Fast-Ion Conductor Coating Strategy Modified LiMn₂O₄ for Rocking-Chair Lithium-Ion Capacitors

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Spinel lithium manganese oxide (LiMn2O4) is an attractive cathode material due to its low cost and earth-abundant manganese redox couple.
• Surface degradation and manganese dissolution limit the cycle life of LiMn2O4.
• Rocking-chair lithium-ion capacitors (LICs) require stable and high-performance cathode materials.

Purpose of the Study:

• To synthesize a LiMn2O4 cathode material coated with LiTaO3 for enhanced fast-ion conductivity.
• To evaluate the performance of the modified LiMn2O4 as a cathode in rocking-chair lithium-ion capacitors.
• To improve the structural stability and electrochemical performance of LiMn2O4 for long cycle life applications.

Main Methods:

• Synthesis of LiMn2O4 coated with LiTaO3 (3TaLMO) with optimized coating thickness.
• Electrochemical characterization of the 3TaLMO material in half-cells.
• Assembly and testing of rocking-chair lithium-ion capacitors using 3TaLMO and activated carbon.

Main Results:

• The 3TaLMO composite exhibited low impedance and the highest lithium-ion diffusion rate.
• Half-cell tests showed excellent cycling stability with 80.90% capacity retention after 2000 cycles at 0.3 A g-1.
• Rocking-chair LICs achieved high energy density (394.5 Wh kg-1), high power density (90 kW kg-1), and 77.27% capacity retention after 2000 cycles at 1.0 A g-1.

Conclusions:

• LiTaO3 coating effectively enhances the structural stability and fast-ion transfer characteristics of LiMn2O4.
• The modified LiMn2O4 demonstrates significant potential as a long-cycle-life faradic cathode material for rocking-chair LICs.
• This surface modification strategy offers a promising pathway for developing advanced energy storage devices.