Synthesis and characterization of activated carbon and manganese-based oxide/layered double hydroxide materials for supercapacitor applications

The aim of this study is to synthesize and characterize cheap, efficient and high-performance 3D activated carbon (AC) from cork (Quercus Suber) by KOH and KHCO3 activation respectively, Co-Mn LDH and MnO2-CNT nanocomposite materials with meso/microporous structures for energy storage application. The AC derived from cork (Q.suber) was synthesized with KOH in order to investigate the electrochemical performance of the AC in relation to KOH activation concentration and the AC synthesized by KHCO3 device because both materials performed well in 1 M KOH alkaline electrolyte, while ACKOH was chosen as the negative electrode in the MnO2-CNT//ACKOH device because both materials showed good performance in 1 M Li2SO4 neutral electrolyte. The aim of the hybrid devices was to take advantage of the individual working potentials of the electrode materials for enhanced electrochemical performance. All devices tested displayed energy densities ranging from 14 - 25 Wh kg-1 with corresponding power densities ranging from 450 – 500 W kg-1 at a specific current of 0.5 Ag-1 in the operating voltage window of between 1.6 V and 2.0 V in aqueous electrolyte media. All the materials tested displayed 99.7% - 100 % long-term cycling stability, showcasing the potential use of these materials as electrode materials for electrochemical capacitors.PhysicsPhDUnrestricte

Asymmetric supercapacitor based on vanadium disulfide nanosheets as a cathode and carbonized iron cations adsorbed onto polyaniline as an anode

The South African Research Chairs Initiative (SARChI) of the Department of Science and Technology and the National Research Foundation (NRF) of South Africa (Grant No. 61056).http://www.elsevier.com/locate/electacta2019-01-10hj2018Physic

Nickel-copper graphene foam prepared by atmospheric pressure chemical vapour deposition for supercapacitor applications

Please read abstract in the article.The National Research Foundation (NRF) of South Africa via iThemba LABS Materials Research Department (MRD) and the South African Research Chairs Initiative (SARChI) of the Department of Science and Technology and the NRF.http://elsevier.com/locate/surfcoathj2021Physic

High performance hybrid supercapacitor device based on cobalt manganese layered double hydroxide and activated carbon derived from cork (Quercus Suber)

Thin Co-Mn layered double hydroxide (LDH) nanoflakes and Activated carbon (AC) from cork raw material (Quercus Suber) with highly porous structure and good textural properties was synthesized by a facile solvothermal and two-step eco-friendly hydrothermal syntheses routes respectively. A hybrid device was successfully fabricated using Co-Mn LDH as the positive electrode and AC as negative electrode. The device exhibited a high energy density of 20.3 W h kg−1 and corresponding power density of up to 435 W kg−1 at 0.5 A g−1 current density in 1 M KOH aqueous electrolyte. The device also displayed a very high stability with 99.7% capacitance retention after 10,000 continuous charge-discharge cycles and negligible degradation after subsequently subjecting it to voltage holding test at its maximum operating voltage for 70 hours. These results showcase the potential use of this hybrid device as possible electrodes for high energy density supercapacitor application.The South African Research Chairs Initiative (SARChI) of the Department of Science and Technology and the National Research Foundation (NRF) of South Africa (Grant No. 61056).http://www.elsevier.com/locate/electacta2018-10-20hj2017Physic

High electrochemical performance of hierarchical porous activated carbon derived from lightweight cork (Quercus suber)

Activated carbon (AC) derived from biomass lightweight cork (Quercus suber) material was synthesized by KOH activation with different mass ratios of Q. suber: KOH in order to investigate the electrochemical properties of the AC in relation to KOH concentration. A well-defined porous activated carbon was obtained with a high surface area of 1081 m2 g−1 and a high pore volume of 0.66 cm3 g−1 when the Q. suber: KOH mass ratio was fixed at 1:2. A specific capacitance of 166 F g−1 was obtained for the symmetric device at 0.5 A g−1 in 1 M Na2SO4 with energy and power densities of 18.6 and 449.4 W Kg−1, respectively. The device displays good cycling stability after floating test for 200 h at 1.8 V and also displays 99.8% capacitance retention after cycling for 5000 cycles. The excellent electrochemical performance of the device makes it a potential material for supercapacitor application.National Research Foundation (NRF) of South Africahttp://link.springer.com/journal/10853Lightweight cork (Quercus suber)2018-09-30hj2017Physic

Measurement of L-shell X-ray production cross sections in 89Y, 158Gd and 209Bi due to 0.3 MeV/u – 1.0 MeV/u 12C ions

Please read abstract in the article.The University of Pretoria, Tshwane University of Technology and iThemba LABS (National Research Foundation of South Africa).https://www.elsevier.com/locate/apradiso2023-09-07hj2022Physic

Electrochemical performance of hybrid supercapacitor device based on birnessite-type manganese oxide decorated on uncapped carbon nanotubes and porous activated carbon nanostructures

Please read abstract in the article.This research work was supported by the South African Research Chairs Initiative ( SARChI ) of the Department of Science and Technology and the National Research Foundation ( NRF ) of South Africa (Grant No. 61056 ). Faith O. Ochai-Ejeh acknowledges NRF through SARChI in Carbon Technology and Materials, the Department of Physics at the University of Pretoria, the TETFund through the University of Nigeria for financial support.http://www.elsevier.com/locate/electacta2019-11-01hj2018Physic

Green and scalable synthesis of 3D porous carbons microstructures as electrode materials for high rate capability supercapacitors

Porous carbon nanostructures have long been studied because of their importance in many natural phenomena and their use in numerous applications. A more recent development is the ability to produce porous carbon materials with tuneable properties for electrochemical applications, which has enabled new research directions towards the production of suitable carbon materials for energy storage applications. Thus, this work explores the activation of carbon from polyaniline (PANI) using a lesscorrosive potassium carbonate (K2CO3) salt, with different mass ratios of PANI and the activating agent (K2CO3 as compared to commonly used KOH). The obtained activated carbon exhibits a specific surface area (SSA) of up to 1700 m2 g 1 for a carbon derived PANI : K2CO3 ratio of 1 : 6. Moreover, the prepared samples were tested as electrode materials for supercapacitors with the results showing excellent electrical double layer capacitor behavior. Charge storage was still excellent for scan rates of up to 2000 mV s 1, and a capacitance retention of 70% at a very high specific current of 50 A g 1 was observed. Furthermore, the fabricated device can deliver an energy density of 25 W h kg 1 at a specific current of 0.625 A g 1 and a power density of 260 W kg 1 in 1-ethyl-3-methylimidazolium bistrifluorosulfonylimide (EMIM-TFSI) ionic liquid, with excellent rate capability after cycling for 16 000 cycles at 3.0 V with 98% efficiency. These results are promising and demonstrate the electrode's potential for energy storage, leading to the conclusion that K2CO3 is a very good alternative to corrosive activation agents such as KOH in order to achieve high electrochemical performance.The South African Research Chairs Initiative of the Department of Science and Technology and National Research Foundation of South Africa (Grant No. 61056). A. Bello acknowledge the National research Foundation (NRF) through the SARCHI chair in Carbon Technology and the African Centres of Excellence Program, the Pan African Materials Institute (PAMI), and the African Development Bank (AfDB).http://www.rsc.org/journals-books-databases/about-journals/rsc-advancesam2019Physic

Nanostructured porous carbons with high rate cycling and floating performance for supercapacitor application

Biomass-derived activated carbon from cork (Quercus Suber) (ACQS) was prepared via a two-step environment-friendly route using mild KHCO3 as the activating agent. This synthesis route makes the material produced less toxic for usage as electrode material for energy storage application. The ACQS has well-defined microporous and mesoporous structures and a specific surface area of 1056.52 m2 g-1 and pore volume of 0.64 cm3 g-1. Three-electrode tests were performed in 6 M KOH, 1 M H2SO4 and 3 M KNO3 aqueous electrolytes, to analyse the material performance in acidic, basic, and neutral media. Specific capacitance values (Cs) of 133 F g-1/167 F g-1 at 1.0 A g-1 was obtained in 3 M KNO3 in the positive/negative potential windows. Due to the observed best performance in neutral 3 M KNO3, further electrochemical analysis of the symmetric device was carried out using the same electrolyte. The device displayed a Cs value of 122 F g-1, energy and power densities of ∼14 W h kg-1 and 450 W kg-1 respectively; at 0.5 A g-1. The device also displayed an excellent stability after potentiostatic floating at a maximum voltage of 1.8 V for 120 h and ∼100% capacitance retention after 10,000 charge-discharge cycles. The excellent stability makes the cork-derived material a potential excellent, cost-effective material for supercapacitor application

Nanostructured porous carbons with high rate cycling and floating performance for supercapacitor application

Biomass-derived activated carbon from cork (Quercus Suber) (ACQS) was prepared via a two-step environment-friendly route using mild KHCO3 as the activating agent. This synthesis route makes the material produced less toxic for usage as electrode material for energy storage application. The ACQS has well-defined microporous and mesoporous structures and a specific surface area of 1056.52 m2 g-1 and pore volume of 0.64 cm3 g-1. Three-electrode tests were performed in 6 M KOH, 1 M H2SO4 and 3 M KNO3 aqueous electrolytes, to analyse the material performance in acidic, basic, and neutral media. Specific capacitance values (Cs) of 133 F g-1/167 F g-1 at 1.0 A g-1 was obtained in 3 M KNO3 in the positive/negative potential windows. Due to the observed best performance in neutral 3 M KNO3, further electrochemical analysis of the symmetric device was carried out using the same electrolyte. The device displayed a Cs value of 122 F g-1, energy and power densities of ∼14 W h kg-1 and 450 W kg-1 respectively; at 0.5 A g-1. The device also displayed an excellent stability after potentiostatic floating at a maximum voltage of 1.8 V for 120 h and ∼100% capacitance retention after 10,000 charge-discharge cycles. The excellent stability makes the cork-derived material a potential excellent, cost-effective material for supercapacitor application