Enhancing Li–O2 battery performance with conductive hierarchical metal–organic framework composite cathodes

Abstract

Li–O₂ batteries are recognized for their high theoretical capacity and energy density, positioning them as excellent candidates for next-generation energy storage. This study explores the use of Metal–Organic Frameworks (MOFs) with high specific surface areas and open metal sites as cathode materials to address existing challenges. We developed conductive “cactus-like” composites by employing hydroxylated graphene (G-OH) as a substrate to grow columnar M₃(HHTP)₂ and M_xM_3−x(HHTP)₂ (M = Cu, Ni) in a one-pot synthesis, enhancing the structure's conductivity and order. The cathode, especially the [Cu_1.5Ni_1.5(HHTP)₂]₁-(G-OH)₁ composition, demonstrated a specific capacity of up to 12 542 mA h g⁻¹ at a current density of 50 mA g⁻¹ and maintained stability over more than 40 cycles at a limited capacity of 500 mA h g⁻¹ in an O₂ atmosphere. This performance surpasses that of M₃(HHTP)₂, M_xM_3−x(HHTP)₂, or G-OH alone, highlighting the potential of MOF-based composites in improving the efficiency and durability of Li–O₂ batteries and opening new avenues for cathode material design.