Dual-modified Co-free Ni-rich LiNi0.94Mg0.01Al0.05O2 cathode materials for enhancing Li-ion battery performance

Abstract

Ultrahigh-nickel-rich cathode materials, such as LiNi_0.94Mg_0.01Al_0.05O₂ (NMA), exhibit exceptional discharge specific capacity but are hindered by inadequate structural and interfacial stability, impeding their widespread adoption. Addressing this challenge, our study introduces a dual-functional modification strategy combining Mo doping and LiF coating for NMA cathodes. This innovative approach yields LiF@Mo-NMA, which demonstrates remarkable performance enhancements. Specifically, LiF@Mo-NMA achieves a specific capacity of 187.4 mAh g⁻¹ at 5C, a substantial increase compared to unmodified NMA's 160.7 mAh g⁻¹. Furthermore, it retains 98.7 % of its capacity after 100 cycles at 0.33C, a significant improvement over NMA's mere 58.0 % retention. In full-cell configurations, LiF@Mo-NMA maintains a capacity retention rate of 78.9 % after 500 cycles at 1C, far surpassing NMA's 38.2 %. The dual modification method's efficacy arises from Mo⁶⁺ doping that refines grain size and strengthens mechanical stress resistance during cycling, combined with an LiF coating that minimizes residual lithium and mitigates HF corrosion in the electrolyte, enhancing interfacial stability. This study underscores the pivotal role of our straightforward dual modification strategy in advancing the performance of nickel-rich cathode materials, paving the way for the commercialization of cobalt-free cathodes.