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Page 10 of 64 Rehman et al. Energy Mater 2024;4:400068 https://dx.doi.org/10.20517/energymater.2024.06

Figure 3. (A) (a) Crystal structure of individual ZnS and SnS . (b) XRD pattern of ZnS/SnS @NCNFs. (c-n) Electron microscopic details
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with elemental mapping of ZnS/SnS @NCNFs. (B) Electrochemical performance characteristics of ZnS/SnS @NCNFs for SIBs.
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Reproduced with permission from [91] . Copyright © 2023 American Chemical Society.
achieved. After an extended period of cycling 500 times, the composite presented a capacity of
522.5 mAh g (at 5.0 A g ) with a value-added rate performance (488.7 at 10 A g ). The effective
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-1
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heterostructured interfaces with C networks efficiently tuned Na /e diffusion channels, which boosted the
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performance of the hybrid. In-situ X-ray diffraction (XRD), complemented with cyclic voltammetry (CV)
during (de)sodiation, was chosen to track mechanistic details, as shown in Figure 4B. The conversion
reaction involved a sequential multistage conversion-alloying (de)sodiation mechanism with an initial
lattice expansion [open circuit voltage (OCV)-1.1V] and final disappearance of SnS and Mn SnS , along
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with the corresponding origin of intermediate Sn S (1.1-0.6 V, 2θ = 12.5) and final transformation to Sn
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(2θ = 23.8) and MnSn (2θ = 34.3). Afterward, gradual appearance of Na Sn (2θ = 21.4) and Na Sn
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4
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(2θ = 37.2) at discharging from 0.6-0.1 V by the alloying of Sn and Na was detected, representing the full
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sedation state. Similarly, during desodiation, the formation of Sn (0.1-1.0 V) followed by the origination of
Na MnS and Na Sn S species (1.0-2.0 V) during conversion was traced at a fully charged state (2.0-3.0 V),
2 3
x
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depicting the formation of Sn S and MnS. The corresponding (de)sodiation process, when traced with in-
2 3
situ transmission electron microscopy (TEM) and selected area electron diffraction (SAED) pattern,
confirmed in-situ XRD results and additionally provided information regarding volume expansions, which
were much less than the reported 420% expansion. Maximum expansions observed in dis(charging) cycles
were from 120 nm in the pristine particle to 129.3 nm in the fully sodiated state with 128.2 nm till the 5th
desodiation step, as presented in Figure 4C.
Tin-based selenides
SnSe and SnSe are among 2D transition metal chalcogenides with orthorhombic and hexagonal layered
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structures, respectively. Due to their wide interlayer spacing, tin selenides (SnSe ) have been considered as
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promising materials for storing more Na . They can also absorb significant volume changes. Theoretical
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capacities of SnSe and SnSe are about 756 and 778 mAh g , respectively. Although they show
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electrochemical behavior similar to Sn-based sulfides and oxides, the bond between Sn and Se is relatively
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weaker which supports faster Na kinetics. However, these selenides alone have compromised Na storage in
most cases due to their low tolerance of volume expansion/contraction. Thus, Tin selenides have mostly
been tested in a composite or hybrid form . Zhang et al. have prepared a SnSe @C nanocomposite, which
[24]
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