One‐Step Synthesis of Ultrathin NiMn Layered Double Hydroxide Nanosheets for Supercapacitors

Abstract

With the help of ethylenediamine (EN), we built through hydrothermal synthesis a multiple‐level NiMn layered double hydroxide nanostructure consisting of ultrathin nanosheets (UNML) with plenty buffer spaces. Such porous structure provides more active sites, shortens the diffusion path of electrolyte ions, and creates massive “live volume” to ensure structural integrity during long‐term cycling. The UNML possesses high specific capacitance (1513 F g−1 at 1 A g−1). Moreover, the hybrid supercapacitor employing UNML and AC as positive and negative electrode delivers enhanced energy density up to 59 Wh kg−1 at a power density of 808 W kg−1 and robust cycling stability with capacitance degradation of 8.7 % after 5000 cycles. This simple strategy is expected to cope with the prevalent issues facing battery‐type electrode materials, ensuring improvement of the overall electrochemical performance.

Spatially Confined Li Growth on Honeycomb-like Lithiophilic Layered Double Hydroxide Nanosheet Arrays toward a Stable Li Metal Anode

“…As shown in Figure 1a, apart from the characteristic peaks of CC, the emerging diffraction peaks located at 11.3, 22.7, 34.4, and 38.7°are corresponding to the (003), (006), (012), and (015) planes of the NiMn-LDHs (JCPDS No. 38−0715), 43,44 respectively, indicating successful preparation of NiMn-LDHs on CC skeleton. Worth mentioning, the diffraction peaks of NiMn-LDHs in the XRD pattern exhibit a low intensity, which is related to the weak crystalline of NiMn-LDHs.…”

“…As shown in Figure a, apart from the characteristic peaks of CC, the emerging diffraction peaks located at 11.3, 22.7, 34.4, and 38.7° are corresponding to the (003), (006), (012), and (015) planes of the NiMn-LDHs (JCPDS No. 38–0715), , respectively, indicating successful preparation of NiMn-LDHs on CC skeleton. Worth mentioning, the diffraction peaks of NiMn-LDHs in the XRD pattern exhibit a low intensity, which is related to the weak crystalline of NiMn-LDHs. , The Raman spectrum in the NiMn-LDHs NAs@CC (Figure S3) displays two classic peaks, at 1345 and 1585 cm –1 , which can be attributed to disorder-induced D band and graphitic G band of the NiMn-LDHs NAs@CC, respectively .…”

Construction of Hierarchical NiCoP@NiFe‐LDH Nanoflakes Heterostructure for High Energy Asymmetric Supercapacitor

“…The mass ratio (m + /m À ) of positive electrode (+) to negative electrode (À ) was eventually determined to 0.28, according to the following charge balance equation (Eq. 9): (9) The energy density (E, W h kg À 1 ) and power density (P, W kg À 1 ) of ASC were respectively calculated according to the following equations (Eqs. 10-11):…”

“…In the past decade, layered double hydroxides (LDHs) have aroused widespread concerns as ideal pseudocapacitive electrode materials in virtue of their advantages of high redox activities, adjustable compositions, laminated structures, low cost and environmental-friendly characteristics. [9,10] For example, Li and co-workers fabricated NiMn-LDH on reduced graphene oxide to deliver a high specific capacitance of 1635 F g À 1 at the current density of 1 A g À 1 . [11] Hollow NiCo-LDH was in-situ grown on carbon substrate for flexible supercapacitor, which displayed a high capacity of 1377 mC cm À 2 at 1 mA cm À 2 .…”

Green fabrication of nickel-iron layered double hydroxides nanosheets efficient for the enhanced capacitive performance

“…For example, Zhao et al [23] fabricated NiTi-LDHs monolayer nanosheets through a reverse microemulsion method with the assistance of sodium dodecyl sulfate (SDS) and 1-butanol, the NiTi-LDHs nanosheets delivered an ultrahigh specific capacitance of 2310 F g À1 at 1.5 A g À1 , whereas the bulk NiTi-LDHs possessed low specific capacitance of 393 F g À1 . Yang et al [24] synthesized ultra-thin NiMn-LDHs nanosheets using a hydrothermal method with the aid of ethylenediamine (EN). The specific capacitance of resulting NiMn-LDHs nanosheets reached 1513 F g À1 at 1 A g À1 , which was almost 1.7 times higher than that of bulky NiMn-LDHs.…”