Using a Dynamic Inhibition Concept to Achieve Content‐Controllable Synthesis of N‐Coordinated Cu Atoms as Reversible Active Site toward Super Li‐Ion Capacitors

Abstract

attractive application potentials as battery-type anodes. [2] Heteroatom doping as one of the most popular strategies has improved Li-ion diffusion kinetics of carbons. [3] However, the dopants are mainly limited to nonmetal heteroatoms, such as N, S, and P. In fact, theoretical simulations suggested that, compared with nonmetal doping, doping of single atomic metals (SAMs) in carbon can better increase adsorption energy, decrease diffusion energy barriers, and exceptionally improve storage capacity. [4] Additionally, experimental investigations show that SAMs in carbon networks are usually coordinated by nonmetal atoms such as N, O, P, and C, [5,6] so SAMs together with their coordination atoms are just like atomic-scale metal compounds such as oxide, nitride, phosphide, and carbide. These metal compounds, especially nanosized ones composited with carbon, are well-known highly active Li-ion storage materials. [7] In the SAM-doped carbon, atomic-scale metal compounds are expected to own higher activity than those nanosized ones due to atomic interface interaction between SAMs and carbon. [6,8] Therefore, doping of SAMs will be a new pathway to design amazing carbon anodes for LICs. Carbon-supported SAMs have exhibited promising application in various catalysis fields. [5,9] Nevertheless, application of SAMs in LICs has not yet been carried out. Pyrolysis using organic precursors and metal compounds as sources is one of the most popular methods to synthesize SAM-doped carbon. [5,9a] During pyrolysis, heteroatoms of organic precursors are converted to nonmetal anchoring sites to stabilize metal atoms. Metal atoms are apt to aggregate due to high surface energy. Various strategies have been employed to suppress metal aggregation such as spatial confinement, [10] Zn-evaporation, [11] constraint of uncoordinated groups, [12] and polymer encapsulation. [13] However, these efforts mainly focus on the static modulation on the organic precursors and metal sources. In fact, evolution of metal atoms and anchoring sites during pyrolysis is a dynamic process. [13c] On the one hand, migration of metal atoms becomes more active at high temperature. On the other hand, nonmetal anchoring sites are not static but dramatically decreased by pyrolysis. Limited anchoring sites are not enough to support high loading of SAMs. The mass content of SAMs is generally less than 1.5 wt%, [5d] which is still Carbon-supported single atomic metals (SAMs) have attracted great interest in energy research. However, it is still a great challenge to control the content of SAMs in carbon. In this work, a dynamic inhibition strategy is proposed to achieve content-controllable synthesis of Cu atoms loaded in carbon nanofibers (CNFs) using polyacrylonitrile (PAN) and Cu(NO 3) 2 as precursors by electrospinning. Interestingly, N-anchoring sites in PAN-derived carbon matrix are dynamically increased to inhibit the aggregation of Cu atoms. Therefore, Cu atom content can be linearly controlled by adjusting the ratio of Cu(NO 3) 2 /PAN, and a high mass conten...

MnO2/MXene–Ti3C2Tx flexible foam for use in lithium ion storage

“…18,19 As a new 2D material, MXene has been widely used in energy storage devices, for instance Li-ion batteries, Li-S batteries and SC. [20][21][22] Because of the unique structure of MXene, such as conductive layer of carbon and abundant surface functional groups, it has unexpected electrochemical performance.…”

One-step fabrication of Cu-based metal organic framework multilayer core–shell microspheres for efficiently catalyzing the oxygen reduction reaction

“…The peaks at 932.2 eV and 952.0 eV show the presence of the Cu 2p 3/2 level and Cu 2p 1/2 level of Cu + . 42,48,52 The peaks at 934.2 eV (Cu 2p 3/2 level) and 954.0 eV (Cu 2p 1/2 level) together with satellite peaks at 942.2 eV and 962.1 eV are associated with Cu 2+ . 42,60 Therefore, the presence of Cu in the synthesized Cu-MOFs changes with different anions.…”

“…3c), which corresponds to Cu-N x . [44][45][46][47] The formation of Cu-N x can be due to the coordination of Cu 2+ with pyridine N. 48 The S 2p spectra (Fig. 3d) show the presence of S 2p 3/2 (163.3 ± 0.1 eV) and S 2p 1/2 levels (164.5 ± 0.1 eV) of thiophene-S (C-S-C).…”

The Advance and Perspective on Electrode Materials for Metal–Ion Hybrid Capacitors

“…The former stores energy through reversible adsorption on the cathode surface, while the latter involves the diffusion of ions within the anode. [56][57][58][59][60] In comparison, battery-type electrode occurs metal-ion deposition/stripping reaction or metal-ion insertion/extraction process at the anode or cathode. Hybrid ion capacitor (HIC) delivers higher power density but lower capacity than metal-ion batteries due to the limitation of redox reaction at battery-type electrode.…”