Ultrathin petal-like NiAl layered double oxide/sulfide composites as an advanced electrode for high-performance asymmetric supercapacitors

Abstract

Layered double hydroxide (LDH) is an important layer-structured material for supercapacitors because of its versatile compositions, high theoretical capacitance, environmental friendliness, and low cost. However, the high resistivity of this material results in capacity fading, limiting its application in energy storage. Herein, we develop a facile approach to synthesize ultrathin petal-like NiAl layered double oxide/sulfide (LDO/LDS) composites with high electrochemical activity using hydrothermal reaction followed by sulfidation process. Scanning electron micrograph shows that the petal-like NiAl LDO/LDS composites are as thin as ~10 nm with a mean lateral dimension of ~1 µm. The NiAl LDO/LDS electrode delivers remarkably high specific capacitance of 2250.5 F g−1 at 1 A g−1 compared with that of NiAl LDH (1740.5 F g−1 at 1 A g−1) and possesses good cycling ability of 88.9% capacitance retention over 5000 cycles at 5 A g−1. Asymmetric supercapacitor (ASC) is fabricated using NiAl LDO/LDS and graphene as positive and negative electrodes, respectively. NiAl LDO/LDS//G ASC exhibits specific capacitance of 153.3 F g−1 at 1 A g−1, high energy density of 47.9 Wh kg−1 at a power density of 750 W kg−1, and reliable cycling stability of 95.68% capacitance retention after 5000 cycles. Results highlight that NiAl LDO/LDS composites are promising materials for energy storage devices with long cycling stability

Sulfidation of Hierarchical NiAl−LDH/Ni−MOF Composite for High‐Performance Supercapacitor

“…The patterns of NiAl−LDH, Ni−MOF, NiAl‐LDH‐0.5/Ni−MOF show obvious similarities, indicating that the samples probably have the same layered topology crystal structure . After sulfurization, the new diffraction peaks at 22.2°, 31.0° and 54.0° of NiAl‐LDH‐0.5/Ni−MOF/S10 are index to characteristic (101), (110) and (122) planes of Ni 3 S 2 (JCPDS: 44‐1418), and the peaks at 28.2° and 48.5° are index to characteristic (110) and (300) planes of Al 2 S 3 (JCPDS: 47‐1313) …”

“…[25] After sulfurization, the new diffraction peaks at 22.2°, 31.0°and 54.0°of NiAl-LDH-0.5/ NiÀ MOF/S10 are index to characteristic (101), (110) and (122) planes of Ni 3 S 2 (JCPDS: 44-1418), [26] and the peaks at 28.2°and 48.5°are index to characteristic (110) and (300) planes of Al 2 S 3 (JCPDS: 47-1313). [27] The surface morphology and structure of the samples were characterized by SEM and TEM. It can be seen from Figure 2a that the NiAl-LDH shows small irregular nanoplates aggregation, indicating that its crystallinity is not good, which is in accord with XRD result.…”

Rational Assembly of CoAl‐Layered Double Hydroxide on Reduced Graphene Oxide with Enhanced Electrochemical Performance for Energy Storage

“…The fitted peaks located at 796.40 eV and 780.62 eV are assigned to Co 3+ , and the binding energy at 797.90 eV and 783.55 eV are ascribed to Co 2+ , indicating the co‐existence of Co 2+ and Co 3+ in the composite. In Figure d, the spectrum of Al 2p displays one peak with a binding energy of 73.35 eV, indicating that Al 3+ exists in the form of Al‐OH . From the C 1s spectrum of Figure e, there is one strong peak with binding energy of 283.52 eV, corresponding to the bond of C−C/C−C.…”

“…Generally, LDHs can be expressed as [M 1‐ x 2+ M x 3+ (OH) 2 ]A x / n n − ⋅yH 2 O, in which M 2+ is divalent metal ions, M 3+ is trivalent metal ions, A n‐ is the interlayer anion, and yH 2 O represents the interlayer water molecules ,. Up to now, many LDHs such as NiCo‐LDHs, NiAl‐LDHs, CoAl‐LDHs and NiCoAl‐LDHs have been described as prospective electrode materials for SCs because of their outstanding properties like good ion exchange behavior and high redox activity . However, the relatively low conductivity of LDHs restricts the electron transfer, resulting in poor charge‐discharge properties, which has a negative effect on the performance of electrode materials…”

Preparation of a NiAl‐Oxide@Polypyrrole Composite for High‐Performance Supercapacitors

“…MnO 2 , CoO x , NiO and Fe 2 O 3 ) are usually utilized as high theoretical capacitance electrode materials due to low cost, low toxicity, environmental friendliness, and multiple oxidation states . Among them, Ni‐based oxides have received intensive interest as promising electrode materials owing to their high redox activity, high theoretical specific capacitance, high chemical stability and relatively low cost . For example, NiO has been reported to have high theoretical specific capacitance of 2584 F g −1 , and then is regarded as a promising electrode material for high‐performance supercapacitors .…”