Enabling Reversible Reaction by Uniform Distribution of Heterogeneous Intermediates on Defect‐Rich SnSSe/C Layered Heterostructure for Ultralong‐Cycling Sodium Storage

Abstract

2D layered Sn‐based materials have attracted enormous attention due to their remarkable performance in sodium‐ion batteries. Nevertheless, this promising candidate involves a complex Na+‐storage process with multistep conversion‐alloying reactions, which induces the uneven dispersion of heterogeneous intermediate accompanied by severe agglomeration of metallic Sn0, inescapably resulting in poor reaction reversibility with sluggish rate capability and inferior cyclic lifespan. Herein, a delicately layered heterostructure SnSSe/C consisting of defect‐rich SnSSe and graphene is designed and successfully achieved via a facile hydrothermal process. The equal anionic substitution of Se in SnSSe crystal can trigger numerous defects, which can not only facilitate Na+ diffusion but also accelerate the nucleation process by inducing quantum‐dot‐level uniform distribution of heterogeneous intermediates, Na2Se/Na2S and Sn0. Concurrently, in situ formed uniform Na2Se/Na2S grain boundaries confined by this unique layered heterostructure may effectively suppress the agglomeration of metallic Sn0 nanograins and boost the reversibility of conversion‐alloying reaction. As a result, the SnSSe/C displays significant improvement in Na‐storage performance, in terms of remarkable rate capability and ultralong cycling lifespan. This work, focusing on controlling intermediate distribution, provides an effective strategy to boost reaction reversibility, which can be wildly employed in conversion‐based electrodes for energy storage regions.

Manipulating Molecular Structure to Trigger Ultrafast and Long‐Life Potassium Storage of Fe0.4Ni0.6S Solid Solution

“…[24,26,27] Such an expanded interplanar spacing can effectively reduce the energy barrier during K-ion intercalation and diffusion in FeNiS solid solution, in terms of enhanced reaction kinetics. [28,29] Ulteriorly, the bright rings in the select area electron diffraction (SAED) pattern (inserted in Figure 1d) are consistent well with the (100) and (001) characteristic planes of the NiS phase, respectively. Moreover, Fe, Ni, and S elements are evenly distributed and nearly overlap each other in the individual skeleton particle in the EDS mapping image (Figure 1g and Figure S6, Supporting Information) and the ratio of Fe to Ni elements in the FNS/C composites is calculated to be close to 0.4:0.6 based on the result in Table S1, Supporting Information.…”

High‐Performance Sodium‐Ion Batteries Enabled by 3D Nanoflowers Comprised of Ternary Sn‐Based Dichalcogenides Embedded in Nitrogen and Sulfur Dual‐Doped Carbon

“…Consequently, as the S 2− content increases, the lattice constants along the c-axis decrease. [20][21][22] Importantly, the absence of impurity diffraction peaks highlights the high purity achieved through microwave synthesis. The composition of SnSe 2 /N-C, SnS 1.5 Se 0.5 /NS-C, and SnS 2 /N-C was further confirmed by Raman spectroscopy in Figure 1b,c.…”

“…Their layered structure, along with multiple ways of sodium storage, including alloying, conversion, and intercalation, make them highly favorable. [7][8][9] Although some studies have explored the failure mechanism of Sn-Mx anodes and the layered structure can enhance sodium ion diffusion, there still exist capacity decay and irreversible capacity in practical applications, as well as a failure to achieve the expected cycle life. [7,10] Extensive studies have revealed that intermediates (Sn 0 and Na x M) nucleate and grow during the conversion reaction of SnM x and Na + in SIBs, leading to agglomeration that hinders the reverse reaction.…”

“…[7,10] Extensive studies have revealed that intermediates (Sn 0 and Na x M) nucleate and grow during the conversion reaction of SnM x and Na + in SIBs, leading to agglomeration that hinders the reverse reaction. [8,11,12] For instance, Zhang et al prepared SnSe 2 /RGO nanocomposites as a SIBs anode with a capacity of 515 mA h g −1 at 0.1 A g −1 over 100 cycles. [13] Qu et al reported a stable cycling performance of 500 mAh g −1 at 1 A g −1 for SnS 2 -RGO after 400 cycles.…”

Polycrystalline Fe- and Sn-based sulfides for high-capacity sodium-ion battery anodes

“…The introduction of highly electrically conductive phases and the creation of lattice boundary/interfaces to accelerate the Na + /e − diffusion have proven to be effective ways to address these problems. 8,9 In SnS 2 , Sn displays its highest valence state and S its lowest—and crystal boundary/interfaces may be formed here by redox reactions, with transition metals serving as suitable reductants. To convert SnS 2 to highly conductive, fast Na + diffuse anodes, in the current work, a DFT calculation was performed to guide the materials synthesis, and Fe was applied as an example reductant due to its being a relatively inexpensive metal.…”