Enhancing the performance of Ni-rich Li[Ni0.88Co0.09Mn0.03]O2 cathode material using surface coating

Abstract

Nickel-rich layered oxide cathodes are becoming increasingly popular for use in lithium-ion batteries (LIBs). However, their widespread application faces challenges due to rapid capacity degradation and poor performance at low temperatures, prompting the development of protective coatings. Wet methods and atomic layer deposition are complex and time-consuming, potentially causing lithium deficiencies. Therefore, this study proposes a facile and cost-effective powder dry coating strategy using a high-energy mixer for the surface modification of LiNi_0.88Co_0.09Mn_0.03O₂ (NCM-88) with graphene oxide (GO). The nanostructured GO layer applied to the NCM-88 surface effectively protects the cathode particles. Various characterization techniques, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), confirm the successful synthesis of GO and uniform coating on NCM-88 particles without altering pristine morphology. Based on the electrochemical test results, the optimized GO coatings exhibit a significant improvement in rate performance and capacity retention. Electrochemical characterization shows that coated NCM-88 with 0.2 wt% GO exhibits the best performance, with an initial discharge capacity of 221.1 mA h g⁻¹ at 0.1C and a capacity retention of approximately 97% after 50 cycles at 2C. In comparison with other studies, the NCM-88 coated with 0.2 wt% GO exhibits superior electrochemical performance, achieving a remarkable discharge capacity of 171.3 mA h g⁻¹ at 1C after 1000 cycles with 90.3% capacity retention, which significantly exceeds the stability and retention rates of pristine and various modified NCM compositions reported in the literature. These results demonstrate the effectiveness of GO surface modification for enhancing the electrochemical performance of NCM-88 cathodes in LIBs.