Anion Storage Behavior of Graphite Electrodes in LiBF₄/Sulfone/Ethyl Methyl Carbonate Solutions

Abstract

The electrolyte solutions of 1 M LiBF 4 dissolved in ethyl methyl carbonate (EMC)/sulfone mixtures are applied for dual-ion batteries using graphite positive electrodes. The representative sulfone solvents include sulfolane (SL) and 3methylsulfolane. Graphite electrodes can deliver higher capacity of anion storage in the solutions of the mixed solvents than those of pure solvents. Traditional electrochemical and in situ X-ray diffraction measurements are performed on Li/graphite cells to probe the anion intercalation process at the interface between graphite electrode and electrolyte solutions. Ionic conductivity, viscosity, and NMR tests are carried out to characterize electrolyte solutions. The effects of ion-pairing between Li + and BF 4 − and the anion solvations by EMC or sulfones on the anion storage in graphite have been addressed.

An Ultrahigh Rate Ionic Liquid Dual-Ion Battery Based on a Poly(anthraquinonyl sulfide) Anode

“…Figure a displays XRD patterns of the pristine KS6 cathode and the fully charged and fully discharged cathode. At the fully charged state, the (002) characteristic peak of graphite shifts left slightly (Figure a), which could be attributed to the intercalation of TFSI – anions, resulting in the increase of space between graphite layers. − On the other hand, in the fully discharged state, the (002) peak returns to the pristine position, suggesting the deintercalation of TFSI – anions. Similarly, for the PAQS anode, when the battery is fully charged, the peak located around 24° disappears because of the insertion of Pyr 14 + cations (Figure b).…”

Hexafluorophosphate Anion Intercalation into Graphite Electrodes from Propylene Carbonate/Gamma-Butyrolactone Solutions

“…1−6 Anion-graphite intercalation compounds (AGICs) are the most popular positive electrode materials in DIBs, 7−9 whose performance is closely related to ingredients of electrolyte solutions, especially those of anions and solvents. The anions in use generally include PF 6 − , 10 BF 4 − , 11,12 FSI − (bisfluorosulfonyl)imide, and TFSI − (bistrifluoromethanesulfonyl)imide. The solvents in DIBs may select propylene carbonate (PC), 13−16 ethylmethyl carbonate (EMC), 17−21 methyl acetate (MA), 22,23 gammabutyrolactone (GBL), 24−26 and sulfolane (SL).…”

“…The solvents in DIBs may select propylene carbonate (PC), 13−16 ethylmethyl carbonate (EMC), 17−21 methyl acetate (MA), 22,23 gammabutyrolactone (GBL), 24−26 and sulfolane (SL). 11,27 Sometimes ionic liquids have been applied in DIBs as well. 28−30 Right now, the close correlation between the storage behavior of anions in a graphite electrode and the solvation state of anions has been confirmed.…”

“…Recently, a dual-ion battery (DIB) has become a promising energy technology to save resources and protect the living environment on earth. − Anion-graphite intercalation compounds (AGICs) are the most popular positive electrode materials in DIBs, − whose performance is closely related to ingredients of electrolyte solutions, especially those of anions and solvents. The anions in use generally include PF 6 – , BF 4 – , , FSI – (bisfluorosulfonyl)­imide, and TFSI – (bistrifluoromethanesulfonyl)­imide. The solvents in DIBs may select propylene carbonate (PC), − ethylmethyl carbonate (EMC), − methyl acetate (MA), , gamma-butyrolactone (GBL), − and sulfolane (SL). , Sometimes ionic liquids have been applied in DIBs as well. − Right now, the close correlation between the storage behavior of anions in a graphite electrode and the solvation state of anions has been confirmed. ,, Therefore, it is an effective way to improve the performance of AGICs in DIBs by tailoring the solvation structures of anions.…”

“…The anions in use generally include PF 6 – , BF 4 – , , FSI – (bisfluorosulfonyl)­imide, and TFSI – (bistrifluoromethanesulfonyl)­imide. The solvents in DIBs may select propylene carbonate (PC), − ethylmethyl carbonate (EMC), − methyl acetate (MA), , gamma-butyrolactone (GBL), − and sulfolane (SL). , Sometimes ionic liquids have been applied in DIBs as well. − Right now, the close correlation between the storage behavior of anions in a graphite electrode and the solvation state of anions has been confirmed. ,, Therefore, it is an effective way to improve the performance of AGICs in DIBs by tailoring the solvation structures of anions.…”