Building Supercapacitors with Electrolytes and Carbon Electrodes: Comparison
View Latest Version
Please note this is a comparison between Version 2 by Alfred Zheng and Version 1 by Tarik Chafik.

Supercapacitors (SCs), also known as “ultracapacitors”, are used in applications requiring rapid energy storage or high-power delivery. Carbon-based materials for supercapacitors derived from affordable coal deposits or crop waste with appropriate characteristics in terms of specific surface area, electrical conductivity, and charge/discharge stability. In addition, the substitution of organic liquids electrolytes with less dangerous solutions, such as aqueous electrolytes containing high concentrations of salt, is a valuable strategy for the design of green devices.

  • energy storage
  • supercapacitors
  • carbon-based electrodes
  • aqueous electrolytes

1. Introduction

Currently, more than 70% of the world’s primary energy demand is dominated by fossil fuels. This scenario is expected to change in the near future with the increasing deployment of renewable energy sources as an urgent response to climate change [1]. The alternative energy sources produce energy from sun and wind that typically are not constant [2]. To ensure the reliability and consistency of renewable energy source output, energy storage devices (ESDs) are required as buffers for the intermittent sources. Furthermore, the use of ESDs could power off-grid energy in remote locations [3,4,5][3][4][5]. Hence, ESDs with high energy and power densities will be crucial in the future to ensure the integration of renewable energy sources into existing power systems and boost the potential for applications related to electric mobility.
ESDs based on batteries and electrochemical supercapacitors (SCs) are in rapid development [6,7,8,9,10,11][6][7][8][9][10][11]. Lithium-ion batteries have not yet been widely used as an efficient storage technology and still need to overcome some disadvantages, mainly those associated with safety, cost, and metal availability [8,12,13,14,15][8][12][13][14][15]. SCs have attracted attention in recent years mostly because of their high power density and long life cycle. Notably, these characteristics of SCs allow them to provide interesting hybrid solutions for the automotive sector, where they are coupled with batteries. 
In general, in an electrochemical ESD, the energy storage processes occur at the electrodes either by Faradic or non-Faradic modes. The Faradic processes are controlled by the kinetics and activation energies of the electrode reactions as well as by the mass transport of reagents/products, which limit device power density. In addition, the electrode materials may undergo transformations during cycling, like the modification of the chemical composition or structure. Furthermore, the electrochemical reactions involved may have a columbic efficiency lower than 100%. For these reasons, despite the high charge storage capacity, Faradic electrodes can show reduced lifetimes compared to those involving non-Faradic processes. The latter occur through the electrostatic storage of charges at the electrode surfaces. This phenomenon drives energy storage in electrochemical capacitors. It is a rapid surface phenomenon that is completely reversible and does not yield to any chemical or structural changes in the electrodes. The fast kinetics and high reversibility of the electrostatic process enable high SC power density and a theoretically unlimited lifetime.

2. Carbon Materials for Supercapacitors

A variety of carbon materials with different morphologies and structures have been used as EDLC electrodes, including activated carbon (AC) obtained from mineral resources or biomasses, carbon nanotubes (CNTs), and graphene, thanks to their large SSA, high porosity, good electronic conductivity, and chemical stability, as well as their wide range of operating temperatures [52][16].
Other synthetic strategies involve the emulsion-assisted production of polymer nanoparticles that, after calcination under N2 atmosphere, release carbon spheres 200–300 nm in diameter with a single cavity inside and a SSA of about 300 m2 g−1 [54][17].
The large SSA of carbon is generally responsible for the high specific capacity of the electrode. Large SSAs can reach 2500 m2 g−1 and deliver specific capacitance from 100 to 250 F g−1 depending on the electrolyte [55][18], and, in turn, the pore size distribution significantly affects the EDLC charge/discharge rate. According to the International Union of Pure and Applied Chemistry (IUPAC), the porosity classifications for macropores, mesopores, and micropores are as follows [56][19]:
-
Macropores with a diameter greater than 50 nm;
-
Mesopores with a diameter between 2 and 50 nm;
-
Micropores with a diameter of less than 2 nm.
It is worth noting that the IUPAC outlines two subcategories of micropores: supermicropores, with diameters between 0.7 nm and 2 nm, and ultramicropores, with diameter less than 0.7 nm [56][19].

2.1. Activated Carbon (AC)

AC is a promising material for SC electrodes because of its relatively low cost, high conductivity, good thermal stability, and corrosion resistance. Several synthesis routes are for the preparation of activated carbons with high a SSA and a porosity that is suitable for EDLC electrodes have been reported in the literature [57][20]. It should be emphasized that these characteristics are influenced by the precursor used and the synthesis and activation process [58,59][21][22]. Furthermore, activated carbon production processes (carbonization and activation) are generally simple and involve cheap and abundant precursors [60][23]. The activation process consists of oxidation via physical or chemical processes that allow for the creation of a random network of pores (macropores, mesopores, or micropores). Usually, physical activation is carried out through the carbonization of materials (for biomass or hard coal see below) at temperatures ranging from 900 °C to 1100 °C under oxidizing conditions. Such a temperature range induces the sublimation of the lower molecular weight fraction and structural rearrangement, whereas the oxidation of carbon results in the creation and/or enlargement of the pores.
Chemical activation proceeds in the presence of chemical agents (e.g., H3PO4, ZnCl2, KOH, etc.) through the dehydration, carbonization, and structural reorganization of the precursor, inducing the development of micropores and mesopores and the functionalization of their surfaces [61][24]. By carefully controlling the activation parameters, it is possible to reach a specific surface area of 3000 m2·g−1 [52][16].
ACs can be easily produced and, consequently, have been commercially available for a long time for many others applications, including air purification, water treatment, energy storage, etc. Indeed, the global market for AC is growing, and it is expected to be worth up to USD 7 billion by 2028 [63][25]. From a business point of view, the use of AC is of interest because related low-cost and abundant precursors such as biomass are considered renewable resources; thus, in terms of sustainability, AC production is of great importance.

2.2. Carbon Nanotubes (CNTs)

CNTs have been reported to have special features of interest for EDLC electrodes. The development of high-power SCs has been driven by their high electrical conductivity and accessible pore network, along with their good thermal and mechanical stability [52][16]. CNTs are classified as single-walled nanotubes (SWCNTs) and multiwalled nanotubes (MWCNTs) based on the number of graphite-like layers rolled into the cylinder, which, in turn, affects the electrical and mechanical characteristics of the resulting materials [52,64][16][26]. The main methods for CNTs synthesis are laser ablation, arc-discharge, and CVD, all of which are experimentally complex and require expensive equipment. In addition, it seems difficult to achieve high purity and good bulky yields [57][20].

2.3. Graphene

Graphene consists of a two-dimensional single-layer of hexagonal rings of sp2 carbon atoms. This carbon arrangement potentially provides an accessible surface area that is much wider than that of any other carbon material used in EDLCs [52,65][16][27]. Graphene can be produced via CVD; chemical [66][28], electrochemical [67][29], or plasma exfoliation from natural graphite; and mechanical cleavage from natural graphite [68][30]. In one study, a graphene ribbon aerogel monolith with high mass loading (11 g cm−2) exhibited a capacitance density of about 150 F g−1 at 1 A g−1 and about 100% capacitance retention after 10,000 cycles [69][31].
However, despite their great potential, carbon materials based on graphene or CNTs are still far from being commonly used in industrial sectors, mainly because of their high production costs.

2.4. Activated Biochar-Based SCs

This section of the present article focuses on the use of biomass as a sustainable and renewable precursor for the production of ACs. The fabrication process of biomass-derived AC has been demonstrated by the carbonization and activation of a huge variety of raw materials [70][32]. During carbonization, biochar is produced as a result of the precursor being subjected to heat treatment in the absence of oxygen. The development of AC surface area and porosity is achieved through physical or chemical activation using oxidizing gases (e.g., O2, steam, etc.) or other oxidizing agents (e.g., KOH, NaOH, ZnCl2, H3PO4), respectively [71,72,73][33][34][35]. In contrast to physical activation, which partially gasifies the char to CO2 in order to enhance the pores, chemical activation involves dehydrating chemicals to prevent the development of tar and boost the carbon yield [74][36]. Chemical activation is sometimes carried out in one step after pyrolysis and sometimes produces AC with a higher carbon yield, larger SSA, and more developed microporosity than physical activation [75][37].
Using low-cost biomass such as biowaste (e.g., agriculture by-products or food industry waste) to derive ACS for SC electrodes could not only pave the way to solve waste management problems [76,77][38][39] but also generate revenue for farmers in the context of circular economy because it changes a waste product in a secondary raw material into a high-value product that could be used to produce SCs [78][40].
In recent years, interest in producing activated carbon from biomass has steadily grown [78,79,80,81,82,83][40][41][42][43][44][45]. Various sources of biowaste, including waste from plants, animals, and vegetables, have been listed in the literature as raw materials that could be used to produce ACs for use as electrode materials in SCs [78,84,85,86,87,88,89][40][46][47][48][49][50][51]. Figure 1 shows some of those biowaste products, specifically the following: olive seeds, lotus calyx, rice husk, mangosteen peel, chrysopogon zizanioides, lemon peel, eggs shells, and idesia polycarpa fruit oil residue.
World 04 00027 g006 550
Figure 1.
Some biowaste products that could be used as precursors for carbon materials to generate electrodes for SCs.
For instance, Yang et al. developed a porous carbon with a SSA of 1471.4 m2 g−1 from corncob that provided an EDLC that could deliver an energy density of 20.15 Wh kg−1 in 6 M KOH electrolyte [90][52]. By following the same procedure, Mitravinda et al. investigated EDLCs based on corn silk-derived AC; the EDLCs showed a promising energy density of ~32.28 Wh kg−1 and a power density of 870.68 W kg−1 [91][53]. This was made possible by the AC’s mesoporous fiber-like morphology and texture, which helped to diffuse electrolytes into and out of the pores during the charge/discharge processes. In another study, Yin et al. used coconut fibers to develop three-dimensional hierarchical porous carbon [92][54] with a high SSA of 2898 m2 g−1 and pore volume of 1.59 cm3 g−1 to allow for an EDLC with 6 M KOH to reach an energy density of 53 Wh kg−1 and an impressive power density of 8200 W kg−1. Moreover, Qin et al. synthesized pine nutshell-derived AC using physical activation [92][54], obtaining an interconnected porous structure with different pore size distributions (micro-, meso-, and macropores). This material was used as an electrode in an EDLC with 6 M KOH electrolyte, releasing 98% of the initial capacity after 10,000 cycles [92][54]. Bridget et al. reported the use of lignin residue from biodigestion plants as a precursor for preparing AC [93][55]. The lignin-derived carbon contained mesopores and micropores showing a high SSA of 1879 m2 g−1. A SC with this lignin-derived carbon electrode exhibited a specific energy and specific power density of up to 10 Wh kg−1 and 6.9 kW kg−1, respectively. Durability tests revealed that the device could maintain 84.5% of its capacitance after 15,000 charge/discharge cycles [93][55]. Table 1 shows the electrochemical performance of some investigated biowaste-derived carbon electrodes and SCs using aqueous electrolytes.
Table 1.
Characteristics of biowaste-derived carbon-based electrodes and the related EDLCs with aqueous electrolytes.
Biowaste SSA (m2 g−1) Specific Capacitance (F/g) Electrolyte for the Assembled Device Energy Density (Wh kg−1) Power Density (kW kg−1) Cyclic Stability

(%)		 Ref.
Lotus calyx 798 223

(1 A/g)		 1 M Na2SO4 17.5 0.8 95.5

(10,000)		 [94][56]
Stem pith of helianthus annuus 1900.2 403.6

(0.5 A/g)		 6 M KOH 5.8 17.3 94.5

(10,000)		 [95][57]
Mangosteen peel 2623 357

(1 A/g)		 1 M Li2SO4 17.28 0.401 80

(10,000)		 [96][58]
Lemon peel 744.78 152.14

(1 mV/s)		 0.5 M H2SO4 4.67 8.113 95.5

(10,000)		 [97][59]
Idesia polycarpa fruit oil residue 1537.1 350.4

(1 A/g)		 6 M KOH 6.4 0.1 3305 308

(1 A/g)		 6 M KOH 8.92 254.995.4

(10,000)		 [98][ -60]
[115][77] Camellia oleifera shell 1750
Coal-based green needle coke 807.69259

(1 A/g)		 1 M H 274.9

(1 A/g)		2SO4 8.61 0.477 94

(20,000)		 [99][61]
6 M KOH 20.51 1031.42 98.5

(5000) [116][78] Syzygium cumini - 253

(0.5 A/g)		 6 M KOH 27.22 0.2 96.5

Coal tar pitch(5000) 2984 320

(0.1 A/g)		[ 6 M KOH100][62]
10.6 50.1 94

(10,000) [117] Chrysopogon zizanioides - 294

(0.5 A/g)		 6 M KOH 16.72 0.2 91.8

(5000)		 [100][62]
[79]
Anthracite 2947 282

(0.5 A/g)		 6 M KOH 9.75 124.65 - [118][80] Baobab fruit shells 2700.65 332

Coal(1 A/g) 6 M KOH 216817.7 166.4 93 215



(10,000)		 (20 A/g)[101][63]
6 M KOH 7.64 50 91.9

(5000) [119][81] Waste wolfberry fruits 1423 365

(0.2 A/g)		 1 M Li2SO4 23.2 0.225
Bituminous coal 3472.41 487

(1 A/g)		 6 M KOH96.4

(10,000) 249.6 10.34 96

(10,000)		[102][64]
[120][82] Camellia pollen 810 300

(1 A/g)		 6 M KOH 14.3 - 84.5

(20,000)		 [103][65]
Rice husk 1183 163.1

(0.2 A/g)		 6 M KOH 5.1 0.049 85

(6000)		 [104][66]
Corn Husk 1370 127

(1 A/g)		 6 M KOH 4.4 0.248 90

(5000)		 [105][67]
Olive Seed 1700 224

(0.25 A/g)		 1 M H2SO4/

1 M Na		2SO4 3–5 20–30 91

(12,500)		 [106][68]
Lignin residue of biodigester 1879 114

(0.5 A/g)		 2.5 M KNO3 10 6.9 84.5

(15,000)		 [93][55]

2.5. Coal-Derived AC-Based SCs

Coal is a low-cost carbon-rich material that exists in large natural reserves. In 2020, global coal reserves were estimated to be 1074 billion tons [107][69]. Restrictions regarding CO2 emissions should reduce the use of coal as a fuel and encourage the adoption of other, renewable energy sources with added value due to their applicability to fast-developing zero-emission vehicles [108][70]. There are five different varieties of coal: peat, lignite, subbituminous, bituminous, and anthracite, all of which are classified according to their carbon content. Peat is a soft, crumbly, dark brown substance formed by the decomposition of dead and partially decaying organic matter on the ground in oxygen-poor conditions. Peat contains the least amount of carbon (less than 60%). Lignite, also known as brown coal, has a brown color and preserves the fibrous aspect of the original wood. Its carbon content varies between 65 and 70%. Subbituminous coal, also known as black lignite, is a dark brown or gray-black coal; its carbon content ranges between 70 and 76%. Anthracite is the most high-quality coal because it contains nearly 95% carbon and has a low moisture content [109][71]. 
Similar to biomass-derived AC production, coal derivatives with a large SSA can be obtained by physical activation in the presence of air, O2, steam, CO2, etc., or by chemical activation using KOH, ZnCl2, NaOH, H3PO4, etc. In recent years, many researchers have investigated different coal-based ACs and their performance as SC electrode materials. Zhao et al. [110][72] used chemical activation by KOH to prepare AC from “hypercoal” with a high surface area of 2540 m2 g−1; Zhao et al. reported a capacitance of 46.0 F g−1. Shi et al. [111][73] assembled a high-performance SC with a specific electrode capacitance of 280 F g−1 and energy density of 38.9 Wh kg−1 at 0.5 A g−1 using an AC produced from anthracite. Zhu et al. [112][74] prepared high-performance coal derivatives via KOH activation, and the optimized sample had a surface area of 2457 m2 g−1 and total pore volume of 1.448 cm3 g−1, which allowed the material to exhibit a specific capacitance of 384 F g−1 in 6 M KOH.
Table 2 summarizes the electrochemical performance of coal-derived AC electrodes, including specific capacitance and power density values, and EDLCs assembled using aqueous electrolytes. Overall, the use of carbon derived from natural resources presents a propitious opportunity to design affordable, cheap, and environmentally friendly SCs.
Table 2. Electrochemical performance of coal-derived carbon-based electrodes (including specific surface area and specific capacitance) and EDLCs (including energy density, power density, and cycling stability) assembled using aqueous electrolytes.
Materials SSA

(m		2 g−1) Specific Capacitance

(F g		−1) Electrolyte for the

Assembled Device		 Energy Density

(Wh kg		−1) Power Density

(W kg		−1) Cyclic Stability

(%)		 Ref.
Sub-bituminous coal 1021 227

(0.5 A/g)		 6 M KOH 25 12.952 82

(10,000)		 [113][75]
Anthracite 3550.7 433

(0.5 A/g)		 6 M KOH 38.9 1000 99

(10,000)		 [111][73]
Coal 2129 323

(0.5 A/g)		 6 M KOH 10 250 93.7

(10,000)		 [114][76]
Coal tar pitch 3305 308

(1 A/g)		 1 M Na2SO4 21.9 461.6 - [115][77]
Coal tar pitch

References

  1. Dias, R.A.; Mattos, C.R.; Balestieri, J.A. The limits of human development and the use of energy and natural resources. Energy Policy 2006, 34, 1026–1031.
  2. Sovacool, B.K. The intermittency of wind, solar, and renewable electricity generators: Technical barrier or rhetorical excuse? Util. Policy 2009, 17, 288–296.
  3. El Shahat, A.; Keyhani, A. Sizing high speed micro generators for smart grid systems. In Smart Power Grids 2011; Springer: Berlin/Heidelberg, Germany, 2012; pp. 177–234.
  4. Ponds, K.T.; Arefi, A.; Sayigh, A.; Ledwich, G. Aggregator of demand response for renewable integration and customer engagement: Strengths, weaknesses, opportunities, and threats. Energies 2018, 11, 2391.
  5. Cao, W. Biomass-Derived Activated Carbons for Electrical Double Layer Supercapacitors: Performance and Stress Effect. Ph.D. Dissertation, University of Kentucky, Lexington, KY, USA, 2019.
  6. Afif, A.; Rahman, S.M.; Azad, A.T.; Zaini, J.; Islan, M.A.; Azad, A.K. Advanced materials and technologies for hybrid supercapacitors for energy storage—A review. J. Energy Storage 2019, 25, 100852.
  7. Luo, B.; Ye, D.; Wang, L. Recent progress on integrated energy conversion and storage systems. Adv. Sci. 2017, 4, 1700104.
  8. Gallo, A.; Simões-Moreira, J.; Costa, H.; Santos, M.; Dos Santos, E.M. Energy storage in the energy transition context: A technology review. Renew. Sustain. Energy Rev. 2016, 65, 800–822.
  9. Dhimish, M.; Schofield, N. Single-switch boost-buck DC-DC converter for industrial fuel cell and photovoltaics applications. Int. J. Hydrogen Energy 2021, 47, 1241–1255.
  10. Kamel, A.A.; Rezk, H.; Abdelkareem, M.A. Enhancing the operation of fuel cell-photovoltaic-battery-supercapacitor renewable system through a hybrid energy management strategy. Int. J. Hydrogen Energy 2021, 46, 6061–6075.
  11. Thounthong, P.; Chunkag, V.; Sethakul, P.; Sikkabut, S.; Pierfederici, S.; Davat, B. Energy management of fuel cell/solar cell/supercapacitor hybrid power source. J. Power Source 2011, 196, 313–324.
  12. Choi, J.W.; Aurbach, D. Promise and reality of post-lithium-ion batteries with high energy densities. Nat. Rev. Mater. 2016, 1, 16013.
  13. Kim, T.; Song, W.; Son, D.-Y.; Ono, L.K.; Qi, Y. Lithium-ion batteries: Outlook on present, future, and hybridized technologies. J. Mater. Chem. A 2019, 7, 2942–2964.
  14. Chen, T.; Jin, Y.; Lv, H.; Yang, A.; Liu, M.; Chen, B.; Xie, Y.; Chen, Q. Applications of lithium-ion batteries in grid-scale energy storage systems. Trans. Tianjin Univ. 2020, 26, 208–217.
  15. Nishi, Y. Lithium ion secondary batteries; past 10 years and the future. J. Power Source 2001, 100, 101–106.
  16. Kang, J.H. Fabrication and Characterization of Nano Carbon-Based Electrochemical Double-Layer Capacitors. Ph.D. Thesis, University of Waterloo, Waterloo, ON, Canada, 2015.
  17. Liu, Y.; Li, L.; Zhang, L.; Han, G.; Liu, Z.; Huang, J.; Zhang, L.; Luo, J.; Zhu, Z.; Qiao, Z.A. Emulsion-assisted interfacial polymerization strategy: Controllable architectural engineering of anisotropic and isotropic nanoparticles for high-performance supercapacitors. Battery Energy 2023, 2, 20220058.
  18. Bizuneh, G.G.; Adam, A.M.; Ma, J. Progress on carbon for electrochemical capacitors. Battery Energy 2023, 2, 20220021.
  19. Rouquerol, J.; Avnir, D.; Fairbridge, C.; Everett, D.; Haynes, J.; Pernicone, N.; Ramsay, J.; Sing, K.; Unger, K. Recommendations for the characterization of porous solids (Technical Report). Pure Appl. Chem. 1994, 66, 1739–1758.
  20. Wei, L.; Yushin, G. Nanostructured activated carbons from natural precursors for electrical double layer capacitors. Nano Energy 2012, 1, 552–565.
  21. Boujibar, O.; Ghamouss, F.; Ghosh, A.; Achak, O.; Chafik, T. Activated carbon with exceptionally high surface area and tailored nanoporosity obtained from natural anthracite and its use in supercapacitors. J. Power Source 2019, 436, 226882.
  22. Boujibar, O.; Ghosh, A.; Achak, O.; Chafik, T.; Ghamouss, F. A high energy storage supercapacitor based on nanoporous activated carbon electrode made from Argan shells with excellent ion transport in aqueous and non-aqueous electrolytes. J. Energy Storage 2019, 26, 100958.
  23. Chafik, T. Nanoporous Carbonated Materials Prepared from the Shell of the Argan Fruit 1–14. WO2012050411A1, 19 April 2012.
  24. Molina-Sabio, M.; Rodrıguez-Reinoso, F. Role of chemical activation in the development of carbon porosity. Colloids Surf. A Physicochem. Eng. Asp. 2004, 241, 15–25.
  25. Markets and Markets. Available online: https://www.researchandmarkets.com/reports/4040498/activated-carbon-market-by-type-powdered (accessed on 20 May 2023).
  26. Moreira, J.V.S.; Corat, E.J.; May, P.W.; Cardoso, L.D.R.; Lelis, P.A.; Zanin, H. Freestanding aligned multi-walled carbon nanotubes for supercapacitor devices. J. Electron. Mater. 2016, 45, 5781–5788.
  27. Karbak, M.; Boujibar, O.; Lahmar, S.; Autret-Lambert, C.; Chafik, T.; Ghamouss, F. Chemical Production of graphene oxide with high surface energy for supercapacitor applications. C 2022, 8, 27.
  28. Xia, Z.Y.; Pezzini, S.; Treossi, E.; Giambastiani, G.; Corticelli, F.; Morandi, V.; Zanelli, A.; Bellani, V.; Palermo, V. The Exfoliation of Graphene in Liquids by Electrochemical, Chemical, and Sonication-Assisted Techniques: A Nanoscale Study. Adv. Funct. Mater. 2013, 23, 4684–4693.
  29. Xia, Z.Y.; Giambastiani, G.; Christodoulou, C.; Nardi, M.V.; Koch, N.; Treossi, E.; Bellani, V.; Pezzini, S.; Corticelli, F.; Morandi, V.; et al. Synergic Exfoliation of Graphene with Organic Molecules and Inorganic Ions for the Electrochemical Production of Flexible Electrodes. Chempluschem 2014, 79, 439–446.
  30. Cheaptubes. Available online: https://www.cheaptubes.com/graphene-synthesis-properties-and-applications/ (accessed on 20 May 2023).
  31. Wang, D.; Sheng, L.; Jiang, M.; Jin, X.; Lin, X.; Lee, S.Y.; Shi, J.; Chen, W. Density and porosity optimization of graphene monoliths with high mass-loading for high-volumetric-capacitance electrodes. Battery Energy 2022, 1, 20220017.
  32. Azam, M.A.; Ramli, N.S.N.; Nor, N.A.N.M.; Nawi, T.I.T. Recent advances in biomass-derived carbon, mesoporous materials, and transition metal nitrides as new electrode materials for supercapacitor: A short review. Int. J. Energy Res. 2021, 45, 8335–8346.
  33. Mestre, A.S.; Carvalho, A.P. Nanoporous carbon synthesis: An old story with exciting new chapters. In Porosity; Ghrib, T., Ed.; IntechOpen: London, UK, 2018; pp. 37–68.
  34. Idris-Hermann, K.T.; Raoul, T.T.D.; Giscard, D.; Gabche, A.S. Preparation and characterization of activated carbons from bitter kola (Garcinia kola) nut shells by chemical activation method using H3PO4; KOH and ZnCl2. Chem. Sci. Int. J. 2018, 23, 1–15.
  35. Jiang, L.; Sheng, L.; Fan, Z. Biomass-derived carbon materials with structural diversities and their applications in energy storage. Sci. China Mater. 2018, 61, 133–158.
  36. Williams, P.T.; Reed, A.R. Development of activated carbon pore structure via physical and chemical activation of biomass fibre waste. Biomass Bioenergy 2006, 30, 144–152.
  37. Şentorun-Shalaby, Ç.D.; Uçak-Astarlıoğlu, M.G.; Artok, L.; Sarıcı, Ç. Preparation and characterization of activated carbons by one-step steam pyrolysis/activation from apricot stones. Microporous Mesoporous Mater. 2006, 88, 126–134.
  38. Zhang, L.; Liu, Z.; Cui, G.; Chen, L. Biomass-derived materials for electrochemical energy storages. Prog. Polym. Sci. 2015, 43, 136–164.
  39. Ayinla, R.T.; Dennis, J.; Zaid, H.; Sanusi, Y.; Usman, F.; Adebayo, L. A review of technical advances of recent palm bio-waste conversion to activated carbon for energy storage. J. Clean. Prod. 2019, 229, 1427–1442.
  40. Sundriyal, S.; Shrivastav, V.; Pham, H.D.; Mishra, S.; Deep, A.; Dubal, D.P. Advances in bio-waste derived activated carbon for supercapacitors: Trends, challenges and prospective. Resour. Conserv. Recycl. 2021, 169, 105548.
  41. Guo, Z.; Yan, N.; Lapkin, A.A. Towards circular economy: Integration of bio-waste into chemical supply chain. Curr. Opin. Chem. Eng. 2019, 26, 148–156.
  42. Dugmore, T.I.; Clark, J.H.; Bustamante, J.; Houghton, J.A.; Matharu, A.S. Valorisation of biowastes for the production of green materials using chemical methods. In Chemistry and Chemical Technologies in Waste Valorization; Springer: Berlin/Heidelberg, Germany, 2017; pp. 73–121.
  43. Yahya, M.A.; Al-Qodah, Z.; Ngah, C.Z. Agricultural bio-waste materials as potential sustainable precursors used for activated carbon production: A review. Renew. Sustain. Energy Rev. 2015, 46, 218–235.
  44. Liu, S.; Ge, L.; Gao, S.; Zhuang, L.; Zhu, Z.; Wang, H. Activated carbon derived from bio-waste hemp hurd and retted hemp hurd for CO2 adsorption. Compos. Commun. 2017, 5, 27–30.
  45. Manasa, P.; Lei, Z.J.; Ran, F. Biomass waste derived low cost activated carbon from carchorus olitorius (Jute fiber) as sustainable and novel electrode material. J. Energy Storage 2020, 30, 101494.
  46. Raj, C.J.; Rajesh, M.; Manikandan, R.; Yu, K.H.; Anusha, J.; Ahn, J.H.; Kim, D.-W.; Park, S.Y.; Kim, B.C. High electrochemical capacitor performance of oxygen and nitrogen enriched activated carbon derived from the pyrolysis and activation of squid gladius chitin. J. Power Source 2018, 386, 66–76.
  47. Na, R.; Wang, X.; Lu, N.; Huo, G.; Lin, H.; Wang, G. Novel egg white gel polymer electrolyte and a green solid-state supercapacitor derived from the egg and rice waste. Electrochim. Acta 2018, 274, 316–325.
  48. Gong, C.; Wang, X.; Ma, D.; Chen, H.; Zhang, S.; Liao, Z. Microporous carbon from a biological waste-stiff silkworm for capacitive energy storage. Electrochim. Acta 2016, 220, 331–339.
  49. Rawal, S.; Joshi, B.; Kumar, Y. Synthesis and characterization of activated carbon from the biomass of Saccharum bengalense for electrochemical supercapacitors. J. Energy Storage 2018, 20, 418–426.
  50. Su, X.-L.; Li, S.-H.; Jiang, S.; Peng, Z.-K.; Guan, X.-X.; Zheng, X.-C. Superior capacitive behavior of porous activated carbon tubes derived from biomass waste-cotonier strobili fibers. Adv. Powder Technol. 2018, 29, 2097–2107.
  51. Song, M.; Zhou, Y.; Ren, X.; Wan, J.; Du, Y.; Wu, G.; Ma, F. Biowaste-based porous carbon for supercapacitor: The influence of preparation processes on structure and performance. J. Colloid Interface Sci. 2019, 535, 276–286.
  52. Yang, S.; Zhang, K. Converting corncob to activated porous carbon for supercapacitor application. Nanomaterials 2018, 8, 181.
  53. Mitravinda, T.; Nanaji, K.; Anandan, S.; Jyothirmayi, A.; Chakravadhanula, V.S.K.; Sharma, C.S.; Rao, T.N. Facile synthesis of corn silk derived nanoporous carbon for an improved supercapacitor performance. J. Electrochem. Soc. 2018, 165, A3369.
  54. Yin, L.; Chen, Y.; Zhao, X.; Hou, B.; Cao, B. 3-Dimensional hierarchical porous activated carbon derived from coconut fibers with high-rate performance for symmetric supercapacitors. Mater. Des. 2016, 111, 44–50.
  55. Mutuma, B.K.; Sylla, N.F.; Bubu, A.; Ndiaye, N.M.; Santoro, C.; Brilloni, A.; Poli, F.; Manyala, N.; Soavi, F. Valorization of biodigestor plant waste in electrodes for supercapacitors and microbial fuel cells. Electrochim. Acta 2021, 391, 138960.
  56. Dhakal, G.; Mohapatra, D.; Kim, Y.-I.; Lee, J.; Kim, W.K.; Shim, J.-J. High-performance supercapacitors fabricated with activated carbon derived from lotus calyx biowaste. Renew. Energy 2022, 189, 587–600.
  57. Liang, T.; Hou, R.; Dou, Q.; Zhang, H.; Yan, X. The Applications of Water-in-Salt Electrolytes in Electrochemical Energy Storage Devices. Adv. Funct. Mater. 2021, 31, 2006749.
  58. Wang, Z.; Yun, S.; Wang, X.; Wang, C.; Si, Y.; Zhang, Y.; Xu, H. Aloe peel-derived honeycomb-like bio-based carbon with controllable morphology and its superior electrochemical properties for new energy devices. Ceram. Int. 2019, 45, 4208–4218.
  59. Surya, K.; Michael, M.S. Hierarchical porous activated carbon prepared from biowaste of lemon peel for electrochemical double layer capacitors. Biomass Bioenergy 2021, 152, 106175.
  60. Yao, S.; Zhang, Z.; Wang, Y.; Liu, Z.; Li, Z. Simple one-pot strategy for converting biowaste into valuable graphitized hierarchically porous biochar for high-efficiency capacitive storage. J. Energy Storage 2021, 44, 103259.
  61. Quan, H.; Tao, W.; Wang, Y.; Chen, D. Enhanced supercapacitor performance of Camellia oleifera shell derived hierarchical porous carbon by carbon quantum dots. J. Energy Storage 2022, 55, 105573.
  62. Vinayagam, M.; Suresh Babu, R.; Sivasamy, A.; Ferreira de Barros, A.L. Biomass-derived porous activated carbon from Syzygium cumini fruit shells and Chrysopogon zizanioides roots for high-energy density symmetric supercapacitors. Biomass Bioenergy 2020, 143, 105838.
  63. Sun, Y.; Xu, D.; Wang, S. Self-assembly of biomass derivatives into multiple heteroatom-doped 3D-interconnected porous carbon for advanced supercapacitors. Carbon 2022, 199, 258–267.
  64. Xu, X.; Sielicki, K.; Min, J.; Li, J.; Hao, C.; Wen, X.; Chen, X.; Mijowska, E. One-step converting biowaste wolfberry fruits into hierarchical porous carbon and its application for high-performance supercapacitors. Renew. Energy 2022, 185, 187–195.
  65. Cao, L.; Li, H.; Xu, Z.; Zhang, H.; Ding, L.; Wang, S.; Zhang, G.; Hou, H.; Xu, W.; Yang, F.; et al. Comparison of the heteroatoms-doped biomass-derived carbon prepared by one-step nitrogen-containing activator for high performance supercapacitor. Diamond. Relat. Mater. 2021, 114, 108316.
  66. Liu, Y.; Tan, H.; Tan, Z.; Cheng, X. Rice husk derived capacitive carbon prepared by one-step molten salt carbonization for supercapacitors. J. Energy Storage 2022, 55, 105437.
  67. Rani, M.U.; Nanaji, K.; Rao, T.N.; Deshpande, A.S. Corn husk derived activated carbon with enhanced electrochemical performance for high-voltage supercapacitors. J. Power Source 2020, 471, 228387.
  68. Elmouwahidi, A.; Bailón-García, E.; Pérez-Cadenas, A.F.; Maldonado-Hódar, F.J.; Carrasco-Marín, F. Activated carbons from KOH and H3PO4-activation of olive residues and its application as supercapacitor electrodes. Electrochim. Acta 2017, 229, 219–228.
  69. Coal—Statistical Review of World Energy 2021-BP. Available online: https://www.bp.com/content/dam/bp/business-sites/en/global/corporate/pdfs/energy-economics/statistical-review/bp-stats-review-2021-full-report.pdf (accessed on 11 July 2023).
  70. Nalbandian, H.; House, P. Non-Fuel Uses of Coal; IEA Coal Research Center: London, UK, 2014.
  71. Voncken, J. The Origin and Classification of Coal. In Geology of Coal Deposits of South Limburg, The Netherlands; Springer: Berlin/Heidelberg, Germany, 2020; pp. 25–40.
  72. Zhao, X.-Y.; Huang, S.-S.; Cao, J.-P.; Xi, S.-C.; Wei, X.-Y.; Kamamoto, J.; Takarada, T. KOH activation of a HyperCoal to develop activated carbons for electric double-layer capacitors. J. Anal. Appl. Pyrolysis 2014, 105, 116–121.
  73. Shi, M.; Xin, Y.; Chen, X.; Zou, K.; Jing, W.; Sun, J.; Chen, Y.; Liu, Y. Coal-derived porous activated carbon with ultrahigh specific surface area and excellent electrochemical performance for supercapacitors. J. Alloys Compd. 2021, 859, 157856.
  74. Peng, Z.; Guo, Z.; Chu, W.; Wei, M. Facile synthesis of high-surface-area activated carbon from coal for supercapacitors and high CO2 sorption. RSC Adv. 2016, 6, 42019–42028.
  75. Bora, M.; Tamuly, J.; Maria Benoy, S.; Hazarika, S.; Bhattacharjya, D.; Saikia, B.K. Highly scalable and environment-friendly conversion of low-grade coal to activated carbon for use as electrode material in symmetric supercapacitor. Fuel 2022, 329, 125385.
  76. Dong, D.; Zhang, Y.; Xiao, Y.; Wang, T.; Wang, J.; Romero, C.E.; Pan, W.-P. High performance aqueous supercapacitor based on nitrogen-doped coal-based activated carbon electrode materials. J. Colloid Interface Sci. 2020, 580, 77–87.
  77. Qin, B.; Wang, Q.; Zhang, X.; Xie, X.; Jin, L.E.; Cao, Q. One-pot synthesis of interconnected porous carbon derived from coal tar pitch and cellulose for high-performance supercapacitors. Electrochim. Acta 2018, 283, 655–663.
  78. Cheng, J.; Lu, Z.; Zhao, X.; Chen, X.; Liu, Y. Green needle coke-derived porous carbon for high-performance symmetric supercapacitor. J. Power Source 2021, 494, 229770.
  79. Liu, H.; Song, H.; Hou, W.; Chang, Y.; Zhang, Y.; Li, Y.; Zhao, Y.; Han, G. Coal tar pitch-based hierarchical porous carbons prepared in molten salt for supercapacitors. Mater. Chem. Phys. 2021, 265, 124491.
  80. Liu, Y.; Qu, X.; Huang, G.; Xing, B.; Fan, Y.; Zhang, C.; Cao, Y. Microporous carbon derived from anthracite as supercapacitor electrodes with commercial level mass loading. J. Energy Storage 2021, 43, 103200.
  81. Dong, D.; Zhang, Y.; Wang, T.; Wang, J.; Romero, C.E.; Pan, W.-p. Enhancing the pore wettability of coal-based porous carbon as electrode materials for high performance supercapacitors. Mater. Chem. Phys. 2020, 252, 123381.
  82. Yang, N.; Ji, L.; Fu, H.; Shen, Y.; Wang, M.; Liu, J.; Chang, L.; Lv, Y. Hierarchical porous carbon derived from coal-based carbon foam for high-performance supercapacitors. Chin. Chem. Lett. 2022, 33, 3961–3967.
More
© Text is available under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/)
Video Production Service
Feedback