Effect of calcination methods on electrochemical performance of NiO used as electrode materials for supercapacitor

Abstract

Ni(OH) 2 precursors were prepared via the precipitation transformation method, which was originated from Na 2 C 2 O 4 , NiSO 4 ⋅6H 2 O and urea. NiO samples were successfully obtained by calcining Ni(OH) 2 precursor with different calcination methods. Some were calcination in a tube furnace under the nitrogen flow and others were calcination in a muffle furnace. The products were well-characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The influence of calcination methods on electrochemical performance of NiO samples were investigated. Moreover, the possible reason was proposed. The charge storage mechanism of NiO positive electrode in aqueous electrolyte was discussed. The electrochemical test showed that the as-prepared NiO prepared in a tube furnace can exhibit a good pseudocapacitance behaviour due to the higher utilization of active material.

Highly Pseudocapacitive NiO Nanoflakes through Surfactant-Free Facile Microwave-Assisted Route

“…Figure a shows the CV measurements of NiO electrode at sweep rates of 5–100 mV s –1 in 6 M KOH electrolyte. It is evident from the voltammograms that there exists a large current separation between the forward and reverse scans, besides no peak formation as reported in previous studies. ,, The appearance of a distinctive symmetrical pattern for these curves signifies NiO electrode with high electrochemical reversibility and kinetically fast charge–discharge during redox reaction (NiO + OH – ↔ NiOOH + e – ). , Moreover, the voltammograms do not reveal the perfect rectangular shape indicating that the NiO nanoflakes possess considerable pseudocapacitive behavior. , The symmetrical shape in cathodic and anodic sweeps can be attributed to the nanoflake morphology of NiO that reduces the diffusion length of ionic species into the electrode which leads to excellent intercalation. , Thus, the swift electrolytic ion transport into the electrode due to the large surface as well as the porous matrix of NiO enhances the faradaic response leading to ideal pseudocapacitive behavior for the NiO electrode. , Interestingly, no significant change in the shape of these CV curves is observed with an increase in the scan rates highlighting enhanced mass transportation capability in the nanosized NiO. This is possibly due to uniform flake morphology of NiO which supports swift charge propagation.…”

“…19,30,42 The appearance of a distinctive symmetrical pattern for these curves signifies NiO electrode with high electrochemical reversibility and kinetically fast charge−discharge during redox reaction (NiO + OH − ↔ NiOOH + e − ). 48,50 Moreover, the voltammograms do not reveal the perfect rectangular shape indicating that the NiO nanoflakes possess considerable pseudocapacitive behavior. 43,51 The symmetrical shape in cathodic and anodic sweeps can be attributed to the nanoflake morphology of NiO that reduces the diffusion length of ionic species into the electrode which leads to excellent intercalation.…”

A novel NiO/BaTiO3 heterojunction for piezocatalytic water purification under ultrasonic vibration

“…Under the periodic vibration of ultrasound, a periodic vibration current appears in the catalyst. The piezoelectric current of the 2NiO/BaTiO 3 composite catalyst is significantly higher than that of BaTiO 3 , indicating that the heterojunction structure built by the load of NiO successfully inhibits the recombination of piezoelectric-induced carriers [23] , [29] , [63] . This result is consistent with the EIS analysis and verifies the mechanism proposed in Fig.…”

“…No other diffraction peaks are observed, indicating that no impurity exists. For the NiO sample, the characteristic diffraction peaks appear at 37.2°, 43.3°, 62.9°, indicating its cubic structure [29] . The XRD patterns of nNiO/BaTiO 3 (n = 1,2, and 3) are basically identical to the pure BaTiO 3 sample.…”

Tuning the annealing temperature to achieve heterostructured nanofibers for high performance lithium-ion batteries

“…Annealing temperature has a crucial effect on the crystallinity, crystal phase and morphology of nanoparticles. [38][39][40][41][42][43][44][45] Siwatch et al 42 obtained three-dimensional flower-shaped NiCo 2 O 4 nanoparticles by adjusting the annealing temperature. Do et al 46 demonstrated that the grain size of CoO increased nearly 5 times (from 6.59 to 31.5 nm) as the calcination temperature increased from 200 1C to 900 1C, and the activation period of the CoO electrode was also prolonged accordingly.…”