High-Areal Capacity, High-Rate Lithium Metal Anodes Enabled by Nitrogen-Doped Graphene Mesh.

Hosts hold great prospects for addressing the dendrite growth and volume expansion of the Li metal anode, but Li dendrites are still observable under the conditions of high deposition capacity and/or high current density. Herein, a nitrogen-doped graphene mesh (NGM) is developed, which possesses a conductive and lithiophilic scaffold for efficient Li deposition. The abundant nanopores in NGM can not only provide sufficient room for Li deposition, but also speed up Li ion transport to achieve a high-rate capability. Moreover, the evenly distributed N dopants on the NGM can guide the uniform nucleation of Li so that to inhibit dendrite growth. As a result, the composite NGM@Li anode shows satisfactory electrochemical performances for Li-S batteries, including a high capacity of 600 mAh g-1 after 300 cycles at 1 C and a rate capacity of 438 mAh g-1 at 3 C. This work provides a new avenue for the fabrication of graphene-based hosts with large areal capacity and high-rate capability for Li metal batteries.

Enhancing Reversibility and Stability of Mg Metal Anodes: High-Exposure (002) Facets and Nanosheet Arrays for Superior Mg Plating/Stripping.

Magnesium metal batteries (MMBs), recognized as promising contenders for post-lithium battery technologies, face challenges such as uneven magnesium (Mg) plating and stripping behaviors, leading to uncontrollable dendrite growth and irreversible structural damage. Herein, we have developed a Mg foil featuring prominently exposed (002) facets and an architecture of nanosheet arrays (termed (002)-Mg), created through a one-step acid etching method. Specifically, the prominent exposure of Mg (002) facets, known for their inherently low surface and adsorption energies with Mg atoms, not only facilitates smooth nucleation and dense deposition but also significantly mitigates side reactions on the Mg anode. Moreover, the nanosheet arrays on the surface evenly distribute the electric field and Mg ion flux, enhancing Mg ion transfer kinetics. As a result, the fabricated (002)-Mg electrodes exhibit unprecedented long-cycle performance, lasting over 6000 h (> 8 months) at a current density of 3 mA cm-2 for a capacity of 3 mAh cm-2. Furthermore, the corresponding pouch cells equipped with various electrolytes and cathodes demonstrate remarkable capacity and cycling stability, highlighting the superior electrochemical compatibility of the (002)-Mg electrode. This study provides new insights into the advancement of durable MMBs by modifying the crystal structure and morphology of Mg.

The comparison of the effect of two methods of face-to-face and E-learning education on learning, retention, and interest in English language course.

This study compared the effect of two face-to-face(F2F) and e-learning education methods on learning, retention, and interest in English language courses. Participants were EFL students studying at Islamic Azad University, for the academic year 2021-2022. A multiple-stage cluster-sampling method was used to select the target participants. Three hundred and twenty EFL learners participated in the study. Students were studying in different majors: accounting, economics, psychology, physical education, law, management, and sociology. Two English tests were applied, a teacher-made VTS (Vocabulary Size Test) and an achievement test (including reading comprehension and grammar questions). Also, a questionnaire was applied to measure the students' learning interest in F2F and online learning groups. The study found significant differences in learning outcomes related to students' English learning and vocabulary retention rates. It was seen that the E-learning group that participated in online sessions through the Learning Management Systems (LMS) platform outperformed the F2F group. Another critical finding revealed that learners' interest in learning English in E-learning classes was higher than in the F2F group. In addition, all constructs of interest (feeling happy, attention, interest, and participation) were higher in scores in the E-learning than in the F2F group. Language teachers, university instructors, educators, syllabus designers, school administrators, and policymakers might rethink their teaching approaches and incorporate E-learning into the curriculum to meet their students' needs.

Bottom-Up Magnesium Deposition Induced by Paper-Based Triple-Gradient Scaffolds toward Flexible Magnesium Metal Batteries.

The development of advanced magnesium metal batteries (MMBs) has been hindered by longstanding challenges, such as the inability to induce uniform magnesium (Mg) nucleation and the inefficient utilization of Mg foil. This study introduces a novel solution in the form of a flexible, lightweight, paper-based scaffold that incorporates gradient conductivity, magnesiophilicity, and pore size. This design is achieved through an industrially adaptable papermaking process in which the ratio of carboxylated multi-walled carbon nanotubes to softwood cellulose fibers is meticulously adjusted. The triple-gradient structure of the scaffold enables the regulation of Mg ion flux, promoting bottom-up Mg deposition. Owing to its high flexibility, low thickness, and reduced density, the scaffold has potential applications in flexible and wearable electronics. Accordingly, the triple-gradient electrodes exhibit stable operation for over 1200 h at 3 mA cm-2 /3 mAh cm-2 in symmetrical cells, markedly outperforming the non-gradient and metallic Mg alternatives. Notably, this study marks the first successful fabrication of a flexible MMB pouch full cell, achieving an impressive volumetric energy density of 244 Wh L-1 . The simplicity and scalability of the triple-gradient design, which uses readily available materials through an industrially compatible papermaking process, open new doors for the production of flexible, high-energy-density metal batteries.

On the Road to the Frontiers of Lithium-Ion Batteries: A Review and Outlook of Graphene Anodes.

Graphene has long been recognized as a potential anode for next-generation lithium-ion batteries (LIBs). The past decade has witnessed the rapid advancement of graphene anodes, and considerable breakthroughs are achieved so far. In this review, the aim is to provide a research roadmap of graphene anodes toward practical LIBs. The Li storage mechanism of graphene is started with and then the approaches to improve its electrochemical performance are comprehensively summarized. First, morphologically engineered graphene anodes with porous, spheric, ribboned, defective and holey structures display improved capacity and rate performance owing to their highly accessible surface area, interconnected diffusion channels, and sufficient active sites. Surface-modified graphene anodes with less aggregation, fast electrons/ions transportation, and optimal solid electrolyte interphase are discussed, demonstrating the close connection between the surface structure and electrochemical activity of graphene. Second, graphene derivatives anodes prepared by heteroatom doping and covalent functionalization are outlined, which show great advantages in boosting the Li storage performances because of the additionally introduced defect/active sites for further Li accommodation. Furthermore, binder-free and free-standing graphene electrodes are presented, exhibiting great prospects for high-energy-density and flexible LIBs. Finally, the remaining challenges and future opportunities of practically available graphene anodes for advanced LIBs are highlighted.

Interface Engineering Toward Expedited Li2 S Deposition in Lithium-Sulfur Batteries: A Critical Review.

Lithium-sulfur batteries (LSBs) with superior energy density are among the most promising candidates of next-generation energy storage techniques. As the key step contributing to 75% of the overall capacity, Li2 S deposition remains a formidable challenge for LSBs applications because of its sluggish kinetics. The severe kinetic issue originates from the huge interfacial impedances, indicative of the interface-dominated nature of Li2 S deposition. Accordingly, increasing efforts have been devoted to interface engineering for efficient Li2 S deposition, which has attained inspiring success to date. However, a systematic overview and in-depth understanding of this critical field are still absent. In this review, the principles of interface-controlled Li2 S precipitation are presented, clarifying the pivotal roles of electrolyte-substrate and electrolyte-Li2 S interfaces in regulating Li2 S depositing behavior. For the optimization of the electrolyte-substrate interface, efforts on the design of substrates including metal compounds, functionalized carbons, and organic compounds are systematically summarized. Regarding the regulation of electrolyte-Li2 S interface, the progress of applying polysulfides catholytes, redox mediators, and high-donicity/polarity electrolytes is overviewed in detail. Finally, the challenges and possible solutions aiming at optimizing Li2 S deposition are given for further development of practical LSBs. This review would inspire more insightful works and, more importantly, may enlighten other electrochemical areas concerning heterogeneous deposition processes.

Integrated Gradient Cu Current Collector Enables Bottom-Up Li Growth for Li Metal Anodes: Role of Interfacial Structure.

3D Cu current collectors have been demonstrated to improve the cycling stability of Li metal anodes, however, the role of their interfacial structure for Li deposition pattern has not been investigated thoroughly. Herein, a series of 3D integrated gradient Cu-based current collectors are fabricated by the electrochemical growth of CuO nanowire arrays on Cu foil (CuO@Cu), where their interfacial structures can be readily controlled by modulating the dispersities of the nanowire arrays. It is found that the interfacial structures constructed by sparse and dense dispersion of CuO nanowire arrays are both disadvantageous for the nucleation and deposition of Li metal, consequently fast dendrite growth. In contrast, a uniform and appropriate dispersity of CuO nanowire arrays enables stable bottom Li nucleation associated with smooth lateral deposition, affording the ideal bottom-up Li growth pattern. The optimized CuO@Cu-Li electrodes exhibit a highly reversible Li cycling including a coulombic efficiency of up to ≈99% after 150 cycles and a long-term lifespan of over 1200 h. When coupling with LiFePO4 cathode, the coin and pouch full-cells deliver outstanding cycling stability and rate capability. This work provides a new insight to design the gradient Cu current collectors toward high-performance Li metal anodes.

Li+ mobility powered by a crystal compound for fast Li-S chemistry.

Placing blocking layers between electrodes has shown paramount prospects in suppressing the shuttle effect of Li-S batteries, but the associated ionic transport would be a concurrent obstacle. Herein, we present a Li-based crystal composited with carbon (LiPN2@C) by a one-step annealing of Li+ absorbed melamine polyphosphate, which simultaneously achieves alleviated polysulfide-shuttling and facilitated Li+ transport. As a homologous crystal, LiPN2 with abundant lithiophilic sites makes Li+ transport more efficient and sustainable. With a LiPN2@C-modified separator, the Li2S cathode exhibits a much-lower activation potential of 2.4 V and a high-rate capacity of 519 mA h g-1 at 2C. Impressively, the battery delivers a capacity of 726 mA h g-1 at 0.5C with a low decay rate of 0.25% per cycle during 100 continuous cycles.

Advances in the Emerging Gradient Designs of Li Metal Hosts.

Developing host has been recognized a potential countermeasure to circumvent the intrinsic drawbacks of Li metal anode (LMA), such as uncontrolled dendrite growth, unstable solid electrolyte interface, and infinite volume fluctuations. To realize proper Li accommodation, particularly bottom-up deposition of Li metal, gradient designs of host materials including lithiophilicity and/or conductivity have attracted a great deal of attention in recent years. However, a critical and specialized review on this quickly evolving topic is still absent. In this review, we attempt to comprehensively summarize and update the related advances in guiding Li nucleation and deposition. First, the fundamentals regarding Li deposition are discussed, with particular attention to the gradient design principles of host materials. Correspondingly, the progress of creating different gradients in terms of lithiophilicity, conductivity, and their hybrid is systematically reviewed. Finally, future challenges and perspective on the gradient design of advanced hosts towards practical LMAs are provided, which would provide a useful guidance for future studies.

Local Concentration Effect-Derived Heterogeneous Li2S2/Li2S Deposition on Dual-Phase MWCNT/Cellulose Nanofiber/NiCo2S4 Self-Standing Paper for High Performance of Lithium Polysulfide Batteries.

Lithium-sulfur (Li-S) batteries are highly attractive for their theoretical energy density and natural abundance, but the drawbacks of low sulfur utilization and rapid capacity fade in high-sulfur-loading cathodes still retard their practical use. To enhance kinetics in high-sulfur-loading Li-S cells, it is important to first understand and control the deposition of Li2S/Li2S from highly soluble lithium polysulfide (LiPS) during discharge processes. Here, we presented a series of multiphase-derived self-standing papers with diverse electronic conductivity and LiPS affinity for highly concentrated LiPS discharge processes and explained the Li2S/Li2S deposition behavior in detail. We demonstrated that high rate capacity and long cycle life of as-assembled paper-LiPS cathodes can be greatly depended on their phase material with high conductivity and LiPS affinity. A high-performance self-standing LiPS host-multiwalled carbon nanotube (MWCNT)/cellulose nanofiber (CNF)/NiCo2S4 (3.5 mg cm-2) can catalyze 2.85 mg cm-2 (based on sulfur) loaded LiPS to deliver a high specific capacity of 1154 mAh g-1 at 0.1C and a high rate performance of 963 mAh g-1 at 1C. We suggest that the insulating phase defect of nano-CNF and both highly electronic conductive (above 50 S cm-1) and LiPS adsorptive NiCo2S4 can promote the local concentration effect of LiPS, thus contributing to fast and stable heterogeneous particle-shaped deposition of Li2S2/Li2S and leading to high kinetics of the LiPS cathode.