Present and future of functionalized Cu current collectors for stabilizing lithium metal anodes

Li metal has been recognized as the most promising anode materials for next-generation high-energy-density batteries, however, the inherent issues of dendrite growth and huge volume fluctuations upon Li plating/stripping normally result in fast capacity fading and safety concerns. Functionalized Cu current collectors have so far exhibited significant regulatory effects on stabilizing Li metal anodes (LMAs), and hold a great practical potential owing to their easy fabrication, low-cost and good compatibility with the existing battery technology. In this review, a comprehensive overview of Cu-based current collectors, including planar modified Cu foil, 3D architectured Cu foil and nanostructured 3D Cu substrates, for Li metal batteries is provided. Particularly, the design principles and strategies of functionalized Cu current collectors associated with their functionalities in optimizing Li plating/stripping behaviors are discussed. Finally, the critical issues where there is incomplete understanding and the future research directions of Cu current collectors in practical LMAs are also prospected. This review may shed light on the critical understanding of current collector engineering for high-energy-density Li metal batteries

Design of a College English Mobile Learning System Based on CAD Model

With the development of mobile Internet technology and the advent of the information age, people's demand for mobile learning is growing and the studies on mobile English learning platform are also drawing more and more attention. In this article, firstly, the background of mobile learning is introduced and a Conversation-Activity-Distribution theoretical model, CAD, is proposed with activity theory, situation cognition theory and distributed cognition theory as the cognitive basis. Then, the students’ demand and expectations for implementation, function and content of the mobile learning system are learned by the combination of experiential researches and questionnaire surveys. A model of college English mobile learning system is proposed based on the CAD model, the overall structure of the model is discussed and its various functional modules introduced. With vocabulary learning as case design, the process design, function design and adaptive design of the system are introduced and the functional interface to the system demonstrated. Theoretically, this article enriches the theoretical basis of mobile learning and improves the methods of mobile learning system. Practically, through the studies on related learning theories, it puts forward a CAD theoretical model and carries out the case study on English vocabulary, which are conducive to the popularization of mobile learning in English learning and the improvement of teaching quality

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

Abstract 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

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.Published versionThis work was financially supported by the National Natural Science Foundation of China (51902261 and 61935017), the National Key Research and Development Program of China (2020YFA0709900), the Joint Research Funds of the Department of Science & Technology of Shaanxi Province and NPU (2020GXLH-Z-024), the Natural Science Basic Research Program of Shaanxi (2021JQ-107), Guangdong Basic and Applied Basic Research Foundation (2020A1515110604), the Natural Science Foundation of Ningbo (202003N4053), and the Fundamental Research Funds for the Central Universities(31020180QD116 and G2021KY05106)

Discovery, synthesis of novel fusidic acid derivatives possessed amino-terminal groups at the 3-hydroxyl position with anticancer activity

A series of novel fusidic acid (FA) derivatives were synthesized and screened for their in vitro cytotoxicity against the Hela, U87, KBV and MKN45 cancer cell lines. Selected FA derivatives with anti-tumor activity were firstly identified including compound 4, which exhibited good anti-proliferative activity with IC50 values in the range of 1.26–3.57 μM. Further research revealed that compound 4 induced Hela cells to undergo apoptosis by increasing the ratio of the cells in the Sub-G0/G1 phase via decreasing the neo-synthesized proteins in a dose-dependent manner from 1 to 10 μM. Compound 4 also showed good in vivo anti-tumor activity against the xenograft tumor of Hela cells and had no apparent toxicity. This study highlights the advantage of introducing the medium-length amino-terminal groups at the 3-OH position of FA to enhance its anti-tumor activity and suggests that compound 4 provides a starting point for designing more potent derivatives in the future. [Display omitted] •Fusidic acid (FA) derivatives with anti-tumor activity were first discovered.•A preliminary structure-activity relationship of the anti-tumor activity was described.•One novel derivative 4 exhibited good anti-tumor activity both in vitro and in vivo.•The mechanism that compound 4 induced Hela cells to undergo apoptosis was first proved

Binary Pd/amorphous-SrRuO3 hybrid film for high stability and fast activity recovery ethanol oxidation electrocatalysis

© 2019 Elsevier Ltd Pd- or Pt-based precious catalysts (PPC) are considered to be the best candidates toward high performance directly ethanol fuel cells (DEFC) applications, owing to their high intrinsic activity for ethanol oxidation reaction (EOR). However, the current major barrier for their commercialization is incompletely oxidized intermediates (IOI, such as CO) that poison the catalysts to affect the durability of the cells. Meanwhile, deactivated PPC catalyst is difficult to be recycled, thus impairing the economic benefits for the commercial applications. Moreover, because of the side effects of additive corrosion and aging, the carbon and organic binders widely used in current catalyst design would make the interactions of the IOI more complex to accelerate activity loss. Here, we report a Pd/amorphous SrRuO3 (Pd/a-SrRuO3) hybrid film as a promising material to overcome these problems. Perovskite SrRuO3 can effectively generate oxygen-contains (*OH, *OOH) for intermediates oxidation, providing an ideal platform to promote self-cleaning of CO on Pd activity sites. On the other hand, in analogy to typical self-adapting effect of amorphous catalyst in oxygen reduction reaction process, metastable state of amorphous SrRuO3 in this work is expected to prolong the activity adaptation region at the initial stage of cycling. Furthermore, our conceptual framework of directly depositing Pd/a-SrRuO3 film on operational electrode provides an effective solution to avoid the side effects related with carbon and binders, leading to superior reactivation phenomena with 98% efficiency. As a result, our designed Pd/a-SrRuO3 hybrid film exhibits superior EOR activity (4.0 A mg-1 Pd), durability (i-t, 60,000s), self-adapting region (exceeding 400 cycles with ending activity of 3.0 A mg-1 Pd at 1000th cycle), and also a long-term operation (CP) up to 300,000s with 10 times reactivation. This demonstration of a Pd/Pt-based hybrid catalyst with dual-capability of self-cleaning and self-adapting characteristics is an important step towards the development of highly durable EOR catalysts, with an enormous potential to promote practical application of DEFC