Improving Lithium‐Ion Diffusion Kinetics in Nano‐Si@C Anode Materials with Hierarchical MoS2 Decoration for High‐Performance Lithium‐Ion Batteries

Abstract A carbon layer on a silicon anode not only acts as a structural buffer to alleviate the tremendous volume expansion of silicon, but also enhances electrical conductivity. However, the carbon layer cannot improve the diffusion kinetics of Li + . Molybdenum disulfide (MoS 2 ) nanosheets are introduced on the outermost layer of yolk‐shell silicon@carbon to design urchin‐like hierarchical anode materials, which is of great benefit in structural stability. By contrast with the yolk‐shell silicon@carbon structure, the diffusion coefficient of Li + is improved, with 3.27 times greater performance during the delithiation processes and 2.04 times greater during the lithiation process with urchin‐like hierarchical structure, showing robust diffusion kinetics. Moreover, the MoS 2 nanosheets are able to enhance the delithiation reversibility of Li 15 Si 4 alloy formed during lithiation process. Because the MoS 2 nanosheets promote the structural stability, delithiation reversibility, and diffusion kinetics of Li + during lithiation/delithiation processes, the prepared hierarchical Si@C@MoS 2 composites exhibit a high reversible specific capacity of 1025 mAh g −1 with a capacity retention of approximately 81 % after 400 cycles at a current density of 1000 mAh g −1 , and the reversible specific capacity can reach 819 mAh g −1 even under a high rate of 5000 mA g −1 .