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

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 CoS-MoB MBene heterostructure. This innovative material was developed through a space-confined growth process, wherein CoS nanoparticles were incorporated within the interstitial layers of MoB MBene, thereby creating a unique composite with enhanced electrochemical properties. The CoS-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 CoS'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 CoS 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 CoS-MoB MBene materials designed in this work can be a rational approach to be applied for high-performance LIBs anodes.