Potential Specific Adsorption of Electrolyte Components Induced by Point Defected Graphene in EDLCs: A DFT Research

Carbon‐based materials are widely used as electrodes in commercial electrochemical double‐layer capacitors (EDLCs). However, zero‐dimensional or point defects that unavoidably appear in the carbon materials may change the electrical double‐layer (EDL) structure in EDLCs, especially the solvent layer, which has not been accurately simulated for a long time. In this study, we investigate the adsorption behavior of solvent molecules and ions in organic electrolytes on graphene with various point defects using DFT calculations. Our results show that electrolyte ions adsorb more strongly on defected graphene through non‐specific adsorption, which could enhance charge storage in EDLCs. Among the different types of defected graphenes, single vacancy (SV) defected substrates exhibit chemical adsorption behavior with acetonitrile (ACN) molecules, which could disrupt the uniformity of the EDL structure and even lead to the conversion from non‐Faraday to Faraday process in the EDL interface. Detailed electronic structure analysis further confirms that N─C and C─C covalent bonds are formed between ACN molecules and SV defected substrates for their frontier molecular orbital satisfies the bonding condition. This work proves the potential specific adsorption of SV defected graphene due to its unique electronic structures and offers theoretical insights for designing high‐performance materials to further optimize EDLCs. ACN molecules exhibit specific adsorption on the single vacancy graphene substrates, which would disrupt the non‐Faraday charge storage mechanism in EDLCs, thereby affecting the reversibility of charge storage.