SnO₂ Quantum Dots: Rational Design to Achieve Highly Reversible Conversion Reaction and Stable Capacities for Lithium and Sodium Storage

Abstract

SnO2 has been considered as a promising anode material for lithium‐ion batteries (LIBs) and sodium ion batteries (SIBs), but challenging as well for the low‐reversible conversion reaction and coulombic efficiency. To address these issues, herein, SnO2 quantum dots (≈5 nm) embedded in porous N‐doped carbon matrix (SnO2/NC) are developed via a hydrothermal step combined with a self‐polymerization process at room temperature. The ultrasmall size in quantum dots can greatly shorten the ion diffusion distance and lower the internal strain, improving the conversion reaction efficiency and coulombic efficiency. The rich mesopores/micropores and highly conductive N‐doped carbon matrix can further enhance the overall conductivity and buffer effect of the composite. As a result, the optimized SnO2/NC‐2 composite for LIBs exhibits a high coulombic efficiency of 72.9%, a high discharge capacity of 1255.2 mAh g−1 at 0.1 A g−1 after 100 cycles and a long life‐span with a capacity of 753 mAh g−1 after 1500 cycles at 1 A g−1. The SnO2/NC‐2 composite also displays excellent performance for SIBs, delivering a superior discharge capacity of 212.6 mAh g−1 at 1 A g−1 after 3000 cycles. These excellent results can be of visible significance for the size effect of the uniform quantum dots.

Energetic-Materials-Driven Synthesis of Graphene-Encapsulated Tin Oxide Nanoparticles for Sodium-Ion Batteries

“…As a critical parameter of the energy density of Na-ion full batteries, the ICE of the Gr-SnO 2 nanoparticles is amongst the highest reported for the anode materials of Na-ion batteries [ 37 , 40 , 41 , 42 , 43 , 44 , 45 , 46 ]. The high ICE can be ascribed to the structural features of the Gr-SnO 2 nanoparticles, where the nanoscale core material shortens the ion diffusion path and the graphene coating facilitates the transport of electrons and ions to the core material [ 13 , 47 ].…”

Conversion‐Alloying Anode Materials for Sodium Ion Batteries

“…By annealing, SnO 2 /NC composites that ultrasmall SnO 2 quantum dots embedded in carbon matrix were generated (Figure 5b). [110] Shen et al prepared PO 4 3− doped SnS 2 @ TiC/C (P-SnS 2 @TiC/C) arrays through hydrothermal method. As shown in figure, individual layers of SnS 2 nanoflakes grew on the outer surface of conductive TiC/C nanowires to form core-branch heterostructure.…”

“…By annealing, SnO 2 /NC composites that ultrasmall SnO 2 quantum dots embedded in carbon matrix were generated (Figure 5b). [ 110 ] Shen et al. prepared PO 4 3− doped SnS 2 @TiC/C (P‐SnS 2 @TiC/C) arrays through hydrothermal method.…”

“…Reproduced with permission. [ 110 ] Copyright 2020, Wiley‐VCH. c) SEM image of P‐SnS 2 @TiC/C arrays.…”

Two-dimensional SnO2 anchored biomass-derived carbon nanosheet anode for high-performance Li-ion capacitors

“…However, like most transition metal oxides, SnO 2 has poor conductivity and suffers from dramatic volume change during charge/discharge process, easy pulverization and agglomeration, which directly affects its cycling performance. [22][23][24][25] One of the common strategies to tackle these problems is to composite SnO 2 with conductive nano-materials, including carbon layer, 26,27 carbon nanotubes (CNTs) 28,29 and graphene 30,31 etc. For example, Cheng and coworkers dispersed SnO 2 quantum dots (z5 nm) in a nitrogendoped porous carbon matrix, the carbon matrix was used as a protective medium to stabilize structural changes.…”