Engineering d‐p Orbital Hybridization in Single‐Atom Metal‐Embedded Three‐Dimensional Electrodes for Li–S Batteries

Abstract

Li-S) batteries is seriously restricted by their low sulfur loading and utilization, sluggish reaction kinetics, and poor cycling stability. [4,5] So far, appropriate active adsorption [6,7] and catalytic centers, such as metal sulfides, [8][9][10] oxides, [11][12][13] nitrides, [14] and vanadium compounds, [15] have been introduced to enhance the sulfur utilization and accelerate the reversible conversion between lithium polysulfides (LiPSs) and Li 2 S. [16,17] However, high weight percentages of these additives sacrifice the overall energy density of Li-S batteries. Single-atom metal catalysts (SACs) comprising monodispersed metal atoms on appropriate substrates have a theoretical 100% atom utilization efficiency, and therefore have a much higher activity than conventional bulk metal and nanoparticle catalysts. [18,19] Various SACs have been introduced into Li-S batteries to improve their electrochemical performance. [20][21][22] Generally, the effects of SACs have been attributed to their good adsorption ability to LiPSs and their high catalytic activity. However, the lack of a fundamental understanding of the catalysis mechanism and the material properties that govern catalytic activity have hindered the selection and rational design of SACs for Li-S batteries. In previous studies, the SACs were usually Single-atom metal catalysts (SACs) are used as sulfur cathode additives to promote battery performance, although the material selection and mechanism that govern the catalytic activity remain unclear. It is shown that d-p orbital hybridization between the single-atom metal and the sulfur species can be used as a descriptor for understanding the catalytic activity of SACs in Li-S batteries. Transition metals with a lower atomic number are found, like Ti, to have fewer filled anti-bonding states, which effectively bind lithium polysulfides (LiPSs) and catalyze their electrochemical reaction. A series of single-atom metal catalysts (Me = Mn, Cu, Cr, Ti) embedded in threedimensional (3D) electrodes are prepared by a controllable nitrogen coordination approach. Among them, the single-atom Ti-embedded electrode has the lowest electrochemical barrier to LiPSs reduction/Li 2 S oxidation and the highest catalytic activity, matching well with the theoretical calculations. By virtue of the highly active catalytic center of single-atom Ti on the conductive transport network, high sulfur utilization is achieved with a low catalyst loading (1 wt.%) and a high area-sulfur loading (8 mg cm −2 ). With good mechanical stability for bending, these 3D electrodes are suitable for fabricating bendable/foldable Li-S batteries for wearable electronics.

P-block tin single atom catalyst for improved electrochemistry in a lithium–sulfur battery: a theoretical and experimental study

“…Therefore, the weakened Li–S bond reflects the catalytic effect of the sulfur redox catalysts. 63 Crystal Occupation Hamiltonian Population (COHP) analysis of the Li–S bond was performed to demonstrate the hybridization scenarios in Li 2 S, and the bond strength of the Li–S bond was quantitatively evaluated by the integrated-COHP (−ICOHP) value. Fig.…”

“…, Fe, Co, V)-based single atom catalysts. 28,62,63 The discrepancy in the cycling stability is essentially ascribed to the synergic effects of the strong adsorption ability and catalytic activity of the Sn–N 4 sites towards polysulfides. The chemical tethering of the polysulfides cannot necessarily lead into good capacity retention because the charge storage capacity can only be achieved through highly reversible electrochemical sulfur redox.…”

Boosting Polysulfide Catalytic Conversion and Facilitating Li+ Transportation by Ion‐Selective COFs Composite Nanowire for LiS Batteries

“…This indicates the active sites of C@COF surface could guide the radical Li 2 S growth and the surface passivation can be avoided. [54,55] when using the CNTs, Li 2 S growth shows a tendency to 2DI model, which formed a uniform Li 2 S nucleation and made its surface easily passivated. [52] The Li 2 S dissolution kinetics was also evaluated.…”

An orbital-based representation for accurate Quantum Machine Learning

“…The FJK framework is general enough to be applicable to situations where magnitude of a complicated process can be estimated with a relatively simple orbitalbased descriptor. 69,70 Further applications were beyond the scope of this work and are part of future work. At the same time, we observed that for a poor choice of a Slater determinant pair representing the change of electronic structure FJK may be less accurate than conventional representations, as exemplified by QM7b's first excitation energies.…”