Enabling Dual‐Ion Batteries via the Reversible Storage of Pyr₁₄⁺Cations into Coronene Crystal

Abstract

Dual‐ion batteries with pure ionic liquid electrolyte (IL‐DIBs) have received increasing interest due to their sustainability, high operating voltage, and environmental friendliness. However, owing to the insertion/extraction of large‐size ionic liquid cations, the conventional IL‐DIBs with a graphite anode suffer from severe volume expansion and graphite exfoliation on the anode, causing a poor cycling performance. Herein, a novel IL‐DIB is constructed by introducing a bulk organic material (coronene) as the anode, against a natural graphite cathode. The results show that, in a voltage window range from 1.0 to 4.4 V, the battery has a high discharge specific capacity of ≈73.3 mA h g−1 and exhibits a good cycling performance for 450 cycles with a lower capacity loss of 0.061 mA h g−1 per cycle at a current density of 300 mA g−1 (3 C). Notably, it still maintains a considerable capacity of ≈55.8 mA h g−1 at a high rate of 10 C. In addition, the reversible intercalation/de‐intercalation of the Pyr14+ cations into/from the coronene anode is investigated by ex situ X‐ray diffraction and Fourier transform infrared spectroscopy, showing an excellent structure stability of the coronene crystal during the charge–discharge process.

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

“…The less binding energy value of −0.90 eV for one BMP intercalation could also be the reason for the experimentally observed poor Coulombic efficiency (60%) for the early stages of the charging process. 48 A subsequent intercalation of BMP cations leads to an increase in the binding energy value up to 1.71 eV. This as well gets reflected in the increase of the overall Columbic efficiency to 80−90%, observed experimentally.…”

“…Owing to the lack of an exact experimental evidence of the BMP-AlCl 4 DGB, we have compared our calculated voltage values with the BMP-TFSI DGB, where both AlCl 4 and TFSI are used as an active intercalant anion species in the DIB study. The experimental voltage window was observed in the range of 1.0−4.6 V for the BMP-TFSI, with a very high voltage discharge plateau achieved at 3.7 V. 48 However, this observation is also reflected in our calculated voltage trends of BMP-AlCl 4 DGB, where the highest discharge voltage value is found to be 3.79 V. Furthermore, our calculated relative energy and the literature study have suggested that the formation of stage-4 is feasible in the case of both BMP and AlCl 4 intercalation into the graphite at the initial state of charging. The average voltage of the stage-2 BMP-stage-4 AlCl 4 is calculated to be 3.29 V, which lies in the range of the experimental voltage window.…”

“…Our calculated highest voltage value of 3.14 V matches the experimental voltage window of 3.0−3.9 V for the coronene-TFSI DIB. 48 To replicate the fully charged state, we have considered the maximum 16 ion-pair intercalation, where BMP cations are intercalated into the 2 × 2 × 2 supercell of coronene, and stage-1 type intercalation is followed for AlCl 4 anions intercalation into graphite (Figure S6, Supporting Information). Consequently, the calculated OCV of 3.1 V falls in the experimental voltage range of 3.0−3.9 V. Moreover, we have measured the gravimetric capacity (C) for our considered DIBs.…”

“…Furthermore, the previous reports have shown that coronene has a low solubility in the IL electrolyte, and there is no loss of the active electrode material. 43,48 Recently, Fang et al have designed a novel organic DIB using coronene as an anode with the BMP-TFSI electrolyte. 48 Inspired from these experimental studies and attractive features of PAHs as an anode, here, we have modeled two DIB systems computationally, a coronene anode used with a graphite cathode and graphite is employed as both the anode and cathode in the other case.…”

“…43,48 Recently, Fang et al have designed a novel organic DIB using coronene as an anode with the BMP-TFSI electrolyte. 48 Inspired from these experimental studies and attractive features of PAHs as an anode, here, we have modeled two DIB systems computationally, a coronene anode used with a graphite cathode and graphite is employed as both the anode and cathode in the other case. We have considered pyrrolidinium-based IL, N-butyl-N-methyl pyrrolidinium chloride (BMP-Cl) with AlCl 3 at a 1:1 molar ratio as the electrolyte.…”