Boosting Manganese Selenide Anode for Superior Sodium-Ion Storage via Triggering α → β Phase Transition

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Graphite and silicon anodes are unsuitable for sodium-ion batteries (SIBs).
• Developing high-performance anode materials is critical for SIB advancement.
• Abundant and low-cost sodium resources drive SIB research.

Purpose of the Study:

• To synthesize and evaluate α-MnSe nanorods derived from δ-MnO2 as anodes for SIBs.
• To investigate the electrochemical mechanism and structural evolution of α-MnSe during sodium-ion insertion/extraction.
• To demonstrate the potential of δ-α-MnSe as a viable anode material for high-performance SIBs.

Main Methods:

• Synthesis of α-MnSe nanorods from δ-MnO2.
• Electrochemical characterization including cyclic voltammetry and galvanostatic cycling.
• First-principles calculations to study Na-ion migration and phase transitions.
• Fabrication and testing of sodium-ion full batteries.

Main Results:

• α-MnSe transforms into β-MnSe after initial cycling, exhibiting a conversion mechanism.
• First-principles calculations confirm Na-ion migration drives the α → β phase transition.
• The resulting β-MnSe structure offers enhanced stability and kinetics with a low Na-ion diffusion barrier.
• The δ-α-MnSe anode shows excellent rate capability and cyclic stability (>1000 cycles) with a low decay rate (0.0267%/cycle).
• Na-ion full batteries achieved a high energy density of 281.2 Wh·kg⁻¹ and outstanding cyclability.

Conclusions:

• δ-α-MnSe nanorods are effective anodes for sodium-ion batteries.
• The phase transition to β-MnSe enhances structural integrity and electrochemical performance.
• This material demonstrates significant potential for practical SIB applications due to its stability and energy density.