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Mu et al. Energy Mater 2022;2:200043 https://dx.doi.org/10.20517/energymater.2022.57 Page 5 of 16

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Figure 2. (A) Schematic illustration of presodiation mechanics by introduction of Na C O implemented by initial charge process .
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(B) Schematic diagram showing multiple functions of DTPA-5Na . (C) Crystal structure and electrochemical characteristics of
[61] [62]
NaCrO . (D) Illustration of electrocatalytically-driven presodiation process based on pouch cell .
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obvious increase from 58 to 128 mAh g , indicating that DTPA-5Na could provide sufficient Na sources
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+
during the first charge. A comprehensive mechanism was also proposed. Na in DTPA-5Na can be
electrochemically extracted after the first charge operation and the generation of poorly crystalline C N
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characteristics of electron conductivity on the surface of the cathode. Interestingly, C N could serve as a
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conductive network to accelerate the electron transfer in the composite cathode. In addition, NaCrO is
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usually employed as a self-sacrificing Na-containing additive for Na-ion full cells, which can offer an
irreversible capacity of 230 mAh g from its irreversible phase transition at high voltage.
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As shown in Figure 2C, Shen et al. employed a NaCrO additive to achieve high capacity, low polarization,
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high energy density and excellent cycle stability in Na V O (PO ) F//HC full cells. During the first cycle, the
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full cell with NaCrO shows charge and discharge capacities of 308 and 118 mAh g -1[61] , respectively, which
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are higher than the capacities of the full cell without additives (charge capacity of 132 mAh g and discharge
capacity of 50.7 mAh g ). In addition to traditional cathode additives, Zhang et al. developed an
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electrocatalytically driven decomposition of Na O with high Na content, which could provide a large
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number of recyclable Na without jeopardizing the integrity of the electrode materials, electrolytes and the
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overall battery [Figure 2D] . High sodium content (88%) sodium oxide (Na O) can provide sufficient
[62]
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cyclable sodium ions that are electrocatalytically-driven by a highly active ruthenium@graphene (Ru@G)
electrocatalyst to compensate the sodium loss during the initial SEI formation and following consumption.
This additional electrocatalytically-driven cathode strategy not only provides numerous cyclable sodium but
also has no adverse effects on the stability of the electrode materials, electrolyte or the whole battery system.
All the steps were based on the current mature commercial battery fabrication process, which can efficiently
ensure its potential practical application. Furthermore, this process does not induce unknown byproducts