Bypassing First-Stage Degradation via Preconversion Interface Engineering in Iron Oxalate Anodes

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Oxalate-based anodes offer high capacity for lithium-ion batteries.
• Early cycling degradation limits their practical use.

Purpose of the Study:

• To investigate the degradation mechanism of iron oxalate anodes.
• To develop a strategy for improving their electrochemical performance and stability.

Main Methods:

• Combined experimental and theoretical analyses to study degradation.
• Interfacial engineering via preconversion thermochemical treatment to form an FeOx passivation layer.
• Incorporation of functional components like graphite and polyacrylonitrile.

Main Results:

• Identified interfacial chemical degradation of oxalate groups as the primary cause of early irreversibility.
• Engineered electrode achieved 92% second-cycle Coulombic efficiency and 96% capacity retention over six cycles.
• Demonstrated long-term stability with 897 mAh g⁻¹ after 100 cycles and 1053 mAh g⁻¹ after 300 cycles at 0.5 A g⁻¹.

Conclusions:

• Preconversion interfacial passivation effectively stabilizes oxalate-based conversion anodes.
• The FeOx layer passivates reactive groups and regulates interfacial chemistry.
• This strategy significantly enhances the performance and durability of high-capacity lithium-ion battery anodes.