Inhibition of Aluminum Corrosion with the Addition of the Tris(pentafluoroethyl)trifluorophosphate Anion to a Sulfonylamide-Based Ionic Liquid for Sodium-Ion Batteries

Ionic liquids (ILs) based on sulfonylamide-type anions have gained widespread utility as electrolytes for secondary batteries. Although sulfonylamide-based IL electrolytes are known to form a stable passivation layer that prevents Al corrosion, the Al electrode in the Na[FSA]-[C₂C₁im][FSA] ([FSA] = bis(fluorosulfonyl)amide and [C₂C₁im] = 1-ethyl-3-methylimidazolium) IL, is found to be afflicted by pitting corrosion at potentials above 4 V vs Na⁺/Na during electrochemical measurement at 90 °C. Therefore, this study investigates the suppressive effect of [FAP]⁻ (FAP = tris(pentafluoroethyl)trifluorophosphate) on the Al corrosion behavior of the IL electrolyte. Here, the inhibited corrosion of the Al electrode is confirmed through a series of cyclic voltammetry measurements, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Charge-discharge tests performed using a Na₃V₂(PO₄)₂F₃ positive electrode demonstrates that the addition of [FAP]⁻ into the IL enhances cycling performance at the intermediate temperature of 90 °C

A Hexafluorophosphate-Based Ionic Liquid as Multifunctional Interfacial Layer between High Voltage Positive Electrode and Solid-State Electrolyte for Sodium Secondary Batteries

Sodium secondary batteries have gained accolades as future energy storage devices due to their low costs and environmental benignity, but are heavily impeded by the poor anodic stabilities of most electrolytes, including solid-state electrolytes (SSE), that render them incompatible with high-voltage positive materials. This study reports, for the first time, a new synthesis technique using a fluorohydrogenate ionic liquid (IL)precursor to prepare a [DEME][PF₆] ([DEME]⁺: N, N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium) with high yield and high purity. Herein, a Na[PF₆]-[DEME][PF₆] IL is formulated and subjected to a series of electrochemical tests to validate its performance in battery applications. The present IL harbors a strong oxidative stability (up to 5.2 V on Pt and >4.5 V on conductive carbon electrodes) that aids in the suppression of oxidative decompositions of one typical SSE, for example, beta alumina solid electrolyte (BASE), thereby extending their electrochemical window in hybrid SSE systems. A hybrid solid-state Na secondary battery employing a high voltage positive electrode, Na₃V₂(PO₄)₂F₃, is assembled using the BASE/IL configuration, and features energy density and superior cycling performance. This work demonstrates that sandwiching an SSE between the oxidatively stable [PF₆]⁻ IL can be an effective design for high voltage operation Na secondary batteries

Transition between individually different and common features in skilled drumming movements

Why do professional athletes and musicians exhibit individually different motion patterns? For example, baseball pitchers generate various pitching forms, e.g., variable wind-up, cocking, and follow-through forms. However, they commonly rotate their wrists and fingers at increasingly high speeds via shoulder and trunk motions. Despite the universality of common and individually different motion patterns in skilled movements, the abovementioned question remains unanswered. Here, we focus on a motion required to hit a snare drum, including the indirect phase of task achievement (i.e., the early movement and mid-flight phases) and the direct phase of task achievement (i.e., the hit phase). We apply tensor decomposition to collected kinematic data for the drum-hitting motion, enabling us to decompose high-dimensional and time-varying motion data into individually different and common movement patterns. As a result, individually different motion patterns emerge during the indirect phase of task achievement, and common motion patterns are evident in the direct phase of task achievement. Athletes and musicians are thus possibly allowed to perform individually different motion patterns during the indirect phase of task achievement. Additionally, they are required to exhibit common patterns during the direct phase of task achievement