Porous insulating matrix for lithium metal anode with long cycling stability and high power

Abstract

Lithium metal anode has great potential for high-energy-density lithium batteries due to its high theoretical capacity, but its practical applications are limited by the uncontrollable growth of lithium dendrites. In this work, we fabricate a facile 3D porous polymer structure with one-step phase inversion method and verify the structure by Stimulated Raman Scattering Microscopy. Such 3D porous structure leads to uniform lithium plating and striping, improving the electrochemical performance remarkably. In Li/Cu cell tests, the porous structure modified Cu delivers high Coulombic Efficiency (CE) of 96% after 240 cycles at 1 mA/cm2, while bare Cu drops to less than 20% after 42 cycles. As for Li/Li cell tests, it delivers stable cycling over 1275 cycles with only 200 mV over potential at 3 mA/cm2 and 1 mAh/cm2 in Li/Li cells. At as high as 4 mA/cm2, it delivers more than 200 cycles with less than 200 mV. With PVdF-HFP interfacial layer, it could hold up to 4 mAh/cm2, it delivers more than 110 hours at 4 mA/cm2 and 4 mAh/cm2. The as-assembled LiFePO4/porous polymer/lithium full cell shows stable capacity around 153 mAh/g and no obvious voltage polarization over 350 cycles at 0.5 C. The stable cycling performance can be attributed to the lower current density from the large specific surface area of as-deposited lithium in porous polymer matrix and confined dendrite growth path in 3D porous structure.