Metal–organic framework coating layer with inherent self-reactivity toward lithium ions to enhance both structural stability and electrochemical performance of LiNi0.9Co0.085Mn0.015O2 cathodes

Abstract

Layered cathode materials present challenges, including crack formation, cation mixing, and unfavorable side reactions with electrolytes, which limits rate and cycling performance. This study developed a lithium-intercalated metal–organic framework (i–MOF) with self-reactivity for Li+ to coat high-Ni cathodes. The 2D-packed structure enables free movement of Li+ on i-MOF and redox reactions between Li+ and carboxylate anions, facilitating rapid intercalation/deintercalation of Li+ into the Li layer of the cathode. The i-MOF layer reduces transition metal dissolution, prevents unfavorable side reactions, provides robust protection against corrosion, and enhances cathode properties such as redox reactions with Li+; high thermal stability (≤600 ℃); rapid Li+ diffusion at the cathode–electrolyte interface; protection against volume expansion and phase transition; and suppression of cathode–electrolyte side reactions. Consequently, i–MOF-coated LiNi0.9Co0.085Mn0.015O2 (i-NCM) exhibited improved electrochemical performance, enhanced structural stability, and minimal phase change. The i-NCM exhibited a higher initial discharge capacity (219.70 mAh g−1) than NCM (206.68 mAh g−1 at 0.1C) and superior cycling stability (144.72 and 106.92 mAh g−1 with 71.10 % and 46.84 % cycle retention after 100 cycles at 25 and 50 ℃, respectively). This study demonstrates the potential of i-MOFs as cathode coating materials for Li-ion batteries.