Kirkendall Growth and Ostwald Ripening Induced Hierarchical Morphology of Ni–Co LDH/MMoS_x (M = Co, Ni, and Zn) Heteronanostructures as Advanced Electrode Materials for Asymmetric Solid-State Supercapacitors

Abstract

By changing the mixed metal sulfide composition, morphology tuning of an active electrode material can be possible, which can have a huge impact on its electrochemical performance. Here, effective morphology tuning of Ni−Co layered double hydroxide (LDH)/MMoS x (M = Co, Ni, and Zn) heteronanostructures is demonstrated by varying the composition of MMoS x . Taking advantage of the benefits associated with Kirkendall growth and Ostwald ripening, tunable morphologies were successfully achieved. Among the Ni−Co LDH/MMoS x (M = Co, Ni, and Zn) heteronanostructures, a Ni−Co LDH/NiMoS x core−shell structured electrode delivered a high specific capacity of 404 mAh g −1 at 3 mA cm −2 and an extraordinary cycling stability (after 10 000 cycles) of 93.2% at 50 mA cm −2 . In addition, an asymmetric supercapacitor (ASC) device coupled with Ni−Co LDH/ NiMoS x as the cathode and Fe 2 O 3 /reduced graphene oxide as the anode exhibited excellent cell capacity and extraordinary cycling stability. Moreover, the ASC device provided a very high specific energy of 72.6 Wh kg −1 at a specific power of 522.7 W kg −1 and maintained the specific power of 23.5 Wh kg −1 at 5357.6 W kg −1 , demonstrating its high applicability to energy storage devices.

Layered Double Hydroxide Hollowcages with Adjustable Layer Spacing for High Performance Hybrid Supercapacitor

“…The characteristic peaks situated at 531.8, 531.2, and 529.9 eV in Figure S10a, Supporting Information, are attributed to the oxygen of chemical adsorption, OH − in CoNi-LDH, and the metal oxide peaks (such as Co-O and Ni-O), respectively. [30][31] In addition, two new peaks situated at 533.1 and 532.4 eV in Figure S10b, Supporting Information, are attributed to C-O and CO, which verifies that the H 2 BDC has been successfully inserted in CoNi-LDH. [32] The pore structures of CoNi-LDH and CoNi-BDC-0.02 were tested with nitrogen adsorption-desorption isotherms.…”

“…This result is much better than the previously reported values in the literature, such as NiCo-LDH/10// CNT (36.1 W h kg −1 at 649 W kg −1 ), [44] NiCo-LDH@NCF//AC (41.5 W h kg −1 at 750 W kg −1 ), [30] CCCH@NiCo-LDH NWAs@ Au-CuO/Cu//VN/CFs (34.97 W h kg −1 at 1410 W kg −1 ), [34] NiCo-LDH//AC (79.6 W h kg −1 at 338 W kg −1 ), [45] CoNi 2 -OH/ L -Asn//N-rGO (64.9 W h kg −1 at 799.9 W kg −1 ), [46] Ni-Co-S/G// PCNS (43.2 W h kg −1 at 800 W kg −1 ), [43] and Ni-Co LDH/ NiMoS x //Fe 2 O 3 /rGO (25.3 W h kg −1 at 5357.6 W kg −1 ). [31] The long-term cycling stability test of the CoNi-BDC-0.02//AC HSC device at a current density of 5 A g −1 is shown in Figure 5i. We can see that CoNi-BDC-0.02//AC HSC can maintain its first capacity of 78.7% after 3500 cycles with satisfying coulombic efficiency (≈99%).…”

In Situ Formation of Co9S8 Quantum Dots in MOF‐Derived Ternary Metal Layered Double Hydroxide Nanoarrays for High‐Performance Hybrid Supercapacitors

“…Therefore, numerous effective strategies based on LDHs, including the reconstruction of transition metal compounds, adjusting the proportion of metal ions, and carbon doping, have been developed to explore higher redox activity with abundant active sites. Notably, modified LDHs, such as NiCo‐LDH/MMoS x heteronanostructures, CNT@NiCo‐LDH, cactus‐like NiCoP/NiCo‐OH, H‐3DRG@NiCo 2 S 4 nanowires, and core–shell structural (Ni, Co) Se 2 /NiCo‐LDH, have displayed novel structural features and considerable exposed active sites. Nevertheless, the derived chemical species on the outer surfaces of LDHs impair the interlayer structure of LDHs to some extent and lead to pore blockage issues, which can decrease the structural stability of materials and increase the mass transport resistance.…”

Heterogeneous assembly of Ni–Co layered double hydroxide/sulfonated graphene nanosheet composites as battery-type materials for hybrid supercapacitors

“…The appearance of doublets at binding energies of 855.3 and 872.9 eV corresponds to the oxidation state of Ni 2+ in association with the other doublets at binding energies of 856.3 and 873.9 eV ascribed to the characteristic of Ni 3+ . 46 Interestingly, Fig. 4b shows that the presence of SGN is capable to raise the abundance of Ni 3+ on the surface of hybrid composites relative to GGN.…”