Additive Manufacturing of Aqueous-Processed LiMn2O4 Thick Electrodes for High-Energy-Density Lithium-Ion Batteries

Enhancing electrode areal capacity of lithium-ion batteries will result in cost saving and better electrochemical performances. Additive manufacturing (AM) is a very promising solution, which enables to build structurally complex electrodes with well-controlled geometry, shape and thickness. Here we report on 3D-printed cathodes based on LiMn2O4 (LMO) as the active material, which are fabricated by robocasting AM via aqueous processing. Such a technology is: i) environmentally friendly, since it works well with water and green binders; ii) fast, due to very short deposition times and rapid drying process because of low amount of solvent in the printable pastes; iii) easily scalable. The cathodes are produced by extruding pastes with higher solid loadings (>70 vol %) than those typically reported in literature. The printing efficiency is strongly affected by both the binder and the carbonaceous additive. The best cathode is composed by LMO, Pluronic as the binder, and a mixture of graphite/carbon black as the electronic conductor, which is critical for achieving optimal electrochemical performance. The cathode with thickness of 200 μm and mass loading of 13 mg cm−2 exhibits good electrochemical areal capacity (2.3 mAh cm−2) and energy density (>32 J cm−2). Our results may boost the development of greener, lower cost and more efficient new generation of LIBs for applications as household energy storage or even micro-battery technology.