Nanoscale surface modification of polymer nanofibers enables uniform lithium nucleation and deposition for stable lithium metal anodes

The growth of lithium dendrites and the huge volume change are the critical issues for the practical application of lithium metal anodes. In this work, a novel strategy is proposed to address the above challenges using oxidized polyacrylonitrile (PAN) nanofibers anchored with well-distributed metal-organic frameworks (MOFs) as the lithium metal anode host. The obtained hybrid structure possesses integrated multiple lithium ion affinities to regulate the lithium ion flux inside the three-dimensional scaffold. On the one hand, the strong chemical lith-ophilicity is achieved with the abundant surface polar groups from oxidized PAN nanofibers and MOFs. On the other hand, the high capillary force from the microporous structure of MOFs serves them as electrolyte nano-reservoirs enabling improved lithium adsorption. Site-selective lithium nucleation and deposition via nanoscale surface modification of oxidized PAN nanofibers regulates the Li plating/stripping behavior and effectively suppresses dendrite growth. As a result, the symmetrical cell based on the composite anode delivers a prolonged cycling life of 5 times longer than that of bare Cu at a high current density of 3 mA cm2. Moreover, when paired with the LiNi0.5Co0.2Mn0.3O2 (NCM) cathode, the assembled full cell also exhibits outstanding rate capability and improved cycling performance.