Creative utilization of natural nanocomposites: nitrogen-rich mesoporous carbon for a high-performance sodium ion battery

A resource-abundant, low-cost and high-performance anode is indispensable to the future success of sodium ion batteries (SIBs) for applications in large-scale energy storage. Animal byproducts are naturally pre-organized organic/inorganic nanocomposite materials composed of collagen and nanominerals. Making the best use of these natural nanocomposites is a good choice to develop carbon anodes for SIBs. Here, using shrimp skin as an example, we demonstrated a simple preparation of nitrogen-rich mesoporous carbon materials from natural nanocomposites and used these carbon materials for developing high-performance SIBs. Collagen was used as a nitrogen-rich precursor of the carbon, while the nanominerals, distributed evenly in the collagen matrix, acted as a hard template to create mesopores. The shrimp skin was subjected to direct pyrolysis under an inert atmosphere followed by removal of minerals, and was hence easily transformed into nitrogen-rich mesoporous carbons subsequently shown to serve as high-performance sodium storage materials. In this way, we turned "trash" into "treasure". The unique microstructure of the nitrogen-rich mesoporous carbon resulted in its exhibiting outstanding performances as anodes for SIBs. The reversible sodium storage capacity reached as high as 434.6 mA h g-1 at 30 mA g-1 with excellent cycle durability and rate capability. These results indicated the creative utilization of the natural nanocomposites to be a facile, sustainable strategy for the synthesis of high-performance sodium storage materials.