Stabilizing Anionic Redox Chemistry in a Mn-Based Layered Oxide Cathode Constructed by Li-Deficient Pristine State

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Li-rich cathode materials are crucial for high-energy-density batteries by enabling anionic and cationic redox.
• Lattice oxygen loss and structural distortion in these materials lead to capacity fade and voltage decay, limiting practical use.

Purpose of the Study:

• To develop a novel O3-type Li-rich cathode material with improved structural stability and electrochemical performance.
• To investigate the relationship between lithium distribution and the redox mechanisms in Li-rich cathode materials.

Main Methods:

• Synthesis of O3-type Li_0.6 [Li_0.2 Mn_0.8 ]O₂ with unique Li distribution.
• Electrochemical testing to evaluate reversible capacity and cycle stability.
• In situ and ex situ spectroscopic techniques to analyze redox reactions and structural evolution.

Main Results:

• The novel material achieved a high reversible capacity of approximately 329 mAh g^-1.
• Stable structural evolution and Li migration processes were observed.
• Irreversible lattice oxygen loss and structure distortion were effectively suppressed, leading to long-term cycling stability (0.045% capacity drop per cycle over 500 cycles).

Conclusions:

• Tuning the Li state in the alkali metal layer is a promising strategy for enhancing Li-rich cathode materials.
• The developed material demonstrates potential for next-generation high-energy-density batteries.
• Understanding and controlling anionic/cationic redox reactions are key to improving battery performance.