Morphology, Microstructure, and Phase States in Selective Laser Sintered Lithium Ion Battery Cathodes

Fabrication of high-energy cathode materials with complex geometries is necessary to enable high-power density in next-generation lithium ion batteries (LIBs). Ceramic three-dimensional (3D) printing techniques are one possible avenue to achieve high performance. Current ceramic 3D-printing methods often suspend the electrochemically active cathode powder in binders that require substantial rheological development to enable printability and secondary binder removal processes to ensure degradation does not occur during electrochemical cycling. In this study, the need for binder additives is circumvented by employing the laser-based 3D-printing technique, selective laser sintering (SLS), for direct fabrication of 3D lithium nickel cobalt aluminum oxide (NCA) cathodes. Thermal stress and part distortion are mitigated by using in-situ substrate heating while operating the 1.07 μm fiber laser in q-switched continuous mode. A parametric single-track study is performed to refine the process parameters for the layer-by-layer selective laser sintering of bulk 3D NCA samples. These bulk 3D samples are porous with 2−3 μm grains and exhibit a dual phase state, including the layered structure (with symmetry R-3 m) and rock salt structure (Fm-3 m). The retention of the electrochemically active layered structure in these samples is promising for the development of binder-free, 3D-printed cathodes for LIBs with enhanced power density.