Description:[0003] Porous carbon are the most often utilized electrode material in electrical conductors (EC) due to their high specific surface area (>1000 m2•g-1), controllable pore size, high conductivity, sustainability and low cost. Fossil fuels have been the primary source of carbon, which are both limited and non-renewable. Besides, burning of fossil fuels accounts for ~76% of the total greenhouse gas emissions. Undeniably, replacing fossil fuels with biomass could renewably produce porous carbon with a lower carbon footprint and embodied energy.
[0004] Among the different biomass materials, coconut palm is considered as the significant source of carbon production as it is the most common agriculture all around the world. Various publications have attempted to fabricate capacitors using coconut as a starting material. For instance, “Low cost, high performance supercapacitor electrode using coconut wastes: eco-friendly approach” (https://doi.org/10.1016/j.jechem.2016.08.002) discloses about porous carbon nanospheres derived from coconut fiber that exhibits maximum specific capacitance of 236 F/g followed by coconut stick and coconut leaves with 208 and 116 F/g respectively at a scan rate of 2 mV/s. Activated carbon using coconut shells as precursor was proposed in “Graphite-type activated carbon from coconut shell: a natural source for eco-friendly non-volatile storage devices”, (DOI: 10.1039/d0ra09182k) and showed specific capacitance of 132.3 F•g-1 in aqueous electrolyte (1.5 M H2SO4), using expanded graphite sheets as current collector substrates. In yet another publication “Activated carbon electrode made from coconut husk waste for supercapacitor application”, (doi: 10.20964/2018.12.19), an activated carbon electrode was produced from coconut husk by using a combination of physical and chemical activation methods showed excellent capacitive properties of a supercapacitor cell, with a very high specific capacitance of 184 F•g-1. “Synthesis, characterization and electrochemical properties of activated coconut fiber carbon (ACFC) and CuO/ACFC nanocomposites for applying as electrodes of supercapacitor devices” (https://doi.org/10.1016/j.surfin.2021.101174) discloses about CuO/Activated Coconut Fiber Carbon (ACFC) nanocomposites and assembled asymmetric supercapacitor (ASC) device with ACFC as a negative electrode and CuO/ACFC-3 Ncps as a positive electrode (ACFC//CuO/ACFC-3) that could exhibit the Cs value of 24.94 F g-1 at 0.5 A•g-1. “Coconut Shell-Derived Activated Carbon for High-Performance Solid-State Supercapacitors”, (https://doi.org/10.3390/en14154546) wherein the solid-state symmetric supercapacitor device delivered a specific capacitance of 88 F•g-1 at 1 A•g-1 and a high energy density of 48.9 Whkg-1 at a power density of 1 kWkg-1.
[0005] However, the above-mentioned capacitors nowhere disclose coconut rachis as a suitable carbon precursor for supercapacitor electrode material. Hence, there has been a need in the art for an improved supercapacitor electrode and method of preparation that is easy to fabricate, cost-effective, and proficient in terms of specific capacitance. In this regard, the electrode and method according to the present invention substantially departs from the conventional concepts and designs of the prior art.
[0006] These and other advantages will be more readily understood by referring to the following detailed description disclosed hereinafter with reference to the accompanying drawing and which are generally applicable to other evaporators to fulfill particular applications illustrated hereinafter. , C , Claims:1. A supercapacitor electrode 100 based on activated carbon from coconut rachis, comprising:
dried activated carbon from coconut rachis 101 with narrow pore size distribution, conducting carbon 103, a binder 105 on a current collecting substrate 109,
wherein the dried activated carbon 101 is present in an amount of at least 70 wt % of the electrode;

2. The supercapacitor electrode 100 as claimed in claim 1, wherein the activated carbon comprises a pore size distribution in the range of 2.05 to 2.13 nm, or with average pore size of 2.09 nm.

3. The supercapacitor electrode 100 as claimed in claim 1, wherein the activated carbon is characterized by a BET surface area of 1600 m2 g-1 or more.

4. The supercapacitor electrode as claimed in claim 1, wherein the conducting carbon is selected from acetylene black, carbon nanotube, grapheme, carbon black powder or a combination thereof.

5. The supercapacitor electrode 100 as claimed in claim 1, wherein the conducting carbon and the binder are each present in an amount of 10 wt % or more of the electrode.

6. The supercapacitor electrode 100 as claimed in claim 5, wherein the binder includes polyvinylidene fluoride, polyvinyl pyrrolidone, polytetrafluoroethylene or a combination thereof.

7. The supercapacitor electrode 100 as claimed in 1, wherein the current collecting substrate material is selected from aluminium, copper, nickel or stainless steel.

8. The supercapacitor electrode 100 as claimed in claim 1, wherein the electrode comprises a specific capacitance of 320 F/g or more at a scan rate of 5 mV/s, or a bulk impedance of 1.41 O or more, or a charge transport impedance of 0.2 O or more for outer and 0.002 O or more for inner Helmholtz layer, or a surface space charge accumulation of 0.08 mF or more at the outer Helmholtz layer and 97.9 mF or more at the inner Helmholtz layer.

9. A method for preparing a supercapacitor electrode 200 based on activated carbon from coconut rachis, the method comprising the steps of:
- providing dried activated carbon 201 with narrow pore size distribution to 65-75% of the weight of the electrode;
- mixing 203 the activated carbon with 25-35% conducting carbon and a binder to form a mixture thereof;
- adding a solvent to the mixture to form slurry; and
- coating 207 degassed slurry uniformly onto a current collecting substrate to a specified mass loading per unit area, thereby forming the electrode.

10. The method 200 as claimed in claim 8, wherein adding the solvent includes adding one or more of N-methylpyrrolidinone, dimethylformamide, dimethylsulfoxide, dimethylacetamide, 1,3-dimethyl-2imidazolidinone or a combination thereof.

11. The method 200 as claimed in claim 8, wherein the current collecting substrate 205 is pre-treated by cleaning and annealing overnight at 60°C with subsequent drying at 120°C for at least an hour.

12. The method 200 as claimed in claim 8, wherein the mass loading of the electrode ranges from 0.001 to 0.01 g.cm-2.