Decreased Electrically and Increased Ionically Conducting Scaffolds for Long-Life, High-Rate and Deep-Capacity Lithium-Metal Anodes.

Lithium (Li) metal batteries are deemed as promising next-generation power solutions but are hindered by the uncontrolled dendrite growth and infinite volume change of Li anodes. The extensively studied 3D scaffolds as solutions generally lead to undesired "top-growth" of Li due to their high electrical conductivity and the lack of ion-transporting pathways. Here, by reducing electrical conductivity and increasing the ionic conductivity of the scaffold, the deposition spot of Li to the bottom of the scaffold can be regulated, thus resulting in a safe bottom-up plating mode of the Li and dendrite-free Li deposition. The resulting symmetrical cells with these scaffolds, despite with a limited pre-plated Li capacity of 5 mAh cm-2, exhibit ultra-stable Li plating/stripping for over 1 year (11 000 h) at a high current density of 3 mA cm-2 and a high areal capacity of 3 mAh cm-2. Moreover, the full cells with these scaffolds further demonstrate high cycling stability under challenging conditions, including high cathode loading of 21.6 mg cm-2, low negative-to-positive ratio of 1.6, and limited electrolyte-to-capacity ratio of 4.2 g Ah-1.

Nitrogen-Doped and Sulfonated Carbon Dots as a Multifunctional Additive to Realize Highly Reversible Aqueous Zinc-Ion Batteries.

Aqueous zinc-ion batteries (ZIBs) using the Zn metal anode have been considered as one of the next-generation commercial batteries with high security, robust capacity, and low price. However, parasitic reactions, notorious dendrites and limited lifespan still hamper their practical applications. Herein, an eco-friendly nitrogen-doped and sulfonated carbon dots (NSCDs) is designed as a multifunctional additive for the cheap aqueous ZnSO4 electrolyte, which can overcome the above difficulties effectively. The abundant polar groups (-COOH, -OH, -NH2 , and -SO3 H) on the CDs surfaces can regulate the solvation structure of Zn2+ through decreasing the coordinated active H2 O molecules, and thus redistribute Zn2+ deposition to avoid side reactions. Some of the negatively charged NSCDs are adsorbed on Zn anode surface to isolate the H2 O/SO4 2- corrosion through the electrostatic shielding effect. The synergistic effect of the doped nitrogen species and the surface sulfonic groups can induce a uniform electrolyte flux and a homogeneous Zn plating with a (002) texture. As a result, the excellent cycle life (4000 h) and Coulombic efficiency (99.5%) of the optimized ZIBs are realized in typical ZnSO4 electrolytes with only 0.1 mg mL-1 of NSCDs additive.

A Multi-Atlas-Based [18F]9-Fluoropropyl-(+)-Dihydrotetrabenazine Positron Emission Tomography Image Segmentation Method for Parkinson's Disease Quantification.

Objectives: [18F]9-fluoropropyl-(+)-dihydrotetrabenazine ([18F]-FP-DTBZ) positron emission tomography (PET) provides reliable information for the diagnosis of Parkinson's disease (PD). In this study, we proposed a multi-atlas-based [18F]-FP-DTBZ PET image segmentation method for PD quantification assessment. Methods: A total of 99 subjects from Xuanwu Hospital of Capital Medical University were included in this study, and both brain PET and magnetic resonance (MR) scans were conducted. Data from 20 subjects were used to generate atlases, based on which a multi-atlas-based [18F]-FP-DTBZ PET segmentation method was developed especially for striatum and its subregions. The proposed method was compared with the template-based method through striatal subregion parcellation performance and the standard uptake value ratio (SUVR) quantification accuracy. Discriminant analysis between healthy controls (HCs) and PD patients was further performed. Results: Segmentation results of the multi-atlas-based method showed better consistency than the template-based method with the ground truth, yielding a dice coefficient of 0.81 over 0.73 on the full striatum. The SUVRs calculated by the multi-atlas-based method had an average interclass correlation coefficient (ICC) of 0.953 with the standardized result, whereas the template-based method only reached 0.815. The SUVRs of HCs were generally higher than that of patients with PD and showed significant differences in all of the striatal subregions (all p < 0.001). The median and posterior putamen performed best in discriminating patients with PD from HCs. Conclusion: The proposed multi-atlas-based [18F]-FP-DTBZ PET image segmentation method achieved better performance than the template-based method, indicating great potential in improving accuracy and efficiency for PD diagnosis in clinical routine.

In-Situ Growth of Mn3 O4 Nanoparticles on Nitrogen-Doped Carbon Dots-Derived Carbon Skeleton as Cathode Materials for Aqueous Zinc Ion Batteries.

Mn3 O4 is a promising cathode material for aqueous zinc ion batteries (ZIBs) which is a new type of low cost, eco-friendly, high security energy storage system, while those previously reported electrochemical capacities of Mn3 O4 are far from its theoretical value. In this work, Mn3 O4 nanoparticles and nitrogen-doped carbon dots (NCDs) are synthesized together through an in-situ hydrothermal route, and then calcined to be a nanocomposite in which Mn3 O4 nanoparticles are anchored on a nitrogen-doped carbon skeleton (designated as Mn3 O4 /NCDs). Although the carbon content is only 3.9 wt.% in the Mn3 O4 /NCDs, the NCDs-derived carbon skeleton provides an electrically conductive network and a stable structure. Such a special nanocomposite has a large specific surface area, plenty of active sites, excellent hydrophilicity and good electronic conductivity. Owing to these structural merits, the Mn3 O4 /NCDs electrode exhibits a preeminent specific capacity of 443.6 mAh g-1 and 123.3 mAh g-1 at current densities of 0.1 and 1.5 A g-1 in ZIBs, respectively, which are far beyond the bare Mn3 O4 nanoparticles synthesized under the similar condition. The electrochemical measurement results prove that carbon dots, as a new type of carbon nanomaterials, have strong ability to modify and improve the performance of existing electrode materials, which may push these electrode materials forward to practical applications.

Black Phosphorus Stabilizing Na2Ti3O7/C Each Other with an Improved Electrochemical Property for Sodium-Ion Storage.

Sodium-ion batteries have increasingly been considered as an attractive alternative to lithium-ion batteries for large-scale applications. High specific capacity and suitable working potential anode materials are one of the keys to search for future developments. Here, a novel and stable sodium titanate/carbon-black phosphorus (NTO/C-BP) hybrids are first fabricated as a promising anode material for advanced sodium-ion batteries. Under the protection of argon (Ar) atmosphere, the direct high-energy mechanical milling of the BP nanoparticle and NTO/C results in the formation of NTO/C-BP hybrids. In other words, the BP nanoparticle can be interconnected with bare NTO by P-O-Ti bonds and/or form stable P-C bonds with the carbon coating layer on the surface of NTO. The NTO/C-BP hybrids are not only beneficial for enhancing specific capacity but also have a great protective effect on the exposure of BP to air by the synergistic effect between BP and NTO/C. The results show that the NTO/C-BP hybrids can deliver very high specific capacity (∼225 mA h g-1 after 55 cycles at 20 mA g-1, ∼183 mA h g-1 after 100 cycles at 100 mA g-1). It is expected from these scientific findings that forming stable P-C bonds and P-O-Ti bonds in this work can serve as a guidance to other Ti-based and P-based electrode materials for practical large-scale application of sodium-ion batteries.