Amorphous Fe2O3 as a high-capacity, high-rate and long-life anode material for lithium ion batteries

Abstract

Despite their widespread application state-of-the-art lithium batteries are still highly limited in terms of capacity, lifetime and safety upon high charging rate. The development of advanced Li-ion batteries with high energy/power density relies increasingly on transition metal oxides. Their conversion reactions enable a combined high capacity and enhanced safety. Nevertheless, their practical application is severely limited by the insufficient cycling stability, poor rate capability and large voltage hysteresis which impact the lifetime and the performance of the battery. Here we report the exceptionally high-performance of an amorphous Fe2O3 anode, which largely outperforms its crystalline counterpart. Besides the advantageous narrow voltage hysteresis, this material exhibits a new breakthrough in terms of cycling stability and rate capacity. A highly reversible charge–discharge capacity of ~1600mAhg−1 was observed after 500 cycles using a current density of 1000mAg−1. A specific capacity of ~460mAhg−1 was achieved using the ever reported large current density of 20,000mAg−1 (~20C), which opens venues for high power applications. The amorphous nature of Fe2O3 anode yields a unique electrochemical behavior and enhanced capacitive storage, which drives the overall electrochemical performance. This work demonstrates that amorphous transition metal oxides (a-TMO) based materials may offer a new perspective towards the development of high performing anodes for the next-generation of Li-ion batteries.