Porous Graphene-like Carbon from Fast Catalytic Decomposition of Biomass for Energy Storage Applications

A novel carbon material made of porous graphene-like nanosheets was synthesized from biomass resources by a simple catalytic graphitization process using nickel as a catalyst for applications in electrodes for energy storage devices. A recycled fiberboard precursor was impregnated with saturated nickel nitrate followed by high-temperature pyrolysis. The highly exothermic combustion of in situ formed nitrocellulose produces the expansion of the cellulose fibers and the reorganization of the carbon structure into a three-dimensional (3D) porous assembly of thin carbon nanosheets. After acid washing, nickel particles are fully removed, leaving nanosized holes in the wrinkled graphene-like sheets. These nanoholes confer the resulting carbon material with ≈75% capacitance retention, when applied as a supercapacitor electrode in aqueous media at a specific current of 100 A·g–1 compared to the capacitance reached at 20 mA·g–1, and ≈35% capacity retention, when applied as a negative electrode for lithium-ion battery cells at a specific current of 3720 mA·g–1 compared to the specific capacity at 37.2 mA·g–1. These findings suggest a novel way for synthesizing 3D nanocarbon networks from a cellulosic precursor requiring low temperatures and being amenable to large-scale production while using a sustainable starting precursor such as recycled fiberwood.Spanish Government Agency Ministerio de Economí a y Competitividad (MINECO) (grant number MAT2016-76526-R)

Cellulose-based bionanocomposites in energy storage applications-A review

The growing demand for energy and environmental issues are the main concern for the sustainable development of modern society. Replacing toxic and expensive materials with inexpensive and biodegradable biomaterials is the main challenge for researchers. Nanocomposites are of the utmost consideration for their application in energy storage devices because of their specific electrochemical properties. Cellulose-based bionanocomposites have added a new dimension to this field since these are developed from available renewable biomaterials. Studies on developing electrodes, separators, collectors, and electrolytes for the batteries have been conducted based on these composites rigorously. Electrodes and separators made of these composites for the supercapacitors have also been investigated. Researchers have used a wide range of micro- and nano-structural cellulose along with nanostructured inorganic materials to produce cellulose-based bionanocomposites for energy devices, i.e., supercapacitors and batteries. The presence of cellulosic materials enhances the loading capacity of active materials and uniform porous structure in the electrode matrix. Thus, it has shown improved electrochemical properties. Therefore, these can help to develop biodegradable, lightweight, malleable, and strong energy storage devices. In this review article, the manufacturing process, properties, applications, and possible opportunities of cellulose-based bionanocomposites in energy storage devices have been emphasized. Its challenges and opportunities have also been discussed

Nanocellulose/zero, one- and two-dimensional inorganic additive based electrodes for advanced supercapacitors

Nowadays, the growing threat of environmental pollution and the energy crisis have accelerated the advancement of sustainable energy sources and highly efficient energy storage technologies. Supercapacitors' outstanding efficiency and accessibility have attracted much interest in portable electronics. However, compared to other energy storage devices, commercially available supercapacitors offer minimal advantages, and it is also very difficult to balance their electrochemical performance, such as cyclability, energy density, and capacitance. Fabricating high-performance supercapacitors with attractive electrical parameters and flexibility depends on the composition of the electrodes. Nanocellulose, which is derived from waste biomass because of its high mechanical strength, strong chemical reactivity, and biodegradability, has been used to integrate 2D, 1D, and zero-dimensional inorganic additive materials to develop a promising material for supercapacitor electrodes. The present review summarises recent advancements in the progress of nanocellulose/2D-, 1D-, and zero-dimensional inorganic material-based composite electrodes for their application in supercapacitors. Different strategies for developing nanocellulose/inorganic additive-based composite electrodes are reviewed, and subsequently, the potential of nanocellulose/multidimensional inorganic additive-based electrodes in supercapacitors is fully elaborated. In the end, current challenges and future directions for the development finally, current challenges and future directions for developing nano cellulose-based nanocomposite electrodes in supercapacitors were also discussed.</p

Lignin as an Active Biomaterial: A Review

Lignin is the second most naturally abundant biopolymer in the cell wall of lignocellulosic compound (15-35%) after cellulose.Lignin can be generated in massive amounts as by-products in biorefineries and pulp and paper industries through differing processes. Most lignin is utilized as generating energy and has always been treated as waste. Due to the high amount of phenolic compounds in lignin, it is considered as a potential material for various polymers, building blocks, and biomaterials production. Even though lignin can be utilized in the form of isolated lignin directly, the modification of lignin can increase the wide range of lignin applications. Lignin-based copolymers and modified lignin show better miscibility with another polymeric matrix, outstanding to the enhanced performance of such lignin-based polymer composites.This article summarizes the properly updated information of lignin’s potential applications, such as bio-surfactant, active packaging, antimicrobial agent, and supercapacitor.Keywords: active packaging, antimicrobial agent, bio-surfactant, lignin, supercapacito

Master of Science

thesisElectrochemical capacitors, or "supercapacitors", are an electrochemical energy storage technology with high-power density and long cycle life compared to batteries. Supercapacitors have many promising applications in electric vehicles, renewable energy storage, consumer electronics, environmental sensors, biomedical implants, and grid energy storage. Conductive polymers are a material of interest for supercapacitor energy storage because of their ability to store energy by both electric double layer capacitance and "pseudocapacitance" (surface reduction-oxidation reactions). Polypyrrole is a widely used conductive polymer for supercapacitor electrodes, as well as in lithium-ion batteries. For applications in environmental sensors, transient electronics, and implantable devices, it is necessary to find supercapacitor electrode materials that are easily biodegradable. A variation of polypyrrole exhibiting methyl carboxylate side chains, which we call "MPC polymer," is presented in this thesis as a dissolvable supercapacitor electrode. It is, to the best of our knowledge, introduced for the first time as a dissolvable electrochemical energy storage material. The supercapacitor characteristics of MPC polymer are characterized for planar electrodes as well as a nanocellulose-based composite. The MPC polymer is found to have capacitance, cycle life, and impedance characteristics comparable to state-of-the-art polypyrrole

Wood-derived lignin-based fibers as supercapacitor electrodes

Today, in order to replace fossil energy sources with renewable energy sources such as solar and wind, reliable energy storage systems that can provide power regardless of the intermittent nature of the energy sources must be created. Especially with the future’s rising energy demands the development of such energy storage systems from green-collar materials with the least negative environmental impact is pressing. Transforming the major cheap and replenishable forest resource, wood, to carbon materials with desirable morphologies can potentially be used as supercapacitors (SC) electrodes with long cycle life and higher power density than batteries today. Forest materials are abundant, but their extraction to manufacturing hold practicality issues due to yet not established procedures. Active research has focused on advancing lignin-based electrospun carbon fibers (ELCFs) and activated carbons with simple, high-yielding mass production units. The ECLF is self-standing and flexible, making them a prospective candidate for flexible and wearable electronics. As of today, the materials face shortcomings such as low electrical conductivity and poor mechanical stability post thermal carbonization especially if the spinning discards fossil based secondary polymers. Research on optimized fractionated high molecular weight lignin solutions from black liquor - an industrial paper and pulp industry byproduct - have improved their spinnability. Turning these lignin-based materials to commercial utilization requires more investigation and understanding of the materials.This thesis discusses the electrochemical performance of lignin fibers as highly reliable supercapacitor electrode material. Grafting the right amount of beneficial functional groups on the ELCF surface by low-power oxygen plasma treatment, the properties of the electrode-electrolyte interface significantly improved the wettability, increased active sites favorable for pseudocapacitance, reduced diffusion limitation, thus enhancing its electrochemical storage ability. Quite often, the surface functional groups have a detrimental impact on a device’s electrochemical performance such as increased resistance, low power performance, low stability, and high self-discharge rate. However, the non-invasive nature of the conducted plasma treatment made a remarkable improvement in the capacitive performance in KOH aqueous medium without compromising power and energy performance metrics. Preliminary quantification performed to understand the charge storage behavior in other aqueous electrolytes H2SO4 and Li2SO4 are also revealed. Furthermore, the observation of enhanced electrochemical performance via applying a voltage of 1.2 V and 10 000 charge-discharge cycles is discussed. With the competition of supercapacitors energy storage ability with batteries, efforts have been taken to make thick electrodes to boost energy density. Electrodes with high areal mass loading in supercapacitor maximize the packing density of the electroactive electrode materials while lowering the manufacturing cost by reducing the number of inactive material layers. Herein, the fabrication and electrochemical performance of 180-280 μm thick activated carbon (AC) electrodes with 2 wt% of hair-like carbonized lignin carbon fibers (LCF) as conductive agent alongside carbon black in the electrode matrix was assessed. In the resulting electrodes, the LCF inclusions into the AC matrix increased flexibility and contributed to improved capacitances due to better conductivity in the electrodes. The reduced resistances suggest that LCFs act as an intermediate layer among AC particles and serve as conductive pathways, facilitating electronic conductivity of more AC particles in deeper layers. Considering the biologically hazardous nature of other commonly used binders like polytetrafluoroethylene, and polyvinylidene fluoride, environmentally friendly binder microfibrillated cellulose (MFC) binder was successfully used to fabricate freestanding electrodes

Green-Synthesized Graphene for Supercapacitors—Modern Perspectives

Graphene is a unique nanocarbon nanostructure, which has been frequently used to form nanocomposites. Green-synthesized graphene has been focused due to environmentally friendly requirements in recent technological sectors. A very important application of green-synthesized graphene-based nanocomposite has been observed in energy storage devices. This state-of-the-art review highlights design, features, and advanced functions of polymer/green-synthesized graphene nanocomposites and their utility in supercapacitor components. Green graphene-derived nanocomposites brought about numerous revolutions in high-performance supercapacitors. The structural diversity of conjugated polymer and green graphene-based nanocomposites has facilitated the charge transportation/storage capacity, specific capacitance, capacitance retention, cyclability, and durability of supercapacitor electrodes. Moreover, the green method, graphene functionality, dispersion, and matrix–nanofiller interactions have affected supercapacitance properties and performance. Future research on innovative polymer and green graphene-derived nanocomposites may overcome design/performance-related challenging factors for technical usages

Edible cellulose-based conductive composites for triboelectric nanogenerators and supercapacitors

Edible electronics will enable systems that can be safely ingested and degraded in the human body after completing their function, such as sensing physiological parameters or biological markers in the gastrointestinal tract, without risk of retention or need of recollection. The same systems are potentially suitable for directly tagging food, monitoring its quality, and developing edible soft actuators control and sensing abilities. Designing appropriate edible power sources is critical to turn such a vision into real opportunities. We propose electrically conductive edible composites based on ethylcellulose and activated carbon as enabling materials for energy harvesting and storage. Free-standing, phase-separated bi-layered films, insulating at the top and with low electrical resistivity (∼10 Ω cm) at the bottom, were produced with a scalable single-step process. Food additives can tune the mechanical and triboelectrical properties of the proposed edible films. We demonstrated their successful operation as electropositive elements in organic triboelectric nanogenerators (TENGs) and as electrodes in fully edible supercapacitors (SC). The TENGs showed ∼60 V peak voltage (root mean square power density ∼2.5 μW cm−2 at 5 Hz), while the SC achieved an energy density of 3.36 mW h g−1, capacity of ∼ 9 mAh g−1, and stability for more than 1000 charge-discharge cycles. These results show that the combination of ethyl cellulose and activated carbon, and the control over their mixture, allow on-demand edible devices for energy generation and storage, serving future edible and green electronics scenarios

Characterization, Modification and Application of Biochar for Energy Storage and Catalysis: A Review

Biomass can be converted to biofuels and bioproducts via thermochemical processes. Biochar is one of the major products of thermochemical conversion of biomass. The efficient use of biochar is critical to improving the economic viability and environmental sustainability of biomass conversion technologies. Applications of biochar for both agricultural and environmental benefits (e.g. as soil amendment, for inorganic pollutant removal) have been studied and reviewed extensively. However, biochar for energy storage materials and catalytic applications has not been widely reviewed in the recent past. This review aims to present the more significant recent advances in several biochar utilizations such as catalysts and supercapacitors. Discussions on biochar production technologies, chemistry, properties, characteristics, and advanced functionalization techniques are provided. It also points out barriers to achieving improvements in the future. Citation: Xiu, S., Shahbazi, A., and Li, R. (2017). Characterization, Modification and Application of Biochar for Energy Storage and Catalysis: A Review. Trends in Renewable Energy, 3(1), 86-101. DOI: 10.17737/tre.2017.3.1.003

Wood-Inspired Morphologically Tunable Aligned Hydrogel for High-Performance Flexible All-Solid-State Supercapacitors

Oriented microstructures are widely found in various biological systems for multiple functions. Such anisotropic structures provide low tortuosity and sufficient surface area, desirable for the design of high-performance energy storage devices. Despite significant efforts to develop supercapacitors with aligned morphology, challenges remain due to the predefined pore sizes, limited mechanical flexibility, and low mass loading. Herein, a wood-inspired flexible all-solid-state hydrogel supercapacitor is demonstrated by morphologically tuning the aligned hydrogel matrix toward high electrode-materials loading and high areal capacitance. The highly aligned matrix exhibits broad morphological tunability (47–12 µm), mechanical flexibility (0°–180° bending), and uniform polypyrrole loading up to 7 mm thick matrix. After being assembled into a solid-state supercapacitor, the areal capacitance reaches 831 mF cm−2 for the 12 µm matrix, which is 259% times of the 47 µm matrix and 403% times of nonaligned matrix. The supercapacitor also exhibits a high energy density of 73.8 µWh cm−2, power density of 4960 µW cm−2, capacitance retention of 86.5% after 1000 cycles, and bending stability of 95% after 5000 cycles. The principle to structurally design the oriented matrices for high electrode material loading opens up the possibility for advanced energy storage applications