Synergic Effect of Dendrite-Free and Zinc Gating in Lignin-Containing Cellulose Nanofibers-MXene Layer Enabling Long-Cycle-Life Zinc Metal Batteries.

Uncontrollable zinc dendrite growth and parasitic reactions have greatly hindered the development of high energy and long life rechargeable aqueous zinc-ion batteries. Herein, the synergic effect of a bifunctional lignin-containing cellulose nanofiber (LCNF)-MXene (LM) layer to stabilize the interface of zinc anode is reported. On one hand, the LCNF provides enough strength (43.7 MPa) at relative low porosity (52.2%) to enable the diffusion limited dendrite suppression, while, on the other hand, the MXene serves as a zinc gating layer, facilitating the zinc ion mobility, restricting the active water/anions from degradation in the electrode/electrolyte interface, and epitaxially guiding zinc deposition along (002) plane. Benefiting from the synergic effect of diffusion limited dendrite suppression and zinc gate, the LM layer enabled a high coulombic efficiency (CE) of 98.9% with a low overpotential of 43.1 mV at 1 mA cm-2 in Zn//Cu asymmetric cells. More importantly, Zn//MnO2 full cells with the LM layer achieve a high-capacity retention of 90.0% for over 1000 cycles at 1 A g-1 , much higher than the full cell without the protective layer (73.9% over 500 cycles). The work provides a new insight in designing a dendrite-free zinc anode for long-cycle-life batteries.