Enhanced Anionic Redox Reaction of Na-Layered Li-Containing Mn-Based Cathodes by Cu-Mediated Reductive Coupling...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Sodium-ion batteries (SIBs) utilize Na-layered Li-containing Mn-based cathodes (NLMOs) for enhanced Na+ storage via anionic redox reactions (ARR).
• Challenges in NLMOs include Mn migration, oxygen loss, and voltage decay during cycling, limiting practical applications.

Purpose of the Study:

• To investigate the role of copper (Cu) in enhancing the anionic redox reaction (ARR) mechanism in NLMOs.
• To improve the Na+ storage capacity and cycling stability of NLMOs for SIBs.

Main Methods:

• Synthesis and electrochemical testing of Cu2+/Fe3+ modified NLMO samples.
• In situ and ex situ characterization techniques to analyze structural and electronic properties.
• Investigation of the reductive coupling mechanism (RCM) and orbital overlaps.

Main Results:

• Cu2+/Fe3+ modified NLMO achieved a Na+ storage capacity of 174 mAh g-1 at 0.2C, outperforming Zn2+/Fe3+ modified (130 mAh g-1) and unmodified NLMO (154 mAh g-1).
• Enhanced electrochemical performance is attributed to increased overlaps between Cu 3d and O 2p orbitals, facilitating the RCM.
• The study confirmed that Cu modification effectively enhances the ARR, leading to improved Na+ storage.

Conclusions:

• Copper plays a crucial role in enhancing the anionic redox reaction (ARR) through the reductive coupling mechanism (RCM) in NLMOs.
• Cu modification significantly improves the Na+ storage capacity and electrochemical performance of NLMOs for SIB applications.
• The findings provide insights into designing advanced cathode materials for high-performance sodium-ion batteries.