Amorphous Tin-Based Composite Oxide: A High-Rate and Ultralong-Life Sodium-Ion-Storage Material

Energy-storage technology is moving beyond lithium batteries to sodium as a result of its high abundance and low cost. However, this sensible transition requires the discovery of high-rate and long-lifespan anode materials, which remains a significant challenge. Here, the facile synthesis of an amorphous Sn2P2O7/reduced graphene oxide nanocomposite and its sodium storage performance between 0.01 and 3.0 V are reported for the first time. This hybrid electrode delivers a high specific capacity of 480 mA h g(-1) at a current density of 50 mA g(-1) and superior rate performance of 250 and 165 mA h g(-1) at 2 and 10 A g(-1), respectively. Strikingly, this anode can sustain 15 000 cycles while retaining over 70% of the initial capacity. Quantitative kinetic analysis reveals that the sodium storage is governed by pseudocapacitance, particularly at high current rates. A full cell with sodium super ionic conductor (NASICON)-structured Na3V2(PO4)(2)F-3 and Na3V2(PO4)(3) as cathodes exhibits a high energy density of over 140 W h kg(-1) and a power density of nearly 9000 W kg(-1) as well as stability over 1000 cycles. This exceptional performance suggests that the present system is a promising power source for promoting the substantial use of low-cost energy storage systems.