Utilizing MOFs Melt-Foaming to Design Functionalized Carbon Foams for 100% Deep-Discharge and Ultrahigh Capacity Sodium Metal Anodes

Meltable metal-organic frameworks (MOFs) offer significant accessibility to chemistry and moldability for developing carbon-based materials. However, the scarcity of low melting point MOFs poses challenges for related design. Here, we propose a MOFs melt-foaming strategy toward Ni single atoms/quantum dots-functionalized carbon foams (NiSA/QD@CFs). Melt-foaming highly depends on two factors: flexible metal-phosphorus bonds with cage-like ligands bridged in a zipper configuration via hydrogen bonds, facilitating MOFs conformational melting below 200 °C, and high annealing rates that lead to MOFs foaming by reducing the energy barrier and enhancing the pyrolysis enthalpy. When used as hosts for sodium metal anodes, foam structure regulates metallic Na to preferentially deposit inside the pores, while Ni SA and QD synergistically enhance Na absorption. Consequently, NiSA/QD@CF electrodes exhibit stable cyclic performance for 1000 h in symmetrical cells, with a low hysteresis voltage of 98 mV at 100 mA/cm