To investigate the electrodeposition behavior, CR2032 coin cells were assembled with different substrates (Be, Mg, Ba, Cu, and Al foils, as well as the 3DHS with and without Mg clusters) as working electrodes and with bare Na as counter electrodes. The glass fiber membrane was used as a separator, and a common electrolyte [1 M NaClO4 in ethylene carbonate/diethyl carbonate (1:1, volume %), 5% fluoroethylene carbonate] was used; the current density performed was 50 μA cm−2. Galvanostatic cycling tests were conducted in a LANHE electrochemical testing system. To investigate the cycling stability of the 3DHS with Mg clusters after Na deposition, electrodes were prepared by preplating Na (6 mA∙hour cm−2) inside the 3DHS with Mg clusters at a current density of 0.25 mA cm−2. To measure performances of full cells, cathodes [Na3V2(PO4)3 and FeS2] were fabricated by mixing active materials, conductive carbon, and binder (mass ratio, 8:1:1) and dried at 60°C overnight. The final areal loadings of the Na3V2(PO4)3 and FeS2 cathodes were 1.61 and 1.23 mg cm−2, respectively.