Porous Metal–Organic Frameworks for Enhanced Performance Silicon Anodes in Lithium-Ion Batteries

Romeo Malik, Melanie. J. Loveridge, Luke J. Williams, Qianye Huang, Geoff West, Paul R. Shearing, Rohit Bhagat, Richard I. Walton - Department of Chemistry, University of Warwick | Department of Chemical Engineering, University College London

Maintaining the physical integrity of electrode microstructures in Li-ion batteries is critical to significantly extend their cycle life. This is especially important for high-capacity anode materials such as silicon, whose operational volume expansion exerts huge internal stress within the anode, resulting in electrode destruction and capacity fade. In this study, we demonstrate that by incorporating metal–organic frameworks (MOFs) with carboxylate organic linkers into Si-based anodes, a stable and flexible pore network is generated to maximize and maintain Li-ion flux throughout the electrode’s architecture. We show that the zirconium carboxylate MOF UiO-67 is a versatile comaterial to boost performance and mitigate the rate of anode degradation that presently limits the lifetime of Si anodes. The cage-like pores in UiO-67 and flexural properties of the 4,4′-biphenyldicarboxylate organic linker are proposed to create robust “ionophores” in the anode film to enhance longer term durability and performance.

How Amira-Avizo Software is used

Cycled electrodes were then transferred to the FIB-SEM (Scios, FEI) instrument for cross-sectional analysis.

This resulted in a smooth image with sharp edges that were subsequently converted to a binary image (white and brown) by applying threshold segmentation in Avizo Software. The brown represents pores and white the solid phase, i.e. silicon, carbonaceous materials, binder, and MOF.
There is no manual segmentation involved, a process which in addition to being labour intensive could
add a bias to the data analysis. From the reconstructed 3D volume, analysis on phase volume and surface area were made using Avizo Software.