Sn–Co Nanoalloys Encapsulated in N-Doped Carbon Hollow Cubes as a High-Performance Anode Material for Lithium-Ion Batteries

Abstract

To address the huge volumetric change and unstable solid electrolyte interphase (SEI) issues of Sn-based anodes, this paper proposes a Sn-Co-C ternary composite with a cubic yolk-shell structure. The proposed Sn-Co nanoalloys encapsulated in N-doped carbon hollow cubes (Sn-Co@C) are simply synthesized by the conformal polydopamine coating of home-made CoSn(OH) hollow nanocubes subsequent with hydrogen reduction. The cubic Sn-Co@C yolk-shell structure possessing an optimized carbon shell thickness displays excellent cyclic performance and superior rate capability when utilized as an anode for lithium-ion batteries. The composite shows an initial discharge capacity of 885 mA h g at 200 mA g with a high capacity retention of ∼91.2% after 180 cycles. It can still deliver a considerable capacity of 560 mA h g at a high current density of 1 A g after 200 cycles. This attractive electrochemical characteristic can be ascribed to the distinct cubic yolk-shell architecture, in which the inner inactive Co can buffer the volumetric expansion of Sn, the void can provide external space for the volumetric change of Sn, and the outer carbon shell can effectively prevent the agglomeration of Sn-Co nanoalloys and maintain the stability of SEI films.

In Situ Construction of Multibuffer Structure 3D CoSn@SnOx/CoOx@C Anode Material for Ultralong Life Lithium Storage

“…The obvious cathodic peak at ≈1.3 V can be attributed to the following reasons: first, the formation of the solid electrolyte interphase (SEI) layer on the electrode surface from the irreversible decomposition of electrolyte; second, the reduction of amorphous SnO x /CoO x to Co/Sn; and third, the irreversible insertion of Li + into void, pore, and defect. The reduction peak around ≈0.75 V is related to the multistep Li–Sn alloying reactions with an activation process . The cathodic peak at ≈0.01 V reflects that Li + react with carbon as well as some alloying reaction of Li with Sn .…”

“…The reduction peak around %0.75 V is related to the multistep Li-Sn alloying reactions with an activation process. [34][35][36] The cathodic peak at %0.01 V reflects that Li þ react with carbon as well as some alloying reaction of Li with Sn. [36] Correspondingly, there are three broad anodic peaks at %0.6, %1.25, and %2.1 V, which are related with the extraction of Li þ from carbon and multiple dealloying processes.…”

“…[36] Correspondingly, there are three broad anodic peaks at %0.6, %1.25, and %2.1 V, which are related with the extraction of Li þ from carbon and multiple dealloying processes. [34,[36][37][38][39] Based on the aforementioned analysis, the lithium-storage mechanism of 3D CoSn@SnO x /CoO x @C electrode is summarized in Figure S9, Supporting Information. After the first cycle, the irreversible peak at 0.75 V disappeared and the CV curves show a high degree of overlapping, indicating the well reversibility of the sample with multishell structure.…”

Polyphosphazene microspheres modified with transition metal hydroxystannate for enhancing the flame retardancy of polyethylene terephthalate

“…The spectrum of Sn 3d (Figure B) demonstrates two peaks at 486.7 and 495.1 eV, corresponding to Sn 4+ 3d 5/2 and Sn 4+ 3d 3/2 , respectively. The peaks at 779.9 and 795.3 eV in Co 2p spectra (Figure C) are assigned to Co 2p 3/2 and Co 2p 1/2 , and the peaks at 797.0 and 781.2 eV are ascribed to Co 2+ in the CS phase . As for the O 1s (Figure D), the peaks at 531.6 and 533.4 eV are attributed to the sulfone group (OS) and OP bonds, respectively .…”

“…Among all of the transition metal compounds, transition metal hydroxystannates containing two kinds of metal elements possess unique physical and chemical properties, such as CuSn(OH) 6 , MgSn(OH) 6 , CoSn(OH) 6 (abbreviated as “CS”), and NiSn(OH) 6 . The most reported transition metal hydroxystannates is CS, which possesses various morphologies like nanocube, nanoboxe, and nanosphere, and be widely used in catalysts, lithium‐ion batteries, supercapacitors, and gas sensors for the excellent catalytic action. As we all know, some special catalytic activity is also needed in flame retardants, which can promote the char formation and reduce the toxic pyrolysis products release in combustion.…”