Improving Ni(OH)₂/C Supercapacitive Performances through Mixed Solvents and Thermal Treatment of XC-72

Abstract

A Ni(OH) 2 /XC-72 nanocomposite was first synthesized via a solvothermal method in mixed solvents of ethylene glycol and H 2 O; using a smaller amount of ethylene glycol not only reduces the cost but also enhances the electrochemical performances of the composite. X-ray diffraction patterns indicate that α-Ni(OH) 2 and β-Ni(OH) 2 are coexistent in the Ni(OH) 2 /XC-72 composite. The capacitance of α,β-Ni(OH) 2 /XC-72 increases from 1649.3 F g −1 of α-Ni(OH) 2 /XC-72 and 1232.5 F g −1 of β-Ni(OH) 2 /XC-72 to 1803.1 F g −1 at 1 A g −1 . To further improve the electrochemical performances of Ni(OH) 2 /XC-72 composite, XC-72 was calcined in an Ar flow at 600 °C (denoted as T-XC-72) to remove some oxygen-containing groups, thus increasing its electronic conductivity and also gaining more defects as nuclei for Ni(OH) 2 particle deposition. The obtained Ni(OH) 2 /T-XC-72 composite delivers a capacitance of 2252.8 F g −1 at 1 A g −1 , which is much higher than that of Ni(OH) 2 /XC-72. Furthermore, 78.1% of capacitance can be retained at 20 mV s −1 with respect to 74.8% of Ni(OH) 2 /XC-72. Additionally, it shows a stability of 80.5% over 1000 cycles at 10 A g −1 , which is also more superior to 75% of Ni(OH) 2 /XC-72. Therefore, this work may provide a cost-effective route to synthesize high-performance electrode materials for supercapacitors.

Gram-Scale Synthesis of Carbon-Supported Sub-5 nm PtNi Nanocrystals for Efficient Oxygen Reduction

“…2, the crystal structure of the as-synthesized PtNi/C was further explored by X-ray diffraction (XRD). The diffraction peak between 20 • and 30 • is consistent with the Vulcan XC-72 [30] (Figure S2). Compared with the standard Pt, all of the characteristic peaks shift to a higher angle due to the Pt lattice contraction after alloying with Ni.…”

Simple deposition of mixed α, β-nickel hydroxide thin film onto nickel foam as high-performance supercapacitor electrode material

“…However, more detail observation through DSC curve demonstrates the presence of two close endothermic peaks which are centered at 185 and 215 °C the, which could be related to the decomposition of α and β-Ni(OH) 2 to NiO, respectively. The result is in good compromise with references [17][18][19][20]30].…”

“…Al-, Co-, Mn-, Zn-, Y-and Cu-substituted α-Ni(OH) 2 [15][16][17]. Furthermore, some studies have been performed on the coprecipitation of mixed α/β-Ni(OH) 2 [18][19][20]. For example, Wang et al found that α/β-Ni(OH) 2 has better electrochemical performance than Al-substituted α-Ni(OH) 2 and usual β-Ni(OH) 2 [21], and they also observed that α/β-Ni(OH) 2 has better supercapacitive characteristics than β-Ni(OH) 2 (i.e.…”

Ultrathin Ni(OH)2 layer coupling with graphene for fast electron/ion transport in supercapacitor

“…As shown in Fig. 2a, the typical diffraction peaks at 12.3°, 33.3°, 38.7°and 61.3°of 2θ are indexed to (003), (101), (015) and (113) diffraction peaks of α-Ni(OH) 2 (JCPDS 38-0715) [45]. The characteristic peak located at 23.6°is assigned to rGO, demonstrating the successful reduction of GO.…”