Nano-Porous Light-Emitting Silicon Chip as a Potential Biosensor Platform

Nano-porous silicon (PS) offers a potential platform for biosensors with benefits both in terms of light emission and the large functional surface area. A light emitting PS chip with a stable and functional surface was fabricated in our laboratory. When protein was deposited on it, the light emission was reduced in proportion to the protein concentration. Based on this property, we developed a rudimentary demonstration of a label-free sensor to detect bovine serum albumin (BSA). A serial concentration of BSA was applied to the light chip and the reduction in light emission was measured. The reduction of the light intensity was linearly related to the concentration of the BSA at concentrations below 10-5 M. The detection limit was 8×10-9 M

Intermolecular Chemistry in Solid Polymer Electrolytes for High-Energy-Density Lithium Batteries

Solid polymer electrolytes (SPEs) have aroused wide interest in lithium batteries because of their sufficient mechanical properties, superior safety performances, and excellent processability. However, ionic conductivity and high-voltage compatibility of SPEs are still yet to meet the requirement of future energy-storage systems, representing significant barriers to progress. In this regard, intermolecular interactions in SPEs have attracted attention, and they can significantly impact on the Li+ motion and frontier orbital energy level of SPEs. Recent advances in improving electrochemcial performance of SPEs are reviewed, and the underlying mechanism of these proposed strategies related to intermolecular interaction is discussed, including ion-dipole, hydrogen bonds, pi-pi stacking, and Lewis acid-base interactions. It is hoped that this review can inspire a deeper consideration on this critical issue, which can pave new pathway to improve ionic conductivity and high-voltage performance of SPEs

Revealing the importance of suppressing formation of lithium hydride and hydrogen in Li anode protection

Abstract The reviving of the “Holy Grail” lithium metal batteries (LMBs) is greatly hindered by severe parasitic reactions between Li anode and electrolytes. Herein, first, we comprehensively summarize the failure mechanisms and protection principles of the Li anode. Wherein, despite being in dispute, the formation of lithium hydride (LiH) is demonstrated to be one of the most critical factors for Li anode pulverization. Secondly, we trace the research history of LiH at electrodes of lithium batteries. In LMBs, LiH formation is suggested to be greatly associated with the generation of H2 from Li/electrolyte intrinsic parasitic reactions, and these intrinsic reactions are still not fully understood. Finally, density functional theory calculations reveal that H2 adsorption ability of representative Li anode protective species (such as LiF, Li3N, BN, Li2O, and graphene) is much higher than that of Li and LiH. Therefore, as an important supplement of well‐known lithiophilicity theory/high interfacial energy theory and three key principles (mechanical stability, uniform ion transport, and chemical passivation), we propose that constructing an artificial solid electrolyte interphase layer enriched of components with much higher H2 adsorption ability than Li will serve as an effective principle for Li anode protection. In summary, suppressing formation of LiH and H2 will be very important for cycle life enhancement of practical LMBs

High-voltage Zn/LiMn0.8Fe0.2PO4 aqueous rechargeable battery by virtue of “water-in-salt” electrolyte

A LiMn0.8Fe0.2PO4 cathode and a Zn anode, for the first time, are combined in a full cell possessing a high operating voltage exceeding 1.8 V. By virtue of a water-in-salt electrolyte containing lithium bis(trifluoromethane sulfonyl)imide (LiTFSI) and ZnSO4, two reversible reactions of Li+ extraction/insertion (cathode) and Zn dissolution/deposition (anode) can be realized in the aqueous system. Such novel battery delivers an energy density of 183 Wh/kg based on the total mass of the active electrode materials. The high reversibility of the system enables sustaining more than 150 cycles (0.3 C) without obvious capacity fading. Moreover, it is demonstrated that the electrochemical characteristics of the LiMn0.8Fe0.2PO4 is critically dependent on the pH value of the electrolyte. Keywords: Zinc-based batteries, LiMnxFe1−xPO4, Water-in-salt electrolyte, Aqueous batteries, High voltag

A label free electrochemical nanobiosensor study

Nano-porous silicon (PS) is an attractive material for incorporation into biosensors, because it has a large surface area combined with the ability to generate both optical and electrical signals. In this paper, we describe a label-free nanobiosensor for bovine serum albumin (BSA). Nano-porous silicon produced in our laboratory was functionalized prior to immobilization of anti-BSA antibody on the surface. Reaction with BSA in phosphate buffered saline (PBS) buffer resulted in an impedance change which was inversely proportional to the concentration of the analyte. The system PBS buffer/antigen-antibody/PS constitutes an electrolyte-insulator-semiconductor (EIS) structure, thus furnishing an impedance EIS nanobiosensor. The linear range of the sensor was 0-0.27 mg mL-1 and the sensitivity was less than 10 µg mL-1

Uneven Stripping Behavior, an Unheeded Killer of Mg Anodes

Uniform magnesium (Mg) plating/stripping under high areal capacity utilization is critical for the practical application of Mg-metal anodes in rechargeable Mg batteries. However, the failure of the Mg-metal anode when cycling under a practical areal capacity (>4 mA h cm$^{−2}$), is of rising concern. The mechanism behind these failures remains controversial. In this work, it is illustrated that the initial plating Mg can be undoubtedly uniform in a wide range of current densities (≤5 mA cm$^{−2}$) and under a practical areal capacity (6 mA h cm$^{−2}$). However, an unusual self-accelerating pit growth is observed in the Mg stripping side under moderate current densities (0.1–1 mA cm$^{−2}$), which severely deteriorates the anode integrity and subsequent Mg plating uniformity, causing failure of the Mg-metal anode or short circuit of the battery. The stripping morphology depends on the applied current density, as non-uniformity versus the current density displays a volcano plot during the stripping process. Through in situ spectroscopy, it is illustrated that this current-dependent behavior is determined by the evolution of chlorine-containing complex ions near the interface. This research reminds that the plating/stripping process of the Mg-metal anode must be considered comprehensively for practical Mg-metal batteries

Singlet oxygen and dioxygen bond cleavage in the aprotic lithium-oxygen battery

Investigation of lithium-oxygen cells on discharge using a mixture of 16O16O and 18O18O gases, showed that O–O bond cleavage occurs during disproportionation of LiO2 to O2 and Li2O2, detected by the presence of isotopic 16O18O. The formation of singlet oxygen, 1O2, was also monitored during disproportionation. While only 4.5% of oxygen was found to undergo bond cleavage and scrambling of oxygen atoms, more than 40% of the singlet oxygen produced during disproportionation came from the scrambling pathway, making it a major source of singlet oxygen generation in lithium-oxygen batteries. Our results demonstrate that Li2O2 formation occurs predominantly by disproportionation, and by controlling the pathway of this step, it may be possible to suppress 1O2 formation, a species that has been implicated in the degradation of lithium-oxygen batteries