• Energy Research

AbstractBatteries are a promising technology in the field of electrical energy storage and have made tremendous strides in recent few decades. In particular, lithium‐ion batteries are leading the smart device era as an essential component of portable electronic devices. From the materials aspect, new and creative solutions are required to resolve the current technical issues on advanced lithium (Li) batteries and improve their safety. Metal‐organic frameworks (MOFs) are considered as tempting candidates to satisfy the requirements of advanced energy storage technologies. In this review, we discuss the characteristics of MOFs for application in different types of Li batteries. A review of these emerging studies in which MOFs have been applied in lithium storage devices can provide an informative blueprint for future MOF research on next‐generation advanced energy storage devices.image

Lithium metal batteries (LMBs) are in the spotlight as a next‐generation battery due to their high theoretical capacity. However, LMBs still suffer from inferior cycle stability owing to dendritic lithium (Li) growth during Li plating and stripping, leading to battery explosion. To solve this problem, solid electrolytes have emerged as a promising candidate by suppressing the dendritic Li growth. Despite numerous efforts, however, many challenges, such as low ionic conductivity, air stability, space charge layer, and contact loss issues, have been encountered. This review aims to provide the current challenges and new insights of solid electrolytes and then explore optimal solutions for next‐generation solid electrolytes.

Strategies for improving the photovoltaic performance of dye-sensitized solar cells (DSSCs) are proposed by modifying highly transparent and highly ordered multilayer mesoporous TiO2 photoanodes through nitrogen-doping and top-coating with a light-scattering layer. The mesoporous TiO2 photoanodes were fabricated by an evaporation-induced self-assembly method. In regard to the modification methods, the light-scattering layer as a top-coating was proved to be superior to nitrogen-doping in enhancing not only the power conversion efficiency but also the fill factor of DSSCs. The optimized bifunctional photoanode consisted of a 30-layer mesoporous TiO2 thin film (4.15 μm) and a Degussa P25 light-scattering top-layer (4 μm), which gives rise to a ∼200% higher cell efficiency than for unmodified cells and a fill factor of 0.72. These advantages are attributed to its higher dye adsorption, better light scattering, and faster photon–electron transport. Such a photoanode configuration provides an efficient way to enhance the energy conversion efficiency of DSSCs.

AbstractSince the beginning of human history, the demand for effective healthcare systems for diagnosis and treatment of health problems has grown steadily. However, traditional centralized healthcare requires hospital visits, making in‐time and long‐term healthcare challenging. Bioelectronics has shown potential in patient‐friendly healthcare owing to the rapid advances in diverse fields of biology and electronics. In particular, wearable and implantable bioelectronics have emerged as an alternative or adjunct to conventional healthcare. To develop into next‐generation healthcare systems, however, custom designs for biological targets with a deepened understanding of the intrinsic features of the target are essential. In addition, bioelectronic systems must be designed eco‐friendly for sustainable healthcare. In this review, bioelectronics as eco‐friendly and patient‐friendly integrated nanoarchitectonics as next‐generation smart healthcare technology are described. For an in‐depth understanding of biological targets and guidelines for target‐tailored design, we discuss target‐specific considerations and relevant key parameters of bioelectronic systems with the representative examples.image

Lithium metal batteries have recently gained tremendous attention owing to their high energy capacity compared to other rechargeable batteries. Nevertheless, lithium (Li) dendritic growth causes low Coulombic efficiency, thermal runaway, and safety issues, all of which hinder the practical application of Li metal as an anodic material. In this review, the failure mechanisms of Li metal anode are described according to its infinite volume changes, unstable solid electrolyte interphase, and Li dendritic growth. The fundamental models that describe the Li deposition and dendritic growth, such as the thermodynamic, electrodeposition kinetics, and internal stress models are summarized. From these considerations, porous carbon-based frameworks have emerged as a promising strategy to resolve these issues. Thus, the main principles of utilizing these materials as a Li metal host are discussed. Finally, we also focus on the recent progress on utilizing one-, two-, and three-dimensional carbon-based frameworks and their composites to highlight the future outlook of these materials.

AbstractHigh electrochemical stability and safety make Na+ superionic conductor (NASICON)‐class cathodes highly desirable for Na‐ion batteries (SIBs). However, their practical capacity is limited, leading to low specific energy. Furthermore, the low electrical conductivity combined with a decline in capacity upon prolonged cycling (>1000 cycles) related to the loss of active material‐carbon conducting contact regions contributes to moderate rate performance and cycling stability. The need for high specific energy cathodes that meet practical electrochemical requirements has prompted a search for new materials. Herein, we introduce a new carbon‐coated Na3VFe0.5Ti0.5(PO4)3 (NVFTP/C) material as a promising candidate in the NASICON family of cathodes for SIBs. With a high specific energy of ∼457 Wh kg−1 and a high Na+ insertion voltage of 3.0 V versus Na+/Na, this cathode can undergo a reversible single‐phase solid‐solution and two‐phase (de)sodiation evolution at 28 C (1 C = 174.7 mAh g−1) for up to 10,000 cycles. This study highlights the potential of utilizing low‐cost and highly efficient cathodes made from Earth‐abundant and harmless materials (Fe and Ti) with enriched Na+‐storage properties in practical SIBs.

AbstractRealizing a lithium sulfide (Li2S) cathode with both high energy density and a long lifespan requires an innovative cathode design that maximizes electrochemical performance and resists electrode deterioration. Herein, a high‐loading Li2S‐based cathode with micrometric Li2S particles composed of two‐dimensional graphene (Gr) and one‐dimensional carbon nanotubes (CNTs) in a compact geometry is developed, and the role of CNTs in stable cycling of high‐capacity Li–S batteries is emphasized. In a dimensionally combined carbon matrix, CNTs embedded within the Gr sheets create robust and sustainable electron diffusion pathways while suppressing the passivation of the active carbon surface. As a unique point, during the first charging process, the proposed cathode is fully activated through the direct conversion of Li2S into S8 without inducing lithium polysulfide formation. The direct conversion of Li2S into S8 in the composite cathode is ubiquitously investigated using the combined study of in situ Raman spectroscopy, in situ optical microscopy, and cryogenic transmission electron microscopy. The composite cathode demonstrates unprecedented electrochemical properties even with a high Li2S loading of 10 mg cm–2; in particular, the practical and safe Li–S full cell coupled with a graphite anode shows ultra‐long‐term cycling stability over 800 cycles.