Visualization of crystal plane selectivity for irreversible phase transition in MnO@C anode

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Transition metal oxides are promising anode materials for lithium-ion batteries (LIBs).
• The precise mechanisms of irreversible reactions during LIB cycling remain unclear.
• Understanding these mechanisms is crucial for improving battery performance and longevity.

Purpose of the Study:

• To elucidate the atomic structural transitions of MnO@C anodes during the first lithiation/delithiation cycle.
• To identify the key factors contributing to capacity degradation in MnO-based anodes.
• To provide insights for optimizing MnO-based materials for advanced LIBs.

Main Methods:

• Investigated the lithiation/delithiation process of MnO@C anodes.
• Analyzed atomic structural transitions using electrochemical methods.
• Quantified lithium ion insertion and extraction in different crystal planes.

Main Results:

• Directly observed the anisotropy of lithiation/delithiation in the MnO crystal plane.
• Determined complete lithium ion insertion/extraction in the MnO₍₂₂₀₎ plane.
• Identified incomplete lithium ion extraction from the MnO₍₂₀₀₎ plane as the primary cause of capacity degradation.

Conclusions:

• The study reveals the detailed reaction mechanisms and structural evolution of MnO@C anodes during electrochemical cycling.
• Anisotropy in lithium ion mobility across different crystal planes significantly impacts anode performance.
• Findings offer critical guidance for designing and fabricating superior MnO-based anode materials for next-generation LIBs.