Search

Co-intercalation reactions make graphite as promising anodes for sodium ion batteries, however, the high redox potentials significantly lower the energy density. Herein, we investigate the factors that influence the co-intercalation potential of graphite and find that the tuning of the voltage as large as 0.38 V is achievable by adjusting the relative stability of ternary graphite intercalation compounds and the solvent activity in electrolytes. The feasibility of graphite anode in sodium ion batteries is confirmed in conjunction with Na1.5VPO4.8F0.7 cathodes by using the optimal electrolyte. The sodium ion battery delivers an improved voltage of 3.1 V, a high power density of 3863 W kg−1both electrodes, negligible temperature dependency of energy/power densities and an extremely low capacity fading rate of 0.007% per cycle over 1000 cycles, which are among the best thus far reported for sodium ion full cells, making it a competitive choice in large-scale energy storage systems., Graphite is a promising anode material for sodium-ion batteries but suffers from the high co-intercalation potential. Here, the authors examine the factors influencing this potential and tailor the stability of graphite intercalation compound, realizing high energy and power densities.

Background Various public health measures have been implemented globally to counter the coronavirus disease 2019 (COVID-19) pandemic. The purpose of this study was to evaluate respiratory virus surveillance data to determine the effectiveness of such interventions in reducing transmission of seasonal respiratory viruses. Method We retrospectively analysed data from the Respiratory Virus Detection Surveillance System in Canada, before and during the COVID-19 pandemic, by interrupted time series regression. Results The national level of infection with seasonal respiratory viruses, which generally does not necessitate quarantine or contact screening, was greatly reduced after Canada imposed physical distancing and other quarantine measures. The 2019–2020 influenza season ended earlier than it did in the previous year. The influenza virus was replaced by rhinovirus/enterovirus or parainfluenza virus in the previous year, with the overall test positivity remaining at approximately 35%. However, during the 2019–2020 post-influenza period, the overall test positivity of respiratory viruses during the COVID-19 was still low (7.2%). Moreover, the 2020–2021 influenza season had not occurred by the end of February 2021. Conclusion Respiratory virus surveillance data may provide real-world evidence of the effectiveness of implemented public health interventions during the current and future pandemics.

Silk proteins are of great interest to the scientific community owing to their unique mechanical properties and interesting biological functionality. In addition, the silk proteins are not burned out following heating, rather they are transformed into a carbonaceous solid, pyroprotein; several studies have identified potential carbon precursors for state-of-the-art technologies. However, no mechanism for the carbonization of proteins has yet been reported. Here we examine the structural and chemical changes of silk proteins systematically at temperatures above the onset of thermal degradation. We find that the β-sheet structure is transformed into an sp2-hybridized carbon hexagonal structure by simple heating to 350 °C. The pseudographitic crystalline layers grew to form highly ordered graphitic structures following further heating to 2,800 °C. Our results provide a mechanism for the thermal transition of the protein and demonstrate a potential strategy for designing pyroproteins using a clean system with a catalyst-free aqueous wet process for in vivo applications., The strength and stability of silk proteins is thought to be related to the high content of β-sheets within their structures. Here, the authors show that when heated at high temperature, and above that of thermal degradation, these β-sheets are transformed into an ordered hexagonal graphitic structure.

Here, we investigate the doping effects on the lithium ion transport behavior in garnet Li7La3Zr2O12 (LLZO) from the combined experimental and theoretical approach. The concentration of Li ion vacancy generated by the inclusion of aliovalent dopants such as Al3+ plays a key role in stabilizing the cubic LLZO. However, it is found that the site preference of Al in 24d position hinders the three dimensionally connected Li ion movement when heavily doped according to the structural refinement and the DFT calculations. In this report, we demonstrate that the multi-doping using additional Ta dopants into the Al-doped LLZO shifts the most energetically favorable sites of Al in the crystal structure from 24d to 96 h Li site, thereby providing more open space for Li ion transport. As a result of these synergistic effects, the multi-doped LLZO shows about three times higher ionic conductivity of 6.14 × 10−4 S cm−1 than that of the singly-doped LLZO with a much less efforts in stabilizing cubic phases in the synthetic condition.

Herein, we propose an advanced energy-storage system: all-graphene-battery. It operates based on fast surface-reactions in both electrodes, thus delivering a remarkably high power density of 6,450 W kg(-1)(total electrode) while also retaining a high energy density of 225 Wh kg(-1)(total electrode), which is comparable to that of conventional lithium ion battery. The performance and operating mechanism of all-graphene-battery resemble those of both supercapacitors and batteries, thereby blurring the conventional distinction between supercapacitors and batteries. This work demonstrates that the energy storage system made with carbonaceous materials in both the anode and cathode are promising alternative energy-storage devices.

Lithium–oxygen chemistry offers the highest energy density for a rechargeable system as a “lithium–air battery”. Most studies of lithium–air batteries have focused on demonstrating battery operations in pure oxygen conditions; such a battery should technically be described as a “lithium–dioxygen battery”. Consequently, the next step for the lithium–“air” battery is to understand how the reaction chemistry is affected by the constituents of ambient air. Among the components of air, CO_2 is of particular interest because of its high solubility in organic solvents and it can react actively with O_2–•, which is the key intermediate species in Li–O_2 battery reactions. In this work, we investigated the reaction mechanisms in the Li–O_2/CO_2 cell under various electrolyte conditions using quantum mechanical simulations combined with experimental verification. Our most important finding is that the subtle balance among various reaction pathways influencing the potential energy surfaces can be modified by the electrolyte solvation effect. Thus, a low dielectric electrolyte tends to primarily form Li_2O_2, while a high dielectric electrolyte is effective in electrochemically activating CO_2, yielding only Li_2CO_3. Most surprisingly, we further discovered that a high dielectric medium such as DMSO can result in the reversible reaction of Li_2CO_3 over multiple cycles. We believe that the current mechanistic understanding of the chemistry of CO_2 in a Li–air cell and the interplay of CO_2 with electrolyte solvation will provide an important guideline for developing Li–air batteries. Furthermore, the possibility for a rechargeable Li–O_2/CO_2 battery based on Li_2CO_3 may have merits in enhancing cyclability by minimizing side reactions.