PVP-Assisted Hydrothermal Synthesis of Nickel-Rich Cobalt-Free Single-Crystal LiNi0.9Mn0.05Al0.05O₂ for Lithium-Ion Batteries

Given cobalt's scarcity and high toxicity, there is a considerable interest in nickel-rich materials with reduced or no cobalt content. However, the majority of such materials are polycrystalline particles, which are susceptible to mechanical breakage and structural deterioration during cycling, resulting in rapid capacity decay. Here, we synthesized dispersed and uniform precursors using a poly(vinylpyrrolidone) (PVP)-assisted hydrothermal approach, followed by calcination to produce nickel-rich, cobalt-free single-crystal LiNi0.9Mn0.05Al0.05O2 (NMA) cathode materials. The single-crystal morphology effectively reduced intergranular cracking in the cathode material, preserving phase transition reversibility and cycle stability. At a current density of 0.5C, S-NMA exhibited a maximum discharge-specific capacity of 179.2 mAh g–1 with a capacity retention of 93.45% after 100 cycles. Additionally, at 55 °C and a current density of 1C, it reached 213.6 mAh g–1 with a capacity retention of 93.3% after 50 cycles. The single-crystal morphology of the cathode material exhibited an outstanding electrochemical performance. This study offers a novel approach to synthesizing nickel-rich single-crystal precursors for cathodes, which holds considerable promise for the advancement of high-performance cathode materials.