Fast formation of anode-free Li-metal batteries by pulsed current.

Anode-free Li-metal batteries offer high energy density but are prone to dendrite formation during charging which can cause catastrophic failures. Ensuring dendrite-free smooth Li deposits during charging is therefore necessary. Suppressing dendrite growth can be achieved by pulsed current charging, especially during the formation cycle that largely determines the corrosion trajectory of a cell. As opposed to the constant-current technique, pulsed current techniques apply intermittently stopped current flows. This work investigates the electroplating of metallic Li onto a Cu foil current collector under constant-current and pulsed current formation protocols. In addition to smoother, less resistive electroplated metallic Li deposits and increased Coulombic efficiency, we show that by employing an optimized pulsed current formation protocol, the formation process is accelerated by a factor of 2 and the Coulombic efficiency was increased by 10% compared to a C/20 protocol. Finally, by employing a simple regression coupled to experimentation, we propose the pseudo-IR-drop to be used for live adjustment of pulsed current protocols i.e., individually approach each cell at all SOC during formation.

Relevance of the Scaphoid Shift Test for the Investigation of Scapholunate Ligament Injuries.

Background: Although it is part of the common clinical examination of scapholunate ligament pathologies, there are only little data on the diagnostic value of the scaphoid shift test. The aim of this study was to evaluate the scaphoid shift test in a large cohort of patients. Materials and Methods: We retrospectively analysed 447 patients who underwent the scaphoid shift test and wrist arthroscopy because of various suspected injuries of the wrist, correlating the results of clinical examination with data obtained during the wrist arthroscopy. Sensitivity, specificity, and positive and negative predictive values were calculated and evaluated. Results: The sensitivity of the scaphoid shift test was low (0.50) when examining the whole cohort. In a subgroup of patients specifically referred for suspected scapholunate ligament injury, the sensitivity was higher (0.61), but the specificity was low (0.62). In detecting more serious lesions (Geissler 3 + 4), the scaphoid shift test demonstrated higher sensitivity (0.66). Conclusions: An isolated scaphoid shift test may only be of limited value in the diagnosis of scapholunate ligament lesions and should, therefore, be viewed as a useful tool for a preliminary assessment, but a negative test should not prevent the surgeon from indicating a more extensive diagnostic workup.

The influence of pore size and surface area of activated carbons on the performance of ionic liquid based supercapacitors.

This study analyses and compares the behaviour of 5 commercial porous carbons in the ionic liquid N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR14TFSI) and its mixture with propylene carbonate (PC) as electrolytes. The results of this investigation show that the existence of a distribution of pore sizes and/or constrictions at the entrance of the pores leads to significant changes in the specific capacitance of the investigated materials. The use of PYR14TFSI as an electrolyte has a positive effect on the EDLC energy storage, but its high viscosity limits the power density. The mixture 50 : 50 wt% propylene carbonate-PYR14TFSI provides high operative voltage as well as low viscosity and thus notably enhances EDLC operation.