Biomass-Derived Sustainable Carbon Materials in Energy Conversion and Storage Applications: Status and Opportunities. A mini review

What is the potential of walnut shell-derived carbon in battery applications?

The environmental implications of utilizing walnut shells (WSs) as a material for energy storage are complex, balanced between advancing technologies and improving efficiency. This review aims to address, for the first time, environmental concerns and health effects associated with this material by conducting an in-depth analysis of carbon materials derived from waste management systems. Beginning with a reevaluation of the structural characteristics, cellular morphology, and physicochemical properties of WSs, this study explores their potential for the efficient synthesis of carbon. By examining various methods for the production of WS-derived materials such as hard carbon, we demonstrate the multifaceted nature of WS biomass as a resource. Subsequently, we shift our focus to ion storage mechanisms in the carbon source (C-S), including storage sensitivity, ion intercalation in micropores, and layer intercalation. An electrochemical analysis of the carbon source reveals its potential applications in energy storage systems. Furthermore, life cycle analysis was employed to assess the environmental impact and economic viability of WS utilization. The findings of the analysis suggest that one of the most valuable attributes of WSs is their potential for creating more environmentally sustainable materials, encouraging researchers to promote the use of green components in sodium batteries. This review underscores, for the first time, the significance of WSs in the field of carbon energy storage and their potential to enhance future prospects. The substantial opportunities in this area warrant further research and development, highlighting the relevance of WS-derived materials in advancing sustainable energy storage solutions.

Advancing Electrical Engineering with Biomass-derived Carbon Materials: Applications, Innovations, and Future Directions

The ongoing global shift towards sustainability in electrical engineering necessitates novel materials that offer both ecological and technical benefits. Biomass-derived carbon materials (BCMs) are emerging as cornerstones in this transition due to their sustainability, cost-effectiveness, and versatile properties. This review explores the expansive role of BCMs across various electrical engineering applications, emphasizing their transformative impact and potential in fostering a sustainable technological ecosystem. The fundamentals of BCMs are investigated, including their unique structures, diverse synthesis procedures, and significant electrical and electrochemical properties. A detailed examination of recent innovations in BCM applications for energy storage, such as batteries and supercapacitors, and their pivotal role in developing advanced electronic components like sensors, detectors, and electromagnetic interference shielding composites has been covered. BCMs offer superior electrical conductivities, tunable surface chemistries, and mechanical properties compared to traditional carbon sources. These can be further enhanced through innovative doping and functionalization techniques. Moreover, this review identifies challenges related to scalability and uniformity in properties and proposes future research directions to overcome these hurdles. By integrating insights from recent studies with a forward-looking perspective, this paper sets the stage for the next generation of electrical engineering solutions powered by biomass-derived materials, aligning technological advancement with environmental stewardship.

Functionalized carbon electrocatalysts in energy conversion and storage applications: A review

Energy crises, along with environmental tampering, are currently a big topic on the global scene. The most promising strategy in the current research trend is the creation of ecologically pleasant renewable green alternative energy sources. Since adequate access to green, ecologically acceptable energy sources promotes industrialization and the well-being of human society. Hence, in this review, the most recent carbon electrocatalysts electrode materials prepared from porous activated carbon (PAC) in electrochemical energy conversion and storage systems due to its long life cycle, porosity and high surface area nature as well as low-cost nature have been clearly discussed. This review aims to demonstrate that the increasing interest in the synthesis of PAC is accompanied by extensive research into their application in supercapacitors, where they continue to be the preferred electrode material. Their challenges and current progress of PAC electrodes are also discussed. The systematic methods of modifying PAC from biomass as well as some commercially available carbon materials have been thoroughly summarized in this review as an alternate high-surface area electrode for the effective generation of energy in many energy conversion and storage devices. The critical assessment is also extends to evaluate its recent advancements, trends in research progress, and future prospects.

Fabrication of Asymmetric Supercapacitors (AC@GQDs//AC) with High Electrochemical Performance Utilizing Activated Carbon and Graphene Quantum Dots

Sugar cane bagasse stands as a prevalent and abundant form of solid agricultural waste, making it a prime candidate for innovative utilization. Harnessing its potential, we embarked on a groundbreaking endeavor to evaluate the sustainability of a molasses-based hydrothermal process to produce graphene quantum dots (GQDs). This pioneering initiative promises remarkable environmental benefits and holds immense economic potential. Embedding crystalline GQDs in activated carbon (AC) boost electrochemical efficiency by enhancing charge-transfer and ion migration kinetics. Optical, structural, and morphological evaluations were used to confirm the formation of GQDs. Transmission electron microscopy (TEM) investigation showed the size, shape, and fact that GQDs were monodispersed, and X-ray diffraction and Fourier transform infrared determined the structure of GQDs. The electrodes with negative (AC) and positive (AC@GQDs) polarity demonstrate a considerable specific capacitance of 220 and 265 F g-1, respectively, when measured at 0.5 A g-1. Additionally, these electrodes exhibit high-rate capabilities of 165 and 230 F g-1 when measured at 5 A g-1, as determined by galvanostatic charge-discharge techniques. The supercapacitor device comprising asymmetric AC//AC@GQDs exhibits a specific capacitance of 118 F g-1. Furthermore, the asymmetric device exhibits exceptional cycling behavior, with an impressive 92% capacitance retention even after undergoing 10,000 cycles. This remarkable performance underscores the immense potential of both the negative and positive electrodes for real-world supercapacitor applications. Such findings pave the way for promising advancements in the field and offer exciting prospects for practical utilization.

"Sweetwoods" Lignin as Promising Raw Material to Obtain Micro-Mesoporous Carbon Materials

Biorefineries with the significant amounts of lignin as a by-product have a potential to increase business revenues by using this residue to produce high value-added materials. The carbon materials from biomass waste increases the profitability of the production of porous carbon used for sorbents and energy production. The purpose of this research is to study the chemical properties of lignin from "Sweetwoods" biorefinery as well as to characterize lignin carbonizates and activated carbons synthesized from them. This paper describes the effect of carbonization conditions (thermal or hydrothermal) on the properties of activated carbon material. It can be concluded that, depending on the carbonization method, the three-dimensional hierarchical porous structure of activated carbon materials based on "Sweetwoods" lignin, has micro- and mesopores of various sizes and can be used for number of purposes: both for high-quality sorbents, catalysts for electrochemical reduction reactions, providing sufficient space for ion mass transfer in electrodes for energy storage and transfer.

Preparation, characterisation and applications of bone char, a food waste-derived sustainable material: A review

The production of increasing quantities of by-products is a key challenge for modern society; their valorisation - turning them into valuable compounds with technological applications - is the way forward, in line with circular economy principles. In this review, the conversion of bones (by-products of the agro-food industry) into bone char is described. Bone char is obtained with a process of pyrolysis, which converts the organic carbon into an inorganic graphitic one. Differently from standard biochar of plant origin, however, bone char also contains calcium phosphates, the main component of bone (often hydroxyapatite). The combination of calcium phosphate and graphitic carbon makes bone char a unique material, with different possible uses. Here bone chars' applications in environmental remediation, sustainable agriculture, catalysis and electrochemistry are discussed; several aspects are considered, including the bones used to prepare bone char, the preparation conditions, how these affect the properties of the materials (i.e. porosity, surface area) and its functional properties. The advantages and limitations of bone chars in comparison to traditional biochar are discussed, highlighting the directions the research should take for bone chars' performances to improve. Moreover, an analysis on the sustainability of bone chars' preparation and use is also included.

A high-capacity, high-power organic electrode via supercritical CO2 impregnation into activated carbon micropores

Herein, we report the impregnation of chloranil into activated carbon micropores using scCO₂. The sample prepared under 105 °C and 15 MPa showed a specific capacity of 81 mAh g_electrode^-1, except for the electric double layer capacity at 1 A g_{electrode-Polytetrafluoroethylene (PTFE)}^-1. Additionally, approximately 90% of the capacity was retained even at 4 A g_{electrode-PTFE}^-1.

Miscanthus-Derived Energy Storage System Material Production

Carbon derived from various biomass sources has been evaluated as support material for thermal energy storage systems. However, process optimization of Miscanthus-derived carbon to be used for encapsulating phase change materials has not been reported to date. In this study, process optimization to evaluate the effects of selected operation parameters of pyrolysis time, temperature, and biomass:catalyst mass ratio on the surface area and pore volume of produced carbon is conducted using response surface methodology. In the process, ZnCl₂ is used as a catalyst to promote high pore volume and area formation. Two sets of optimum conditions with different pyrolysis operation parameters in order to produce carbons with the highest pore area and volume are determined as 614 °C, 53 min, and 1:2 biomass to catalyst ratio and 722 °C, 77 min, and 1:4 biomass to catalyst ratio with 1415.4 m²/g and 0.748 cm³/g and 1499.8 m²/g and 1.443 cm³/g total pore volume, respectively. Carbon material produced at 614 °C exhibits mostly micro- and mesosized pores, while carbon obtained at 722 °C comprises mostly of meso- and macroporous structures. Findings of this study demonstrate the significance of process optimization for designing porous carbon material to be used in thermal and electrochemical energy storage systems.

Bio-Waste-Derived Hard Carbon Anodes Through a Sustainable and Cost-Effective Synthesis Process for Sodium-Ion Batteries

Sodium-ion batteries (SIBs) are postulated as sustainable energy storage devices for light electromobility and stationary applications. The anode of choice in SIBs is hard carbon (HC) due to its electrochemical performance. Among different HC precursors, bio-waste resources have attracted significant attention due to their low-cost, abundance, and sustainability. Many bio-waste materials have been used as HC precursors, but they often require strong acids/bases for pre-/post-treatment for HC development. Here, the morphology, microstructure, and electrochemical performance of HCs synthesized from hazelnut shells subjected to different pre-treatments (i. e., no pre-treatment, acid treatment, and water washing) were compared. The impact on the electrochemical performance of sodium-ion cells and the cost-effectiveness were also investigated. The results revealed that hazelnut shell-derived HCs produced via simple water washing outperformed those obtained via other processing methods in terms of electrochemical performance and cost-ecological effectiveness of a sodium-ion battery pack.