Ultrathin SnO₂ Nanosheets: Oriented Attachment Mechanism, Nonstoichiometric Defects, and Enhanced Lithium-Ion Battery Performances

Abstract

We successfully synthesized large-scale and highly pure ultrathin SnO2 nanosheets (NSs), with a minimum thickness in the regime of ca. 2.1 nm as determined by HRTEM and in good agreement with XRD refinements and AFM height profiles. Through TEM and HRTEM observations on time-dependent samples, we found that the as-prepared SnO2 NSs were assembled by “oriented attachment” of preformed SnO2 nanoparticles (NPs). Systematic trials showed that well-defined ultrathin SnO2 NSs could only be obtained under appropriate reaction time, solvent, additive, precursor concentration, and cooling rate. A certain degree of nonstoichiometry appears inevitable in the well-defined SnO2 NSs sample. However, deviations from the optimal synthetic parameters give rise to severe nonstoichiometry in the products, resulting in the formation of Sn3O4 or SnO. This finding may open new accesses to the fundamental investigations of tin oxides as well as their intertransition processes. Finally, we investigated the lithium-ion storage of the SnO2 NSs as compared to SnO2 hollow spheres and NPs. The results showed superior performance of SnO2 NSs sample over its two counterparts. This greatly enhanced Li-ion storage capability of SnO2 NSs is probably resulting from the ultrathin thicknesses and the unique porous structures: the nanometer-sized networks provide negligible diffusion times of ions thus faster phase transitions, while the “breathable” interior porous structure can effectively buffer the drastic volume changes during lithiation and delithiation reactions.

Optical and magnetic properties of (Er, F) co-doped SnO$_{2}$ nanocrystals

“…The peak at around 531.39 eV was assigned to O-Sn 4+ bonding and the peak at 531.87 eV was attributed to the nonstoichiometric oxides present in the surface region [28,29]. The atomic concentrations of Sn, O, and F were 23%, 44%, and 33%.…”

An elastic carbon layer on echeveria-inspired SnO2 anode for long-cycle and high-rate lithium ion batteries

“…It showed a stable cyclic performance, in which a capacity of 765 mA h g À1 and CE of 99.4% could be obtained at the end of prolonged cycle. These excellent cycling stability and rate capability of the E-SnO 2 @C might be attributed to structural design of E-SnO 2 @C. Specifically, the E-SnO 2 @C nanoleaves possessed short distances for Li + diffusion and large electrode-electrolyte contact areas for faster Li + flux across the interface, which all-together led to an enhanced rate capability [40,41]. Moreover, a local empty space in the hierarchical and nanoporous structures and low-dimensional building blocks mixed with elastic and ultrathin carbon film could effectively accommodate the large volume change and increase both ionic and electronic conductivity of anode material, thus improving the lithium-storage properties [42].…”

Effect of the sheet thickness of hierarchical SnO 2 on the gas sensing performance

“…Subsequently, the intermediates join with each other at a planar, forming nanosheets [54,55]. With the prolonged time, the intermediate sheets consecutively rotate in 3-dimensional space so as to achieve full fusion [56]. Following that, the nanosheets self-assemble into nanoflowers via van der Waal forces, hydrogen, ionic and covalent bonding etc.…”