The impact of the solid film deposit (mainly Li2S) on the complex electrochemistry of a Li–S cell is studied in detail. Already a simple, straightforward experiment strongly indicates that this impact might be much smaller than usually assumed. Notably, a similar phenomenon is demonstrated for another battery operated on the same basic principle: the magnesium–sulfur battery. In order to better detect the surface-specific phenomena associated with formation and properties of the solid surface deposit, we construct special electrochemical cells with a flat glassy carbon disc or other well-defined materials. Different model systems are prepared in which crucial variables such as the electrode configuration, separator type, and state of charge are varied in a systematic and controlled way. Electrochemical results are supplemented with data from microstructural analysis, in particular focused ion beam–scanning electron microscopy (FIB-SEM) imaging and X-ray diffraction analysis. We show that the growth of the surface film is more complex than generally assumed and that its defect-rich morphology hardly represents any obstacle for electrochemical reaction(s) to take place. Rather, the cell operation is limited by diffusional processes and depletion of polysulfide concentration in electrolyte. The new insight into the occurrence, properties, and especially the impact of solid film deposits on operation of the Li–S system is expected to have important implications for future design of Li–S practical cells.

The limpet radula is a feeding organ, which contains more than 100 rows of teeth. During their growth the teeth mature and advance in position along the radula. The simpler doccoglossan radulae operate by grinding rocky substrates, extracting the algae by rasping and scraping with the teeth functioning as shovels. Less is known about the rhipidoglossan radulae, used as rakes or brooms that brush and collect loose marine debris. This type of radula is found in the giant keyhole limpet (Megathura crenulata). The large size of this organism suggests that the rhipidoglossan radula entails a technological superiority for M. crenulata in its habitat. The structure and function of the radulae teeth have however not been reported in detail. Using a combination of 2D and 3D microscopy techniques coupled with amino acid analysis and X-ray scattering, we reveal the working components of M. crenulata’s radula. It is characterized by numerous marginal teeth surrounding a pair of major hook-like lateral teeth, two pairs of minor lateral teeth and a large central tooth. The mature major lateral teeth show pronounced signs of wear, which gradually increase towards the very front end of the radula and are evidence for scraping. An abrupt change in the amino acid composition in the major lateral teeth and the concurrent formation of a chitinous fiber-network mark the onset of tooth maturation. In comparison to the simpler rock-scraping doccoglossate limpets, the radula of M. crenulata forms an elaborate feeding apparatus, which can be seen as a natural harvest machine.

Metallic lithium is considered to be one of the most promising anode materials since it offers high volumetric and gravimetric energy densities when combined with high-voltage or high-capacity cathodes. However, the main impediment to the practical applications of metallic lithium is its unstable solid electrolyte interface (SEI), which results in constant lithium consumption for the formation of fresh SEI, together with lithium dendritic growth during electrochemical cycling. Here we present the electrochemical performance of a fluorinated reduced graphene oxide interlayer (FGI) on the metallic lithium surface, tested in lithium symmetrical cells and in combination with two different cathode materials. The FGI on the metallic lithium exhibit two roles, firstly it acts as a Li-ion conductive layer and electronic insulator and secondly, it effectively suppresses the formation of high surface area lithium (HSAL). An enhanced electrochemical performance of the full cell battery system with two different types of cathodes was shown in the carbonate or in the ether based electrolytes. The presented results indicate a potential application in future secondary Li-metal batteries.

In this work, abundant and environmentally friendly nano-fibrillated (NFC) cellulose is used for fabrication of porous separator membranes according to the procedure adopted from papermaking industry. As-prepared NFC separators were characterized in terms of thickness, porosity, wettability, electrochemical stability and electrochemical performance in lithium-sulfur and Li-symmetrical pouch cells and compared to a commercial Celgard 2320 separator membrane. Results demonstrated that morphology and electrochemical performance of NFC separator outperforms the conventional polyolefin separator. Due to exceptional interplay between lithium metal and cellulose, this research provides a self-standing NFC separator that can be used besides the lithium-sulfur also in other lithium metal battery configurations.

Revealed degradation mechanisms in the HSA CSP coatings through accelerated testing and materials characterization enable absorber service life prediction.