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Synthesis steps and nomenclature of obtained hard carbons: T1 marks the pre-pyrolysis temperature (synthesis of peat to carbonaceous material). The letter A appended to the ending of hard carbon notation indicates that between two pyrolysis stages, the material was treated with KOH and HCl. T2 marks the post-pyrolysis temperature (synthesis of carbonaceous material to carbon)
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Herein we demonstrate how peat, abundant and cheap biomass, can be successfully used as a precursor to synthesize peat-derived hard carbons (PDCs), applicable as electrode materials for sodium-ion batteries (SIB). The PDCs were obtained by pre-pyrolysing peat at 300–800 °C, removing impurities with base–acid solution treatment and thereafter post-p...
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Sodium‐ion batteries capable of operating at rate and temperature extremes are highly desirable, but elusive due to the dynamics and thermodynamics limitations. Herein, a strategy of electrode–electrolyte interfacial chemistry modulation is proposed. The commercial hard carbon demonstrates superior rate performance with 212 mAh g⁻¹ at an ultra‐high...
Hard carbon is a promising anode material for sodium-ion batteries (SIBs) due to its abundance. However, it exhibits low reversible capacity and slow kinetics if inappropriate microstructural features are developed during synthesis. Herein, N/S co-doped phenolic resin-based hard carbon microspheres are prepared by a scalable strategy, and the elect...
With sodium-ion batteries (SIBs) finding widespread application, the demand grows for hard carbon, the most popular anode material for SIBs. Hydrothermal carbonization facilitates the production of hard carbon with desired characteristics from various sources. Despite the considerable volume of literature addressing this subject, there is a notable...
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... Conversely, organic compounds with lower hydrogen content and higher oxygen content tend to form nongraphitic structures [22]. Researchers have reported about synthesis of hard carbon from different biomasses, like, Cotton [23], peat moss [24], banana peels [25], walnut shells [26,27], corn cob [28], sugarcane waste [29], bamboo powder wastes [30], coconut shells [31], etc. We developed hard carbon from biomass precursors which are one of the most abundant biowaste in our country which is peanut shells [32]. ...
Sulphur-free hard carbon from peanut shells has been successfully synthesized. Pre-treatment of potassium hydroxide (KOH) plays a crucial role in the enhancement of physical and electrochemical properties of synthesized hard carbon, specifically enhancing the active surface area. Field Emission Scanning Electron Microscopy (FESEM) analysis also supports the enhanced BET surface area and distribution of pores. Raman spectroscopy shows the carbonized product as hard carbon. X-ray photoelectron spectroscopy (XPS) provides the presence of oxygen-functionalized hard carbon. XRD pattern confirms the amorphous nature of the carbon. Electrochemical impedance spectroscopy indicates the charge transfer kinetics, which also shows that the charge transfer resistance of HC-800K7 is minimal among all KOH-pre-treated samples. An initial specific capacity of 320 mAhg⁻¹ has been recorded for the HC-800K7 sample at 0.1 Ag⁻¹ current rate. After 500 cycles, the reversible charge capacity is found to retain at 231 mAhg⁻¹. It gives 73.13% capacity retention after 500 cycles. Cyclic voltammetry shows the formation of SEI at the first few cycles and thereafter the SEI stabilized. HC-800K7 delivers high capacity and longer cycle stability. The results show that KOH activation enhances the electrochemical performance of the material.
... These carbon materials typically demonstrated 200-300 mAh g −1 capacity, with the most recent studies showing as high capacity as 478 mAh g −1 . [19][20][21][22][23][24] There are many carbon containing precursor materials that can be converted into hard carbons via pyrolysis, such as paper, 25 oatmeal 26 or phenolic resins/nanotubes. 27 However, for wide scale adaptability of SIB technology the electrode materials precursors need to be abundant and/or cheap such as biowaste 28 or leftover biomass. ...
This comprehensive study sheds light on the promising potential of lignin-derived carbonaceous materials as sustainable and cost-effective anode materials for sodium-ion batteries, contributing to the development of eco-friendly energy storage technologies. Lignin, a complex and abundant biopolymer, undergoes a facile pyrolysis process to produce carbonaceous materials. The unique microstructure of lignin-derived carbon, characterized by a relatively high surface area and interconnected porous network, facilitates efficient sodium ion diffusion and accommodates volume changes during cycling. The effects of pre-treatment methods, carbonization conditions, and structural modifications of lignin on the electrochemical performance are systematically investigated. Furthermore, the electrochemical mechanisms underlying the sodiation/desodiation processes in lignin-derived carbon (LDC) based anodes are elucidated through advanced characterization techniques, including in situ spectroscopy and microscopy. Among the different hard carbon materials, pre-pyrolyzed lignin-derived carbon LDC-300-1400 (300 shows which pre-treatment pyrolysis temperature was used and 1400°C is the post-pyrolysis temperature) shows the most favourable outcomes, demonstrating a reversible capacity of 359 mAh g ⁻¹ , 1st cycle coulombic efficiency of 81%, and good rate capabilities. Hydrothermally pre-treated LDCs show a slightly lower specific capacity value reaching up to 337 mAh g ⁻¹ .
... Accordingly, the development of such materials is actively pursued. [8][9][10][11][12][13][14][15][16][17][18][19][20][21] Carbon materials are the most studied candidates and can offer excellent input/output densities. Systems with a carbon positive electrode depend on an electrical double layer for reversible ionic physisorption/desorption, and the capacity of the entire system is determined by the double layer capacitance and pseudocapacitance. ...
Porous carbon materials prepared with different activation methods were evaluated as positive electrodes for zinc-ion capacitors. Higher capacities were obtained with chemically activated carbons than with steam-activated carbons, with KOH-activated carbon showing the highest capacity. Furthermore, the dependence of charge–discharge characteristics on electrolyte was explored using seven different electrolyte types. Gas evolution was observed during the charging reaction in alkaline electrolytes such as potassium hydroxide and tetraethylammonium hydroxide, but no gas generation was observed in acidic electrolytes. In addition, the discharge capacity tended to be higher for chlorine- ion-containing electrolytes such as zinc chloride and ammonium chloride.
... While many articles handling pyrolysis of different organic precursors into carbon materials [10,12,34,35,[41][42][43][44][45] have been published, peat is a distinctly cheap and easily workable material that has been studied and shows good potential for pyrolysis into carbon materials with different characteristics [14,36,[46][47][48][49][50][51]. ZnCl 2 has been used for chemical activation previously by many groups [10,34,36,39,[51][52][53], where both Varila et. ...
Highly microporous adsorbents have been under considerable scrutiny for efficient adsorptive storage of H2. Of specific interest are sustainable, chemically activated, microporous carbon adsorbents, especially from renewable and organic precursor materials. In this article, six peat-derived microporous carbon materials were synthesized by chemical activation with ZnCl2. N2 and CO2 gas adsorption data were measured and simultaneously fitted with the 2D-NLDFT-HS model. Thus, based on the obtained results, the use of a low ratio of ZnCl2 for chemical activation of peat-derived carbon yields highly ultramicroporous carbons which are able to adsorb up to 83% of the maximal adsorbed amount of adsorbed H2 already at 1 bar at 77 K. This is accompanied by the high ratio of micropores, 99%, even at high specific surface area of 1260 m2 g−1, exhibited by the peat-derived carbon activated at 973 K using a 1:2 ZnCl2 to peat mass ratio. These results show the potential of using low concentrations of ZnCl2 as an activating agent to synthesize highly ultramicroporous carbon materials with suitable pore characteristics for the efficient low-pressure adsorption of H2.
... [8] Graphite is one of the most common negative electrodes used in LIBs due to its high theoretical capacity (372 mAh g À 1 ), however it is electrochemically disfavored in SIBs as a consequence of sodium's large ionic radius (1,02 Å compared to 0,76 Å for Li). [9,10] Therefore, several types of anode materials have been investigated, mainly carbon materials (carbon black, hard carbon, carbon spheres), transition metal-based compounds (sulfides, oxides) and alloys. [11][12][13][14][15][16] Amidst all of the mentioned materials, hard carbon is considered the most promising negative electrode for high energy SIBs thanks to its high plateau capacity at low potential (E < 0,2 V Na + /Na) and the possibility of being obtained from biomass-derived precursors, including waste. ...
... [11][12][13][14][15][16] Amidst all of the mentioned materials, hard carbon is considered the most promising negative electrode for high energy SIBs thanks to its high plateau capacity at low potential (E < 0,2 V Na + /Na) and the possibility of being obtained from biomass-derived precursors, including waste. [10,17] Consequently, SIBs anodes provide the opportunity to introduce the principles of sustainability and circular economy in battery design by producing hard carbons from biomass waste. [18] The scientific community has taken up the task, as can be seen in the literature, where there are several works reporting the production and performance of carbonaceous anodes from many types of biowaste: macadamia nutshell, lychee seeds, shaddock peel, water caltrop shell, rice husk, sugarcane bagasse, date palm, kelp and dandelion [19][20][21][22][23][24][25][26][27] are only a few examples. ...
... This can be: (1) a single-step high temperature pyrolysis (T > 1000°C); (2) a two-step pyrolysis including a low temperature step in the range 300-800°C and a second one at high temperature; (3) a combination of hydrothermal carbonization (HTC: water hydrolysis/carbonization at 180-280°C under autogenous pressure) and pyrolysis; (4) a single-step pyrolysis of pretreated biomass trough acid hydrolysis (H 3 PO 4 and HCl at room temperature) or heteroatom-doping (with B, P, S, F and N). [10,[29][30][31][32][33][34] From these procedures, the use of a hydrothermal step prior to pyrolysis (3) has been widely used to produce activated carbons, [35,36] carbon dots [37] and hard carbons. [38] When comparing single step high temperature pyrolysis (1) to a combination of HTC and pyrolysis (3), this latter method has demonstrated to increase carbon yield and enhance electrochemical performance of the resulting hard carbons. ...
Over the last years, hard carbon (HC) has been the most promising anode material for sodium‐ion batteries due to its low voltage plateau, low cost and sustainability. In this study, biomass waste (spent coffee grounds, sunflower seed shells and rose stems) was investigated as potential material for hard carbon preparation combining a two‐step method consisting of on hydrothermal carbonization (HTC), to remove the inorganic impurities and increase the carbon content, and a subsequent pyrolysis process. The use of HTC as pretreatment prior to pyrolysis improves the specific capacity in all the materials compared to the ones directly pyrolyzed by more than 100 % at high C‐rates. The obtained capacity ranging between 210 and 280 mAh g⁻¹ at C/15 is similar to the values reported in literature for biomass‐based hard carbons. Overall, HC obtained from sunflower seed shell performs better than that obtained from the other precursors with an initial Coulombic efficiency (ICE) of 76 % and capacities of 120 mAh g⁻¹ during 1000 cycles at C with a high capacity retention of 86–93 %.
... Polymers 2022,14, 5489 ...
Carbon derived from biomass waste usage is rising in various fields of application due to its availability, cost-effectiveness, and sustainability, but it remains limited in tissue engineering applications. Carbon derived from human hair waste was selected to fabricate a carbon-based bioscaffold (CHAK) due to its ease of collection and inexpensive synthesis procedure. The CHAK was fabricated via gelation, rapid freezing, and ethanol immersion and characterised based on their morphology, porosity, Fourier transforms infrared (FTIR), tensile strength, swelling ability, degradability, electrical conductivity, and biocompatibility using Wharton’s jelly-derived mesenchymal stem cells (WJMSCs). The addition of carbon reduced the porosity of the bioscaffold. Via FTIR analysis, the combination of carbon, agar, and KGM was compatible. Among the CHAK, the 3HC bioscaffold displayed the highest tensile strength (62.35 ± 29.12 kPa). The CHAK also showed excellent swelling and water uptake capability. All bioscaffolds demonstrated a slow degradability rate (<50%) after 28 days of incubation, while the electrical conductivity analysis showed that the 3AHC bioscaffold had the highest conductivity compared to other CHAK bioscaffolds. Our findings also showed that the CHAK bioscaffolds were biocompatible with WJMSCs. These findings showed that the CHAK bioscaffolds have potential as bioscaffolds for tissue engineering applications.
... Fascinating nanospherical carbon materials have been synthesised from glucose, white sugar solutions, and Estonian well-decomposed peat powder [97,137,149,150,157,[299][300][301][302][303][304], shown in Fig. 10. Highly homogeneous carbon material consisting of nano-and microspheres with diameters nearly 0.9-1.0 ...
... An increase in the PC molar ratio in the mixed solvent system also decreases the limiting capacity of negatively charged electrodes. The exchange of NaClO 4 to NaPF 6 increases the capacity values notably [303]. It should be noted that for C(EP), there is no noticeable dependence of limiting capacity values on the chemical nature of the cation tested, i.e., for LiBF 4 and NaBF 4 , as well as for LiClO 4 and NaClO 4 ; nearly comparable high capacity values (320-360 mAh·g −1 ) have been established. ...
The electrochemistry nowadays has many faces and challenges. Although the focus has shifted from fundamental electrochemistry to applied electrochemistry, one needs to acknowledge that it is impossible to develop and design novel green energy transition devices without a comprehensive understanding of the electrochemical processes at the electrode and electrolyte interface that define the performance mechanisms. The review gives an overview of the systematic research in the field of electrochemistry in Estonia which reflects on the excellent collaboration between fundamental and applied electrochemistry.
... However, Sodium-ion batteries (SIBs) display complex diffusion kinetics, which is their major drawback. Despite the comparable electrochemistry with LIBs, SIBs exhibits lower theoretical density, specific energy, and capacity of only 35 mAh g 21 (Adamson et al., 2020). The root cause of this problem has not yet been fully understood and explained; however, few theories have been suggested concerning the particle size and binding energy of Na-ions. ...
... Also, the poor intercalation of Na-ions is caused by the weaker binding affinity of the ions to graphite particles, solvent molecules, and other functional groups in the system (Górka et al., 2016;Saavedra Rios et al., 2020). It is also worth knowing that sodium has a low melting point and tends to form dendritic compounds and the formation of SEI during the first charging cycle on the surface of some materials (Adamson et al., 2020;. It is, therefore important to develop electrode materials that can overcome these shortcomings. ...
... While the first yield a low energy capacity, the latter is not sufficiently conductive for the application . Carbons with relatively low SSA and degree of graphitization are potential candidates for SIB electrodes (Adamson et al., 2020). According to Adamson, the lower surface area of hard carbons reduces the area available for SEI formation. ...
Hydrogels with high scientific interest and numerous applications have become the most important materials. Currently, natural polymer-based hydrogels are more preferred than synthetic ones because of their biocompatibility and ecofriendly nature. In 1960 first-time hydrogels were reported, and they are defined as three-dimensional high molecular weight materials with the capacity to hold water or biological fluids within its porous structure without getting disintegrated. Hydrogels based on 2-hydroxymethylmethacrylate and ethylene dimethacrylate are mostly used in ophthalmology. These can absorb water more than 90%; hence, they are also known as super absorbents. Functional groups like –OH, –COOH, –CONH2, and –SO3H are the main key feature of such properties. Hydrogels are similar to natural tissues in appearance, so these can be used to prepare biocompatible materials. They have high absorption capacity, smoothness, elasticity, and low interfacial tension with solutions, which make them highly attractive. They are more responsive to physiological pH, ionic strength, temperature, and electric currents, which make these smart materials. These three-dimensional hydrophilic networks have been widely studied and extensively used in various fields like biomedical, wastewater treatment, agriculture and horticulture.
This chapter deals with the synthesis of hydrogels through grafting of poly(acrylamide) onto derivatized gum rosin through free radical graft copolymerization in the presence of KPS as an initiator and N,N-methylene bisacrylamide as a crosslinker. Different reaction parameters such as the amount of solvent, pH of the reaction medium, reaction time, concentration of crosslinker, initiator, monomer and reaction temperature were optimized for getting the candidate polymer with maximum fluid uptake capacity.
... Porous hard carbon (PHC) present excellent theoretical capacity, resulting from the large number of active sites offered by its porous and disordered structures [26][27][28][29][30]. To derive low-cost, sustainable, and environmentally green PHC, several methods have been reported [13,18,21,[31][32][33]. ...
A facile one-step sonochemical activation method is utilized to fabricate biomass-derived 3D porous hard carbon (PHC-1) with tuned-surface and is compared with the conventional two-step activation method. As raw biomass offers good KOH impregnation, ultrasonication power diffuses both K⁺ and OH⁻ ions deep into its interior, creating various nanopores and attaching copious functional groups. In contrast, conventional activation lacks these features under the same carbonization/activation parameters. The high porosity (1599 m²/g), rich functional groups (O = 8.10%, N = 0.95%), and well-connected nanoporous network resulting from sonochemical activation, remarkably increased specific capacity, surface wettability, and electrode stability, consequently improved electrochemical performance. Benefiting from its suitable microstructure, PHC-1 possesses superior specific capacity (330 mAh/g at 20 mA/g), good capacity retention (89.5%), and excellent structural stability over 500 sodiation/desodiation cycles at high current density (1000 mA/g). Apart from modus operandi comparison, the two activation methods also provide mechanistic insights as the low-voltage plateau region and graphitic layers decrease simultaneously. This work suggests a scalable and economical approach for synthesizing large-scale activated porous carbons that are used in various applications, be it energy storage, water purification, or gas storage, to name a few.
... The properties like capacitance, characteristic relaxation time, and energy and power density of SC depend strongly on the physical characteristics of the electrode material . Very high power densities have been measured for SCs based on different carbon electrode materials, i.e., sol-gel method derived carbon materials, as well as D-glucose-derived carbons, white sugar derived carbon, and Estonian well-decomposed peat derived carbon materials [8,9,14,15,20,21]. The sol-gel method-derived carbon-based supercapacitors demonstrated excellent power densities but moderate energy densities [8,9]. ...
... Similarly to various carbide-derived carbons (CDC) [6][7][8][9]12] as well D-glucose, white sugar and peat-derived carbon (PDC)-based SC [14,15], the energy densities in comparison with batteries are moderate, and for high energy density recuperation systems, energy density of SC should be increased [16][17][18][19][20][21][22][23][24]. In order to increase the energy density of the SCs, some attempts to apply electrolytes with specifically adsorbing ions [16][17][18][19][20], as well as the redox active electrodes, including different d-metals oxides, have been conducted [21][22][23][24][25]. ...
... The shape of Nyquist (Z″ vs. Z′ where Z″ is the imaginary part and Z′ is the real part of impedance) plots (Fig. 5a) for Zn thin foil|carbon cloth single cells is noticeably different from those usually observed for the two ideally polarizable carbon electrode based SC system [8,9,11,12,14,15,28]. There is no clearly limiting capacitive behaviour (i.e., socalled knees) at very low ac frequencies observed for many ideally polarizable, i.e., adsorption step rate limited supercapacitors cells [8, 9, 11-15, 28, 29, 37-40]. ...
Asymmetrical Zn thin foil|carbon cloth two-electrode cells based on 1 M Zn(ClO4)2 aqueous solution have been tested using cyclic voltammetry, constant current charge/discharge, and electrochemical impedance methods. The Ragone plots have been calculated from constant power measurements data. Very high gravimetric and volumetric energy densities at moderate gravimetric and volumetric power densities have been calculated, nearly 2–3 times higher than those for the best sol–gel method prepared two carbon electrode single cells. It was found that even at high power density (10 kW kg−1), the energy density values are comparable with the results for best CDC and sol–gel methods prepared carbon materials based supercapacitors. It has been observed that studied asymmetrical two-electrode cells demonstrated higher energy densities (~ 70 W h kg−1) than the ionic liquid based symmetrical cells what show energy density up to 47 W h kg−1 and capacitance ~ 120 F g−1. However, the power densities and relaxation times for Zn(ClO4)2 aqueous electrolyte based supercapacitors still need to be increased and decreased, respectively, to meet the needs of very quick short pulses high power energy storage applications.
