Superior performance lithium-ion battery anode based on Co₉S₈ nanoparticles layered in-situ growth with capacitive...

Identifying new anode materials that possess high energy density, outstanding cycling stability, and superior rate capability has emerged as a pivotal research focus in the development of lithium-ion batteries (LIBs). Herein, we successfully synthesized a novel Co₉S₈-MoB MBene heterostructure. This innovative material was developed through a space-confined growth process, wherein Co₉S₈ nanoparticles were incorporated within the interstitial layers of MoB MBene, thereby creating a unique composite with enhanced electrochemical properties. The Co₉S₈-MoB MBene electrode showed excellent performance, retaining 756.34 mAh/g capacity after 200 cycles at 100 mA/g (initial capacity 828.67 mAh/g), with an impressive retention rate of 91.27 %. Even at a high current density (800 mA/g), the specific capacity of 632.1 mAh/g was maintained with a retention rate of 79.83 % after 700 cycles, and the Coulombic efficiency was consistently around 99 %. The excellent cycling stability and rate performance are attributed to the two-dimensional layered structure of conductive MoB MBene. Density functional theory (DFT) calculations reveal that MoB MBene's low lithium diffusion barrier significantly decreases the Co₉S₈'s lithium binding energy, through rapid kinetic charge transfer, improving the efficiency of lithium-ion insertion and extraction. The incorporation of MoB MBene restricts the volume expansion of Co₉S₈ during lithiation and delithiation, and facilitates the formation of surface capacitance and the development of diffusion-controlled pseudocapacitors. The excellent electrochemical performance suggests that the Co₉S₈-MoB MBene materials designed in this work can be a rational approach to be applied for high-performance LIBs anodes.