Study of the Active Carbon from Used Coffee Grounds as the Active Material for a High-Temperature Stable Supercapacitor with Ionic-Liquid Electrolyte

Abstract

This study reveals a simple approach to recycle wasted coffee grounds into highly valuable carbon material with superior electrochemical performance. Activated carbon prepared from wasted coffee grounds has been formed via hydrothermal acidic hydrolysis followed by a KOH chemical activation at 800 ∘C. To understand the electrochemical properties of the sample, a set of characterization tools has been utilized: N2 and CO2 adsorption–desorption isotherms, thermal gravimetric analysis, Fourier transform infrared spectroscopy, Raman spectroscopy and scanning electron microscopy. The specific surface area obtained from a Brunner–Emmett–Teller (BET) analysis reached 2906±19m2g−1. Prepared sample (designated as ACG-800KOH) was tested as electrode material in an electric double layer capacitor (EDLC) device with ionic liquid PYR13-TFSI as an electrolyte. The EDLC test was conducted at temperatures ranging from 20 to 120 ∘C. The specific material capacitance reached 178 Fg−1 measured at 20 ∘C and 50 A g−1 and was in the range 182 to 285 Fg−1 at the 20 to 120 ∘C temperature range.

Preparation of Activated Carbons from Spent Coffee Grounds and Coffee Parchment and Assessment of Their Adsorbent Efficiency

“…These values were in the range from 286 • C to 316 • C (70% weight loss) and from 376 • C to 410 • C (29% weight loss) for raw parchment. Those weight losses were reported to be a thermal decomposition of the amorphous cellulose regions and oxidation of the carbon skeleton [55]. Similar thermogravimetric curves were previously reported from materials with hemicellulose and lignin content [53,56,57].…”

Improving EDLC Device Performance Constructed from Plasticized Magnesium Ion Conducting Chitosan Based Polymer Electrolytes via Metal Complex Dispersion

“…In times of intensive development of electric vehicles around the world, supercapacitors (SCs) play a large role [ 1 ]. SCs act as a power buffer during energy transfer from the fuel cell of the propulsion engine of the vehicle [ 1 ].…”

“…In times of intensive development of electric vehicles around the world, supercapacitors (SCs) play a large role [ 1 ]. SCs act as a power buffer during energy transfer from the fuel cell of the propulsion engine of the vehicle [ 1 ]. Lithium–ion batteries are usually used as the main energy source due to their high energy density, but when it comes to sudden demand for high power, e.g., acceleration or braking, high power density characteristic of SCs comes in handy [ 2 ].…”

Biomass Porous Carbons Derived from Banana Peel Waste as Sustainable Anodes for Lithium-Ion Batteries

“…A high specific surface area causes a high first cycle loss and, hence, the overall battery capacity in a full cell will reduce significantly. This drawback could be converted to an advantage if high surface biomass derived carbon is used as an electroactive material in supercapacitors (EDLCs) or ion-capacitors (ICs) [78], or even as an anode for Na-ion batteries, where hard carbons are highly recommended [79]. 1 C rate is referred to the theoretical capacity of graphite (1 C = 372 mA g −1 ).…”