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Page 34 of 64 Rehman et al. Energy Mater 2024;4:400068 https://dx.doi.org/10.20517/energymater.2024.06

Figure 17. (A) Cross-sectional SEM images of (a) CMT, (b) CMT@Bi O , and (c) CMT@Bi-C. (d) Image showing surface morphology
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and (e-g) elemental mapping of CMT@Bi-C. (B) Cycle performance of CMT@Bi-C at 10 A g at high temperature. (C) Post cycling
analysis of CMT@Bi-C. Cross-section SEM images before and after battery cycling test for (a and d) CMT, (b and e) CMT@Bi-C, and
(c and f) CMT@Bi(MP)-C anodes are shown. Reproduced with permission from [189] . Copyright © 2023 Elsevier.
electrode showed good integrity with diminished SEI and minimal structural changes [Figure 17C].
Similarly, Sb Bi alloy anodes in SIBs delivered a high ICE of 87.1% at 0.1 A g . The electrode exhibited low
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polarization effects. It could furnish a high capacity of 625 mAh g after 100 cycles at 1 A g -1[42] .
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Electrochemical performances of representative alloy-based anode materials explored for SIBs were
compared. Results are provided in Table 2.
MATERIAL DESIGN STRATEGIES
Nanostructuring and controlling morphology
Alloying SIB anodes face multiple issues, including high volume expansions, particle aggregation with
pulverization, high drop in ICE, low Na and electronic mobilities, and unfavored kinetics, all leading to low
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reversible capacities. From the material’s perspective, many of these limitations can be fixed by opting for
rational material design such as nanostructuring and controlled morphological architectures to have a real-
world benefit of improved performance. The high and active surface area of nanostructured alloys not only
enhances interfacial interactions between electrolyte and electrode, but also offers high Na diffusion at
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shortened paths, particularly over carefully designed nano-morphologies, thereby enhancing the kinetics of
ion transfer. Although nanosizing offers the above-mentioned benefits of adding mechanical strength and
mitigating pulverization of other detrimental effects, they entail different degrees of drawbacks, including