Stereolithography of 3D Sustainable Metal Electrodes towards High‐Performance Nickel Iron Battery

Abstract The present‐day ubiquity of smart devices used under extreme conditions demands robust and more sustainable energy storage. Therefore, lightweight electrodes with both excellent electrochemical and mechanical performance to meet these needs are of great importance. Moreover, the recycling of current energy storage devices poses significant environmental concerns, a particularly daunting prospect given the increasing waste volume of metal‐based electrodes. To that end, these challenges of performance and sustainability are addressed by leveraging accessible digital light processing (DLP) technology and tailored post‐process heat treatment to fabricate a metal‐based 3D substrate with ultrahigh precision and hierarchical porosity. Here, a 4‐mm‐thickness metal‐based electrode with NiCo₂S₄ loading of 18.38 mg cm^–2 achieves a high areal capacity of 7.327 mA h cm^–2 at 44.85 mA cm^–2, providing a promising way to fabricate high‐performance thick electrodes. Most importantly, these electrodes can be fabricated from recyclable metal salt feedstock. The geometric freedom offered by 3D printing supplemented by finite element analyses allows for optimized complex structures to be fabricated. Through rational design realized by 3D printing, a desirable compromise between building density, mechanical properties, electrochemical performances, and environment‐friendly processing cycle can be arrived upon.