Preparation and characterization of flexible lithium iron phosphate/graphene/cellulose electrode for lithium ion batteries

Efficient Structural Regulation Platform for the Controlled Synthesis of LiFePO4 Cathodes with Shorter Li-Ion Diffusion Paths

The rate performance of lithium iron phosphate (LiFePO4) is mainly limited by its poor electronic conductivity and slow Li-ion diffusion rate. Graphene-based materials are often compounded with LiFePO4 (LFP) to improve their rate performance, mainly because of their excellent electrical conductivity. Unlike most past composite work focusing on the conductive network between LFP and graphene, in this work, we further developed the functionality of graphene-based materials as nanoparticle carriers, where the nitrogen-doping strategy endows graphene with properties that make it an efficient structural regulation platform during the solvothermal process. Compared to reduced graphene oxide, not only does the nitrogen-doped sites confer more nucleation growth sites for LFP on the graphene surface during the solvothermal process, but also the localized formation of an EG-enriched microenvironment helps to further inhibit the in situ growth of LFP along [010]. The efficient structural regulation platform assisted the synthesis of (010)-oriented LFP with a smaller particle size, which further shortens the Li-ion diffusion paths. The optimized LFP composite electrode materials exhibit a discharge-specific capacity of 133.1 mA·h/g at 10C, which exceeds/is comparable to that of previously reported LFP compounded with graphene-based materials. This work broadens the functionality of graphene-based carriers and provides new ideas for the controllable synthesis of nanoparticles.

Exploring nanocellulose frontiers: A comprehensive review of its extraction, properties, and pioneering applications in the automotive and biomedical industries

Material is an inseparable entity for humans to serve different purposes. However, synthetic polymers represent a major category of anthropogenic pollutants with detrimental impacts on natural ecosystems. This escalating environmental issue is characterized by the accumulation of non-biodegradable plastic materials, which pose serious threats to the health of our planet's ecosystem. Cellulose is becoming a focal point for many researchers due to its high availability. It has been used to serve various purposes. Recent scientific advancements have unveiled innovative prospects for the utilization of nanocellulose within the area of advanced science. This comprehensive review investigates deeply into the field of nanocellulose, explaining the methodologies employed in separating nanocellulose from cellulose. It also explains upon two intricately examined applications that emphasize the pivotal role of nanocellulose in nanocomposites. The initial instance pertains to the automotive sector, encompassing cutting-edge applications in electric vehicle (EV) batteries, while the second exemplifies the use of nanocellulose in the field of biomedical applications like otorhinolaryngology, ophthalmology, and wound dressing. This review aims to provide comprehensive information starting from the definitions, identifying the sources of the nanocellulose and its extraction, and ending with the recent applications in the emerging field such as energy storage and biomedical applications.

Self-Supporting Flexible Paper-Based Electrode Reinforced by Gradient Network Structure

At present, the self-supporting paper-based electrode has some problems, such as low mechanical strength and insufficient flexibility, which restrict its application in flexible electronics. In this paper, FWF is used as the skeleton fiber, and the contact area and the number of hydrogen bonds of the fiber are increased by grinding the fiber and adding nanofibers to bridge it, and a level three gradient enhanced skeleton support network structure is constructed, which effectively improves the mechanical strength and foldability of the paper-based electrodes. The tensile strength of FWF15-BNF5 paper-based electrode is 7.4 MPa, the elongation at break is increased to 3.7%, the electrode thickness is as low as 66 μm, the electrical conductivities is 5.6 S cm^-1, and the contact angle to electrolyte as low as 45°, which has excellent electrolyte wettability, flexibility, and foldability. After three-layer superimposed rolling, the discharge areal capacity reached 3.3 mAh cm^-2 and 2.9 mAh cm^-2 at the rate of 0.1 C and 1.5 C, respectively, which was superior to the commercial LFP electrode, it had good cycle stability, and the areal capacity was 3.0 mAh cm^-2 and 2.8 mAh cm^-2 after 100 cycles at the rate of 0.3 C and 1.5 C.

Cellulose: Characteristics and applications for rechargeable batteries

Cellulose, an abundant natural polymer, has promising potential to be used for energy storage systems because of its excellent mechanical, structural, and physical characteristics. This review discusses the structural features of cellulose and describes its potential application as an electrode, separator, and binder, in various types of high-performing batteries. Various surface and structural characteristics of cellulose (e.g., fiber size, surface functional groups, the hierarchy of pores, and porosity levels) that contribute to its electrochemical performance are discussed. Cellulose structure/property/processing/function relationships are further focused and elucidated in terms of the latest developments in the emerging field of sustainable materials in Li-Ion, Na-Ion, and LiS batteries.

A current collect-free Li1.2Ni0.13Co0.13Mn0.54O2flexible film for high-performance lithium-ion batteries

Due to the high demand for more convenient flexible devices, there are more requirements for higher performance of flexible batteries. The layered lithium-rich manganese-based Li_1.2Ni_0.13Co_0.13Mn_0.54O₂cathode material has the advantages of higher energy density, higher discharge capacity and environmentally friendly, so it can be used for high-performance flexible electrode cathode material. Its theoretical capacity can reach more than 250 mAh g^-1, which is higher than most cathode materials currently used in commercialization. Here we synthesize Li_1.2Ni_0.13Co_0.13Mn_0.54O₂(LNCM) cathode, and then use a simple method to make a current collect-free LNCM flexible film. This film has excellent flexibility and electrochemical performance. At 25 mA g^-1, its initial discharge capacity reaches 314.0 mAh g^-1. After 200 cycles of 500 mA g^-1, its capacity retention rate is 82.1%, the attenuation is about 0.08% per cycle. Moreover, by bending at any position of the flexible film, it can still remain intact, and the soft-packaged battery made by the flexible film can still be used under the bending condition and keep the brightness of the LED lamp unchanged. This shows that using Li_1.2Ni_0.13Co_0.13Mn_0.54O₂to make high-performance flexible electrodes is a simple and effective method, which is expected to be practically applied to flexible electronic devices.

Flexible Tellurium-Based Electrode for High-Performance Lithium-Tellurium Battery

Low-dimensional nanomaterials have attracted considerable attention for next-generation flexible energy devices owing to their excellent electrochemical properties and superior flexibility. Herein, uniform Tellurium nanotubes (Te NTs) were prepared through a facile hydrothermal method, and then a flexible and freestanding electrode was fabricated with Te NTs as active materials and a small amount of nanofibrillated celluloses (NFCs) as a flexible matrix through a vacuum filtration method without adding extra conductive carbon or a binder. The resulting Te-based electrode exhibits a high volumetric capacity of 1512 mAh cm⁻³ at 200 mA g⁻¹, and delivers admirable cyclic stability (capacity retention of 104% over 300 cycles) and excellent rate performance (833 mAh cm⁻³ at 1000 mA g⁻¹), which benefits from the unique structure and intrinsically superior conductivity of Te NTs. After bending 50 times, the Te-based electrode delivers a desirable volumetric capacity of 1117 mAh cm⁻³, and remains 93% of initial capacity after 100 cycles. The results imply that the Te-based electrode exhibits excellent electrochemical properties and superior flexibility simultaneously, which can serve as a potential candidate for the flexible lithium batteries.

Layer-by-Layer Self-Assembled Nanostructured Electrodes for Lithium-Ion Batteries

Gaining control over the nanoscale assembly of different electrode components in energy storage systems can open the door for design and fabrication of new electrode and device architectures that are not currently feasible. This work presents aqueous layer-by-layer (LbL) self-assembly as a route towards design and fabrication of advanced lithium-ion batteries (LIBs) with unprecedented control over the structure of the electrode at the nanoscale, and with possibilities for various new designs of batteries beyond the conventional planar systems. LbL self-assembly is a greener fabrication route utilizing aqueous dispersions that allow various Li⁺ intercalating materials assembled in complex 3D porous substrates. The spatial precision of positioning of the electrode components, including ion intercalating phase and electron-conducting phase, is down to nanometer resolution. This capable approach makes a lithium titanate anode delivering a specific capacity of 167 mAh g^-1 at 0.1C and having comparable performances to conventional slurry-cast electrodes at current densities up to 100C. It also enables high flexibility in the design and fabrication of the electrodes where various advanced multilayered nanostructures can be tailored for optimal electrode performance by choosing cationic polyelectrolytes with different molecular sizes. A full-cell LIB with excellent mechanical resilience is built on porous insulating foams.

Toward Low-Cost All-Organic and Biodegradable Li-Ion Batteries

This work presents an alternative method for fabricating Li-ion electrodes in which the use of aluminum/copper current collectors and expensive binders is avoided. Low-cost natural cellulose fibers with a 2-mm length are employed as binder and support for the electrode. The objective of this method is to eliminate the use of heavy and inactive current collector foils as substrates and to replace conventional costly binders with cellulose fibers. Moreover, no harmful solvents, such as N-methylpyrrolidone, are employed for film fabrication. Water-soluble carbons are also utilized to reduce the preparation time and to achieve a better repartition of carbon in the electrode, thus improving the electrochemical performance. Flexible and resistant LiFePO₄ (LFP), Li₄Ti₅O₁₂ (LTO), organic 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA), and graphite electrodes are obtained with active mass loadings similar to those obtained by the current casting method. The initial discharge capacity of approximately 130 mAh·g⁻¹ at 2 C is obtained for an LFP/LTO paper battery with an approximately 91.6% capacity retention after 1000 cycles. An all-organic prelithiated PTCDA/graphite cell without a transition metal is prepared and electrochemically tested. It is one of the first self-standing batteries that is composed of organic redox active molecules and biodegradable components reported in literature.

Flexible Li[Li0.2Ni0.13Co0.13Mn0.54]O2/Carbon Nanotubes/Nanofibrillated Celluloses Composite Electrode for High-Performance Lithium-Ion Battery

Rapidly-growing demand for wearable and flexible devices is boosting the development of flexible lithium ion batteries (LIBs). The exploitation of flexible electrodes with high mechanical properties and superior electrochemical performances has been a key challenge for the rapid practical application of flexible LIBs. Herein, a flexible composite electrode was prepared from the mixed solutions of Li[Li_0.2Ni_0.13Co_0.13Mn_0.54]O₂ (LLOs), carbon nanotubes(CNTs), and nanofibrillated celluloses (NFCs) via a vacuum filtration method. The resulting LLOs/CNTs/NFCs electrode delivered an initial discharge capacity of 253 mAh g⁻¹ at 0.1 C in the voltage range from 2.0 to 4.6 V, and retained a reversible capacity of 178 mAh g⁻¹ with 83% capacity retention after 100 cycles at 1 C. The LLOs/CNTs/NFCs electrode exhibited excellent flexibility along with repeated bending in the bending test. The LLOs/CNTs/NFCs electrode after bending test remained a discharge capacity of 149 mAh g⁻¹ after 100 cycles at 1 C, and the corresponding capacity retentions was 76%. The excellent electrochemical performance and high flexibility can be ascribed to the framework formed by CNTs with high conductivity and NFCs with good mechanical properties. The results imply that the as-fabricated electrode can be a promising candidate for the flexible LIBs.