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Cross-nanoflower CoS 2 on rGO nanosheets has been synthesized by simply controlling the pre-reaction step during hydrothermal route. Three-dimensional CoS 2 cross-nanoflowers of 150–200 nm in diameter are formed in-situ through self-assembling with rGO nanosheets reduced from GO (shorten as CoS 2 –NF/rGO-NS). From XRD, SEM, XPS and TEM analysis, these CoS 2 nanoflowers are composed of single crystal nano-slices of 20–30 nm in thickness and evenly distributed in the networks of flexible/conductive rGO nanosheets. Owing to both capacitive-controlled and diffusion-controlled mechanisms existing in the discharging/charging processes, CoS 2 –NF/rGO-NS composites show excellent rate performance and cycling stability as anode materials. According to DFT calculations/simulations, the corresponding diffusion barrier (E bar) is derived to be 0.47 eV along ⟨100⟩ diffusion direction for CoS 2 cross-nanoflower, indicating an effective lithium ion diffusion channel. Their enhanced electrochemical properties are therefore attributed to synergistic effects of two components: highly active/stable nanoflower-like CoS 2 –NF structure and flexible/conductive reduced graphene nanosheets (rGO-NS). Image 1 • 150–200 nm CoS 2 cross-nanoflower in-situ self-assembled on rGO nanosheet. • CoS 2 nanoflower composited of 20–30 nm single crystal nanochips in thickness. • CoS 2 nanochips provide a good Li+ diffusion channel along ⟨100⟩ by DFT calculations. • Advanced performance owing to highly active CoS 2 and pseudocapacitive effect by rGO. [ABSTRACT FROM AUTHOR]