All-Dry Solid-Phase Synthesis of Single-Crystalline Ni-Rich Co-Poor Ternary Cathodes for Li-Ion Batteries

All-dry solid-phase synthesis (ADSPS) is considered an eco-friendly and cost-effective method for preparing Ni-rich Co-poor cathodes, yet slow ion diffusion during the solid-phase sintering process results in agglomerate particles with severe Li/Ni mixing. Herein, a Mg/Sr-codoped and ZrO2-coated single-crystalline LiNi0.73Co0.05Mn0.22O2 cathode with a well-layered structure is fabricated through the ADSPS method. The Sr ions effectively accelerate the ion migration at the grain boundary to facilitate particle coarsening, while the Mg ions act as "pillar ions" to decrease the Li/Ni mixing and improve the structural stability. Moreover, the ZrO2 coating layer can further alleviate the interfacial side reactions to hinder the structure degradation and enhance the particle integrity. Therefore, the resultant single-crystalline cathodes deliver a high reversible capacity of 192.4 mAh g–1 and display an impressive retention of 87.5% after 300 cycles at 0.5 C in a pouch-type full cell. The ADSPS strategy in this work shows great potential for the synthesis of single-crystalline Ni-rich ternary cathodes for Li-ion batteries.