Potentiostatic Reconstruction of Nickel‐Cobalt Hydroxysulfate with Self‐Optimized Structure for Enhancing Energy Storage

Abstract

Transition metal chalcogenides (TMCs) are widely used as energy storage materials, however, most studies have neglected the reconstruction process that occurs during the operation. Thus, the intrinsic energy storage mechanism of TMCs and the identification and modulation of the reconstruction process are not adequately investigated. Herein, a proactive modulation strategy for reconstruction kinetics under nonoperating conditions is proposed, and a potentiostatic reconstruction method is developed. The effects of three electrochemical techniques of potentiostatic, cyclic voltammetry, and galvanostatic on reconstruction products are also revealed. Notably, under potentiostatic reconstruction, the needle‐like nickel‐cobalt sulfide precursor is transformed into columnar, polycrystalline, defect‐rich nickel‐cobalt hydroxysulfate (NCHS‐E), and the process is analyzed in detail by in situ and ex situ characterization. NCHS‐E exhibits an excellent electrochemical performance with a specific capacity of 5040 mC cm−2 at 1 mA cm−2 and capacity retention of 67.1% at 50 mA cm−2. Kinetic analysis and theoretical calculations show that NCHS‐E has fast charge transfer ability and low deprotonation energy, indicating a favorable energy storage pathway. This work proves the important potential of reconstruction kinetic modulation to optimize the structure and properties of the products and provides new insights into the mechanism of reconstruction occurrence.

Carbon quantum dot regulated electrochemical activation of Co0.03Ni0.97LDH for energy storage

“…S11,† most of the S species in the CQDs were oxidized into SO 4 2− during the hydrothermal reaction and the following CV activation. 22 However, the relative intensity of the C–S and M–S signals increased after CV activation.…”

“…Among them, cobalt/nickel double hydroxide (CoNiLDH), a typical electrochemically activated material, has been extensively investigated for its electrochemical activation mechanisms. 21 During the electrochemical activation, the transformation of the morphology 22 and dynamic changes 16 in the content between Ni 2+ and Ni 3+ , Co 2+ and Co 3+ are the critical factors affecting the energy storage performance of CoNiLDH. The previous work 23 reported that the increased Co 3+ content via electrochemical activation could improve the electrochemical performance of CoNiLDH.…”

Phase Engineering of Nonstoichiometric Cu2–xSe as Anode for Aqueous Zn-Ion Batteries

“…First, the density of state (DOS) profiles of hexagonal CuSe and cubic Cu 2– x Se were compared (Figure S7). The results indicate that the cubic Cu 2– x Se has a much higher DOS at the Fermi level than that of the hexagonal CuSe, suggesting the superiority of the intrinsic conductivity. , Furthermore, charge-density analysis was employed to study the electron redistribution behavior at the electrode interface (Figure a). The obvious electronic interaction and polarization can be observed at the interface between Zn 2+ and Cu 2– x Se, contributing to a faster electrochemical kinetics of the Cu 2– x Se electrodes .…”

Robust Interfacial Effect in Multi-interface Environment through Hybrid Reconstruction Chemistry for Enhanced Energy Storage

“…To address this issue, electrochemical oxidation presents a straightforward route for in situ topology reconstruction of precursors into defective and active structures, resulting in more available active sites and enriched ion-migration channels. − However, despite its achievements, concerns regarding the microstructure evolution persist, as the in situ triggered oxidative and locally strongly acidic/alkaline environment may result in an unfavorable phase transition and partial dissolution of active species (Figure a). − And the reconstructed microstructures are generally characterized by inferior conductivity and poor durability, leading to a performance that still falls far short of the theoretical value. An upgraded electrochemical oxidation reaction system is required to ensure optimal activity and reaction kinetics for the reconstructed phase structure, which is crucial for the development and broad applications of energy materials.…”