Early Stage Anodic Instability of Glassy Carbon Electrodes in Propylene Carbonate Solvent Containing Lithium Hexafluorophosphate

Abstract

Irreversible changes to the morphology of glassy carbon (GC) electrodes at potentials between 3.5 and 4.5 V vs Li/Li in propylene carbonate (PC) solvent containing lithium hexafluorophosphate (LiPF) are reported. Analysis of cyclic voltammetry (CV) experiments in the range of 3.0 to 6.0 V shows that the capacitance of the electrochemical double-layer increased irreversibly beginning at potentials as low as 3.5 V. These changes resulted from nonfaradaic interactions, and were not due to oxidative electrochemical decomposition of the electrode and electrolyte, anion intercalation, nor caused by the presence of water, a common impurity in organic electrolyte solutions. Atomic force microscopy (AFM) images revealed that increasing the potential of a bare GC surface from 3.0 to 4.5 V resulted in a 6× increase in roughness, in good agreement with the changes in double-layer capacitance. Treating the GC surface via exposure to trichloromethylsilane vapors resulted in a stable double-layer capacitance between 3.0 and 4.5 V, and this treatment also correlated with less roughening. These results inform future efforts aimed at controlling surface composition and morphology of carbon electrodes.

Widening Electrochemical Window of Mg Salt by Weakly Coordinating Perfluoroalkoxyaluminate Anion for Mg Battery Electrolyte

“…We consider these features indicative of early-stage interfacial instability attributed to adsorption of the electrolyte, impurities, or side reactions involving changes in bonding at the electrode-electrolyte interface. 48 Notably, these features were also distinctly different on each electrode material, which again suggest that the early-state interfacial instability features are surface-dependent. Additionally, the high anodic stability was corroborated with reversibility parameter, defined as the ratio of charges in faradaic process to charges in non-faradaic process ( Figure S16).…”

Probing Graphene Interfacial Reactivity via Simultaneous and Colocalized Raman–Scanning Electrochemical Microscopy Imaging and Interrogation

“…Controlling the reactivity of electrodes through film formation is central to applications in energy storage, e.g., the solid electrolyte interphase on graphite anodes in lithium ion batteries, − which is of interest to our group. Understanding film formation due to the decomposition of solution-phase redox species is pertinent due to the emergence of redox-flow, mediator-based Li–air and charge-overload protected Li-ion batteries. − The formation of these films results from the degradation of the solution species by processes triggered by the large polarizations applied to battery electrodes. − When combined together to create a platform for an in-depth study of interface characteristics, the methodology presented here provides a multimodal technique applicable to an immense number of materials and future experimental procedures.…”