A sodium ion intercalation material: A comparative study of amorphous and crystalline FePO₄

Due to their low cost, high abundance and eco-friendly features, Na-ion batteries are becoming alternative choices for rechargeable batteries, especially in large scale applications. Generally, the well-crystallized materials have many advantages over amorphous materials, such as long cycle life, high rate performance and other electrochemical properties. However, the amorphous FePO₄ we report here exhibits outstanding cycling stability and rate performance which are derived from its amorphous nature and wafer-like porous morphology. A comparative study of amorphous and crystalline FePO₄ has been carried out as cathode materials for Na-ion batteries. The present study not only reports a synthetic method which is facile, inexpensive, and scalable for mass production, but it also motivates further exploration of other amorphous materials for Na-ion batteries.