Effect of sodium alginate-sodium carboxymethylcellulose gel layer on the stability of Zn anodes
Here,we propose a green and self-crosslinking strategy to in-situ prepare a sodium carboxymethylcellu-lose(CMC)and sodium alginate(SA)layer on the Zn electrode(Zn@SA+CMC)via the superionic bonds between the carboxylate groups and Zn2+.Scanning electron microscopy(SEM)images confirm a porous structure of the SA+CMC layer.The functional effects of the gel layer are as follows.Firstly,the layer is rich in hydroxyl groups,which can be tightly adsorbed onto the Zn anode surface to form a protective layer and separate the Zn anode from the elec-trolyte.Secondly,the protective layer is a gel film,making it mechanically flexible,which can accommodate the vol-ume change during Zn plating.Thirdly,the SA+CMC gel layer possesses zincophilicity,reduces interfacial resis-tance,lowers the nucleation energy barrier,and increases ionic conductivity,thereby promoting uniform Zn deposi-tion and effectively inhibiting dendritic growth.As a result,the Zn@SA+CMC symmetrical cell sustained over 890 h of long-term stability at a high current density of 3 mA·cm-2 and the Zn@SA+CMC half cell could provide as high a Coulombic efficiency of 99.8％over 3 700 h(1 850 cycles).Furthermore,the Zn@SA+CMC||MnO2 full cell deliv-ered a specific capacity of 185.1 mAh·g-1 at 0.3 A·g-1,maintaining stability for over 1 200 cycles.
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