Stable cycling of high-density three-dimensional sintered LiCoO2 plate cathodes

High-density sintered plate-type cathodes composed of only an active material can achieve a high energy density of lithium-ion batteries (LIBs) beyond the current state of the art. However, slow lithium ion movement in the solid-state cathode plate and deterioration of the grain boundary of sintered cathodes over many charge/discharge cycles are obstacles to commercialization. Herein, we present a new three-dimensional high-density sintered LiCoO 2 plate cathode with periodically aligned channels, which enable fast charging/discharging of high-energy-density LIBs. In addition, we investigate the grain-boundary cracking mechanism and introduce a conductive coating agent to LiCoO 2 cathodes that prevents crack propagation, enhances electron transfer between sintered LiCoO 2 grains, and prevents the formation of an undesirable cathode electrolyte interphase. In full-cell experiments, the cell with a sintered LiCoO 2 cathode with industrial-level current density (3.5 mA cm −2 ) has a volumetric capacity (723 mAh cm −3 ) 21% higher than that of a conventional cathode (597 mAh cm −3 ). The cathode coated with the conductive agent shows a 30% higher cycle life after testing for 500 cycles compared to the bare cathode. High-density sintered cathodes are fabricated with an industrially acceptable cycle lifetime of 84% capacity retention over 500 cycles at 1 C. • A high-density 3D sintered-LiCoO 2 -plate cathode (HTS-LCO) was developed. • The conductive coating (C-PAI) prevented severe grain-boundary cracking in HTS-LCO. • HTS-LCO gave volumetric capacity 21% higher than that of a conventional cathode. • HTS-LCO exhibited good cycle stability at an industrial level current density.