Evaluating 3D printed mesh geometries in ceramic LiB electrodes

Abstract

Additive manufacturing techniques have the potential to promote a paradigmatic change in the electrode fabrication processes for lithium-ion batteries (LiBs) as they may offer alternative component designs to boost their performance or to customise the application. The present research work explores the use of low-cost fused filament fabrication (FFF) 3D printing to fabricate Li4Ti5O12 (LTO) mesh electrodes in the search for enlarged electrochemically active areas. Using different nozzle diameters (ND), we have 3D printed several mesh electrodes that after sintering allow an increase in the surface to volume ratio by up to ≈290% compared to conventional flat cylindrical geometries. As the conventional route to produce 3D printed meshes, i.e. stacking of consecutive layers with a 90º rotation, leads to problems of vertical misalignment that may affect the electrical contact, we have developed a new compact design that maximises the contact between layers. All the 3D printed mesh electrodes with thicknesses of 400 and 800 μm, exhibit electrochemical performance very close to those of thin (70 μm) electrodes, e.g. 175 mAh/g at C/2 in the case of ND = 100 μm, which is the theoretical capacity value for LTO. At higher C-rates, 800 μm-thick mesh electrodes with larger ND exhibit a marked drop in the reversible capacity (28 mAh/g at 8C), although the values obtained improve notably those of the equivalent thick solid electrode (almost null at 8C). The compact design demonstrated superior performance at high C-rates, improving by ≈70% the results of the best conventional mesh electrode at 8C for 800 μm electrodes. These results highlight the potential of FFF-3D printing to generate novel high aspect ratio geometries and the impact of design and printing parameters on the performance of LiB electrode materials. Exploring alternative efficient geometries may facilitate the integration of thick electrodes in high energy density LiBs.