Converting Ni-loaded biochars into supercapacitors: Implication on the reuse of exhausted carbonaceous sorbents

Abstract

Biochar derived from waste biomass has proven as a promising sorbent for removal of heavy metals from wastewater. However, proper disposal of such a heavy metal-containing biochar is challengeable. The major objective of this study is to create a reuse way by converting the heavy metal-loaded biochar into supercapacitor. Two biochars were produced from dairy manure and sewage sludge, respectively, and subjected to sorption of Ni from solution, and then the Ni-loaded biochar underwent microwave treatments for fabrication of supercapacitor. The specific capacitance of biochar supercapacitor increased with Ni loading, especially the Ni-loaded biochar further treated with microwave in which the capacitance increased by over 2 times, compared to the original biochar supercapacitors. The increase of capacitance in the Ni-loaded biochar supercapacitor following microwave treatment was mainly attributed to the conversion of Ni into NiO and NiOOH, which was evidenced by X-ray diffraction and X-ray photoelectron spectroscopy. The biochar supercapacitors, especially microwave-treated Ni-loaded biochar supercapacitors exhibited the high stability of specific capacitance, with less than 2% loss after 1000 charge-discharge cycles. This study demonstrated that Ni-loaded biochar can be further utilized for generation of supercapacitor, providing a potential way for the reuse of exhausted carbonaceous sorbents.

Catalytic HTL ‐derived biochar and sol‐gel synthesized (Mn, Ti)‐oxides for asymmetric supercapacitors

“…Typically, lower specific capacitance was observed with the biochar. Microwave activated Ni‐loaded biochar based supercapacitors showed a specific capacitance of 123 F/g at scan rate of 5 mV/s with ≤ 2% loss after 1000 charge‐discharge cycles 75 . Electrospun nanofiber mats prepared using HTL‐derived biochar from pinewood and polyacrylonitrile exhibited a gravimetric capacitance of 37.6 F/g at a current density of 500 mA/g and scan rate of 100 mV/s, which found to retain 95% specific capacitance after 1000 charge‐discharge cycles 20 .…”

“…Microwave activated Ni-loaded biochar based supercapacitors showed a specific capacitance of 123 F/g at scan rate of 5 mV/s with ≤ 2% loss after 1000 charge-discharge cycles. 75 Electrospun nanofiber mats prepared using HTL-derived biochar from pinewood and polyacrylonitrile exhibited a gravimetric capacitance of 37.6 F/g at a current density of 500 mA/g and scan rate of 100 mV/s, which found to retain 95% specific capacitance after 1000 chargedischarge cycles. 20 Thus, the use of inexpensive biochar for a supercapacitor could yield reasonable specific capacitance and cycling stability as compared to graphene electrode.…”

Chestnut-Derived Activated Carbon as a Prospective Material for Energy Storage

“…Activated carbons of developed porosity are valuable electrode materials for supercapacitor application [ 20 , 21 , 22 ]. Biomass as a precursor for electrode material has to fulfil several criteria, in particular, biochar should have: (i) high carbon content (to provide good electric conductivity), (ii) low amount of impurities (to avoid further purification and limit side reactions during operation of the device), (iii) high surface area (to assure high electric double-layer capacitance) and (iv) tailored porosity (with pore sizes accessible for ions).…”

Carbon-based nanomaterial hybrids energy storage applications

“…20 This has also called for research for other carbon-based materials like biomass-derived carbon, functionalised graphene, carbon nanotubes etc. 9,[33][34][35][36][37][38][39] An EDLC stores its charge electrostatically. Hence there is no transfer of charge between the electrolyte and electrode.…”

“…8 7 For EDLCs, biomass-derived carbons are gaining a lot of interest because of their extremely low cost and environmental-friendly nature and are much cheaper than other carbon-based products like graphene, Carbon Nanotubes (CNT) etc. 39,56…”