A Multifunctional Natural Clay Mineral Additive for Stabilizing Ni-Rich Layered Oxide Cathodes

Abstract

Layered Ni-rich lithium transition metal oxides exhibit high specific capacities and broad application potential in various advanced energy storage systems. However, even trace amounts of water in the electrolyte can trigger irreversible phase transitions and detrimental interfacial reactions, such as transition metal ions (TMs) dissolution and HF-induced corrosion, ultimately leading to premature battery failure. Herein, natural clay mineral halloysite (7Å HNT) acts as a multifunctional additive and is applied in the LiNi 0.6 Mn 0.2 Co 0.2 O 2 (NCM622) electrode to improve its cycle stability. The external Si-O-Si surface and internal Al-OH lumen of HNT can effectively scavenge H 2 O/HF and suppress TMs dissolution, thereby preventing cathode microstructural degradation and mitigating crosstalk side reactions. Additionally, the negatively charged outer surface of HNT promotes the accumulation of Li⁺ near the electrode interface, which helps to alleviate concentration polarization and enhance interfacial lithium-ion transport, thereby improving the rate capability. As a result, the assembled HNT-LiNi 0.6 Mn 0.2 Co 0.2 O 2 //Li (HNT-NCM) cell displays a high capacity retention of 86.6% after 500 cycles at 2 C. Even at 55 °C, the HNT-NCM//Li cell retains 79.5% of its original capacity after 150 cycles, exhibiting a 22.1% enhancement in capacity retention compared to the pristine NCM//Li cell. This work proposed a straightforward yet efficient approach for constructing a protective barrier to mitigate the hazards of H 2 O, TMs, and HF in modern battery systems.Broader contextNi-rich layered oxide cathodes such as LiNi 0.6 Mn₀ 0.2 Co 0.2 O 2 (NCM622) hold great promise for high-energy lithium batteries owing to their high capacity and cost-effectiveness. However, their interfacial and structural instability under high-voltage and high-temperature conditions, aggravated by trace moisture-induced HF corrosion and transition metal dissolution, severely limits their practical application. This study introduces a green and sustainable strategy using natural halloysite (HNT) as a multifunctional cathode additive to scavenge H 2 O/HF and capture dissolved metal ions, thereby suppressing electrolyte decomposition and cathode degradation. The external Si-O-Si surface and internal Al-OH lumen of HNT provide abundant active sites for impurity adsorption, while its negatively charged surface enriches Li + at the interface, reducing concentration polarization and enhancing ion transport. The natural HNT-based design of the multifunctional cathode presents a promising strategy for achieving stable, high-rate, and high-temperature performance in next-generation Ni-rich lithium batteries.