Synthesis of hierarchical Na 2 FeP 2 O 7 spheres with high electrochemical performance via spray drying

Hierarchical Na2FeP2O7 spheres with nanoparticles were successfully fabricated by a facile spray drying method. A relatively low drying temperature was introduced in order to form a carbon layer on the surface. As a cathode material for sodium-ion batteries, it delivered a reversible capacity of 84.4 mAh g−1 at 0.1 C and showed excellent cycling and rate performance (64.7 mAh g−1 at 5 C). Furthermore, a full sodium battery was fabricated using SP-Na2FeP2O7 as the cathode and hard carbon as the anode, suffering almost no capacity loss after 400 cycles at 1 C. Due to its superior electrochemical property and the low materials cost, Na2FeP2O7 is becoming a promising cathode material for large-scale energy storage systems.