Shish-kebab-like heterostructured cellulose nanofibers towards advanced lithium metal battery separators

Ideal separators are able to suppress dendrite growth for high-energy and high-safety lithium metal batteries. This study reports a shish-kebab-like heterostructure consisting of bacterial cellulose (BC) nanofibers as the shish and grown polydopamine (PDA) kebabs. The PDA kebabs impart the separators with high porosity (81.4 %), superior ionic conductivity (1.89 mS cm^-1), high lithium ion transference number (0.76) and good interfacial compatibility. Stable lithium metal anodes with few dendrites are thus realized by the separators, and the cells with a LiFePO₄-based cathode deliver a high specific capacity of 148.9 mAh g^-1 after 100 cycles at 0.5C.