Rational Engineering of p‐n Heterogeneous ZnS/SnO₂ Quantum Dots with Fast Ion Kinetics for Superior Li/Na‐Ion Battery

Abstract

Constructing heterogeneous nanostructures is an efficient strategy to improve the electrical and ionic conductivity of metal chalcogenide‐based anodes. Herein, ZnS/SnO2 quantum dots (QDs) as p‐n heterojunctions that are uniformly anchored to reduced graphene oxides (ZnS‐SnO2@rGO) are designed and engineered. Combining the merits of fast electron transport via the internal electric field and a greatly shortened Li/Na ion diffusion pathway in the ZnS/SnO2 QDs (3–5 nm), along with the excellent electrical conductivity and good structural stability provided by the rGO matrix, the ZnS‐SnO2@rGO anode exhibits enhanced electronic and ionic conductivity, which can be proved by both experiments and theoretical calculations. Consequently, the ZnS‐SnO2@rGO anode shows a significantly improved rate performance that simple counterpart composite anodes cannot achieve. Specifically, high reversible specific capacities are achieved for both lithium‐ion battery (551 mA h g−1 at 5.0 A g−1, 670 mA h g−1 at 3.0 A g−1 after 1400 cycles) and sodium‐ion battery (334 mA h g−1 at 5.0 A g−1, 313 mA h g−1 at 1.0 A g−1 after 400 cycles). Thus, this strategy to build semiconductor metal sulfides/metal oxide heterostructures at the atomic scale may inspire the rational design of metal compounds for high‐performance battery applications.

Ni-Doped SnO2 Nanoparticles Anchored on Carbon Nanotubes as Anode Materials for Lithium-Ion Batteries

“…This is because as the cycle proceeds, the active substances are gradually activated, which is expressed as a rise in capacity. 43 This also holds true for SC and SnO 2 , as shown by long cycling of SC at 1.0 A g −1 (Figure S1), where the capacity is realized as a decrease followed by an increase. The initial part of the capacity loss is due to the generation of an irreversible SEI film and Li 2 O.…”

“…It can be observed that the discharge capacity of SNC has a slow decreasing trend in the initial stage until after 100 cycles, the capacity slowly increases and finally reaches a large reversible discharge capacity of 1245.7 mA h g –1 when it is cycled to 400 cycles. This is because as the cycle proceeds, the active substances are gradually activated, which is expressed as a rise in capacity . This also holds true for SC and SnO 2 , as shown by long cycling of SC at 1.0 A g –1 (Figure S1), where the capacity is realized as a decrease followed by an increase.…”

p–n heterogeneous Sb2S3/SnO2 quantum dot anchored reduced graphene oxide nanosheets for high-performance lithium-ion batteries

“…3c). 6 The two characteristic peaks centred at about 495.6 and 487.3 eV in the Sn 3d XPS spectra are assigned to Sn 3d 3/2 and Sn 3d 5/2 of Sn 4+ species, 27 respectively (Fig. 3d).…”

“…3 Metal oxides (SnO 2 , Fe 3 O 4 , ZnO, MnO, etc. 4–7 ) and metal sulfides (Sb 2 S 3 , MoS 2 , ZnS, FeS, etc. 8–12 ) as conversion reaction-based electrodes stand out from various LIB anode materials due to their low cost and high theoretical specific capacity.…”

“…22 According to the energy band, the electrons in the p-type semiconductor would transfer to the n-type semiconductor, which makes the p-type semiconductor reach an unstable charge-deficient state, thus requiring low-valence Li + to realize charge balance that leads to the acceleration of Li + -embedding in the p-type semiconductor to improve ion diffusion kinetics. 23 Tin oxide (SnO 2 ), a typical n-type semiconductor, has a high specific capacity, 6 and can be a potential candidate material to assemble with p-type Sb 2 S 3 to construct a high-powered p–n heterogeneous Sb 2 S 3 /SnO 2 anode material. 24 For example, Zhang et al synthesized a bundle-like Sb 2 S 3 @SnO 2 nanocomposite anode through a simple hydrothermal method followed by a hydrothermal process, which shows superior electrochemical performance to those of individual Sb 2 S 3 and SnO 2 .…”