Modulating electronic structure to expedite Na ₄ Fe ₃ (PO ₄ ) ₂ P ₂ O ₇ reaction kinetics for high‐power Na‐ion batteries

Abstract The Na 4 Fe 3 (PO 4 ) 2 P 2 O 7 (NFPP) has considered as a very attractive cathode material for Na‐ion batteries mainly due to its cheap price and high security. Its low electron transfer rate is usually improved by coating a layer of hard carbon, which however exhibits a low graphitization degree because of the relatively low NFPP synthesis temperature (~ 500 °C). In this study, a highly‐conductive hybrid carbon has been employed to accelerate redox reaction kinetics of NFPP by modulating electronic structure for achieving high‐power Na‐ion batteries. The hybrid carbon is derived from the mixed polyethylene glycol (PEG) and glucose, in which the low ether bond energy (~ 340 kJ mol −1 ) of PEG facilitates the free radical generation during pyrolysis with high graphitization degree while glucose improves the uniformity of the carbon coating. As a result, the optimized cathode exhibits a very high reversible capacity of 90.8 mAh g −1 at 20C within 2.0–4.0 V with 85.3% capacity retention after 10,000 cycles, highlighting huge application potentials in two‐wheeled electric vehicles, backup energy storage, and so forth.