Design of Exfoliated and Ultrathin 2D Ni-MOF/F-MWCNT Nanosheets for Advanced LIB Anodes: Combined Experimental and Computational Insights

Abstract

Two-dimensional (2D) metal-organic frameworks (MOFs) have attracted attention as anode candidates for lithium-ion batteries (LIBs), thanks to their high surface area and tunable structures. Nevertheless, their tendency to restack restricts lithium-ion transport and charge transfer, compromising electrochemical performance. In this work, we report a straightforward and efficient approach to exfoliate stacked Ni-MOF into ultrathin nanosheets using dually functionalized multiwalled carbon nanotubes (F-MWCNTs) as both spacers and structural modulators. Thus, the in situ incorporation of F-MWCNTs prevents nanosheet restacking and promotes a well-dispersed architecture, thereby enhancing active site accessibility for lithium storage. Comprehensive characterization (XRD, FTIR, Raman, XPS, SEM, TEM, and HRTEM) confirms the successful exfoliation and preservation of Ni-MOF structural integrity. Density functional theory (DFT) and ab initio MD reveal that F-MWCNTs enhance energetic stability, mechanical integrity, and electronic conductivity. The optimized Ni-MOF/F-MWCNT electrode demonstrated remarkable electrochemical performance, delivering an initial discharge/charge capacity of 2967/2034 mAh g^-1 at 100 mA g^-1, and retained 1735 mAh g^-1 at 200 mA g^-1 after 300 cycles, confirming its excellent cycling stability. Furthermore, it maintained 1094 mAh g^-1 at 5 A g^-1 after 100 cycles, highlighting its strong rate capability. DFT calculations further demonstrate preferential lithium adsorption sites, reduced Li⁺-diffusion barriers, and dendrite suppression, consistent with ex-situ XPS/FTIR and operando FTIR studies. This work provides mechanistic insight and establishes ultrathin 2D Ni-MOF/F-MWCNT nanosheets as a promising LIB anode.