Manman Ren

Preparation and lithium storage performance of yolk–shell Si@void@C nanocomposites

Yolk-shell Si@void@C nanocomposites are prepared via a facile method of resorcinol-formaldehyde coating and LiOH etching, without SiO2 pre-modification on Si particles, expensive carbon sources, or environmentally-unfriendly HF solutions. Profiting from these favorable features, Si@void@C nanocomposites exhibit considerable reversible capacities (628 mA h g(-1) after 100 cycles) and good rate performances.

Facile synthesis of Mn-doped hollow Fe2O3 nanospheres coated with polypyrrole as anodes for high-performance lithium-ion batteries

Mn-doped Fe2O3/PPy hollow composite nanospheres were fabricated by a facile solvothermal method. The Mn–Fe2O3/PPy electrode showed an improved electrochemical performance in terms of high rate capability and long cycling performance compared with Fe2O3 without Mn doping and PPy coating. At current densities of 500 mA g−1 and 1000 mA g−1, the Mn–Fe2O3/PPy exhibited an initial capacity of 1214.7 and 924.9 mA h g−1, and the capacity was maintained at 795.7 and 643.6 mA h g−1 after 200 cycles.

Uniform core–shell Cu6Sn5@C nanospheres with controllable synthesis and excellent lithium storage performances

Metallic tin (Sn) is one of the most promising alternatives to graphite anodes for lithium ion batteries due to its higher theoretical capacity, higher packing density and safer thermodynamic potential, while the huge volume transformation during repeated cycling leads to rapid pulverization and consequently poor capacity retention. This work provides an easy-to-control method to prepare uniform core–shell Cu6Sn5@C nanospheres in which Cu@Sn cores (40–50 nm in diameter) are well encapsulated by PANI-derived carbon layers with a thickness of ∼5 nm. The obtained Cu6Sn5@C exhibits an excellent cycling ability and good rate capabilities. Both the reversible capacity (518 mA h g−1) after 100 cycles and the initial coulombic efficiency (89.2%) are the highest values in Cu6Sn5-based materials. The impressive cycling performance is believed to result from the carbon coating that not only prevents particle agglomeration during the synthesis but also accommodates the vast structural transformation of the Cu6Sn5 nanocores during the electrochemical (de)lithiation process, so ensuring good ionic and electronic transport to the core. The effect of synthesis conditions on the composition are also investigated systematically.