3D Printed Nanocarbon Frameworks for Li‐Ion Battery Cathodes

The use of conductive carbon materials in 3D-printing is attracting growing academic and industrial attention in electrochemical energy storage due to the high customization and on-demand capabilities of the additive manufacturing. However, typical polymers used in conductive filaments for 3D printing show high resistivity and low compatibility with electrochemical energy applications. Removal of insulating thermoplastics in as-printed materials is a common post-printing strategy, however, excessive loss of thermoplastics can weaken the structural integrity. This work reports a two-step surface engineering methodology for fabrication of 3D-printed carbon materials for electrochemical applications, incorporating conductive poly(ortho-phenylenediamine) (PoPD) via electrodeposition. A conductive PoPD effectively enhances the electrochemical activities of 3D-printed frameworks. When PoPD-refilled frameworks casted with LiMn2O4 (LMO) composite materials used as battery cathode, it delivers a capacity of 69.1 mAh g−1 at a current density of 0.036 mA cm−2 (≈1.2 C discharge rate) and good cyclability with a retained capacity of 84.4% after 200 cycles at 0.36 mA cm−2. This work provides a pathway for developing electroactive 3D-printed electrodes particularly with cost-efficient low-dimensional carbon materials for aqueous rechargeable Li-ion batteries.