Three different polymers were synthesized and evaluated as solid polymer electrolytes: poly(ε-caprolactone) (PCL), polystyrene-poly(ε-caprolactone) (SC), and polystyrene-poly(ε-caprolactone-r-trimethylene carbonate) (SCT).

Na-O batteries are regarded as promising candidates for energy storage. They have higher energy efficiency, rate capability, and chemical reversibility than Li-O batteries; in addition, sodium is cheaper and more abundant compared to lithium. However, inconsistent observations and instability of discharge products have inhibited the understanding of the working mechanism of this technology. In this work, we have investigated a number of factors that influence the stability of the discharge products. By means of in operando powder X-ray diffraction study, the influence of oxygen, sodium anode, salt, solvent, and carbon cathode were investigated. The Na metal anode and an ether-based solvent are the main factors that lead to the instability and decomposition of NaO in the cell environment. This fundamental insight brings new information on the working mechanism of Na-O batteries.

The interaction between a fibre optic evanescent wave sensor and the positive electrode material, lithium iron phosphate, in a battery cell is presented. The optical–electrochemical combination was investigated in a reflection‐based and a transmission‐based configuration, both leading to comparable results. Both constant current cycling and cyclic voltammetry were employed to link the optical response to the charge and discharge of the battery cells, and the results demonstrated that the optical signal changed consistently with lithium ion insertion and extraction. More precisely, cyclic voltammetry showed that the intensity increased when iron was oxidised during charge and then decreased as iron was reduced during discharge. Cyclic voltammetry also revealed that the optical signal remained unchanged when essentially no oxidation or reduction of the electrode material took place. This shows that optical fibre sensors may be used as a way of monitoring state of charge and electrode properties under dynamic conditions.

Optical fiber sensors integrated into sodium-ion batteries could provide a battery management system (BMS) with information to identify early warning signs of plating, preventing catastrophic failure and maintaining safe operation during fast charging. This work shows the possibility of directly detecting plating of sodium metal in electrochemical cells by means of operando fiber optic evanescent wave (FOEW) spectroscopy. The results include measurements with FOEW sensors on bare copper substrates as well as on hard carbon anodes during operation in both half-and full-cell configurations. Full cells using hard carbon anodes and Prussian white cathodes with high areal capacities (>1.5 mAh cm −2 ) and integrated FOEW sensors are shown to cycle well in pouch cells. The results also include measurements to demonstrate plating on hard carbon during sodiation at different rates.

The aim was to determine the fluoride concentration in saliva after intake of a dinner meal prepared with fluoridated salt. The investigation had a randomized cross-over design, and 10 healthy adolescents with natural fluoride content (1.06 ppm) in their drinking water participated after informed consent. After a run-in week, the subjects were served a standardized dinner of spaghetti with minced meat sauce prepared with either fluoridated salt (test arm) or non-fluoridated salt (control arm). The fluoride concentration of the test salt was 250 ppm. Samples of stimulated whole saliva was collected at baseline, directly after eating (0 min) and then after 10, 30 and 180 min. After a 1-week wash-out period, the experimental procedure was repeated with the opposite salt. Fluoride concentration in saliva was measured with a fluoride-specific electrode and the post-ingestion levels were compared with baseline using repeated-measures ANOVA.The mean baseline concentrations were 10.9 and 8.0 µg/l in the test and control arms, respectively. Immediately after the intake, the mean fluoride values increased significantly to 81.6 µg/l in the test arm and to 31.5 µg/l in the control arm (p < 0.05). The fluoride levels remained elevated (p < 0.05) for 30 min after ingestion of the test meal but not following the control meal. In conclusion, consumption of a dinner meal prepared with fluoridated salt increased the salivary fluoride levels for about 30 min.