Single-Phase Solid-Solution Reaction Facilitated Sodium-Ion Storage in Indium-Substituted Monoclinic Sodium-Iron...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Sodium-ion batteries (NIBs) are a promising alternative to lithium-ion batteries.
• High energy density cathodes are crucial for NIB adoption.
• Iron-rich NASICONs offer potential but face challenges like voltage hysteresis.

Purpose of the Study:

• To develop a NASICON-type cathode with enhanced performance for NIBs.
• To investigate the effect of indium doping on cathode properties.
• To address voltage hysteresis and improve sodium-ion diffusion.

Main Methods:

• Synthesis of NaFe2-xInx(PO4)(MoO4)2 (NFIPM) NASICON cathode.
• Magnetic susceptibility (M-T) and Electron Paramagnetic Resonance (EPR) measurements.
• First-principle calculations and in situ X-ray diffraction (XRD).

Main Results:

• Indium doping in NFIPM creates a stable single-phase solid-solution.
• Enhanced sodium-ion diffusion and reduced energy bandgap observed.
• Optimized NFIPM10 shows 111.85 mAh g⁻¹ capacity at 0.1 C and 800 cycles at 2 C.
• In situ XRD confirms reversible structural stability during cycling.

Conclusions:

• Strategic indium doping effectively enhances sodium-ion diffusion and electrochemical performance.
• NFIPM demonstrates potential as a high-performance cathode material for sodium-ion batteries.
• This work highlights the role of doping in overcoming limitations in NASICON-based cathodes.