Zero-Strain Na₂FeSiO₄ as Novel Cathode Material for Sodium-Ion Batteries

Abstract

A new cubic polymorph of sodium iron silicate, Na2FeSiO4, is reported for the first time as a cathode material for Na-ion batteries. It adopts an unprecedented cubic rigid tetrahedral open framework structure, i.e., F4̅3m, leading to a polyanion cathode material without apparent cell volume change during the charge/discharge processes. This cathode shows a reversible capacity of 106 mAh g(-1) and a capacity retention of 96% at 5 mA g(-1) after 20 cycles.

Polyanion‐Type Electrode Materials for Sodium‐Ion Batteries

“…A very slight volume change was also observed during cycling owing to the stable structure of the polymorphs. Just recently, the crystal structure of F $\overline{4}$3 m Na 2 FeSiO 4 via both the solid‐state method and the sol−gel method was reported for the first time 118. A reversible capacity of 106 mAh g −1 was obtained between 1.5 and 4.0 V at 30 °C.…”

Synthesis, Structure, and Sodium Mobility of Sodium Vanadium Nitridophosphate: A Zero-Strain and Safe High Voltage Cathode Material for Sodium-Ion Batteries

“…One strategy is to develop Na-containing host materials from lithium analogues. Such efforts have resulted in tremendous successes in realizing some known polyanionic frameworks, such as phosphate NaMPO 4 /Na 3 M 2 (PO 4 ) 3 [7,8], pyrophosphate Na 2 MP 2 O 7 [9], fluorophosphate NaMPO 4 F/Na 3 M 2 (PO 4 ) 2 F 3 [10,11], sulfate Na x M(SO 4 ) 2 [12], fluorosulfate NaMSO 4 F [13], silicate Na 2 M(SiO 4 ) [14], and mixed polyanionic Na 4 M 3 (PO 4 ) 2 (P 2 O 7 ) [15,16] compounds (where M represents the transition metal ion). Basically, the electrochemical properties of anticipated polyanion electrode materials, including the operating potential and specific capacity, rely on the Mn + /M (n+x)+ redox Energies 2017, 10, 889 2 of 9 process and the natures of polyanionic frameworks, i.e., electronegativity and molecular weight [17].…”

Li/Na Ion Intercalation Process into Sodium Titanosilicate as Anode Material

“…To identify structure evolution, we adopted ex‐situ XRD and accompanied refinement to explore lattice parameter change during discharge/charge. The XRD accompanied refinement has been proved as an effective method, including “zero strain” materials which has minute lattice parameter change during ion intercalation . XRD refinement results of electrode under various discharge/charge states provide more details of Na 2 TiSiO 5 lattice structural change.…”