Identification of the different contributions of pseudocapacitance and quantum capacitance and their electronic-structure-based intrinsic transport kinetics in electrode materials

Some rules are developed to classify the contributions of quantum capacitance and pseudocapacitance in electrode systems. We also find that the correlated intrinsic ion transport kinetics in different electrode materials can be compared based on the applied voltages, chemical potentials, and electronic structures according to the density functional theory calculations as exemplified by employing the electrodes of graphite, LiFePO 4 , LiTiS 2 , LiCoO 2 , and Ti 3 C 2 T x MXene. • Classifications of the pseudocapacitance and quantum capacitance were proposed. • Intrinsic charge transport kinetics can be compared based on the classifications. • Electrode materials with different kinetics can be screened through calculations. The boundary between quantum capacitance and pseudocapacitance is blurred due to their similarity in electronic populations. Here we propose the rules to classify the contributions of quantum capacitance and pseudocapacitance and their effects on the intrinsic ion transport kinetics based on the applied voltages and electronic structures. Systems including graphite, LiFePO 4 , LiTiS 2 , LiCoO 2 , and Ti 3 C 2 T x MXene are employed to illustrate their different intrinsic kinetics according to the classifications based on the density functional theory calculations and the reported experimental measurements. These results can facilitate the step to screen the electrode materials with different kinetics through calculations.