Grid-patterned three-dimensionally printed Li₄Ti₅O₁₂ anodes: hierarchical porosity and carbon framework enable high...

Improving electron transport during charge/discharge cycles, protecting the Li₄Ti₅O₁₂ (LTO) surface from electrolyte degradation and/or volume expansion, and enhancing electrolyte penetration and ion transport remain critical challenges for practical lithium-half cells. Interestingly, carbon coating of LTO improves its electronic conductivity and surface stability, addressing inherent material limitations. Density Function Theory (DFT) calculations also confirm that this type of coating enhances both the electrical properties and surface stability of LTO, further highlighting its potential to boost battery performance. In this study, carbon-coated LTO (LTO@C) was synthesized via an in-situ solution method followed by low-temperature calcination. Theoretical insights from DFT calculations were used to guide the design of the carbon coating. The resulting LTO@C was incorporated into 3D-printed electrodes using direct ink writing (DIW), which featured abundant micropores. The anodes were constructed with varying thicknesses of 350 μm (4 layers), 625 μm (6 layers), 789 μm (8 layers), and 1120 μm (12 layers), corresponding to mass loadings of approximately 11, 17, 25, and 36 mg cm^-2, respectively. These 3D-printed LTO@C anodes were tested in lithium-ion batteries (LIBs) and demonstrated remarkable electrochemical performance. The 12-layer anode achieved an outstanding areal capacity of 4.68 ± 0.19 mAh cm^-2 after 200 cycles, with a high areal power density of 12.10 mW cm^-2 and an energy density of 8.31 mWh cm^-2 at 0.1C. This synthetic methodology not only enhances the electrochemical performance of 3D-printed LTO@C compared to conventional tape-cast LTO@C but also provides an efficient carbon modification approach, overcoming key limitations of traditional thermal carbonization methods.