Cyclohexanehexone with Ultrahigh Capacity as Cathode Materials for Lithium‐Ion Batteries

Abstract

Organic carbonyl compounds show potential as cathode materials for lithium-ion batteries (LIBs) but the limited capacities (<600 mA h g^-1 ) and high solubility in electrolyte restrict their further applications. Herein we report the synthesis and application of cyclohexanehexone (C₆ O₆ ), which exhibits an ultrahigh capacity of 902 mA h g^-1 with an average voltage of 1.7 V at 20 mA g^-1 in LIBs (corresponding to a high energy density of 1533 Wh kg^-1 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow></mml:mrow> <mml:mrow><mml:mi>C</mml:mi> <mml:msub><mml:mrow></mml:mrow> <mml:mn>6</mml:mn></mml:msub> <mml:mi>O</mml:mi> <mml:msub><mml:mrow></mml:mrow> <mml:mn>6</mml:mn></mml:msub> </mml:mrow> </mml:msub> </mml:math> ). A preliminary cycling test shows that C₆ O₆ displays a capacity retention of 82 % after 100 cycles at 50 mA g^-1 because of the limited solubility in high-polarity ionic liquid electrolyte. Furthermore, the combination of DFT calculations and experimental techniques, such as Raman and IR spectroscopy, demonstrates the electrochemical active C=O groups during discharge and charge processes.