Optimized Bicompartment Two Solution Cells for Effective and Stable Operation of Li–O2 Batteries

Lithium–oxygen batteries are in fact the only rechargeable batteries that can rival internal combustion engines, in terms of high energy density. However, they are still under development due to low‐efficiency and short lifetime issues. There are problems of side reactions on the cathode side, high reactivity of the Li anode with solution species, and consumption of redox mediators via reactions with metallic lithium. Therefore, efforts are made to protect/block the lithium metal anode in these cells, in order to mitigate side reactions. However, new approach is required in order to solve the problems mentioned above, especially the irreversible reactions of the redox mediators which are mandatory to these systems with the Li anode. Here, optimized bicompartment two solution cells are proposed, in which detrimental crossover between the cathode and anode is completely avoided. The Li metal anode is cycled in electrolyte solution containing fluorinated ethylene carbonate, in which its cycling efficiency is excellent. The cathode compartment contains ethereal solution with redox mediator that enables oxidation of Li₂O₂ at low potentials. The electrodes are separated by a solid electrolyte membrane, allowing free transport of Li ions. This approach increases cycle life of lithium oxygen cells and their energy efficiency.     

The use of electric,magnetic, and electromagnetic field for directed cell migration and adhesion in regenerative medicine

Directed cell migration and adhesion is essential to embryonic development, tissue formation and wound healing. For decades it has been reported that electric field (EF), magnetic field (MF) and electromagnetic field (EMF) can play important roles in determining cell differentiation, migration, adhesion, and evenwound healing. Combinations of these techniques have revealed new and exciting explanations for how cells move and adhere to surfaces; how the migration of multiple cells are coordinated and regulated; how cellsinteract with neighboring cells, and also to changes in their microenvironment. In some cells, speed and direction are voltage dependent. Data suggests that the use of EF, MF and EMF could advance techniques in regenerative medicine, tissue engineering and wound healing. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:5–16, 2017     

Syntrophic interactions among anode respiring bacteria (ARB) and Non‐ARB in a biofilm anode: electron balances

We demonstrate that the coulombic efficiency (CE) of a microbial electrolytic cell (MEC) fueled with a fermentable substrate, ethanol, depended on the interactions among anode respiring bacteria (ARB) and other groups of micro‐organisms, particularly fermenters and methanogens. When we allowed methanogenesis, we obtained a CE of 60%, and 26% of the electrons were lost as methane. The only methanogenic genus detected by quantitative real‐time PCR was the hydrogenotrophic genus, Methanobacteriales, which presumably consumed all the hydrogen produced during ethanol fermentation (～30% of total electrons). We did not detect acetoclastic methanogenic genera, indicating that acetate‐oxidizing ARB out‐competed acetoclastic methanogens. Current production and methane formation increased in parallel, suggesting a syntrophic interaction between methanogens and acetate‐consuming ARB. When we inhibited methanogenesis with 50 mM 2‐bromoethane sulfonic acid (BES), the CE increased to 84%, and methane was not produced. With no methanogenesis, the electrons from hydrogen were converted to electrical current, either directly by the ARB or channeled to acetate through homo‐acetogenesis. This illustrates the key role of competition among the various H₂ scavengers and that, when the hydrogen‐consuming methanogens were present, they out‐competed the other groups. These findings also demonstrate the importance of a three‐way syntrophic relationship among fermenters, acetate‐consuming ARB, and a H₂ consumer during the utilization of a fermentable substrate. To obtain high coulombic efficiencies with fermentable substrates in a mixed population, methanogens must be suppressed to promote new interactions at the anode that ultimately channel the electrons from hydrogen to current. Biotechnol. Bioeng. 2009;103: 513–523. © 2009 Wiley Periodicals, Inc.     

Iron‐Oxide‐Based Advanced Anode Materials for Lithium‐Ion Batteries

Iron oxides, such as Fe₂O₃ and Fe₃O₄, have recently received increased attention as very promising anode materials for rechargeable lithium‐ion batteries (LIBs) because of their high theoretical capacity, non‐toxicity, low cost, and improved safety. Nanostructure engineering has been demonstrated as an effective approach to improve the electrochemical performance of electrode materials. Here, recent research progress in the rational design and synthesis of diverse iron oxide‐based nanomaterials and their lithium storage performance for LIBs, including 1D nanowires/rods, 2D nanosheets/flakes, 3D porous/hierarchical architectures, various hollow structures, and hybrid nanostructures of iron oxides and carbon (including amorphous carbon, carbon nanotubes, and graphene). By focusing on synthesis strategies for various iron‐oxide‐based nanostructures and the impacts of nanostructuring on their electrochemical performance, novel approaches to the construction of iron‐oxide‐based nanostructures are highlighted and the importance of proper structural and compositional engineering that leads to improved physical/chemical properties of iron oxides for efficient electrochemical energy storage is stressed. Iron‐oxide‐based nanomaterials stand a good chance as negative electrodes for next generation LIBs.     

Recent Developments on and Prospects for Electrode Materials with Hierarchical Structures for Lithium‐Ion Batteries

Since their successful commercialization in 1990s, lithium‐ion batteries (LIBs) have been widely applied in portable digital products. The energy density and power density of LIBs are inadequate, however, to satisfy the continuous growth in demand. Considering the cost distribution in battery system, it is essential to explore cathode/anode materials with excellent rate capability and long cycle life. Nanometer‐sized electrode materials could quickly take up and store numerous Li⁺ ions, afforded by short diffusion channels and large surface area. Unfortunately, low thermodynamic stability of nanoparticles results in electrochemical agglomeration and raises the risk of side reactions on electrolyte. Thus, micro/nano and hetero/hierarchical structures, characterized by ordered assembly of different sizes, phases, and/or pores, have been developed, which enable us to effectively improve the utilization, reaction kinetics, and structural stability of electrode materials. This review summarizes the recent efforts on electrode materials with hierarchical structures, and discusses the effects of hierarchical structures on electrochemical performance in detail. Multidimensional self‐assembled structures can achieve integration of the advantages of materials with different sizes. Core/yolk–shell structures provide synergistic effects between the shell and the core/yolk. Porous structures with macro‐, meso‐, and micropores can accommodate volume expansion and facilitate electrolyte infiltration.     

Fabrication of Hybrid Silicate Coatings by a Simple Vapor Deposition Method for Lithium Metal Anodes

Lithium metal anodes are highly promising for next‐generation rechargeable batteries. However, implication of lithium metal anodes is hampered by the unstable electrochemical behavior. Herein, the fabrication of hermetic coatings of hybrid silicate on lithium metal surface using a simple vapor deposition technique under the ambient condition is reported. Such coatings consist of a “hard” inorganic moiety that helps to suppress lithium dendrites and a “soft” organic moiety that enhances the toughness. Lithium metal batteries, including Li–LiFePO₄ and Li–S batteries, made with such coated anodes show significantly improved lifetime. This work provides a simple yet effective approach to stabilize lithium metal anodes for high‐performance lithium metal batteries.     

Sodium‐Ion Batteries: From Academic Research to Practical Commercialization

Sodium‐ion batteries (SIBs) have been considered as the most promising candidate for large‐scale energy storage system owing to the economic efficiency resulting from abundant sodium resources, superior safety, and similar chemical properties to the commercial lithium‐ion battery. Despite the long period of academic research, how to realize sodium‐ion battery commercialization for market applications is still a great challenge. Thus, from the perspective of future practical application, this review will identify the factors that are restricting commercialization, and evaluate the existing active materials and sodium‐ion‐based full‐cell system. The design and development trends that are needed for SIBs to meet the requirements of practical applications in large‐scale energy storage will also be discussed in detail.     

Macroporous Catalytic Carbon Nanotemplates for Sodium Metal Anodes

Because of its remarkably high theoretical capacity and favorable redox voltage (?2.71 V vs the standard hydrogen electrode), Na is a promising anode material for Na ion batteries. In this study, macroporous catalytic carbon nanotemplates (MC‐CNTs) based on nanoweb‐structured carbon nanofibers with various carbon microstructures are prepared from microbe‐derived cellulose via simple heating at 800 or 2400 °C. MC‐CNTs prepared at 800 °C have amorphous carbon structures with numerous topological defects, and exhibit a lower voltage overpotential of ≈8 mV in galvanostatic charge/discharge testing. In addition, MC‐CNT‐800s exhibit high Coulombic efficiencies of 99.4–99.9% during consecutive cycling at current densities ranging from 0.2 to 4 mA cm^?2. However, the carbon structures of MC‐CNTs prepared at 800 °C are gradually damaged by cycling. This results in significant capacity losses after about 200 cycles. In contrast, MC‐CNTs prepared at 2400 °C exhibit well‐developed graphitic structures, and maintain predominantly stable cycling behaviors over 1000 cycles with Coulombic efficiencies of ≈99.9%. This study demonstrates the superiority of catalytic carbon nanotemplates with well‐defined pore structures and graphitic microstructures for use in Na metal anodes.     

Solution‐Processable Conjugated Polymers as Anode Interfacial Layer Materials for Organic Solar Cells

In recent years, solution‐processed conjugated polymers have been extensively used as anode interfacial layer (AIL) materials in organic solar cells (OSCs) due to their excellent film‐forming property and low‐temperature processing advantages. In this review, the authors focus on the recent advances in conjugated polymers as AIL materials in OSCs. Several of the main classes of solution‐processable conjugated polymers, including poly(3,4‐ethylenedioxythiophene):(styrenesulfonate), polyaniline, polythiophene, conjugated polyelectrolytes, sulfonated poly(diphenylamine), and crosslinked polymers as AIL materials are discussed in depth, and the mechanisms of these AIL materials in enhancing OSC performances are also elucidated. The structure–property relationships of various conjugated polymer AIL materials are analyzed, and some important design rules for such materials toward high efficiencies and stable OSCs are presented. In addition, some chemical and physical approaches to optimize the photoelectronic and physic properties of conjugated polymer AIL materials, which improve their performance in modifying OSCs, are also highlighted. Considering the significance of tandem OSCs, the relevant applications of conjugated polymer AIL materials in constructing interconnection layers for tandem OSCs are also mentioned. Finally, a brief summary is presented and some perspectives to help researchers understand the current challenges and opportunities in this area are proposed.