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Synthesis of snowflake-shaped Co3O4 with a high aspect ratio as a high capacity anode material for lithium ion batteries

In this study, snowflake-shaped Co3O4 nanosheets (Co3O4-SF) are successfully fabricated by a facile ammonia-assisted hydrothermal route followed by calcination at 450 °C. Material characterizations indicate that the as-prepared Co3O4-SF shows an ultrathin structure with 10 μm width and 100 nm thickness, suggesting micro-/nanostructures and a high aspect ratio of 100. Reactant concentration and reaction duration are considered as important synthesis parameters for snowflake-shaped Co3O4 fabrication. It is also found that ammonia plays critical roles in the formation of the snowflake structure. By simply manipulating the ammonia amount, the material structure can be easily changed to hexagonal nanosheets (Co3O4-HX). More importantly, when Co3O4 anodes with these two interesting structures are evaluated in a coin cell, the snowflake-shaped Co3O4 electrode delivers remarkable capacities (1044 mA h g−1 at 500 mA g−1) with better retention (86–98% at 500–1000 mA g−1) after 100 cycles and excellent rate performance (977 mA h g−1 at 3000 mA g−1) at various current densities. Due to the unique structure and properties, snowflake-shaped Co3O4 anodes with superior battery performance demonstrate great potential in lithium ion batteries.