PH-driven dissolution–precipitation: a novel route toward ultrathin Ni(OH)2 nanosheets array on nickel foam as binder-free anode for Li-ion batteries with ultrahigh capacity

Abstract

In this paper, for the first time, we report on the growth of ultrathin Ni(OH) 2 nanosheet arrays on a nickel foam (NF) via a novel pH-driven dissolution-precipitation route, carried out by a hydrothermal treatment of the NF in an acidic medium without the introduction of other nickel sources. Acid etching of the NF surface leads to nano-pits and produces Ni(H 2 O) n 2+ ions at the early stage of the reaction. With the elapsed time, an increase in the pH level occurs and the Ni(H 2 O) n 2+ ions gradually hydrolyze and preferentially precipitate on the nano-pits, serving as nucleation sites and leading to ultrathin Ni(OH) 2 nanosheet arrays on an NF. The effects of the experimental parameters, such as reaction time, acid type and starting pH value, on the Ni(OH) 2 growth are also investigated. Because the nano-pits are integrated parts of the NF and the deposition of Ni(OH) 2 nanosheets on such nano-pits ensures intimate contact between them, the Ni(OH) 2 /NF is robust enough to withstand a violent sonication process and efficient and rapid electron transfer is achieved. As a binder-free anode for Li-ion batteries, the Ni(OH) 2 /NF exhibits an unexpected ultrahigh capacity of 1689 mA h g −1 and excellent cycling stability.

NiO as a Bifunctional Promoter for RuO2 toward Superior Overall Water Splitting

“…The synthetic strategy used for fabricating hierarchical RuO 2 /NiO/NF is illustrated in Figure a. Typically, well‐defined Ni(OH) 2 nanoflake arrays were first grown on NF using a simple hydrothermal reaction in aqueous HCl solution reported by Tian et al As can be seen in the X‐ray diffraction (XRD) pattern of Ni(OH) 2 /NF (Figure S1, Supporting Information), all the diffraction peaks can be indexed to hexagonal Ni(OH) 2 (JCPDS card No. 03‐0177), except for the background peaks originating from the cubic NF substrate (JCPDS card No.…”

Remarkable electrochemical lithium storage behaviour of two-dimensional ultrathin α-Ni(OH)2 nanosheets

“…Especially, there are reversible reductionpeaks locating at the potential window of 1.4-1.8 V observed in every cycle except a small difference in the peak position, which is absent in the previous reports. [28][29][30] Consequently, these obvious reduction peaks should contribute the additional capacities. Unfortunately, we cannot obtain direct findings that can explicate the origin of the reversible reduction peaks.…”

“…28 However, our current values are lower than that of the direct nanostructured electrodes consisting of ultrathin Ni(OH) 2 nanosheet arrays on nickel foam, which can exhibit initial discharge and charge capacities of 4325 and 3206 mAh g −1 . 29 The irreversible capacity loss of the first cycle is partly attributed to the initial SEI film formation. Based on the complete reduction of Ni 2+ to Ni 0 , the theoretical value of nickel hydroxide anode is assumed to be 578 mAh g −1 .…”

“…41 Additionally, the present initial Coulombic efficiency is slightly higher than that (68.7% and 74.1%) of the reported β-Ni(OH) 2 nanosheet and Ni(OH) 2 nanosheet/nickel foam electrodes. 28,29 After the first discharge-charge process, the Coulombic efficiency increases to over 92% in the subsequent cycles. Unfortunately, the α-Ni(OH) 2 nanosheets exhibit obvious capacity decay in the early cycles, which are common in the transitional metal oxide and hydroxide anode materials.…”

NiMoO4@Ni(OH)2 core/shell nanorods supported on Ni foam for high-performance supercapacitors

“…4 To date, various materials, including carbonaceous materials, transition metal oxides, conducting polymers, and hybrid composites, have been widely studied as electrodes for supercapacitors. [9][10][11] The development of nanostructured materials provides a promising solution to enhance the capacitive performance because of their high surface area, short electron and ion transport pathways. [9][10][11] The development of nanostructured materials provides a promising solution to enhance the capacitive performance because of their high surface area, short electron and ion transport pathways.…”