A quantum capacitance of the graphene/Li$_3$V$_2$(PO$_4$)$_3$ composite during delithiation

By the ab initio method, the electron-energy structure of the graphene/Li$_3$V$_2$(PO$_4$)$_3$ composite with different mass concentrations was studied. The structures of the composite were explored with the step-by-step extraction of lithium from the supercell of the composite, which simulates its states during the charging of the electrode material. For each stage of delithiation, the distribution of quantum capacitance as a function of the applied voltage was calculated. Based on the analysis of these distributions, it was proposed an approach for estimating the dependence of the accumulated quantum capacitance taking into account changes in composition, which simulates the charging curve in real experiments. The obtained results allow us to draw conclusions about the nature of the quantum capacitance and its relationship with the charge/discharge curves of the electrodes of lithium-ion batteries.