A water-gating and zinc-sieving lignocellulose nanofiber separator for dendrite-free rechargeable aqueous zinc ion battery

The sustainable development of rechargeable aqueous zinc-ion batteries (RZIBs) is severely limited by the uncontrolled zinc dendritic growth and side reactions on the anode. Herein, a lignocellulose nanofiber (LCNF) separator from waste palm with dual-function of water-gating and zinc-sieving is developed for the dendrite-free zinc anode. The obtained LCNF separator offer hydrophobic surface (96°), uniform nanopores (∼20 nm), excellent mechanical performance (47.8 MPa), and high ionic conductivity (18.1 mS cm−1). Therefore, the LCNF separator enables increased zinc deposition kinetics, and reduced desolvation barrier of hydrated zinc ions, effectively suppressing the Zn dendrite growth and promoting the uniform Zn plating/stripping on zinc anode. Such separator enables excellent performance: a low polarization of 60.1 mV and steady charge-discharge in a Zn//Zn symmetric cell for 3500 h at the current density of 0.5 mA cm−1; dendrite-free zinc plating/stripping at 99.0 % coulombic efficiency in a Cu//Zn asymmetric cell for over 250 cycles at 1 mA cm−2; 280.1 mAh g−1 in MgVO//Zn full battery with the retention of 89.7 % for over 2000 cycles at 5 A g−1. In addition, this LCNF separator can be completely degraded in the natural soil within two weeks, exhibiting a low environmental impact with their natural biodegradability. This design of green separator for dendrite-free RZIBs also provides a new insight for the sustainable development of other metal-ion rechargeable batteries.