Pyrrolidinium-Based Organic Cation (BMP)-Intercalated Organic (Coronene) Anode for High-Voltage Dual-Ion Batteries: A Comparative Study with Graphite

Abstract

Among the post-lithium-ion batteries, rechargeable dual-ion batteries (DIBs) have bright opportunities for the development of cheap and safe batteries possessing a good electrochemical performance. The DIBs with pure ionic liquid (IL) electrolytes featuring a high voltage, sustainability, and environmental friendliness have received attention from researchers. Owing to intercalation/deintercalation of large size IL cations, the conventional dual-graphite batteries (DGBs) have suffered from severe volume expansion, thus limiting the overall reversibility of the DGBs. Herein, we have modeled two DIBs, introducing an organic cation-intercalated polycyclic aromatic hydrocarbon anode (coronene) coupled with a graphite cathode and a DGB in the other case. Pyrrolidinium-based IL, N-butyl-N-methyl pyrrolidinium chloride (BMP-Cl) with the AlCl3 salt has been employed as an electrolyte. Applying the first-principles calculation, we have investigated the systematic intercalation of the BMP cation into the coronene and graphite anodes. The BMP-intercalated graphite anode shows a higher binding energy (2.36 eV) compared to that of the coronene anode (1.71 eV). In the fully charged state, a calculated discharge voltage of 3.1 and 3.05 V and a maximum capacity of 116 and 130 mA h g-1 have been observed for the graphite coronene dual-ion battery (GCDIB) and DGB, respectively. However, the percentage of volume expansion of the graphite anode is higher (148%) compared to that of the coronene anode (53%) upon a full intercalation of BMP cations, indicating more exfoliation-prone nature of graphite compared to coronene. The density of states and Bader charge analysis reveal that the BMP cation is intercalated successfully, indicating a reduction of electrode materials during the charging process. Furthermore, we have explained the merits of choosing the AlCl4 anion compared to other commonly used anions such as TFSI in DIBs. These results support a clear understanding of BMP cation intercalation into both coronene and graphite anodes and motivate the fabrication of a new class of low-cost organic anode DIBs with an optimum electrochemical performance. ©