Unlocking the Dual-Functionality of G/LCO Cathodes: A DFT Study of Quantum Capacitance Evolution under Delithiation
Vladislav V. Shunaev1, Alexander A. Petrunin1, Semen G. Levitskiy1, Olga E. Glukhova1,2; 1Saratov State University, Saratov, Russia; 2I.M. Sechenov First Moscow State Medical University
Abstract
We present a DFT study of delithiation in 2D LiCoO₂ films and 3D graphene/LCO sandwich composites (8:1 mass ratio). Graphene provides a comprehensive stabilizing effect: the energy difference between G/LCO and pristine LCO increases from ~0.1 to ~8.9 eV at x=0.5, while the Fermi level variation in G/LCO (0.95 eV) is nearly twice smaller than in pristine LCO (1.62 eV). This indicates that graphene effectively buffers electronic charge, mitigating detrimental voltage shifts during cycling. Using an original methodology for accumulated quantum capacitance that accounts for composition evolution during delithiation, we demonstrate that in the intercalation regime the differential quantum capacitance of G/LCO reaches ~4095 F/g — about five times higher than the classical estimate that assumes a fixed electronic structure. The specific charge at U≈–0.87 V is ~2958 C/g (822 mAh/g), which is 45% higher than predicted by the classical approach. These results show that G/LCO composites perform effectively in both electrostatic (supercapacitor) and intercalation (Li-ion battery) modes. The proposed approach not only reveals the fundamental mechanisms of graphene influence on the electronic characteristics of LCO during delithiation, but also establishes G/LCO as a promising dual-purpose cathode material for next-generation hybrid energy storage systems.
Speaker
Shunaev V.V.
Saratov State University
Russia
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