Rational design of dual-ion doped cobalt-free Li-rich cathode materials for enhanced cycle stability of lithium-ion pouch cell batteries.

The synergistic effect of single-crystal structure and dual doping in Li-rich cobalt-free cathode materials was thoroughly investigated. Lithium-ion pouch cells employing Sb/Sn doped Li1.2Mn0.6Ni0.2O2 and graphite exhibited a specific capacity of 191.01 mA h g-1 at 1C rate and exceptionally stable performance upon cycling, with capacity retention of 87.24% of their initial capacity after 250 cycles at 1C rate. The strategic combination of morphology manipulation and dual ion doping has markedly diminished cation mixing and expanded the Li interstitial sites within the cathode lattice. This work offers significant insights into the mechanisms responsible for the structural decline of Li-rich cobalt-free cathodes, emphasizing the importance of stabilizing the cathode lattice structure at high potential. These findings suggest promising potential for this material to meet the demanding energy density criteria for electric vehicles. Finally, this research provides practical strategies for effectively implementing high-voltage cobalt-free cathodes, offering valuable guidance for future applications.

Advancing lithium-sulfur battery efficiency: utilizing a 2D/2D g-C3N4@MXene heterostructure to enhance sulfur evolution reactions and regulate polysulfides under lean electrolyte conditions.

Lithium-sulfur batteries (LSBs) show promise for achieving a high energy density of 500 W h kg-1, despite challenges such as poor cycle life and low energy efficiency due to sluggish redox kinetics of lithium polysulfides (LiPSs) and sulfur's electronic insulating nature. We present a novel 2D Ti3C2 Mxene on a 2D graphitic carbon nitride (g-C3N4) heterostructure designed to enhance LiPS conversion kinetics and adsorption capacity. In a pouch cell configuration with lean electrolyte conditions (∼5 µL mg-1), the g-C3N4-Mx/S cathode exhibited excellent rate performance, delivering ∼1061 mA h g-1 at C/8 and retaining ∼773 mA h g-1 after 190 cycles with a Coulombic efficiency (CE) of 92.7%. The battery maintained a discharge capacity of 680 mA h g-1 even at 1.25 C. It operated reliably at an elevated sulfur loading of 5.9 mg cm-2, with an initial discharge capacity of ∼900 mA h g-1 and a sustained CE of over 83% throughout 190 cycles. Postmortem XPS and EIS analyses elucidated charge-discharge cycle-induced changes, highlighting the potential of this heterostructured cathode for commercial garnet LSB development.

Regioselective Protection and Deprotection of Nanocellulose Molecular Design Architecture: Robust Platform for Multifunctional Applications.

Regioselectively substituted nanocellulose was synthesized by protecting the primary hydroxyl group. Herein, we took advantage of the different reactivities of primary and secondary hydroxyl groups to graft large capping structures. This study mainly focuses on regioselective installation of trityl protecting groups on nanocellulose chains. The elemental analysis and nuclear magnetic resonance spectroscopy of regioselectively substituted nanofibrillated cellulose (NFC) suggested that the trityl group was successfully grafted in the primary hydroxyl group with a degree of substitution of nearly 1. Hansen solubility parameters were employed, and the binary system composed of an ionic liquid and pyridine as a base was revealed to be the optimum condition for regioselective functionalization of nanocellulose. Interestingly, the dissolution of NFC in the ionic liquid and the subsequent deprotection process of NFC substrates hardly affected the crystalline structure of NFC (3.6% decrease in crystallinity). This method may provide endless possibilities for the design of advanced engineered nanomaterials with multiple functionalities. We envisage that this protection/deprotection approach may lead to a bright future for the fabrication of multifunctional devices based on nanocellulose.

Thermoconformational Behavior of Cellulose Nanofiber Films as a Device Substrate and Their Superior Flexibility and Durability to Glass.

The design and high-throughput manufacturing of thin renewable energy devices with high structural and atomic configurational stability are crucial for the fabrication of green electronics. Yet, this concept is still in its infancy. In this work, we report the extraordinary durability of thin molecular interlayered organic flexible energy devices based on chemically tuned cellulose nanofiber transparent films that outperform glass by decreasing the substrate weight by 50%. The nanofabricated flexible thin film has an exceptionally low thermal coefficient of expansion of 1.8 ppm/K and a stable atomic configuration under a harsh fabrication condition (over 190 °C for an extended period of 5 h). A flexible optoelectronic device using the same renewable cellulose nanofiber film substrate was found to be functionally operational over a life span of 5 years under an intermittent operating condition. The success of this device's stability opens up an entirely new frontier of applications of flexible electronics.

One-pot fabrication of flexible and luminescent nanofilm by in-situ radical polymerization of vinyl carbazole on nanofibrillated cellulose.

Photoresponsive functionalized nanofilms were prepared via radical polymerization of carbazole units on a nanofibrillated cellulose (NFC) backbone via one-pot procedure. Herein, NFC was functionalized with active carbazole units as pendant organic moieties. The nanofilms were characterized by UV-vis and fluorescence spectroscopy, Fourier transformed infrared (FTIR) and Raman spectroscopy, 13C NMR and proton NMR spectra, contact angle analysis, mechanical testing, and scanning electron microscopy (SEM). The fabricated nanofilms exhibited large tensile strength (∼110 MPa), higher hydrophobicity and luminescence activity. The results indicated that the prepared optically active nanofilms present potential applications in the fields of flexible organic light emitting devices.

Current State of Applications of Nanocellulose in Flexible Energy and Electronic Devices.

Novel and unique applications of nanocellulose are largely driven by the functional attributes governed by its structural and physicochemical features including excellent mechanical properties and biocompatibility. In recent years, thousands of groundbreaking works have helped in the development of targeted functional nanocellulose for conductive, optical, luminescent materials, and other applications. The growing demand for sustainable and renewable materials has led to the rapid development of greener methods for the design and fabrication of high-performance green nanomaterials with multiple features, and consequently new challenges and opportunities. The present review article discusses historical developments, various fabrication and functionalization methods, the current stage, and the prospects of flexible energy and hybrid electronics based on nanocellulose.

Flexible electrically conductive films based on nanofibrillated cellulose and polythiophene prepared via oxidative polymerization.

Industrial ecology, sustainable manufacturing, and green chemistry have been considered platform-based approaches to the reduction of the environmental footprint. Recently, nanofibrillated cellulose (NFC) has gained significant interest due to its mechanical properties, biodegradability, and availability. These outstanding properties of NFC have encouraged the development of a more sustainable substrate for electronics. In this context, the combination of NFC and conductive polymers may create a new class of biocomposites to be used in place of conventional electronics which are not optimally designed for use in flexible and mechanically robust devices. In this study, polythiophene was grafted onto nanocellulose surface at appropriate reaction times to obtain a strong, flexible, foldable films with capacity for electrical conductivity. Nanocomposites films were synthesized by a one-step reaction in which a 3-methyl thiophene monomer was oxidatively polymerized onto nanocellulose backbone. The nature of the fabricated NFC films changed from insulator to semiconductor material upon oxidative polymerization.