Aqueous-Based Vacuum-Assisted Surface Engineering for Stabilizing Ni-Rich Cathodes by Suppressing Surface Degradation

Ni-rich cathodes materials are widely recognized as leading candidates for future-generation lithium-ion batteries attributable to their exceptionally high energy density. Nonetheless, practical use is hindered by accelerated capacity fade, which arises from structural degradation and parasitic interfacial reactions during prolonged cycling. To address the above issues, an interfacial engineering strategy is proposed. At the precursor stage, a mixed solution of LiOH and Al(H₂PO₄)₃ is applied via a wet-chemical process and rapidly evaporated through low-temperature vacuum-assisted distillation, forming a preliminary coating on the surface of Ni_0.8Co_0.1Mn_0.1(OH)₂. Subsequent high-temperature calcination yields a cathode material with a Li₃PO₄/LiAlO₂ composite coating. This method not only effectively prevents corrosion of the precursor in aqueous solution, but also ensures the formation of a dense and uniformly distributed coating layer. The resulting coating layer significantly enhances lithium-ion (Li⁺) diffusion kinetics, reduces interfacial impedance, and suppresses leaching of transition metal (TM) ions. As a result of the synergistic effects of these modifications, the modified cathode retains 90.8% of its capacity after 150 cycles at 1 C, notably outperforming the unmodified sample (2.8–4.3 V 79.05%). This study offers a scalable and controllable approach for surface reconstruction and stabilization of Ni-rich cathodes.