Lignin complex nanoparticles grafted cellulose nanofibers for high-performance lithium metal battery separator

Nanocellulose separator is liable to trigger dendrite growth while being paired with lithium metal anodes due to the lack of functional species. This study introduces cationic lignin complex nanoparticles into nanocellulose separator via electrostatic interactions to stabilize lithium anodes for high-performance lithium metal batteries. The lignin complex nanoparticles, grafted on cellulose nanofibers, contribute to the enhancement in the porosity (76.2% vs 52.3%), electrolyte uptake (371.6% vs 174.1%), ionic conductivity (1.45 vs 0.76 mS cm^-1) and lithium ion transference number (0.71 vs 0.34). More importantly, the composite separator promotes homogeneous lithium deposition to remarkably inhibit dendrite growth on lithium anodes with generation of a robust SEI layer. The assembled lithium metal battery shows long-life cycling with a low capacity decay (0.057% per cycle) as well as superior rate capability.