Research on 3D-Printed Grid Geometries of Ceramic Lithium Battery Electrodes in the Journal of Physics

The Energy Materials and 3D Printing Laboratory at the Institute of Renewable Energy, University of Castilla–La Mancha (UCLM), Spain, has published a research article entitled “Evaluating 3D printed mesh geometries in ceramic LiB electrodes” in the Journal of Physics: Energy. The study employed low-cost fused filament fabrication (FFF) 3D printing to produce mesh geometries in ceramic LiB electrodes. By optimizing both design and printing parameters, the researchers generated novel high-aspect-ratio geometries aimed at enhancing the performance of LiB electrode materials.

Original article link: https://doi.org/10.1088/2515-7655/ad2497
Shenzhen AdventureTech website: https://www.adventure-tech.cn/

Research Content
Additive manufacturing (AM) technologies have introduced significant innovations in the fabrication of lithium-ion battery (LiB) electrodes, offering new perspectives for alternative component design. The present study focuses on employing low-cost fused filament fabrication (FFF) 3D printing technology to manufacture Li₄Ti₅O₁₂ (LTO) mesh electrodes, aiming to explore new approaches to enlarge the electrochemically active surface area. The work was validated using different nozzle diameters (ND), leading to the development of a new compact design that maximizes interlayer contact. All 3D-printed mesh electrodes with thicknesses of 400 and 800 µm exhibited electrochemical performance comparable to that of a thin electrode (70 µm). For instance, under ND = 100 µm, a specific capacity of 175 mAh·g⁻¹ at C/2 was achieved, which corresponds to the theoretical capacity of LTO.

Integrating thick electrodes into high-energy-density LiBs remains a major challenge. Li-ion batteries are at the forefront of energy storage technologies for several key industrial applications, including portable electronics, electric vehicles, and renewable energy–based hybrid systems. Although LiBs outperform other energy storage devices in terms of energy density, reliability, and cycling performance, surpassing the specific capacity of conventional LiB materials requires innovative structural designs. In this work, a novel approach is proposed using 3D-printed mesh electrodes that not only enhance interlayer contact but also facilitate the integration of thick electrodes in high-energy-density LiBs.

Initially, the nozzle path was defined as a continuous line to avoid issues associated with non-continuous extrusion, such as retraction. Consequently, the continuous layers were typically arranged with a 90° rotation between consecutive layers, as shown in Figure 1(a). However, this approach often led to vertical misalignment within the mesh electrodes, which could negatively affect the electrical contact between layers. Therefore, a new compact design was introduced in this study, in which identical continuous layers were stacked directly on top of each other (Figure 1(b)), thereby improving interlayer contact and enhancing the overall electrochemical performance.
 

Figure 1. 3D printing strategy for fabricating mesh electrodes.

(a) Conventional grid slicing, consisting of stacked continuous layers rotated by 90° between successive layers.
(b) Compact design, consisting of stacked identical continuous layers to maximize interlayer contact.

In this work, sintered 3D-printed electrodes—including planar and various grid-type geometries—were tested to maximize the electrolyte–electrode contact area. At the macroscopic level, the printed electrodes accurately replicated the 3D models. SEM images of the sintered electrodes confirmed that the obtained geometries matched their respective designs, with wall thickness corresponding to the nozzle diameter (ND). Cross-sectional SEM analysis further revealed good interlayer contact, with no major defects or delamination observed (Figure 2).
 

Figure 2. Top-view (a), (c), (e), (g) and corresponding cross-sectional (b), (d), (f), (h) SEM micrographs of the 3D-printed mesh electrodes.

The use of mesh geometries results in a gradual increase in the surface-to-volume ratio, thereby enlarging the electrolyte–electrode contact area, which can have a positive impact on battery performance. As shown in Table 1, the experimental measurements are in close agreement with the CAD model values. The slight deviations observed are attributed to the gravitational effect on the softened filament during the 3D printing process.

Table 1. Geometrical analysis of CAD models and 3D-printed electrodes.

Here, S denotes the surface area, V the volume, and S/V the surface-to-volume ratio, calculated for both the CAD model ((S/V)CAD) and the 3D-printed and sintered electrodes ((S/V)printed). The ratio (SN0X/SThick)printed represents the surface area of each 3D-printed and sintered mesh electrode corresponding to a given nozzle diameter (SN0X), normalized to the surface area of the thick solid electrode (SThick).

High-magnification SEM images (Figure 3) reveal that all mesh structures exhibit very similar microstructures after debinding and sintering, with approximately 75% relative density. The microstructure is predominantly composed of equiaxed submicron pores (0.3–0.5µm in diameter), consistent with previous findings. The LTO grains within the sintered electrodes range from 0.5 to 1.5 µm, which is close to the original particle size of the LTO powder (0.2–1.0 µm) used for filament preparation.

Figure 3. SEM micrographs showing the microstructure of the sintered LTO electrode (a) and the initial LTO powder used for filament fabrication.

As shown in Figure 4, the 3D printing process followed by debinding and sintering heat treatments does not cause any degradation that could negatively affect the electrochemical performance of the active material.

Figure 4. X-ray diffraction patterns and Le Bail fitting of LTO (a) commercial powder and (b) sintered powder.

Experimental data (red circles), calculated profile (black solid line), difference curve (blue line), and Bragg peak positions (green vertical marks) are shown. Figure 5 presents the electrochemical profiles corresponding to the first discharge/charge cycle of the different 3D-printed electrodes at various C-rates. As expected, the thick solid LTO electrode exhibits a significant capacity loss compared with the theoretical value (175 mAhg^-1), regardless of the tested C-rate.

Figure 5. First electrochemical discharge/charge cycles of solid (a, b) and mesh LTO electrodes (c–h) at different C-rates (C/10–8C). 

Electrode thicknesses were 400 µm for (a), (c), (e), (g) and 800 µm for (b), (d), (f), (h). For the mesh electrodes, different nozzle diameters were tested: ND = 400 µm (c, d), ND = 200 µm (e, f), and ND = 100 µm (g, h). As shown in Figure 5, the compact electrodes exhibited reversible capacities closer to those of the thin electrode. At low to moderate C-rates (from C/2 to 2C), the electrochemical response was nearly identical, whereas at higher C-rates (4C–8C), the compact mesh electrodes demonstrated superior performance for both 400 µm and 800 µm thicknesses, showing an approximately 60% increase in reversible capacity at 8C.

Figure 6. Comparison of C-rate performance between compact and conventional mesh electrodes with thicknesses of (a) 400 µm and (b) 800 µm.

Figure 7. Normalized reversible capacities of 3D-printed mesh electrodes with thicknesses of (a) 400 µm and (b) 800 µm.

It illustrates the impact of different mesh geometries evaluated in this study on electrochemical performance, relative to thin solid LTO electrodes. All mesh electrodes with ND = 100 µm exhibited excellent reversibility, with Coulombic efficiencies exceeding 98–99% in most cases. At moderate C-rates, up to 2C, the specific reversible capacities were nearly identical for all electrodes. However, at higher C-rates (4C and 8C), the ND = 100 µm electrodes demonstrated superior performance, particularly for the compact design, likely due to improved contact between continuous layers within the mesh. These results highlight that electrochemical performance can be enhanced through geometric design, which maximizes the contact area between the electrolyte and active electrode material, and by defining printing patterns that improve interlayer connectivity.

Results

By optimizing both design and printing parameters, mesh geometries fabricated in ceramic LiB electrodes using low-cost fused filament fabrication (FFF) 3D printing were able to maximize interlayer contact, addressing the vertical misalignment issues often observed in conventional 3D-printed mesh electrodes. At higher C-rates, 800 µm-thick mesh electrodes with larger nozzle diameters (ND) exhibited a significant decrease in reversible capacity. These results highlight the potential of FFF 3D printing to generate novel high-aspect-ratio geometries for improved electrode performance.