Mesoporous Amorphous FePO₄Nanospheres as High-Performance Cathode Material for Sodium-Ion Batteries

Abstract

FePO4 nanospheres are synthesized successfully through a simple chemically induced precipitation method. The nanospheres present a mesoporous amorphous structure. Electrochemical experiments show that the FePO4/C electrode demonstrates a high initial discharging capacity of 151 mAh g(-1) at 20 mA g(-1), stable cyclablilty (94% capacity retention ratio over 160 cycles), as well as high rate capability (44 mAh g(-1) at 1000 mA g(-1)) for Na-ion storage. The superior electrochemical performance of the FePO4/C nanocomposite is due to its particular mesoporous amorphous structure and close contact with the carbon framework, which significantly improve the ionic and electronic transport and intercalation kinetics of Na ions.

Polyanion‐Type Electrode Materials for Sodium‐Ion Batteries

“…In addition to the abovementioned polyanion compounds, which have already been widely studied for Na‐ion batteries, other polyanion compounds such as carbonophosphates,120, 121, 122 amorphous polyanion compounds,123, 124, 125, 126 and molybdenates,127, 128 have also been researched.…”

Phosphate Framework Electrode Materials for Sodium Ion Batteries

“…Copyright 2014, Nature Publishing Group. (b,c) Reproduced with permission 10. Copyright 2014, American Chemical Society.…”

“…Fang et al also reported a mesoporous amorphous FePO 4 embedded in carbon matrix. The obtained FePO 4 /C exhibited a high initial discharge capacity of 151 mAh g –1 at 20 mA g –1 with stable cyclability (94% capacity retention ratio over 160 cycles) (Figure 8b,c) as well as high rate capability (44 mAh g –1 at 1000 mA g –1 ), and the electrode kept amorphous structure at different states of charge 10. Multi‐walled carbon nanotubes, graphene and carbonized polyaniline decorated FePO 4 were also synthesized with well‐improved electrochemical performances 148, 149, 150, 151.…”

“…A large variety of compounds, such as transition metal oxides,6, 7, 8, 9 phosphates,10, 11, 12 ferrocyanide,13, 14, 15 hard carbon,16, 17, 18, 19 metal alloys,20, 21, 22 and organic materials,23, 24, 25 have demonstrated considerable Na‐storage capacities for SIBs. However, most of them suffer from structural instability during Na‐insertion/extraction reactions.…”

A Safer Sodium‐Ion Battery Based on Nonflammable Organic Phosphate Electrolyte

“…Similar to their Li counterparts,1 though sodium‐based system has similar electrochemical reaction characteristics compared to lithium‐based one, the larger ionic radius for sodium ion cause sluggish kinetics and volume change during Na storage, leading to lower capacity, poor cycling and rate properties of the Na storage materials. Recently, major efforts have been devoted to promote the electrochemical performance of Na storage materials, for example, Na x MO 2 ,2, 3, 4, 5, 6, 7, 8, 9, 10 polyanionic framework compounds,11, 12, 13, 14, 15, 16, 17, 18, 19 hexacyanoferrate,20, 21, 22, 23, 24, 25, 26, 27 for the cathode materials, and hard carbons,28, 29, 30, 31, 32, 33 alloys,34, 35, 36, 37, 38, 39, 40, 41 oxides,42, 43 sulfides37, 44, 45, 46 for the anode materials.…”