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Page 10 of 16 Mu et al. Energy Mater 2022;2:200043 https://dx.doi.org/10.20517/energymater.2022.57

Figure 5. (A) Schematic illustration of chemical presodiation of commercial HC anode with a Naph-Na solution [32] . (B) Schematic
diagram of ultrafast presodiation of reduced graphene oxide (rGO) anode in using Na-Naph dissolved in DME (top) and the
open-circuit voltage and initial Coulombic efficiency of rGO anode with various presodiation times (bottom) [80] . (C) Scheme of
presodiation process with different Na sources (left: Na metal, right: Na-Naph-DME) and a suggested scalable roll-to-roll technique for
industrial manufacturing [81] . (D) Schematic illustration of chemical presodiation and the following SEI film generation process on
available HC anodes [30] .

and Coulombic efficiency of 95.7% during the initial cycle [Figure 6C]. Generally, the electrochemical
presodiation treatment can generate a homogenous and stable SEI film on the surface of the anode, which
can effectively suppress electrolyte decomposition and active Na loss during the initial cycle, boosting the
initial Coulombic efficiency. However, in contrast, the complex process of assembling and disassembling
the half cell reduces the feasibility of scalable production. To address the above problems, an additional Na
metal electrode was introduced between the electrolyte and anode of the full cell, which could accomplish
the presodiation process by a specific charging step .
[35]

CONCLUSIONS AND OUTLOOK
Sodium-based energy storage devices provide a highly economic, efficient and sustainable alternative for
large-scale electrochemical energy storage systems. However, many challenges are remaining towards
further commercialization and industrialization, such as the low initial Coulombic efficiency and