Synthesis of Flower-Like, Hyperbranched Na₃FePO₄CO₃ Nanocrystals and Their Electrochemical Performance as Cathodes in Aqueous Rechargeable Sodium-Ion Batteries

Abstract

Aqueous rechargeable sodium-ion batteries (ARSBs) have received much attention due to their low cost, the vast abundance of sodium, and the possible application for a smart grid-scale energy storage system. Here, we synthesized Na3FePO4CO3, a cathode material for ARSBs by a low-temperature ionothermal method using deep eutectic solvent and investigated its electrochemical performance. The physical characterization of the synthesized cathode material was done using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, thermogravimetry analysis, differential thermal analysis, and X-ray photoelectron spectroscopy to evaluate crystal size, structure, elemental composition, morphology, and oxidation state. The electrochemical behavior of Na3FePO4CO3 in 2 M Na2SO4 was studied using cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge-discharge techniques. The study revealed that at high current rates, the synthesized cathode material, Na3FePO4CO3 exhibited excellent electrochemical performance. The full cell NaTi2(PO4)3/2 M Na2SO4/Na3FePO4CO3 delivers a discharge capacity of 78.6 mAh g−1 at C/5 rate which is 82% of the theoretical capacity (96 mAh g−1 for one-electron reaction) and 41.62 mAh g−1 at 2 C rate Further, it retains a discharge capacity of 70 mAh g−1 over 100 cycles with good cyclability.

Low‐Cost Polyanion‐Type Cathode Materials for Sodium‐Ion Battery

“…Na 3 FePO 4 CO 3 only provides a voltage plateau of 2.7 V, which significantly limits the corresponding energy density. [ 99 ] Manjunatha et al [ 100 ] employed Na 3 FePO 4 CO 3 for superior performance in aqueous rechargeable SIBs, which demonstrates the application of Na 3 FePO 4 CO 3 in aqueous batteries. Sadrnezhaad et al [ 101 ] prepared Na 3 MnPO 4 CO 3 by modified Hummers method, as shown in Figure 18c.…”

“…Reproduced with permission. [ 100 ] Copyright 2021, American Chemical Society. b) Charge/discharge curves of Na 3 FePO 4 CO 3 at 10 mA g −1 .…”

“…Figure 18. a) Structure of Na 3 MPO 4 CO 3 (M = Mn, Fe) viewed from [010]. Reproduced with permission [100]. Copyright 2021, American Chemical Society.…”

Perspective on Iron‐Based Phosphate Cathode for Commercial Sodium‐Ion Cells

“…Xie et al recently prepared a Na 3 FePO 4 CO 3 by the mechanical balling process, which delivers a more extensive discharge capacity of 159 mAh g −1 (1.66 mole Na per formula) at 60 °C. [ 97 ] For the relatively low operation potential (2.6 V vs Na/Na + ), restrict its energy density at cell level in the non‐aqueous electrolyte, Shiprath et al extended applications of Na 3 FePO 4 CO 3 cathode in aqueous SIBs, which exhibited impressive electrochemical performance. [ 98 ] The carbonate phosphates with two electronic reactions per formula theoretically provide high capacity, but the Na diffusion kinetics and structure stability need further enhanced.…”

Progress on Fe‐Based Polyanionic Oxide Cathodes Materials toward Grid‐Scale Energy Storage for Sodium‐Ion Batteries

“…Recently, Shiprath et al successfully synthesized NFPC nanoparticles with the flower-like hyperbranched structure by a low-temperature ion-thermal method. They employed them as the cathode of the aqueous full sodium-ion battery NaTi 2 (PO 4 ) 3 | Na 2 SO 4 |Na 3 FePO 4 CO 3 , which could provide a discharge capacity of 78.6 mAh g -1 at 0.2 C and 41.62 mAh g -1 at 2 C. [189] The result may inspire the exploration of sodium iron carbonate-phosphates material as anode for aqueous SIBs. [177] Copyright 2016, Royal Society of Chemistry.…”