Controlled and sustained release of drug-like small molecules in an aqueous medium still remains a challenging problem due to rapid infiltration of liquid water in most reported drug release systems. However, internal-superhydrophobicity with an antifouling property extending beyond the surface of a material recently has been recognized as a potential avenue for sustained and extended release of drug-like small molecules. Sluggish removal of metastable trapped air in a superhyrophobic material provides a basis to achieve extended release of encapsulated small molecules. In this article, naturally abundant medical-cotton-extensively used in wound management including control of bleeding, absorbance of secretions and protecting wounds from contamination-is strategically exploited in tailoring (from rapid to extended) the release of small molecules by appropriate modulation of liquid water wettability. Modulation included bio-mimicked adhesive and non-adhesive superhydrophobicity of the medical cotton without erosion of any polymeric material. In this process, amine 'reactive' nano-complexes (RNC) were prepared by just mixing branched poly(ethylenimine) (BPEI) with dipentaerythritol pentaacrylate (5Acl) in ethanol with appropriate compositions. Then they were covalently immobilized on fibrous medical-cotton through a facile and robust 1,4-conjugated addition reaction. Residual acrylate moieties in the immobilized RNC provide an opportunity to tailor water wettability through strategic and appropriate post-chemical modification of RNC-coated medical cotton with a primary amine containing various small molecules. This medical-cotton with tunable wettability was exploited further to control the release rate of small molecules from rapid (<24 h) to sustained (>100 days) times. A volatile solvent induced transient and reversible switching of anti-fouling properties which allowed further varying the amount of post-loading small molecules into the medical cotton up to 2.36 wt% without compromising the embedded anti-wetting property. Thus, our current approach has immense potential to develop appropriate materials for a sustained and controlled release of small molecules from a clinically relevant substrate (i.e., medical-cotton) and may be useful in various bio-medical applications including improving wound management, preventing bacterial infections, better pain management, etc.

Silyl groups are included in a wide range of electrolyte additives to enhance the performance of state-of-the-art Li-ion batteries. A recognized representative thereof is tris-(trimethylsilyl)­phosphate (TMSPa) which, along with the similarly structured phosphite, has been at the center of numerous electrolyte studies. Even though the silyl group has already been widely reported to be specifically reactive towards fluorides, herein, a reactivity towards several Lewis bases typically found in Li-ion cells is postulated and investigated with the aim to establish a more simplified and generally applicable reaction mechanism thereof. Both gaseous and electrolyte soluble reactants and products are monitored by combining nuclear magnetic resonance and injection cell-coupled mass spectrometry. Experimental observations are supported by computational models. The results clearly demonstrate that the silyl groups react with water, hydroxide, and methoxide and thereby detach in a stepwise fashion from the central phosphate in TMSPa. Intermolecular interaction between TMSPa and the reactants likely facilitates dissolution and lowers the free energy of reaction. Lewis bases are well known to trigger side reactions involving both the Li-ion electrode and electrolyte. By effectively scavenging these, the silyl group can be explained to lower cell impedance and prolong the lifetime of modern Li-ion batteries.

Ethylene carbonate (EC) is the archetype solvent in Li-ion batteries. Still, questions remain regarding the numerous possible reaction pathways of EC. Although the reaction pathway involving direct EC reduction and solid electrolyte interface (SEI) formation is most commonly discussed, EC ring-opening is often observed, but seldom addressed, especially with respect to SEI formation. By applying online electrochemical mass spectrometry, the EC ring-opening reaction on carbon is found to start already at ~2.5 V vs. Li+/Li as initiated by oxygenic carbon surface groups. Later, OH- generated from H2O reduction reaction at ~1.6 V further propagates EC to ring-open. The EC reduction reaction occurs <0.9 V, but is suppressed depending on the extent of EC ring-opening at higher potentials. Electrode/electrolyte impurities and handling conditions are found to have a significant influence on both processes. In conclusion, SEI formation is shown to be governed by several kinetically competing reaction pathways whereby EC ring-opening can play a significant role.

The solid electrolyte interphase (SEI) is arguably one of the most critical components of the Li‐ion cell. Despite decades of studies of the SEI, its intrinsic complexity and the lack of suitable characterization tools still prevent a real consensus on the governing mechanisms to be reached. Herein, operando Raman spectroscopy supported by complimentary online electrochemical mass spectrometry is employed to study the SEI formation on Au in a model electrolyte based on LiClO4 in ethylene carbonate (EC). Both the electrolyte itself and cell contaminants, such as O2, CO2, and H2O, contribute in stepwise electro‐/chemical processes to the build‐up of the SEI. Effects associated with electrode/electrolyte double‐layer charging, electrode adsorbate polarization (stark effect), and SEI dissolution are discerned. Lithium carbonate and lithium oxide are identified as major products formed already ≈2 V versus Li+/Li. Although Raman spectroscopy provides deeper insights into the underlying mechanisms, complementary techniques are necessary to support spectral interpretations. Classical challenges in the field of surface science, such as contaminations, have to be systematically addressed if the puzzle of the SEI ever will be completed.

The initial formation cycles are critical to the performance of a lithium-ion battery (LIB), particularly in the case of silicon anodes, where the high surface area and extreme volume expansion during cycling make silicon susceptible to detrimental side reactions with the electrolyte. The solid electrolyte interface (SEI) that is formed during these initial cycles serves to protect the surface of the anode from a continued reaction with the electrolyte, and its composition reflects the composition of the electrolyte. In this work, ReaxFF reactive force field simulations were used to investigate the interactions between ether-based electrolytes with high LiTFSI salt concentrations (up to 4 mol/L) and a silicon oxide surface. The simulation investigations were verified with galvanostatic testing and post-mortem X-ray photoelectron spectroscopy, revealing that highly concentrated electrolytes resulted in the faster formation and SEIs containing more inorganic and silicon species. This study emphasizes the importance of understanding the link between electrolyte composition and SEI formation. This ReaxFF approach demonstrates an accessible way to tune electrolyte compositions for optimized performance without costly, time-consuming experimentation.