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

Abstract 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//MnO 2 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.