Mixed cellulose ester membrane as an ion redistributor to stabilize zinc anode in aqueous zinc ion batteries

[Display omitted] •Mixed cellulose ester (MCE) separator is applied to tailor the zinc deposition in AZBs based on physical and chemical effect.•The physical shunting effect by the uniform and dense pore structure can control and homogenize the ion movement.•The mechanism of physical pore effect is illuminated by comparing MCE membranes with similar component but different pore size.•The chemical guiding effect for ion diffusion is realized by the coordination between polar functional groups in MCE and Zn2+. Aqueous zinc-ion batteries (AZBs) with high energy density, low cost and environmental characteristics, have become the promising device for energy storage. However, uncontrolled zinc dendrite growth remains an impediment to the popularization of AZBs. The unrestricted two-dimensional (2D) ions diffusion is the main cause of the above defect. In this work, mixed cellulose ester (MCE) membrane is proposed as the separator. A dense homogeneous pore structure can achieve a physical shunting effect on ion diffusion, which can control and homogenize the ion motion. Further, the mechanism of this physical pore effect is confirmed by comparing the behavior of Zn deposition in MCE systems with different pore sizes but the same composition. As conjectured, a membrane with a smaller pore size is more favorable. In addition, the MCE contains many polar oxygen-containing functional groups that can facilitate and modulate ion diffusion through coordination. This chemical ion guiding effect, together with the above physical pore effect, gives the separator the ability to suppress dendrite formation. Zn/Zn symmetric cells with this membrane exhibit ultralong cycle life exceeding 1250 h at 0.5 mA cm−2 and 1000 h at 5 mA cm−2. And the Zn//MnO2 battery presents excellent cycle stability for more than 500 cycles with a capacity retention of 90.67%. This work proposes MCE separators and reveals their coordinated regulation of physical and chemical effects on metal-based anodes. This will shed light on the development of high-performance separators and AZBs.