High temperature supercapacitors using water-in-salt electrolytes: stability above 100 °C.

The high temperature performance of water-in-salt electrolytes was investigated using a carbon-based electrode with commercial cell components. Supercapacitors using 21 m Li bis(trifluoromethylsulphonyl)imide (TFSI) and 21 m LiTFSI + 7 m Li trifluoromethanesulphonyl electrolytes are shown to operate at a voltage of 2 V at 100 °C and 120 °C, respectively, with gravimetric capacitances exceeding 100 F g-1.

Pneumothorax Rate and Diagnostic Adequacy of Computed Tomography-guided Lung Nodule Biopsies Performed With 18 G Versus 20 G Needles: A Cross-Sectional Study.

PURPOSE: Conflicting data exist with regard to the effect of needle gauge on outcomes of computed tomography (CT)-guided lung nodule biopsies. The purpose of this study was to compare the complication and diagnostic adequacy rates between 2 needle sizes: 18 G and 20 G in CT-guided lung nodule biopsies. MATERIALS AND METHODS: This retrospective cohort study examined CT-guided lung biopsies performed between March 2014 and August 2016 with a total of 550 patients between the ages of 30 and 94. Biopsies were performed using an 18-G or a 20-G needle. Procedure-associated pneumothorax and other complication rates were compared between the 2 groups. Univariate and multiple logistic regression analyses were performed. RESULTS: There was no significant difference in pneumothorax rate between 18 G (n=125) versus 20 G (n=425) (rates: 25.6% vs. 28.7%; P=0.50; odds ratio [OR]=0.86; 95% confidence interval [CI]=0.54-1.35), chest tube insertion rate (4.8% vs. 5.6%; P=0.71; OR=0.84; 95% CI=0.34-2.11), or diagnostic adequacy (95% vs. 93%; P=0.36; OR=1.51; 95% CI=0.61-3.72). Multiple logistic regression analysis demonstrated emphysema along the biopsy path (OR=3.12; 95% CI=1.63-5.98) and nodule distance from the pleural surface ≥4 cm (OR=1.85; 95% CI=1.05-3.28) to be independent risk factors for pneumothorax. CONCLUSION: No statistically significant difference in pneumothorax rate or diagnostic adequacy was found between 18-G versus 20-G core biopsy needles. Independent risk factors for pneumothorax include emphysema along the biopsy path and nodule distance from the pleural surface.

Electrochemically Exfoliated Graphene Electrode for High-Performance Rechargeable Chloroaluminate and Dual-Ion Batteries.

The current state-of-the-art positive electrode material for chloroaluminate ion batteries (AIBs) or dual-ion batteries (DIBs) is highly crystalline graphite; however, the rate capability of this material at high discharge currents is significantly reduced by the modest conductivity of graphite. This limitation is addressed through the use of graphene-based positive electrodes, which can improve the rate capability of these batteries due to their higher conductivity. However, conventional methods of graphene production induce a significant number of defects, which impair the performance of AIBs and DIBs. Herein, we report the use of a defect-free graphene positive electrode, which was produced using the electrochemical exfoliation of graphite in an aqueous solution with the aid of Co2+ as an antioxidant. The Co-treated graphene electrode achieved high capacities of 150 mAh g-1 in DIBs and 130 mAh g-1 in AIBs with high rate capability for both batteries. The charge-discharge mechanism of the batteries is examined using in situ Raman spectroscopy, and the results revealed that the intercalation density of [AlCl4]- or [PF6]- increased from a dilute staging index graphite intercalation compound (GIC) to a stage 1 GIC within the operating voltage window. The simple production method of high-quality graphene in conjunction with its high performance in DIBs should enable the use of graphene for DIB technologies.

Systematic Comparison of Graphene Materials for Supercapacitor Electrodes.

A comparison of the performance of graphene-based supercapacitors is difficult, owing to the variety of production methods used to prepare the materials. To the best of our knowledge, there has been no systematic investigation into the effect of the graphene production method on the supercapacitor performance. In this work, we compare graphene produced through several routes. This includes anodic and cathodic electrochemically exfoliated graphene, liquid phase exfoliated graphene, graphene oxide, reduced graphene oxide, and graphene nanoribbons. Graphene oxide exhibited the highest capacitance of approximately 154 F g-1 in 6 M KOH at 0.5 A g-1 attributed to oxygen functional groups giving an additional pseudocapacitance and preventing significant restacking; however, the capacitance retention was poor, owing to the low conductivity. In comparison, the anodic electrochemically exfoliated graphene exhibited a capacitance of approximately 44 F g-1, the highest of the 'pure' graphene materials, which all exhibited superior capacitance retention, owing to their higher conductivity. The cyclability of all of the materials, with the exception of reduced graphene oxide (70 %), was found to be greater than 95 % after 10 000 cycles. These results highlight the importance of matching the graphene production method with a specific application; for example, graphene oxide and anodic electrochemically exfoliated graphene would be best suited for high energy and power applications, respectively.