Preparation of lithium iron phosphate battery by 3D printing

Three-dimensional (3D) printed batteries are considered a special class of energy storage devices that allow flexible control of the electrode structure on a microscopic scale, which is crucial to improving the energy density of miniaturized devices. In this study, lithium iron phosphate (LFP) porous electrodes were prepared by 3D printing technology. The results showed that with the increase of LFP content from 20 wt% to 60 wt%, the apparent viscosity of printing slurry at the same shear rate gradually increased, and the yield stress rose from 203 Pa to 1187 Pa. The rheological property and printability of the slurry show that the printing slurry of 40 wt% LFP has excellent conformal property and self-supporting property. Due to the porous skeleton shortening the transfer distance of ions and electrons and enhancing the efficiency of the electrode reaction, the rate performances and cycle stability of LFP batteries were improved. The 3D-printed battery containing an active material loading of 15.9 mg cm-2 achieved a specific capacity of 121.7 mA h g-1 at 0.5C after 200 cycles and coulombic efficiency higher than 99.7 %, and the LFP battery had an energy density of 350 W h kg-1. These results suggest that 3D printing is an effective strategy for developing batteries with high active material loadings and energy densities at micro sizes.