A Small-Molecule Organic Cathode with Two Electron-Withdrawing Cyano Bonds for Li-Ion Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Organic Chemistry

Background:

• Perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) is an effective n-type organic cathode for Li-ion batteries, operating at approximately 2.5V.
• Improving the working potential of organic cathodes is crucial for advancing Li-ion battery technology.

Purpose of the Study:

• To design and synthesize a novel organic cathode with an enhanced working potential.
• To investigate the electrochemical performance of the new material in Li-ion half and full cells.

Main Methods:

• Synthesis of 1,7-dicyano-perylene-tetracarboxylic dianhydride (PTCDA-2CN) by introducing two cyano groups onto the PTCDA structure.
• Electrochemical evaluation using Li-ion half-cells and full-cells with a LiC6 anode.
• Analysis of discharge capacities, cycling stability, and working potential.

Main Results:

• PTCDA-2CN exhibits a higher working potential of approximately 2.8V, an increase of 0.3V compared to PTCDA.
• The theoretical specific capacity is maintained at 121 mAh g⁻¹.
• In half-cells, PTCDA-2CN shows discharge capacities of 117-107 mAh g⁻¹ with 91% retention over 100 cycles.
• Full cells achieve capacities of 116-98 mAh g⁻¹ at 50 mA g⁻¹ with a median voltage of 2.7V.

Conclusions:

• PTCDA-2CN demonstrates significantly improved working potential for n-type organic cathodes in Li-ion batteries.
• The material exhibits excellent electrochemical performance, making it a promising candidate for next-generation energy storage.
• This work contributes to the development of high-performance organic electrodes for advanced Li-ion batteries.