With the arising of global climate change and resource shortage, in recent years, increased attention has been paid to environmentally friendly materials. Trees are sustainable and renewable ...materials, which give us shelter and oxygen and remove carbon dioxide from the atmosphere. Trees are a primary resource that human society depends upon every day, for example, homes, heating, furniture, and aircraft. Wood from trees gives us paper, cardboard, and medical supplies, thus impacting our homes, school, work, and play. All of the above-mentioned applications have been well developed over the past thousands of years. However, trees and wood have much more to offer us as advanced materials, impacting emerging high-tech fields, such as bioengineering, flexible electronics, and clean energy. Wood naturally has a hierarchical structure, composed of well-oriented microfibers and tracheids for water, ion, and oxygen transportation during metabolism. At higher magnification, the walls of fiber cells have an interesting morphologya distinctly mesoporous structure. Moreover, the walls of fiber cells are composed of thousands of fibers (or macrofibrils) oriented in a similar angle. Nanofibrils and nanocrystals can be further liberated from macrofibrils by mechanical, chemical, and enzymatic methods. The obtained nanocellulose has unique optical, mechanical, and barrier properties and is an excellent candidate for chemical modification and reconfiguration. Wood is naturally a composite material, comprised of cellulose, hemicellulose, and lignin. Wood is sustainable, earth abundant, strong, biodegradable, biocompatible, and chemically accessible for modification; more importantly, multiscale natural fibers from wood have unique optical properties applicable to different kinds of optoelectronics and photonic devices. Today, the materials derived from wood are ready to be explored for applications in new technology areas, such as electronics, biomedical devices, and energy. The goal of this study is to review the fundamental structures and chemistries of wood and wood-derived materials, which are essential for a wide range of existing and new enabling technologies. The scope of the review covers multiscale materials and assemblies of cellulose, hemicellulose, and lignin as well as other biomaterials derived from wood, in regard to their major emerging applications. Structure–properties–application relationships will be investigated in detail. Understanding the fundamental properties of these structures is crucial for designing and manufacturing products for emerging applications. Today, a more holistic understanding of the interplay between the structure, chemistry, and performance of wood and wood-derived materials is advancing historical applications of these materials. This new level of understanding also enables a myriad of new and exciting applications, which motivate this review. There are excellent reviews already on the classical topic of woody materials, and some recent reviews also cover new understanding of these materials as well as potential applications. This review will focus on the uniqueness of woody materials for three critical applications: green electronics, biological devices, and energy storage and bioenergy.
Li metal has been attracting increasing attention as an anode in all-solid-state batteries because of its lowest electrochemical potential and high capacity, although the problems caused by dendritic ...growth impedes its further application. For a long time, all-solid-state Li metal batteries (ASLBs) are regarded to revive Li metal due to high mechanical strength. However, numerous works revealed that the dendrite issue widely exists in ASLBs, and the mechanism is complex. This review provides a systematic and in-depth understanding of the thermodynamic, kinetic, electrochemical, chemomechnical, structural stability, and characterizations of Li dendrite in ASLBs. First, the mechanisms for dendrite formation and propagation in polymer, ceramic and glass electrolyte were discussed. Subsequently, based on these mechanisms of dendrite growth, we reviewed various strategies for dendrite suppression. Furthermore, advanced characterization techniques were reviewed for better understanding of dendrite in solid-state batteries.
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Driven by the increasing demand for energy worldwide, the development of high-energy, high-power, safe, and reliable batteries is one of the most important goals at the forefront of energy research. Li metal has been receiving increasing attention as an anode in all-solid-state-batteries (ASLBs) because of its lowest electrochemical potential, high capacity, and light weight. However, Li metal application is highly impeded by the problematic dendrite issue. For a long time, ASLBs were regarded to revive Li metal due to high mechanical strength. However, recent studies have proved that the Li dendrite also grows and propagates in the solid electrolyte during cycling, and even more severely than in batteries using liquid electrolytes, because of the uneven charge distribution at the interface of electrolyte and electrode. Many efforts have been devoted to study Li metal dendrite in liquid electrolyte. Still, as of yet there is no comprehensive in-depth review to summarize the mechanisms and corresponding suppression strategies of dendrite in ASLBs. In this review, a systematic discussion of dendrite growth mechanisms, the corresponding Li dendrite suppression strategies, and advanced characterization techniques in ASLBs are critically discussed and summarized.
Li metal has been receiving increasing attention as an anode in all-solid-state batteries because of its lowest electrochemical potential and high capacity, although the safety problem caused by dendritic growth of Li impedes its further application. Numerous works found the dendrite issue to widely exist in all-solid-state Li metal batteries (ASLBs), and the mechanism is complex and mystifying. This review focuses on the dendrite issue in ASLBs. First, the mechanisms for dendrite formation and propagation in polymer electrolyte and ceramic/glass electrolyte were determined. Subsequently, based on these mechanisms for dendrite growth, we summarized various strategies for dendrite suppression reported recently. Additionally, advanced characterization techniques were reviewed for a better understanding of dendrite studies in solid-state batteries. This review provides an in-depth demonstration of the thermodynamic, kinetic, electrochemical, chemomechnical, and structural stability and evolution of Li dendrite in ASLBs.
Metallic phase 2D molybdenum disulfide (MoS2) is an emerging class of materials with remarkably higher electrical conductivity and catalytic activities. The goal of this study is to review the atomic ...structures and electrochemistry of metallic MoS2, which is essential for a wide range of existing and new enabling technologies. The scope of this paper ranges from the atomic structure, band structure, electrical and optical properties to fabrication methods, and major emerging applications in electrochemical energy storage and energy conversion. This paper also thoroughly covers the atomic structure–properties–application relationships of metallic MoS2. Understanding the fundamental properties of these structures is crucial for designing and manufacturing products for emerging applications. Today, a more holistic understanding of the interplay between the structure, chemistry, and performance of metallic MoS2 is advancing actual applications of this material. This new level of understanding also enables a myriad of new and exciting applications, which motivated this review. There are excellent reviews already on the traditional semiconducting MoS2, and this review, for the first time, focuses on the uniqueness of conducting metallic MoS2 for energy applications and offers brand new materials for clean energy application.
This review focuses on accelerating the investigation of metallic conducting MoS2
with large electron density and building the fundamental knowledge needed to advance its application to various challenges in energy storage and clean energy generation. It can be a valuable resource for this new field, which is rapidly expanding in terms of both scope and interest from the scientific community.
A long-standing challenge in material design is to overcome the conflict between strength and toughness, because they are generally mutually exclusive. To address this challenge, we rationally design ...cellulose-based nanopaper and investigate the dependence of their mechanical properties on constituent cellulose fiber size. Surprisingly, we find that both the strength and toughness of the nanopaper increase simultaneously (40 and 130 times, respectively) as the average diameter of constituent cellulose fibers decreases from 27 μm to 11 nm, suggesting the promising potential toward an anomalous but highly desirable scaling law: the smaller, the stronger and the tougher. There are abundant opportunities to use the fundamental bottom-up strategy to design a novel class of functional materials that are both strong and tough.
The quest for both strength and toughness is perpetual in advanced material design; unfortunately, these two mechanical properties are generally mutually exclusive. So far there exists only limited success of attaining both strength and toughness, which often needs material-specific, complicated, or expensive synthesis processes and thus can hardly be applicable to other materials. A general mechanism to address the conflict between strength and toughness still remains elusive. Here we report a first-of-its-kind study of the dependence of strength and toughness of cellulose nanopaper on the size of the constituent cellulose fibers. Surprisingly, we find that both the strength and toughness of cellulose nanopaper increase simultaneously (40 and 130 times, respectively) as the size of the constituent cellulose fibers decreases (from a mean diameter of 27 μm to 11 nm), revealing an anomalous but highly desirable scaling law of the mechanical properties of cellulose nanopaper: the smaller, the stronger and the tougher. Further fundamental mechanistic studies reveal that reduced intrinsic defect size and facile (re)formation of strong hydrogen bonding among cellulose molecular chains is the underlying key to this new scaling law of mechanical properties. These mechanistic findings are generally applicable to other material building blocks, and therefore open up abundant opportunities to use the fundamental bottom-up strategy to design a new class of functional materials that are both strong and tough.
Renewable and clean “green” electronics based on paper substrates is an emerging field with intensifying research and commercial interests, as the technology combines the unique properties of ...flexibility, cost efficiency, recyclability, and renewability with the lightweight nature of paper. Because of its excellent optical transmittance and low surface roughness, nanopaper can host many types of electronics that are not possible on regular paper. However, there can be tremendous challenges with integrating devices on nanopaper due to its shape stability during processing. Here we demonstrate for the first time that flexible organic field-effect transistors (OFETs) with high transparency can be fabricated on tailored nanopapers. Useful electrical characteristics and an excellent mechanical flexibility were observed. It is believed that the large binding energy between polymer dielectric and cellulose nanopaper, and the effective stress release from the fibrous substrate promote these beneficial properties. Only a 10% decrease in mobility was observed when the nanopaper transistors were bent and folded. The nanopaper transistor also showed excellent optical transmittance up to 83.5%. The device configuration can transform many semiconductor materials for use in flexible green electronics.
All-solid-state lithium batteries (ASLBs) are promising for the next generation energy storage system with critical safety. Among various candidates, thiophosphate-based electrolytes have shown great ...promise because of their high ionic conductivity. However, the narrow operation voltage and poor compatibility with high voltage cathode materials impede their application in the development of high energy ASLBs. In this work, we studied the failure mechanism of Li6PS5Cl at high voltage through in situ Raman spectra and investigated the stability with high-voltage LiNi1/3Mn1/3Co1/3O2 (NMC) cathode. With a facile wet chemical approach, we coated a thin layer of amorphous Li0.35La0.5Sr0.05TiO3 (LLSTO) with 15–20 nm at the interface between NMC and Li6PS5Cl. We studied different coating parameters and optimized the coating thickness of the interface layers. Meanwhile, we studied the effect of NMC dimension to the ASLBs performance. We further conducted the first-principles thermodynamic calculations to understand the electrochemical stability between Li6PS5Cl and carbon, NMC, LLSTO, NMC/LLSTO. Attributed to the high stability of Li6PS5Cl with NMC/LLSTO and outstanding ionic conductivity of the LLSTO and Li6PS5Cl, at room temperature, the ASLBs exhibit outstanding capacity of 107 mAh g–1 and keep stable for 850 cycles with a high capacity retention of 91.5% at C/3 and voltage window 2.5–4.0 V (vs Li–In).
Li metal anodes have attracted considerable research interest due to their low redox potential (−3.04 V vs standard hydrogen electrode) and high theoretical gravimetric capacity of 3861 mAh/g. ...Battery technologies using Li metal anodes have shown much higher energy density than current Li-ion batteries (LIBs) such as Li–O2 and Li–S systems. However, issues related to dendritic Li formation and low Coulombic efficiency have prevented the use of Li metal anode technology in many practical applications. In this paper, a thermally conductive separator coated with boron-nitride (BN) nanosheets has been developed to improve the stability of the Li metal anodes. It is found that using the BN-coated separator in a conventional organic carbonate-based electrolyte results in the Coulombic efficiency stabilizing at 92% over 100 cycles at a current rate of 0.5 mA/cm2 and 88% at 1.0 mA/cm2. The improved Coulombic efficiency and reliability of the Li metal anodes is due to the more homogeneous thermal distribution resulting from the thermally conductive BN coating and to the smaller surface area of initial Li deposition.
Metallic-phase MoS2 (M-MoS2) is metastable and does not exist in nature. Pure and stable M-MoS2 has not been previously prepared by chemical synthesis, to the best of our knowledge. Here we report a ...hydrothermal process for synthesizing stable two-dimensional M-MoS2 nanosheets in water. The metal-metal Raman stretching mode at 146 cm(-1) in the M-MoS2 structure, as predicted by theoretical calculations, is experimentally observed. The stability of the M-MoS2 is associated with the adsorption of a monolayer of water molecules on both sides of the nanosheets, which reduce restacking and prevent aggregation in water. The obtained M-MoS2 exhibits excellent stability in water and superior activity for the hydrogen evolution reaction, with a current density of 10 mA cm(-2) at a low potential of -175 mV and a Tafel slope of 41 mV per decade.
Sodium (Na)-ion batteries offer an attractive option for low cost grid scale storage due to the abundance of Na. Tin (Sn) is touted as a high capacity anode for Na-ion batteries with a high ...theoretical capacity of 847 mAh/g, but it has several limitations such as large volume expansion with cycling, slow kinetics, and unstable solid electrolyte interphase (SEI) formation. In this article, we demonstrate that an anode consisting of a Sn thin film deposited on a hierarchical wood fiber substrate simultaneously addresses all the challenges associated with Sn anodes. The soft nature of wood fibers effectively releases the mechanical stresses associated with the sodiation process, and the mesoporous structure functions as an electrolyte reservoir that allows for ion transport through the outer and inner surface of the fiber. These properties are confirmed experimentally and computationally. A stable cycling performance of 400 cycles with an initial capacity of 339 mAh/g is demonstrated; a significant improvement over other reported Sn nanostructures. The soft and mesoporous wood fiber substrate can be utilized as a new platform for low cost Na-ion batteries.
Batteries constructed via 3D printing techniques have inherent advantages including opportunities for miniaturization, autonomous shaping, and controllable structural prototyping. However, 3D‐printed ...lithium metal batteries (LMBs) have not yet been reported due to the difficulties of printing lithium (Li) metal. Here, for the first time, high‐performance LMBs are fabricated through a 3D printing technique using cellulose nanofiber (CNF), which is one of the most earth‐abundant biopolymers. The unique shear thinning properties of CNF gel enables the printing of a LiFePO4 electrode and stable scaffold for Li. The printability of the CNF gel is also investigated theoretically. Moreover, the porous structure of the CNF scaffold also helps to improve ion accessibility and decreases the local current density of Li anode. Thus, dendrite formation due to uneven Li plating/stripping is suppressed. A multiscale computational approach integrating first‐principle density function theory and a phase‐field model is performed and reveals that the porous structures have more uniform Li deposition. Consequently, a full cell built with a 3D‐printed Li anode and a LiFePO4 cathode exhibits a high capacity of 80 mA h g−1 at a charge/discharge rate of 10 C with capacity retention of 85% even after 3000 cycles.
High‐aspect ratio lithium metal batteries are enabled through a 3D printing technique using nanocellulose from trees as ink surfactant, viscosifier, and conductive scaffold. The full cell achieves a high reversible capacity of 80 mAh g–1 at 10 C and remains stable for over 3000 cycles with high capacity retention of 85%.
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