Pore-Free Single-Crystalline Particles for Durable Na-Ion Battery Cathodes

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• O3-type layered oxides are promising cathode materials for sodium-ion batteries (SIBs) due to their high energy density.
• Polycrystalline Na[Ni0.6Co0.2Mn0.2]O2 (PC-NCM) cathodes suffer from structural and interfacial instability, limiting their practical application in SIBs.
• Developing stable and high-performance cathode materials is crucial for advancing SIB technology.

Purpose of the Study:

• To design and synthesize a single-crystalline O3-type Na[Ni0.6Co0.2Mn0.2]O2 (SC-NCM) cathode.
• To investigate the structural and electrochemical properties of SC-NCM for SIBs.
• To address the degradation pathways observed in polycrystalline counterparts.

Main Methods:

• Synthesis of single-crystalline O3-type Na[Ni0.6Co0.2Mn0.2]O2 (SC-NCM) via a molten-salt method.
• Electrochemical characterization including cycling performance and stability testing.
• Structural analysis to understand the enhanced stability of SC-NCM.

Main Results:

• The mechanically robust SC-NCM exhibits enhanced tolerance to particle cracking due to the absence of pores.
• SC-NCM demonstrates stable cycling performance with 73% capacity retention over 350 cycles.
• A simple, cost-effective molten-salt synthesis route was employed, avoiding complex quenching processes.

Conclusions:

• Single-crystalline SC-NCM effectively mitigates degradation pathways, leading to improved cycling stability in SIBs.
• The molten-salt synthesis offers a practical and scalable approach for producing advanced cathode materials.
• This study provides a new direction for developing high-performance cathode materials for practical sodium-ion batteries.