3D‐Printed Na ₃ V ₂ (PO ₄ ) ₃ Electrodes for Symmetric Sodium‐Ion Batteries

Lithium's rising demand, uneven resource distribution, and sustainability concerns motivate the development of alternative battery chemistries, including sodium‐ion batteries (SIB). Within the battery field, symmetric configurations have drawn significant interest due to their simplified design, improved interfacial stability, enhanced safety, and strong recyclability potential arising from identical electrode chemistries for both electrodes. Additionally, 3D printing processes enable the creation of free‐form battery components and complex 3D electrode geometries, promoting enhanced ion diffusion into three dimensions. Here, vat photopolymerization 3D printing is employed to fabricate current collector‐free Na 3 V 2 (PO 4 ) 3 (NVP) electrodes with complex lattice geometries with the aim of utilizing them as both positive and negative electrodes in a symmetric NVP/NVP SIB. Extensive materials characterization, coupled with advanced electrochemical testing, is showcased for the 3D‐printed NVP electrodes. The results demonstrate that 3D‐printed NVP electrodes can exhibit dual electrochemical characteristics, serving both as positive and negative electrodes in SIB, while harnessing the benefits inherent to 3D printing technology. Finally, the 3D‐printed symmetric NVP/NVP batteries exhibit a constant operating voltage slightly above 1.7 V versus Na/Na + and a reversible specific capacity of ∼80 mAh g −1 after 100 cycles at 0.05 C.