Recent findings demonstrate that cellulose, a highly abundant, versatile, sustainable, and inexpensive material, can be used in the preparation of very stable and flexible electrochemical energy ...storage devices with high energy and power densities by using electrodes with high mass loadings, composed of conducting composites with high surface areas and thin layers of electroactive material, as well as cellulose‐based current collectors and functional separators. Close attention should, however, be paid to the properties of the cellulose (e.g., porosity, pore distribution, pore‐size distribution, and crystallinity). The manufacturing of cellulose‐based electrodes and all‐cellulose devices is also well‐suited for large‐scale production since it can be made using straightforward filtration‐based techniques or paper‐making approaches, as well as utilizing various printing techniques. Herein, the recent development and possibilities associated with the use of cellulose are discussed, regarding the manufacturing of electrochemical energy storage devices comprising electrodes with high energy and power densities and lightweight current collectors and functional separators.
The recent progress of cellulose, as an appealing natural material that can outperform traditional synthetic materials, for use in energy‐storage devices is described. Cellulose can bring benefits in the fabrication and properties of energy‐storage materials and devices, eventually enabling significant improvements in electrochemical performance, mechanical flexibility, cost competitiveness, and form factors, which are difficult to achieve with conventional power source technologies.
The inability to guide the nucleation locations of electrochemically deposited Li has long been considered the main factor limiting the utilization of high‐energy‐density Li‐metal batteries. In this ...study, an electrical conductivity gradient interfacial host comprising 1D high conductivity copper nanowires and nanocellulose insulating layers is used in stable Li‐metal anodes. The conductivity gradient system guides the nucleation sites of Li‐metal to be directed during electrochemical plating. Additionally, the controlled parameter of the intermediate layer affects the highly stable Li‐metal plating. The electrochemical behavior is confirmed through experiments associated with the COMSOL Multiphysics simulation data. The distributed Li‐ion reaction flux resulting from the controlled electrical conductivity enables stable cycling for more than 250 cycles at 1 mA cm−2. The gradient system effectively suppresses dendrite growth even at a high current density of 5 mA cm−2 and ensures Li plating and stripping with ultra‐long‐term stability. To demonstrate the high‐energy‐density full‐cell application of the developed anode, it is paired with the LiNi0.8Co0.1Mn0.1O2 cathode. The cells demonstrate a high capacity retention of 90% with an extremely high Coulombic efficiency of 99.8% over 100 cycles. These results shed light on the formidable challenges involved in exploiting the engineering aspects of high‐energy‐density Li‐metal batteries.
An electrical conductivity gradient interfacial host composed of simply fabricated 1D high conductivity copper nanowires and nanocellulose insulating layers shows stable lithium metal plating/stripping during electrochemical reaction. The conductivity gradient offers to guide the nucleation of lithium metal deposition, resulting in a high capacity retention of 90% with an extremely high Coulombic efficiency of 99.8% over 100 cycles as a full‐cell test.
The ongoing surge in demand for high‐performance energy storage systems inspires the relentless pursuit of advanced materials and structures. Components of energy storage systems are generally based ...on inorganic/metal compounds, carbonaceous substances, and petroleum‐derived hydrocarbon chemicals. These traditional materials, however, may have difficulties fulfilling the ever‐increasing requirements of energy storage systems. Recently, nanocellulose has garnered considerable attention as an exceptional 1D element due to its natural abundance, environmental friendliness, recyclability, structural uniqueness, facile modification, and dimensional stability. Recent advances and future outlooks of nanocellulose as a green material for energy storage systems are described, with a focus on its application in supercapacitors, lithium‐ion batteries (LIBs), and post‐LIBs. Nanocellulose is typically classified as cellulose nanofibril (CNF), cellulose nanocrystal (CNC), and bacterial cellulose (BC). The unusual 1D structure and chemical functionalities of nanocellulose bring unprecedented benefits to the fabrication and performance of energy storage materials and systems, which lie far beyond those achievable with conventional synthetic materials. It is believed that this progress report can stimulate research interests in nanocellulose as a promising material, eventually widening material horizons for the development of next‐generation energy storage systems, that will lead us closer to so‐called Battery‐of‐Things (BoT) era.
Recent advances and future outlook of nanocellulose for potential use in energy storage systems are described as a green material opportunity. The unusual 1D structure and chemical functionalities of nanocellulose bring unprecedented benefits in the fabrication and properties of energy storage materials and systems, which lie far beyond those achievable with traditional synthetic materials.
Nanocellulose has emerged as a sustainable and promising nanomaterial owing to its unique structures, superb properties, and natural abundance. Here, we present a comprehensive review of the current ...research activities that center on the development of nanocellulose for advanced electrochemical energy storage. We begin with a brief introduction of the structural features of cellulose nanofibers within the cell walls of cellulose resources. We then focus on a variety of processes that have been explored to fabricate nanocellulose with various structures and surface chemical properties. Next, we highlight a number of energy storage systems that utilize nanocellulose-derived materials, including supercapacitors, lithium-ion batteries, lithium-sulfur batteries, and sodium-ion batteries. In this section, the main focus is on the integration of nanocellulose with other active materials, developing films/aerogel as flexible substrates, and the pyrolyzation of nanocellulose to carbon materials and their functionalization by activation, heteroatom-doping, and hybridization with other active materials. Finally, we present our perspectives on several issues that need further exploration in this active research field in the future.
Nanocellulose from various kinds of sources and nanocellulose-derived materials have been developed for electrochemical energy storage, including supercapacitors, lithium-ion batteries, lithium-sulfur batteries, and sodium-ion batteries.
The multiscale chemomechanical interplay in lithium‐ion batteries builds up mechanical stress, provokes morphological breakdown, and leads to state of charge heterogeneity. Quantifying the interplay ...in complex composite electrodes with multiscale resolution constitutes a frontier challenge in precisely diagnosing the fading mechanism of batteries. In this study, hard X‐ray phase contrast tomography, capable of nanoprobing thousands of active particles at once, enables an unprecedented statistical analysis of the chemomechanical transformation of composite electrodes under fast charging conditions. The damage heterogeneity is demonstrated to prevail at all length scales, which stems from the unbalanced electron conduction and ionic diffusion, and collectively leads to the nonuniform utilization of active particles spatially and temporally. This study highlights that the statistical mapping of the chemomechanical transformation offers a diagnostic method for the particles utilization and fading, hence could improve electrode formulation for fast‐charging batteries.
Hard X‐ray phase contrast tomography, capable of nano‐probing thousands of active particles at once, enables an unprecedented statistical analysis of the chemomechanical transformation of composite electrodes under fast charging conditions. This study offers a diagnosing method for the particles utilization and fading, hence could improve the electrode formulation for fast‐charging batteries.
The current surge in demand for high-performance batteries has inspired the relentless pursuit of advanced battery materials and chemistry. Notably, all-solid-state lithium-ion batteries and lithium ...metal batteries that have recently come into the spotlight have stimulated our research interest in solid-state electrolytes as a promising alternative to conventional liquid electrolytes. Among the various solid-state electrolytes explored to date, polymeric single lithium-ion conductors (polymeric SLICs) have garnered considerable attention as an organic approach that is different from the widely investigated solid inorganic electrolytes. A salient feature of polymeric SLICs is the predominant contribution of Li
+
ions to the ionic conductivity, thus enabling the Li
+
ion transference number to reach almost unity. This exceptional single ion transport behavior of polymeric SLICs, in combination with their solid-state nature, flexibility and facile processability, brings remarkable benefits to the battery structure and performance, which lie far beyond those achievable with typical dual-ion conductive electrolytes. In this review, we describe the current status and challenges of polymeric SLICs in terms of chemical/structural design and synthesis strategies. Also, the development direction and future outlook of polymeric SLICs are presented with a focus on their potential for application in the newly emerging Li battery systems.
Forthcoming smart energy era is in strong pursuit of full‐fledged rechargeable power sources with reliable electrochemical performances and shape versatility. Here, as a naturally ...abundant/environmentally friendly cellulose‐mediated cell architecture strategy to address this challenging issue, a new class of hetero‐nanonet (HN) paper batteries based on 1D building blocks of cellulose nanofibrils (CNFs)/multiwall carbon nanotubes (MWNTs) is demonstrated. The HN paper batteries consist of CNF/MWNT‐intermingled heteronets embracing electrode active powders (CM electrodes) and microporous CNF separator membranes. The CNF/MWNT heteronet‐mediated material/structural uniqueness enables the construction of 3D bicontinuous electron/ion transport pathways in the CM electrodes, thus facilitating electrochemical reaction kinetics. Furthermore, the metallic current collectors‐free, CNF/MWNT heteronet architecture allows multiple stacking of CM electrodes in series, eventually leading to user‐tailored, ultrathick (i.e., high‐mass loading) electrodes far beyond those accessible with conventional battery technologies. Notably, the HN battery (multistacked LiNi0.5Mn1.5O4 (cathode)/multistacked graphite (anode)) provides exceptionally high‐energy density (=226 Wh kg−1 per cell at 400 W kg−1 per cell), which surpasses the target value (=200 Wh kg−1 at 400 W kg−1) of long‐range (=300 miles) electric vehicle batteries. In addition, the heteronet‐enabled mechanical compliance of CM electrodes, in combination with readily deformable CNF separators, allows the fabrication of paper crane batteries via origami folding technique.
CNFs/CNTs‐based hetero‐nanonet paper batteries are presented as a 1D material‐mediated cell architecture strategy to enable ultrahigh energy density and shape versatility far beyond those achievable with conventional battery technologies. Owing to the 3D bicontinuous electron/ion transport pathways and exceptional mechanical compliance, the hetero‐nanonet paper batteries provide unprecedented improvements in the electrochemical reaction kinetics, energy density, and origami foldability.
Porous crystalline materials such as covalent organic frameworks and metal–organic frameworks have garnered considerable attention as promising ion conducting media. However, most of them ...additionally incorporate lithium salts and/or solvents inside the pores of frameworks, thus failing to realize solid-state single lithium-ion conduction behavior. Herein, we demonstrate a lithium sulfonated covalent organic framework (denoted as TpPa-SO 3 Li) as a new class of solvent-free, single lithium-ion conductors. Benefiting from well-designed directional ion channels, a high number density of lithium-ions, and covalently tethered anion groups, TpPa-SO 3 Li exhibits an ionic conductivity of 2.7 × 10–5 S cm–1 with a lithium-ion transference number of 0.9 at room temperature and an activation energy of 0.18 eV without additionally incorporating lithium salts and organic solvents. Such unusual ion transport phenomena of TpPa-SO 3 Li allow reversible and stable lithium plating/stripping on lithium metal electrodes, demonstrating its potential use for lithium metal electrodes.
Conventional self‐charging systems are generally complicated and highly reliant on the availability of energy sources. Herein, a chemically self‐charging, flexible solid‐state zinc ion battery ...(ssZIB) based on a vanadium dioxide (VO2) cathode and a polyacrylamide‐chitin nanofiber (PAM‐ChNF) hydrogel electrolyte is developed. With a power density of 139.0 W kg‐1, the ssZIBs can deliver a high energy density of 231.9 Wh kg‐1. The superior electrochemical performance of the ssZIBs is attributed to the robust tunnel structure of the VO2 cathode and the entangled network of PAM‐ChNF electrolyte, which provide efficient pathways for ion diffusion. Impressively, the designed ssZIBs can be chemically self‐charged by the redox reaction between the cathode and oxygen in ambient conditions. After oxidation for 6 h in air, the ssZIBs manifest a high discharging capacity of 263.9 mAh g‐1 at 0.2 A g‐1, showing excellent self‐rechargeability. With the assistance of a small amount of acetic acid added to the hydrogel electrolyte, the galvanostatic discharging and chemical self‐charging cycles can reach 20. More importantly, such ssZIBs are able to operate well at chemical or/and galvanostatic charging hybrid modes, demonstrating superior reusability. This work brings a new prospect for designing flexible chemically self‐charging ssZIBs for portable self‐powered systems.
The robust tunnel structure of a vanadium dioxide cathode and the network of a polyacrylamide–chitin nanofiber hydrogel electrolyte provide efficient pathways for ion diffusion, lead to superior electrochemical performance for solid‐state zinc‐ion batteries. In addition, the flexible chemically self‐charging ssZIBs demonstrate excellent self‐rechargeability and superior reusability, which provide a facile route for portable self‐powered systems.
To dramatically improve the performance of non-precious catalyst-based anion exchange membrane fuel cells (AEMFCs), a conceptual change in the structure of conventional electrocatalysts is needed. ...Here we report a novel work function tailoring of graphene
via
adopting a graphene shell-encapsulated Co nanoarchitecture to efficiently activate the graphitic carbon shell as an exclusive and main active site for the oxygen reduction reaction (ORR). Theoretical calculations and electrochemical analysis suggest that the charge transfer from core Co nanoparticles to the outer graphene shell results in a significant change in the electronic structure of the graphene shell and reduces its work function. The present catalyst shows high ORR catalytic activity but exceptionally enhanced durability compared to a Pt catalyst in alkaline media, which is attributed mainly to the reduced work function of the outer graphene shell and the 3D nanographene structure providing a large number of active carbon sites. The single cell using the graphene shell-encapsulated Co nanoparticles as a cathode catalyst produces a high maximum power density of 412 mW cm
−2
, making this among the best non-precious catalysts for the ORR reported so far. Therefore, our results demonstrate a promising strategy to rationally design inexpensive and durable oxygen reduction catalysts, and this hybrid concept will provide a new perspective for catalyst structures which can practically be used in AEMFCs.
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