One-step constructed oxygen vacancies and Fe-doping to improve the electrochemical performance of Li-rich Mn-based cathode

Abstract

Layered Li-rich (LLR) oxide electrodes are expected to be strong contenders for next-generation lithium-ion battery materials. However, irreversible anionic redox reactions during cycling lead to oxygen loss and capacity and voltage fading. Here, One-step synthesis strategy with Fe(NH4)2·(SO4)2 has been proposed to achieve Fe-ion replacement and induce the generation of oxygen vacancies. Oxygen vacancies can inhibit the irreversible O release and alleviate the corrosion of the surface and interior of the material by electrolysis. The doping of Fe ions can further stabilize the structure and improve the cycle stability of the material. Owing to this "one stone two birds" modification strategy, the modified materials exhibit significantly reduced interfacial impedance and enhanced cycling stability. Therefore, compared 183.9 mAh g−1 and 69.78% for the original materials, the discharge-specific capacities of 223.1 mAh g−1 at 1 C (1 C = 250 mA g−1) with 81.8% capacity retentions after 300 cycles for the modified materials. Furthermore, the voltage decay is significantly suppressed to 0.002 V/cycle. This work provides a novel idea for manipulating structural stability to enhance the electrochemical performance of Li-rich materials.