Temperature-Tunable Operando Nondestructive Detection of Electronic and Geometrical Structures in Battery Electrodes.

Real-time monitoring of the structural evolution of battery materials is crucial for understanding their underlying reaction mechanisms, which cannot be satisfied by the typically used post-mortem analysis. While more and more operando techniques were constructed and employed, they are all based on ambient working conditions that are not generally the case for real-world applications. Indeed, batteries work in an environment where self-heat dissipation increases the surrounding temperature, and extreme temperature applications (<-20 °C or >60 °C) are also frequently proposed. Operando characterization techniques under variable temperatures are therefore highly desired for tracking battery reactions under real-working conditions. Here, we develop a methodology to operando monitor the electronic and geometrical structures of battery materials over a wide range of temperatures based on X-ray spectroscopies. It is substantiated with data collected on a model LiNi0.90Co0.05Mn0.05O2/Si@C pouch cell under operando quick X-ray absorption fine structure spectroscopy, by which we found a temperature-dependent structure evolution behavior that is highly correlated with the electrochemical performance. Our work establishes an exemplary protocol for analyzing battery materials under temperature-variable environments that can be widely used in other related fields.

Corrosion inhibition activity of a natural polysaccharide from Dysosma versipellis using tailor-made deep eutectic solvents.

In this work, a total of 18 types of choline chloride, betaine, and L-proline-based deep eutectic solvents (DESs) were synthesized to determine the extraction yield of a natural polysaccharide (PSA) from Dysosma versipellis using an ultrasound-assisted extraction method. Results indicate that the choline-oxalic acid-based DES has the best extraction yield for PSA due to the proper physical-chemical properties between PSA and DES. To evaluate the optimal extraction conditions, a response surface methodology was carried out. Under the optimal conditions, the extraction yield of PSA reaches 10.37 % (± 0.03 %), higher than the conventional extraction methods. Findings from FT-IR and NMR suggest that the extracted PSA belongs to a neutral polysaccharide with (1 â†’ 6)-linked α-d-glucopyranose in the main chain. Interestingly, results from various electrochemical measurements show the extracted PSA exhibits excellent corrosion inhibition performance for mild steel (MS) in a 0.5 M HCl solution, with 90.8 % of maximum corrosion inhibition efficiency at 210 mg L-1. SEM and XPS measurements reveal the formation of a protective layer on the MS surface. The adsorption behaviour of extracted PSA well obeys the Langmuir adsorption isotherm containing the chemisorption and physisorption. Additionally, theoretical calculations validate the experimental findings.

Eu-TiO2 Nanocomposite with High Photoelectrochemical Activity for Enhanced Photocatalysis of Rhodamine B.

A novel Eu-TiO2 nanocomposite prepared by a sol-gel method is used for the degradation of rhodamine B (RhB) present in dyes wastewater. The X-ray diffraction (XRD), Raman spectroscopy and transmission electron microscopy (TEM) show the anatase phase and globular shape of Eu- TiO2 nanocomposite, UV-vis diffuse reflectance spectroscopy and low temperature N2 adsorption (BET) indicate Eu-TiO2 possesses a narrow band gap (2.98 eV) and a high specific surface area (112.1 m² · g-1), respectively. Furthermore, the prepared Eu-TiO2 exhibits unprecedented higher photocatalytic activity towards RhB than P25 TiO2. The degradation ratio of RhB is up to 93% within 100 min irradiation of simulated solar lights by the obtained Eu-TiO2, which demonstrated firstly by the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis. The high photocatalytic performance may be ascribed to the efficient Eu loading in favor of the absorption of visible-light and the separation of photogenerated charges.