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A composite anode consisting of hollow SnO2 microspheres covered by glass-like B2O3 layers was prepared via a combined hydrothermal-impregnation method, which results in much improved electrochemical performance in lithium ion batteries, relative to pristine SnO2 anodes. The cycling and rate capabilities of the SnO2–B2O3 composite anodes were investigated as a function of B2O3 content. The balance between increased electron-acceptor effect and compromised electronic conductivity due to addition of B2O3 is maximized around 20 wt% B2O3 loading. The best performing SnO2–B2O3 composite anode exhibits a specific capacity of 622.7 mAh g−1 up to 160 cycles, and is able to maintain a capacity above 528.6 mAh g−1 at rate of 5C. These enhanced performance characteristics are attributed to the unique composite structures consisting of the hollow SnO2 cores and the B2O3 buffer layers, which likely are beneficial for reducing the overall volume changes. Importantly, the decreased charge transfer resistance and increased Li+ diffusion coefficient, resulting from B2O3 coating, lead to overall improvement of rate performance for the composite anodes. Such-fabricated composite structures are stable during the Li+ insertion/extraction, thereby promoting cycling stability.

We report here the preparation of nanostructured polypyrroles (PPys) with different morphologies (nanospherical or nanofibrillar) through a surfactant-assisted oxidative polymerization route. Nanofibrillar PPy has a higher redox current, presumably due to a higher surface area accessible to the electrolytes and a lower charge transfer resistance compared to that of the spherical PPy. The impedance spectrum of spherical PPy at lower frequencies suggests a semi-infinite diffusion process, while nanofibrillar PPy displays barrier diffusion and capacitor characteristics. Electrodeless (chemical) deposition of Au particles from AuCl 4 − aqueous solution using nanostructured PPy also shows different morphologies, presumably due to a difference in growth kinetics dominated by the differences in surface area and surface chemistry. Our work demonstrates control over the electrochemical responses and charge transfer mechanisms of these conducting polymers. This control arises from their unique length scale geometries and surface areas that allows for the fabrication of Au nanoparticles with tunable morphologies. Our work in the controlled synthesis of nanostructured conducting polymers and metal nanoparticles opens up new opportunities for nanofiber-based electronic and sensory devices.