Atomic Scale Optimization Strategy of Al-Based Layered Double Hydroxide for Alkali Stability and Supercapacitors

Abstract

The pseudocapacitor material is easily decomposed when immersed in alkaline solution for a long time. Hence, it is necessary to find a strategy to improve the alkali stability of pseudocapacitor materials. In addition, the relationship between alkali stability and electrochemical performance is still unclear. In this work, a series of Al-based LDH (Layered double hydroxide) and derived Ni/Co-based sulfides are prepared, and corresponding alkali stability and electrochemical performance are analyzed. The alkali stability of CoAl LDH is so poor and can be improved effectively by doping of Ni. Ni1Co2S4 and Ni2Co1Al LDH exhibit an outstanding alkali stability, and Ni2Co1S4 exhibits an extremely poor alkali stability. The variable valence state of Co element and the solubility of Al in alkali solution are the fundamental reasons for the poor alkali stability of CoAl LDH and Ni2Co1S4. Ni2Co1S4 showed an outstanding electrochemical performance in a three-electrode system, which is better than that of Ni1Co2S4, indicating that there is no direct correlation between alkali stability and electrochemical properties. Sulfidation improved the electrical conductivity and electrochemical activity of electrode materials, whereas alkali etching suppressed the occurrence of the electrochemical reaction. Overall, this work provides a clear perspective to understand the relationship between alkali stability and electrochemical properties.

Nanostructured ZnCo2O4@NiMn-LDH Electrodes for Supercapacitor and Zinc-Air Battery Application

“…Their growing significance stems from their diverse utility across catalysis, separation, biotechnology, and electrochemistry 32 They have special achievements in electrochemical pseudocapacitors and the oxygen evolution reaction as an electrocatalyst due to its unique layered structure and redox activity 33 and also good ionic conductivity, special electronic configuration, reduced ion diffusion distance, and relatively high surface area, such as NiCo−LDH, CoMn− LDH, and CoV−LDH. 34−37 In addition, NiMn-LDHs have been used in many energy-related applications due to their higher chemical stability, 38,39 adjustable composition, and uniform distribution of metal cations and exchangeable interlayer anions. 40 The core−shell heterostructure possesses high conductivity, in which core material exhibits high electrical conductivity, and the shell structure is well-known for pseudocapacitive transition metal oxide/hydroxides.…”

“…It is also known as a hydrotalcite-like compound and it is one of the widely studied inorganic materials in various applications. , [M 1– x 2+ M x 3+ (OH) 2 ] x + [A x / n n – · m H 2 O] x − is the general formula of bimetallic layered doubled hydroxide (LDH) as lamellar structured material, where M 2+ and M 3+ represent the bivalent and trivalent metal cations, respectively, and A n – denotes the charge-balancing anion of valence n , which have emerged as significant members of the 2D inorganic family. Their growing significance stems from their diverse utility across catalysis, separation, biotechnology, and electrochemistry They have special achievements in electrochemical pseudocapacitors and the oxygen evolution reaction as an electrocatalyst due to its unique layered structure and redox activity and also good ionic conductivity, special electronic configuration, reduced ion diffusion distance, and relatively high surface area, such as NiCo–LDH, CoMn–LDH, and CoV–LDH. − In addition, NiMn-LDHs have been used in many energy-related applications due to their higher chemical stability, , adjustable composition, and uniform distribution of metal cations and exchangeable interlayer anions …”