A cobalt-based metal–organic framework and its derived material as sulfur hosts for aluminum–sulfur batteries with the chemical anchoring effect

Abstract

With the urgent need to explore high-performance electrochemical energy storage systems, rechargeable Al-ion batteries (AIBs) have attracted attention from researchers and engineers due to their traits, such as abundance and safety. Among all the issues waiting to be solved, the development of a reliable positive electrode material with high specific capacity is an absolute priority for the commercialization of AIBs. Sulfur has a natural advantage when used as the active material, and its theoretical specific capacity is as high as 1675 mA h g⁻¹. MOFs and MOF-derived materials have been proved to be promising hosts for Li–S batteries. Herein, we report a novel Al–S battery system employing MOF (ZIF-67) and MOF-derived materials as sulfur host materials. After being chemically combined with sulfur, the composite still maintains its unique well-defined polyhedron morphology. The voltage hysteresis phenomenon is effectively alleviated with the aid of the host matrix. DFT calculations confirm that ZIF-67 and carbonized ZIF-67-700 polyhedrons can act as an anchor point towards sulfur (S₈) and polysulfides (Al₂S₃, Al₂S₆, Al₂S₁₂, and Al₂S₁₈), preventing the detrimental dissolution and shuttle effect. These findings can enlighten future researchers regarding Al–S batteries and broaden the application of MOFs in the field of electrochemical energy storage systems.