Cooperation of Dimethyl and Diethyl Carbonates in Hexafluorophosphate Anion Intercalation into Graphite Electrode

Abstract

In dual-ion batteries, electrolyte solutions must comply with the positive electrodes of anion graphite intercalation compounds. The solutions of LiPF 6 dissolved into ethylmethyl carbonate (EMC) cater to this need. In this paper, the mixtures of dimethyl carbonate (DMC) and diethyl carbonate (DEC) are employed in charge of EMC. The storage of PF 6 − synergistically solvated by both DMC and DEC in graphite has been identified by in/ex situ XRD measurements and conventional electrochemical tests. An optimized electrochemical performance in the solution of LiPF 6 −DEC/DMC is achieved if the volume ratio of DEC/DMC equals to 4. The solvation states in the LiPF 6 −DMC/DEC solutions are characterized by IR spectra analysis.

Hexafluorophosphate Intercalation into the Graphite Electrode from Mixed Cyclic Carbonates

“…Thus, we can gain a deeper understanding of the relationship between the storage behavior of anions’ intercalation into the graphite cathode and the solvation structures of the anions. Actually, we have pursued some preliminary studies on the intercalation behaviors of anions into the graphite cathode from some solvent mixtures including carbonates. − The competition and cooperation between different solvents toward solvating with the anion could be witnessed, especially in the LiBF 4 solutions based on mixed cyclic carbonates . Then it must be of interest to systematically grasp the underlying rules of intercalation behavior of the PF 6 – anion in the mixtures of cyclic carbonates, which may be vital for deep insight into the electrochemical performance of graphite cathodes in dual-ion batteries.…”

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

“…Such a phenomenon used to take place in the electrolyte solutions dissolved in mixed solvents. 10,26,32 To shed more light on such a matter, we have to glean more case studies and sum up our experience. Herein, we pick up the combination of PF 6…”

“…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.…”

“…In contrast, to precisely control the storage of anions simultaneously bound with different solvents in graphite electrodes is not an easy task at all. Such a phenomenon used to take place in the electrolyte solutions dissolved in mixed solvents. ,, To shed more light on such a matter, we have to glean more case studies and sum up our experience. Herein, we pick up the combination of PF 6 – anions and PC/GBL solvent mixtures subjected to this investigation.…”

Intercalation of multiply solvated hexafluorophospate anion into graphite electrode from mixtures of methyl acetate, ethyl methyl and ethylene carbonates

“…In most of these cases, the co-intercalation of single solvent specie together with anion into graphite electrode was always witnessed [5][6][7][8], even for some solutions containing two kinds of solvents [9][10][11][12][13][14][15][16]. It was only recently that the co-intercalation of anion with two solvent species into graphite electrode began to attract our attention [17][18][19][20][21]. In fact, investigating the intercalation of multiply solvated anions into graphite electrode is not an easy task.…”