Interlayer Engineering of VS2 Nanosheets via In Situ Aniline Intercalative Polymerization toward Long-Cycling Magnesium-Ion Batteries.

Rechargeable magnesium batteries (RMBs) show great potential in large-scale energy storage systems, due to Mg2+ with high polarity leading to strong interactions within the cathode lattice, and the limited discovery of functional cathode materials with rapid kinetics of Mg2+ diffusion and desirable cyclability retards their development. Herein, we innovatively report the confined synthesis of VS2/polyaniline (VS2/PANI) hybrid nanosheets. The VS2/PANI hybrids with expanded interlayer spacing are successfully prepared through the exfoliation of VS2 and in situ polymerization between VS2 nanosheets and aniline. The intercalated PANI increases the interlayer spacing of VS2 from 0.57 to 0.95 nm and improves its electronic conductivity, leading to rapid Mg-ion diffusivity of 10-10-10-12 cm2 s-1. Besides, the PANI sandwiched between layers of VS2 is conducive to maintaining the structural integrity of electrode materials. Benefiting from the above advantages, the VS2/PANI-1 hybrids present remarkable performance for Mg2+ storage, showing high reversible discharge capacity (245 mA h g-1 at 100 mA g-1) and impressive long lifespan (91 mA h g-1 after 2000 cycles at 500 mA g-1). This work provides new perspectives for designing high-performance cathode materials based on layered materials for RMBs.

A High-Nickel Layered Double Hydroxides Cathode Boosting the Rate Capability for Chloride Ion Batteries with Ultralong Cycling Life.

Chloride-ion batteries (CIBs) have drawn growing attention in large-scale energy storage applications owing to their comprehensive merits of high theoretical energy density, dendrite-free characteristic, and abundance of chloride-containing materials. Nonetheless, cathodes for CIBs are plagued by distinct volume effect and sluggish Cl- diffusion kinetics, leading to inferior rate capability and short cycling life. Herein, an unconventional Ni5 Ti-Cl LDH is reported with a high nickel ratio as a cathode material for CIB. The reversible capacity of Ni5 Ti-Cl LDH retains 127.9 mAh g-1 over 1000 cycles at a large current density of 1000 mA g-1 , which exceeds that of ever reported CIBs, with extraordinary low volume change of 1.006% during a whole charge/discharge process. Such superior Cl-storage performance is attributed to synergetic contributions consisting of high redox activity from Ni2+ /Ni3+ and pinning Ti that restrains local structural distortion of LDH host layers and enhances adsorption intensity of chloride atoms during the reversible Cl- intercalation/de-intercalation in LDH gallery, which are revealed by a comprehensive study including X-ray photoelectron spectroscopy, kinetic investigations, and DFT calculations. This work provides an effective strategy to design low-cost LDHs materials for high-performance CIBs, which are also applicable to other types of halide-ion batteries (e.g., fluoride-ion and bromide-ion batteries).

Electronic structure engineering on NiSe2 micro-octahedra via nitrogen doping enabling long cycle life magnesium ion batteries.

Multivalent ion batteries have attracted great attention because of their abundant reserves, low cost and high safety. Among them, magnesium ion batteries (MIBs) have been regarded as a promising alternative for large-scale energy storage device owing to its high volumetric capacities and unfavorable dendrite formation. However, the strong interaction between Mg2+ and electrolyte as well as cathode material results in very slow insertion and diffusion kinetics. Therefore, it is highly necessary to develop high-performance cathode materials compatible with electrolyte for MIBs. Herein, the electronic structure of NiSe2 micro-octahedra was modulated by nitrogen doping (N-NiSe2) through hydrothermal method followed by a pyrolysis process and this N-NiSe2 micro-octahedra was used as cathode materials for MIBs. It is worth noting that N-NiSe2 micro-octahedra shows more redox active sites and faster Mg2+ diffusion kinetics compared with NiSe2 micro-octahedra without nitrogen doping. Moreover, the density functional theory (DFT) calculations indicated that the doping of nitrogen could improve the conductivity of active materials on the one hand, facilitating Mg2+ ion diffusion kinetics, and on the other hand, nitrogen dopant sites could provide more Mg2+ adsorption sites. As a result, the N-NiSe2 micro-octahedra cathode exhibits a high reversible discharge capacity of 169 mAh g-1 at the current density of 50 mA g-1, and a good cycling stability over 500 cycles with a maintained discharge capacity of 158.5 mAh g-1. This work provides a new idea to improve the electrochemical performance of cathode materials for MIBs by the introduction of heteroatom dopant.

A Zero-Strain Insertion Cathode Material for Room-Temperature Fluoride-Ion Batteries.

A fluoride-ion battery (FIB) is a novel type of energy storage system that has a higher volumetric energy density and low cost. However, the high working temperature (>150 °C) and unsatisfactory cycling performance of cathode materials are not favorable for their practical application. Herein, fluoride ion-intercalated CoFe layered double hydroxide (LDH) (CoFe-F LDH) was prepared by a facile co-precipitation approach combined with ion-exchange. The CoFe-F LDH shows a reversible capacity of ∼50 mAh g-1 after 100 cycles at room temperature. Although there is still a big gap between FIBs and lithium-ion batteries, the CoFe-F LDH is superior to most cathode materials for FIBs. Another important advantage of CoFe-F LDH FIBs is that they can work at room temperature, which has been rarely achieved in previous reports. The superior performance stems from the unique topochemical transformation property and small volume change (∼0.82%) of LDH in electrochemical cycles. Such a tiny volume change makes LDH a zero-strain cathode material for FIBs. The 2D diffusion pathways and weak interaction between fluoride ions and host layers facilitate the de/intercalation of fluoride ions, accompanied by the chemical state changes of Co2+/Co3+ and Fe2+/Fe3+ couples. First-principles calculations also reveal a low F- diffusion barrier during the cyclic process. These findings expand the application field of LDH materials and propose a novel avenue for the designs of cathode materials toward room-temperature FIBs.

Controllable construction of hierarchically porous carbon composite of nanosheet network for advanced dual-carbon potassium-ion capacitors.

Benefitting from the abundance and inexpensive nature of potassium resources, potassium-ion energy storage technology is considered a potential alternative to current lithium-ion systems. Potassium-ion capacitors (PICs) as a burgeoning K-ion electrochemical energy storage device, are capable of delivering high energy at high power without sacrificing lifespan. However, owing to the sluggish kinetics and significant volume change induced by the large K+-diameter, matched electrode materials with good ion accessibility and fast K+ intercalation/deintercalation capability are urgently desired. In this work, pine needles and graphene oxide (GO) are utilized as precursors to fabricate oxygen-doped activated carbon/graphene (OAC/G) porous nanosheet composites. The introduction of GO not only induces the generation of interconnected nanosheet network, but also increases the oxygen-doping content of the composite, thus expanding the graphite interlayer spacing. Experimental analysis combined with first-principle calculations reveal the transport/storage mechanism of K+ in the OAC/G composite anode, demonstrating that the high surface area, sufficient reactive sites, enlarged interlayer distance and open channels in the porous nanosheet network contribute to rapid and effective K+ diffusion and storage. When incorporated with pine needle-activated carbon as cathode, the assembled dual-carbon PICs can function at a high voltage of 5 V, exhibiting a high energy density of 156.7 Wh kg-1 at a power density of 500 W kg-1 along with a satisfied cycle life, which highlights their potential application in economic and advanced PICs.

An improved bioinspired strategy to construct nitrogen and phosphorus dual-doped network porous carbon with boosted kinetics potassium ion capacitors.

Potassium-ion capacitors (PICs) have drawn appreciable attention because PICs can masterly integrate the virtues of the high energy density of battery-type anode and high power density of capacitor-type cathode. However, the sanguine scenario involves the incompatible capacity and sluggish kinetics in the PIC device. Herein, we report the synthesis of nitrogen and phosphorus-doped network porous carbon materials (NPMCs) via a self-sacrifice template strategy, which possesses a desired three-dimensional structure and prosperous electrochemical properties for K+ storage capacity. The obtained hierarchical porous carbon delivers a high reversible capacity of 420 mA h g-1 at 0.05 A g-1 and good cycling performance owing to its high concentration of reversible carbon defects and strong charge transfer kinetics. As expected, an advanced PIC device was assembled with a working voltage as high as 4.5 V, delivering an extraordinary energy density of 81.6 W h kg-1 as well as a splendid long life. Systematic characterization analysis combined with density functional theory calculations indicates that the strategy for preparing PIC devices with outstanding performance in this work can provide new insights for the development of PICs for an extensive range of applications.

Polyvinylpyrrolidone assisted transformation of Cu-MOF into N/P-co-doped Octahedron carbon encapsulated Cu3P nanoparticles as high performance anode for lithium ion batteries.

The large volume expansion and poor electrical conductivity of copper phosphide (Cu3P) during the cycle limit their further application as anode of lithium-ion batteries. Therefore, polyvinylpyrrolidone (PVP) modified Cu3(BTC)2-derived (BTC = 1, 3, 5-Benzentricarboxylic acid) in-situ N/P-co-doped Octahedron carbon encapsulated Cu3P nanoparticles (Cu3P@NPC) are successfully prepared through a two-step process of carbonization and phosphating. The N/P-co-doped Octahedron carbon matrix improves the conductivity of Cu3P and moderates the volume expansion during the lithiation/delithiation process. Meanwhile, the interaction between the Cu3P and the doped carbon matrix is methodically explored by using density functional theory (DFT). Through the analysis of the partial charge density, the density of states and the Bader charge, and the calculation results verify the correctness of the experimental observation results, that is, Cu3P@NPC has good electrochemical performance. The results show that Cu3P@NPC, as the anode of Lithium-ion batteries, has excellent electrochemical performance: it exhibits satisfactory rate performance (251.9 mAh g-1 at 5.0 A g-1) and excellent cycle performance (336.4 mAh g-1 at 1 A g-1 over 1000 cycles). This article provides an effective strategy for the encapsulation of metal phosphide nanoparticles in a doped carbon matrix.

Carbon defects applied to potassium-ion batteries: a density functional theory investigation.

Functionalized carbon nanomaterials are potential candidates for use as anode materials in potassium-ion batteries (PIBs). The inevitable defect sites in the architectures significantly affect the physicochemical properties of the carbon nanomaterials, thus defect engineering has recently become a vital research area for carbon-based electrodes. However, one of the major issues holding back its further development is the lack of a complete understanding of the effects accounting for the potassium (K) storage of different carbon defects, which have remained elusive. Owing to pressing research demands, the construction strategies, adsorption difficulties, and structure-activity relationships of the carbon defect-involved reaction centers for the K adsorption are systematically summarized using first principles calculations. Carbon defects affect the ability to trap K by affecting the geometry, charge distribution, and conductive behavior of the carbon surface. The results show that carbon doping with pyridinic-N, pyrrolic-N, and P defect sites tend to act as trapping K sites because of electron-deficient sites. However, graphite-N and sulfur doping are less capable of trapping K. In addition, it has been proved using calculations that the defects can inhibit the growth of the K dendrite. Finally, using the molten salt method, we prepared the undoped and nitrogen-doped carbon materials for comparison, verifying the results of the calculation.

Design of a Scalable Dendritic Copper@Ni2+, Zn2+ Cation-Substituted Cobalt Carbonate Hydroxide Electrode for Efficient Energy Storage.

Design and fabrication of novel electrode materials with excellent specific capacitance and cycle stability are urgent for advanced energy storage devices, and the combinability of multiple modification methods is still insufficient. Herein, Ni2+, Zn2+ double-cation-substitution Co carbonate hydroxide (NiZnCo-CH) nanosheets arrays were established on 3D copper with controllable morphology (3DCu@NiZnCo-CH). The self-standing scalable dendritic copper offers a large surface area and promotes fast electron transport. The 3DCu@NiZnCo-CH electrode shows a markedly improved electrochemical performance with a high specific capacity of ∼1008 C g-1 at 1 A g-1 (3.2, 2.83, and 1.26 times larger than Co-CH, ZnCo-CH, and NiCo-CH, respectively) and outstanding rate capability (828.8 C g-1 at 20 A g-1) due to its compositional and structural advantages. Density functional theory (DFT) calculation results illustrate that cation doping adjusts the adsorption process and optimizes the charge transfer kinetics. Moreover, an aqueous hybrid supercapacitor based on 3DCu@NiZnCo-CH and rGO demonstrates a high energy density of 42.29 Wh kg-1 at a power density of 376.37 W kg-1, along with superior cycling performance (retained 86.7% of the initial specific capacitance after 10,000 cycles). Impressively, these optimized 3DCu@NiZnCo-CH//rGO devices with ionic liquid can be operated stably in a large potential range of 4 V with greatly enhanced energy density and power capability (110.12 Wh kg-1 at a power density of 71.69 W kg-1). These findings may shed some light on the rational design of transition-metal compounds with tunable architectures by multiple modification methods for efficient energy storage.

CuO@NiCoFe-S core-shell nanorod arrays based on Cu foam for high performance energy storage.

Growing electroactive materials directly on a three-dimensional conductive substrate can effectively reduce the "ineffective area" of the electrode during the electrochemical reaction, increase the utilization rate of the material, and thus increase the energy density of the device. Using the network structure of the three-dimensional conductive substrate to design electrode materials with unique microstructures can also improve the stability of the materials. In this work, we obtained different copper-based materials on the copper foam (CF) by in-situ growth method, and designed an independent three-dimensional layered CuO@NiCoFe-S (CuO@NCFS) core-shell nanostructure composite material. CuO@NCFS exhibits excellent electrochemical performance, reaching a specific capacitance of 4551 mF cm-2 at a current density of 1 mA cm-2 with good cycle stability (94.2% after 5000 cycles). In addition, the asymmetric supercapacitor (ASC) uses CuO@NCFS as the positive electrode and rGO as the negative electrode, which can provide an energy rate density of 4.5 mW cm-2 at a high energy density of 99.9 µWh cm-2. The findings provide some insight into rational design of electrode materials for high performance energy storage.

Dimensions of Coach Work Passion and Sportsman Performance: An Empirical Study on Psychological Attributes of Athletes in China / Dimensiones de la pasión por el trabajo del entrenador y el rendimiento deportivo: un estudio empírico sobre los atributos psicológicos de los atletas en China

In recent years, the value of sports and other physical activities has increased considerably and the role of the coaches of sportsmen is essential in providing trainings to sportsmen to help them achieve their objectives and improve their performance. The purpose of this study is to understand the passion of sports coaches for their China with the aim of knowing which type of passions yield good performance among sportsmen. For this reason, the study seeks to study the Coaches’ work passion in which harmonious and obsessive work passion was included, and to see its impact on performance of the sportsmen with mediating role of psychological empowerment. To achieve the objectives of this study, quantitative study was carried out in which questionnaires were filled out by respondents including coaches, trainers and sportsmen. After analyzing the questionnaires, it was revealed that there is significant and positive impact of harmonious work passion on the performance of the sportsmen, while in the case of obsessive work passion, the results showed that there is significant and a negative relation of obsessive work passion with the performance of sportsmen. This study contains both theoretical and practical insights that can help stakeholders in the sports sector determine how desired results (in terms of performance) can be obtained from the coaches’ work passion.(AU)