PNNL

Abstract

Intercalation-type metal oxides are promising negative electrode materials for safe and stable operation of rechargeable lithium-ion batteries due to the reduced risk of Li plating at low voltages. Nevertheless, lower energy and power density along with cycling instability remain bottlenecks for their implementation, especially for desirable fast-charging applications. Here, we report for the first time a nanostructured rock salt Nb2O5 material formed through repeated electrochemical cycling with Li+, wherein an amorphous-to-crystalline transformation is observed in nanochanneled Nb2O5. This electrode can reversibly cycle three lithium per Nb2O5, corresponding to a capacity of 269 mAh g-1 at 20 mA g-1, and retains a capacity of 191 mAh g-1 at a high rate (1 A g-1). It exhibits superb cycling stability with a capacity of 225 mAh g-1 at 200 mA g-1 for 400 cycles, and a Coulombic efficiency of 99.93%. We attribute the enhanced performance to the framework of the new cubic structure, which promotes low-energy migration paths. Our work suggests that inducing crystallization of amorphous nanomaterials through electrochemical cycling is a new avenue for creating unconventional high-performance metal oxide electrode materials.