PF₆^– Intercalation into Graphite Electrode from Propylene Carbonate

Abstract

LiPF6-propylene carbonate (PC) solutions show some compatibility with the graphite positive electrode in dual-ion batteries. The relationship between the anion storage capacity and LiPF6 concentration is investigated by galvanostatic charge–discharge tests. Ex situ X-ray diffraction (XRD) measurements are carried out on graphite electrode recovered from Li/graphite cells at the end of charge to probe the storage situation of PC-solvated PF6 – inside graphite electrode. In situ XRD measurements on Li/graphite cells are performed to trace the crystal structural changes of anion–graphite intercalation compounds. Electrochemical quartz crystal microbalance (EQCM) measurement is conducted on graphite electrode to evaluate the transport of solvent during the anion storage. Nuclear magnetic resonance (NMR) and infrared (IR) spectroscopic studies on the solutions reveal the interactions between ions and PC solvent. The electrochemical performance of graphite is correlated with solvation state of LiPF6-PC solution.

Upcycling of Spent LiCoO2 Cathode to Lithium Dual‐Ion Battery Anode

“…− ions in a fourstage process. [63][64][65] This process can be denoted as Stage IV to Stage I reaction. During the charging of the battery, PF 6 − ions start intercalating within the layers of graphite.…”

Rational Design of Functional Electrolytes Towards Commercial Dual‐Ion Batteries

“…Although HCEs are essential for energy‐dense DIBs, some ubiquitous issues associated with insufficient ionic conductivity and poor wettability to separators need to be taken into consideration for their practical applications [12] . In general, the ionic conductivity σ , which quantifies the ion conduction and determines how fast the energy stored in electrodes can be delivered, is decided by two factors: ion solvation/charge dissociation and subsequent ion migration, in terms of the free‐moving ion number n i and the ionic mobility μ i : [53] $$$\vcenter{\openup.5em\halign{$\displaystyle{#}$\cr \sigma =\sum _{{\rm i}}{n}_{{\rm i}}{\mu }_{{\rm i}}{Z}_{{\rm i}}e\hfill\cr}}$$$ …”

“…Therefore, a high concentration of active anions and cations in the electrolyte is highly desired to increase the energy density of DIBs. Nonetheless, highly concentrated salts would inevitably bring issues of increased viscosity as well as aggravated ionic association in electrolytes, both of which could reduce the ionic conductivity of electrolytes and power density of the assembled DIBs [12] . Meanwhile, more attention should be paid to the periodic changes in the ion concentration of electrolytes at different state‐of‐charge (SOC) levels, because a series of important electrolyte properties such as oxidation stability, ionic conductivity, as well as compatibility with current collectors [13] are closely correlated with the electrolyte concentration.…”

Formation of lithiated gold and its use for the preparation of reference electrodes — an EQCM study

“…In the 1990s, it was used to study the behavior of battery electrolyte solutions on Au electrodes [23], for the study of the deposition and stability of SEI forming Li compounds in the UPD region of lithium [24] or to monitor the mass change of electrodeposited Li on Ni-coated crystals [25]. Nowadays, it is mainly used to investigate intercalation processes at both the cathode and anode or formation of SEI on graphite, usually together with dissipation monitoring taking into account the porous structure of the layers [26,27]. However, to the best of our knowledge, it has so far never been used to monitor alloy formation between Li and Au during long-term galvanostatic Li deposition that is of interest in relation with the preparation of our PEEK embedded lithiated gold wire reference electrodes (AuLi-Ref).…”