3D printing of lattice-structured hard carbon negative electrodes for sodium-ion batteries using vat photopolymerization

Purpose Additive manufacturing (AM) offers new opportunities for the design of advanced and shape-conformable energy storage systems. This study aims to explore the fabrication and performance of 3D-printed hard carbon (HC) negative electrodes for sodium-ion batteries (SIBs) using vat photopolymerization (VPP), a high-resolution AM technique. Design/methodology/approach Two composite resins with different ratios of active material (HC) to conductive additive (carbon black C45) were formulated (HC:C45 = 12:1 and 7:1) and 3D printed into three different geometries (solid, gyroid and cubic), then thermally postprocessed to remove the insulating polymer matrix and consolidate the carbon network. The mechanical, morphological, electrical and electrochemical properties of the resulting electrodes were systematically investigated. Findings Sintered electrodes with solid geometry demonstrated enhanced mechanical performance compared to their green state counterparts, with increases of 12.9% in specific flexural strength and 259% in flexural modulus for the 12:1 composition. Lattice-patterned electrodes, particularly gyroid and cubic architectures, enabled improved electrolyte infiltration due to the porosity conferred by the infill patterns, resulting in higher retained specific capacities during galvanostatic cycling. The gyroid design (12:1) delivered the highest specific capacity values of about 150 mAh.g-1 at a C-rate of C/20 after 35 cycles. Originality/value For the first time, this work reports the development of HC-loaded photocurable resins successfully printed using VPP for SIB applications. The study demonstrates the viability of integrating structural design, 3D printing and functional carbon materials to fabricate mechanically stable and electrochemically active electrodes, providing a foundation for future 3D-printed energy storage systems.