over 300 cycles with an initial discharge capacity of about 2750 mA h g.

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Carbon nanofiber (CNF)/3D nanoporous (3DNP) Si hybrid materials were prepared by chemical etching of melt-spun Si/Al-Cu-Fe alloy nanocomposites, followed by carbonization using a pitch. CNFs were successfully grown on the surface of 3DNP Si particles using residual Fe impurities after acidic etching, which acted as a catalyst for the growth of CNFs. The resulting CNF/3DNP Si hybrid materials showed an enhanced cycle performance up to 100 cycles compared to that of the pristine Si/Al-Cu-Fe alloy nanocomposite as well as that of bare 3DNP Si particles. These results indicate that CNFs and the carbon coating layer have a beneficial effect on the capacity retention characteristics of 3DNP Si particles by providing continuous electron-conduction pathways in the electrode during cycling. The approach presented here provides another way to improve the electrochemical performances of porous Si-based high capacity anode materials for lithium-ion batteries.

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