Morphology evolution of CoNi‐LDHs synergistically engineered by precipitant and variable cobalt for asymmetric supercapacitor with superior cycling stability

Abstract

Cobalt–nickel layered double hydroxides (CoNi‐LDHs) have been extensively synthesized through precipitation methods for their application in supercapacitors (SC). However, the influence of precipitant quantity on both morphology evolution and SC performance has been an underexplored area. This study systematically examines the morphological changes in CoNi‐LDHs by varying the alkaline quantity and evaluates the performance of asymmetric SC. The findings reveal a progressive transformation in the morphology of CoNi‐LDHs with an increase in alkaline content, starting from nanorod (Co1Ni2(OH)2‐1HMA), progressing to nanorod/nansosheet composite (Co1Ni2(OH)2‐4HMA), and ultimately evolving into nanosheet (Co1Ni2(OH)2‐8HMA). This evolution is attributed to the synergetic effect of the precipitant and variable cobalt, which provides multiple valences and induces morphology evolution. The resulting LDHs demonstrate different SC performances: (1) Co1Ni2(OH)2‐1HMA exhibits a maximum capacitance of 1764 F/g, while Co1Ni2(OH)2‐4HMA and Co1Ni2(OH)2‐8HMA show values of 1460 F/g and 1676 F/g, respectively; (2) rate capabilities showcase percentages of 60.5% for Co1Ni2(OH)2‐1HMA, 83.1% for Co1Ni2(OH)2‐4HMA, and 66.3% for Co1Ni2(OH)2‐8HMA; (3) maximum energy densities are recorded at 72.1 Wh/kg for Co1Ni2(OH)2‐1HMA, 41.3 Wh/kg for Co1Ni2(OH)2‐4HMA, and 62.8 Wh/kg for Co1Ni2(OH)2‐8HMA. Particularly, Co1Ni2(OH)2‐8HMA exhibits superlong cycling stability, retaining approximately 99% capacitance after 25000 consecutive charge/discharge cycles at 7.0 A/g. This result underscores its significant potential for efficient energy storage applications.

Optimized Fabrication of Supercapacitor Using MOF-Derived NiCo2O4 with Porous Carbon as Cathode: Electrochemical Characterization and Stability Analysis using Time Series Analysis Technique

“…The energy density and power density for the ASC NiCo Along with other parameters, the long cycle life of the supercapacitor device plays a crucial role in practical application. 64,65 Therefore, the device was subjected to 2000 continuous GCD cycles at 40 mA cm −2 to analyze stability. Figure 8b displays the initial activation of the material, and thereafter an excellent capacity retention for NiCo 2 O 4 /PC/ NF−PANI/NF ASC is observed after 2000 cycles.…”

Activation-Free Synthesis of Chitin-Derived Porous Carbon: Application for Electrical Energy Storage

“…CV was also performed at various scan rates after infiltrating the ultramicropores, and the distortion of the rectangular voltammogram became more pronounced with scan rate, typical of EDLC electrodes without redox behavior (Figure S5). 68,69 The voltammograms of all the CDPCs showed almost the same current values and shape by the 10th cycle regardless of the heating rate. This is also observed for CDAC due to the existence of ultramicropores (Figure S6).…”

Elevated temperature-driven coordinative reconstruction of an unsaturated single-Ni-atom structure with low valency on a polymer-derived matrix for the electrolytic oxygen evolution reaction

“…28 Ni 2+ in atomic form and as nanoparticles of metallic Ni play a major role in electrochemical processes for enhanced energy density with synergistically engineered composition of bimetallic systems. 29 The role of Ni,Co–N bonding-induced d–p coupled electron transfer for optimal initial adsorption and splitting of water depends on the inter-layer electron transfer to boost surface catalytic activity. 30 Efficient OER involves several features including cationic promotion, anion adjustment, defect sites, and ultrathin structures.…”