A strategy to improve Coulombic efficiency and cycling stability of Li-rich Mn-based cathodes via oxygen vacancies and nitrogen-carbon coating

Due to the exceptional specific capacity, high energy density, and low cost, Li-rich manganese-based cathode materials (LRMCs) have emerged as promising candidates for next-generation lithium-ion batteries. However, their practical applications are hindered by relatively low initial Coulombic efficiency (ICE), continuous voltage fading during cycling, and poor capacity retention. In this study, Polyvinylpyrrolidone (PVP) and melamine are employed to treat the material surface, generating oxygen vacancies and forming a protective nitrogen-doped carbon layer. The presence of oxygen vacancies not only enhances Li + diffusion kinetics but also plays a critical role in suppressing voltage decay by activating stable cationic redox and minimizing irreversible oxygen release, which is key to the enhanced ICE. Additionally, the N-doped carbon coating establishes efficient electron conduction networks, facilitating efficient charge transfer. The modified materials exhibit an initial discharge capacity of 301.65 mAh g −1 at 0.1C (vs. 268.13 mAh g −1 for the pure Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 (LMNCO)), with an ICE of 87.88 % (pristine 77.46 %). After 200 cycles, the capacity retention reaches 85.17 % (compared to 45.16 % for the pure materials), and the voltage decay decreases from 0.72 V to 0.51 V. This study provides an important exploration for overcoming the challenges in the development of high-performance Li-rich manganese-based cathode materials.