Synergistic Electronic and Crystal Structure Regulation of Na2+2xFe2-x(SO4)3 via Zr Doping for High-Performance Sodium-Ion Batteries

Abstract

Na 2.5 Fe 1.71 Zr 0.02 (SO 4 ) 3 with a synergistically optimized electronic and crystal structure are designed for high-performance sodium ion batteries. The orbital interaction induced by Zr doping significantly improves its intrinsic conductivity. Additionally, the longer Na-O bonds after Zr doping accelerate Na + transfer kinetics. Ultimately, the Na 2.5 Fe 1.71 Zr 0.02 (SO 4 ) 3 exhibits a high specific capacity of 96.4 mAh g -1 at 0.1 C with 85% retention after 10000 cycles at 30 C.