Synergistic Na-storage reactions in Sn4P3 as a high-capacity, cycle-stable anode of Na-ion batteries.

Room-temperature Na-ion batteries have attracted great interest as a low cost and environmentally benign technology for large scale electric energy storage, however their development is hindered by the lack of suitable anodic host materials. In this paper, we described a green approach for the synthesis of Sn4P3/C nanocomposite and demonstrated its excellent Na-storage performance as a novel anode of Na-ion batteries. This Sn4P3/C anode can deliver a very high reversible capacity of 850 mA h g(-1) with a remarkable rate capability with 50% capacity output at 500 mA g(-1) and can also be cycled with 86% capacity retention over 150 cycles due to a synergistic Na-storage mechanism in the Sn4P3 anode, where the Sn nanoparticles act as electronic channels to enable electrochemical activation of the P component, while the elemental P and its sodiated product Na3P serve as a host matrix to alleviate the aggregation of the Sn particles during Na insertion reaction. This mechanism may offer a new approach to create high capacity and cycle-stable alloy anodes for Na-ion batteries and other electrochemical energy storage applications.