3D Hierarchically Porous High-Mass Loading SiOx Anodes Enabled by Consecutive Multi-Layer Printing and Mid-Infrared Laser Annealing

Abstract

Developing high-energy-density SiOx anodes for lithium-ion batteries requires the strategy to address critical issues related to poor electron/ion transport kinetics and large volumetric changes during cycling. In this study, a novel approach is presented that combines digitally programmable 3D printing and mid-infrared laser annealing techniques. The chemical scheme is designed for synthesizing carbon-SiOx nanocomposites using a soft-templated sol-gel method, in which molecularly incorporated carbon nanodomains are capable of efficiently absorbing mid-infrared wavelength photons. During laser annealing, the carbon nanodomains serving as photothermal agents enable not only a highly efficient, localized carbothermal reduction to produce electrochemically active SiOx but also trigger the carbonization/graphitization of the polyacrylic acid binder for forming an electrically conductive framework. Consequently, this results in the formation of dual-porous SiOx anode, featuring mesopores (approximate to 8 nm in diameter) and macropores (100-600 nm in diameter). In parallel, the digitally programmable 3D printing process defines a grid-pore channel architecture (with a spacing of approximate to 200 mu m). It comprehensively enhances electron/ion transport and structural integrity in ultrathick electrodes. The resulting 3D anode achieves a high areal capacity of 9.5 mAh cm-2 at a mass loading as high as 6.6 mg cm-2. Combinatorial analyses reveal that the 3D-printed and laser-annealed SiOx anode achieves a significantly enhanced electrochemical performance, attributed to a substantial increase in electrical conductivity and Li-ion diffusion coefficient, along with the formation of a LiF-rich thin SEI layer.