One of the global problems is environmental pollution by different biowaste. To solve the problem, biowaste must be recycled. Waste-free technology is also a way of saving exhaustible raw materials. Research on electrochemical energy sources is currently the most dynamically developing area of off-grid energy. Electrochemical capacitors can operate for a long time without changing performance, they have smaller dimensions, high mechanical strength, and a wide operating temperature range. These properties are effective energy-saving devices. Therefore, supercapacitors are widely used in various industries.
Raw Material | S | BET | (m | 2 | /g) | Current Density (A/g) |
Specific Capacitance (F/g) |
Types of Test Cells | Reference |
---|---|---|---|---|---|---|---|---|---|
Petroleum coke | 2964 | 0.05 | 220 | Two-electrode cell with symmetrical electrodes. |
[25] | ||||
Coal | 1032 | 0.5 | 108 | Three-electrode cell with Hg/HgO as the reference electrode, AC as the working | [26] | ||||
Pitch | 3145 | 0.05 | 272 | electrode and platinum plate as the counter electrode. Two-electrode cell with symmetrical electrodes. |
[27] |
Non-Conventional Biowaste Raw Materials
Recently, renewable biowaste-derived activated carbons have attracted significant attention due to their interesting characteristics of naturally porous or hierarchical structured and heteroatom doping [28]. This biowaste-derived activated carbon has reduced electrochemical properties compared to carbon fibers, commercial activated carbon, CNTs, etc. However, their major advantage is low cost, ease of production, environmental friendliness, and the presence of their inherent functional groups and heteroatoms, which makes them a suitable substitute for carbonaceous materials derived from fossil fuels. Biowaste-derived activated carbon has been identified as a suitable electrode for energy storage devices due to its required pore size, large specific surface area, low equivalent series resistance, and high stability [29]. Non-conventional raw materials are very diverse, and most of them could be easily found in daily lives, such as food waste (coconut shell [30], pecan nutshell waste [31], ginkgo shells [32], onion peel [33], pomelo peel [34], garlic peel [35], orange peel [36], etc.), animal waste (crab shell [37], pork bone [38], blackfish bone [38], eel bone [38], fish bladder [39], etc.), plant waste (Couroupita guianansis [40], Elm flower [41], kapok flower [42], hemp stem [43], pine cones [4], banana leaves [44], etc.). Figure 2 illustrates the types of biowaste-derived activated carbon. Notably, the raw material types increase yearly due to the demand for activated carbon-based supercapacitors.Raw Material | S | BET | (m | 2 | /g) | Current Density (A/g) |
Specific Capacitance (F/g) |
Types of Test Cells | Reference |
---|---|---|---|---|---|---|---|---|---|
Plant waste |
Material | Capacitance Retention, % | Reference | |||||||
---|---|---|---|---|---|---|---|---|---|
Rice husk-derived carbon | 98.5 (after 5000 charge–discharge cycles) | [107] | [58] | ||||||
Sugarcane bagasse | 725 | 0.2 | |||||||
Rice husk-derived carbon/MnO | 265 | 2 | Three-electrode cell (working (AC), reference (saturated calomel electrode), a counter (Pt wire). | 80.2 (after 5000 charge–discharge cycles) | [52] | ||||
[ | 107 | ] | [58] | Elm flower | 2048.6 | 20 | |||
Bamboo-based activated carbon | 99.98 (after 1000 charge–discharge cycles) | [104] | 216 | [Two-electrode cell with symmetrical electrodes. |
59][41] | ||||
Kapok flower | 1904.1 | 1 | 286.8 | Three-electrode cell (counter (Pt wire), reference electrode (Ag/AgCl), working (AC) cell. | [42] | ||||
Bamboo-based activated carbon/MnO | 2 | 89.29 (after 1000 charge–discharge cycles) | [104] | Sakura petals | 1433.8 | 0.2 | 265.8 | Three-electrode working (AC), counter (Pt sheet), reference (a saturated calomel electrode). | [53] |
[ | 59 | ] | Lignin | 1425 | 10 mV/s | 140.9 | Three-electrode cell (working (AC), counter (Pt), and references (Ag/AgCl)). | [54] | |
Food waste | |||||||||
Garlic peel | 3325.2 | 1 | 424.42 | Two-electrode cell with symmetrical electrodes. |
[35] | ||||
Onion peel | 3150 | 0.5 | 169 | Three-electrode cell (working (AC), counter (glassy carbon), and references (Ag/AgCl)). | [33] | ||||
Pomelo peel | 1582 | 0.5 | 180 | Three-electrode cell (reference (Hg/HgO), a counter (graphite sheet), working (porous carbon)). | [34] | ||||
Orange peel | 1391 | 0.5 | 407 | [ | 36] | ||||
Three-electrode cell (working (porous carbon), counter (Pt strip), and reference (saturated calomel electrode). | Animal waste | ||||||||
Crab shell | 3442 | 0.2 | 280.6 | Two-electrode cell with symmetrical electrodes. |
[37] | ||||
Pork bone | 1260 | 0.5 | 263 | Three-electrode cell (working (AC), counter (Pt foil), reference (saturated calomel electrode)). | [38] | ||||
Blackfish bone | 1202 | 0.5 | 302 | Three-electrode cell (working (AC), counter (Pt foil), reference (saturated calomel electrode)). | [38] | ||||
Eel bone | 1163 | 0.5 | 264 | Three-electrode cell (working (AC), counter (Pt foil), reference (saturated calomel electrode)). | [38] |