Boosting the Supercapacitive Behavior of CoAl Layered Double Hydroxides via Tuning the Metal Composition and Interlayer Space

Abstract

Layered double hydroxides (LDHs) are promising supercapacitor materials due to their wide chemical versatility, earth abundant metals and high specific capacitances. Many parameters influencing the supercapacitive performance have been studied such as the chemical composition, the synthetic approaches, and the interlayer anion. However, no systematic studies about the effect of the basal space have been carried out. Here, two‐dimensional (2D) CoAl‐LDHs were synthesized through anion exchange reactions using surfactant molecules in order to increase the interlayer space (ranging from 7.5 to 32.0 Å). These compounds exhibit similar size and dimensions but different basal space to explore exclusively the interlayer distance influence in the supercapacitive performance. In this line, Co : Al ratios of 2 : 1, 3 : 1 and 4 : 1 were explored. In all cases, an enhancement of the specific capacitance was observed by increasing the basal space, reaching ca. 50 % more than the value obtained from the less‐spaced 2 : 1 CoAl‐LDH (going from ca. 750 to 1100 F.g−1 at 1 A.g−1). This increment mainly occurs because of the increase in the electrochemical surface area (up to ca. 260 %) and the higher electrolyte diffusion. Interestingly, the best performance is achieved for the lowest Co : Al ratio (i. e. the highest Al content) revealing the important role of the electrochemically inert Al in the structure.

The Missing Link in the Magnetism of Hybrid Cobalt Layered Hydroxides: The Odd–Even Effect of the Organic Spacer

“…Moreover, the χ M ⋅T product also increases exhibiting a sharp peak at 47 K vs. 14 K, for n= 4 and n= 5 samples, respectively (Figures 1 A and E and insets). Additionally, the temperature‐independent component in χ M ⋅T confirms the absence of extrinsic magnetic impurities such as Co III spinels, emphasizing the phase purity of the whole family [38, 43] . Spontaneous magnetization is confirmed by the strong increase of DC magnetization (Figures 1 B and F) and by a peak in the in‐phase and out‐of‐phase components observed in the dynamic AC susceptibility measurements, with values of T M =62 K for n= 4 and T M =21 K for n= 5, respectively (Figures 1 D and H).…”

“…2925–2850 cm −1 can be attributed to asymmetric and symmetric CH 2 stretching vibrations. Their intensity increases with the length of the molecule [16, 37, 38] . The strong bands at ca.…”

Influence of Fe-clustering on the water oxidation performance of two-dimensional layered double hydroxides

“…14–16 These highly tunable structures, defined by the formula M II 1− x M III x (OH) 2 A n / x n − · m (H 2 O), represent a perfect platform to design Fe-based materials with interesting properties for use in several fields such as anion exchange, water cleaning, magnetism, catalysis, energy storage, anticorrosion, drug delivery, among others. 17–20…”

Hierarchical CuCo Carbonate Hydroxide Nanowires@FeCo‐Layered Double Hydroxide Hexagonal Nanosheets of Penetrating Architecture for High‐Performance Asymmetric Supercapacitor

“…Typically, transition metal layered double hydroxides (LDHs) are an attractive class of potential faradic electrode materials owing to their high theoretical specific capacitance/capacity, unique 2D layered crystal structure, tunable chemical composition, and robust stability in alkaline environment [13–18] . However, the poor conductivity and easily restacking tendency of LDHs impede their charge transfer and surface reactions, resulting in poor rate capability and a measured specific capacitance/capacity far below the theoretical one [19–22] .…”