CuCo-Layered Double Hydroxide Nanosheet-Based Polyhedrons for Flexible Supercapacitor Cells

Abstract

Herein, a flexible high-performance supercapacitor cell using nanostructured CuCo-layered double hydroxide (LDH) as power source electrode material is reported for the first time, where the CuCo-LDH hollow nanopolyhedrons are developed by tuning the Cu/Co ratio in the LDH host layers. Among various Cu/Co ratios, a solid-state symmetrical and flexible cell made with active Cu1.65Co1-LDH nanomaterial in [EMIM]­[BF4] electrolyte furnishes a specific capacity of 609.4 C g–1 and a specific capacitance of 244 F g–1 (0.603 F g–1 considering the total dry mass of the device) and exhibits a wide cell voltage of 2.5 V and is expected to be considered one of the best among the LDH family. It delivers high energy density (52.89 Wh kg–1) and power density (1215 W kg–1) values and tunable bending (0 to 180°) and twisting conditions. The flexible cell offers long-term stability (89% retention after 10000 charge–discharge cycles) and steady Coulombic efficiency at different bending angles. This work also offers valuable concepts for understanding the exceptional charge storage characteristics as accredited to high surface area furnishing abundant active sites, shortened ion diffusion length, and consequent faster ion switching, synergism between balanced Cu and Co ions, and major surface versus bulk charge contribution processes.

Hierarchical Nanocages Assembled by NiCo-Layered Double Hydroxide Nanosheets for a High-Performance Hybrid Supercapacitor

“…The energy density and power density of the NiCo-LDH-210//CNF HSC device were sketched from the Ragone plots, as shown in Figure 8e. Encouragingly, the HSC device can store a maximum energy density of 57.3 W h kg −1 at a power density of 1600 W kg −1 , and this remained at 35.6 W h kg −1 at 8000 W kg −1 , which are much superior to those of recently reported LDH-based HSC devices, such as ZnCo 2 O 4 @Ni-Al LDH//AC (50.1 W h kg −1 at 3400 W kg −1 ), 46 HA-NiCo-LDH//AC (44.9 W h kg −1 at 348 W kg −1 ), 47 NCZ-LDH-100@PANI//AC (37.2 W h kg −1 at 362 W kg −1 ), 48 NF@F-NCCH12//AC (35.3 W h kg −1 at 375 W kg −1 ), 49 NiCo-LDH/10//CNT (36.1 W h kg −1 at 649 W kg −1 ), 50 Cu 1.65 Co 1 -LDH//Cu 1.65 Co 1 -LDH (52.89 W h kg −1 at 1215 W kg −1 ), 51 and NiCo LDH@rGO (35 W h kg −1 at 750 W kg −1 ), 52 It also surpasses many cobalt-based compound HSC devices, such as EO-Co-MOF@CoNiO 2 /CC//AC (27.4 W h kg −1 at 750 W kg −1 ) 53 and Co 3 O 4 -NSs/CNTs-5%//rGO (37.2 W h kg −1 at 160.2 W kg −1 ). 54 Figure 8f presents the cyclic stability of the NiCo-LDH-210//CNF HSC device at a current density of 4 A g −1 .…”

Freestanding Binder-Free Electrodes with Nanodisk-Needle-like MnCuCo-LTH and Mn1Fe2S2 Porous Microthorns for High-Performance Quasi-Solid-State Supercapacitors

“…The CV profile for MnCuCo_LTH clearly depicted the presence of all of the peaks, which were observed individually in MnCo_LDH and CuCo_LDH, respectively. The use of different potential windows for CV and GCD measurements is commonly observed in supercapacitor electrodes because CV is performed at a constant potential, while GCD involves measurements at a constant current per unit mass. , The LDH-based electrodes were expected to show their respective metal-ion-directed redox peaks among the previously mentioned redox reactions. Along with this, CV profile for bare Ni foam was also collected to show its negligible contribution in the observed enclosed area.…”

One-pot synthesis of porous crystal structured nanosponge-like pristine copper metal–organic framework for hybrid supercapacitor application

“…After connection to an external circuit (discharging), the anode materials gain electrons from the cathode through the external circuit and come to a stable oxidation state (Cu 3+ to Cu 2+ ) by releasing adsorbed electrolytic ions from the surface. 28–30 The Cu-BDC oxidation and reduction reactions are represented in eqn (1)–(3).Cu 2+ ⇌ Cu 3+ + e − CuC 8 H 4 O 4 + OH − ⇌ CuC 8 H 5 O 5 + e − CuC 8 H 4 O 4 ⇌ CuC 8 H 5 O 5 + e − + H + …”