Design And Performance Research Of Multifunctional Modified Layer On Zn Anode

Zn ion batteries has been widely concerned because of their high safety,wide distribution of Zn metal and environmental friendliness.However,the application of ZIBs is seriously restricted due to dendrite growth and side reactions of Zn anode.In this research,aiming at the above issues of Zn anode,hydrophobic and hydrophilic modified layer is designed on the surface of zinc anode to improve the cycle stability of zinc anode.The specific research work is as follows:（1）A hydrophobic B-PVDF layer composed of boron particles（B）and polyvinylidene fluoride（PVDF）is designed on the surface of Zn anode.The flux of Zn²⁺is uniformed by boron particles and the dendrite growth of Zn anode is inhibited.The direct contact between Zn anode and electrolyte is obstructed by the hydrophobic PVDF layer and the side reactions is inhibited.The symmetric battery of B-PVDF@Zn anode maintained excellent cycle stability for 1050 h at a current density of 1 m A cm^-2 with a planting capacity of 0.5 m Ah g^-1.The specific capacity of B-PVDF@Zn//V₂O₅battery is 101.2 m Ah g^-1 after 400 cycles,and the capacity retention rate is 62.1%.The improved cycle life and specific capacity proved that the B-PVDF layer can effectively enhance the cycle stability of aqueous Zn ion battery.（2）A hydrophilic sodium alginate（SA）gel is utilized to construct SA modified layer on the surface of Zn anode,and the SA@Zn anode is obtained.The H₂O molecules are adsorbed by hydrophilicity modified layers,thus inhibiting side reactions.The polar groups（-OH）provide adsorption sites for Zn²⁺,which can be transported to the surface of Zn anode along the molecular chain,and the growth of Zn dendrites is inhibited.The modified anode exhibits excellent cycling stability of 2300h at a current density of 0.5 m A cm^-2,with a stable overpotential of 34 m V.At a current density of 0.5 A g^-1,the specific capacity of SA@Zn//Mn O₂ full battery is 105.4 m Ah g^-1 after 400 times cycle.Ultra-low overpotential and long cycle life proved that SA modified layer can improve the stability of Zn anode.（3）A hydrophilic SAW layer composed of tungsten powder（W）and sodium alginate gel is constructed on the surface of Zn anode,and the SAW@Zn anode is obtained.The surface electric field can be uniformed by tungsten powder,the deposition process of Zn²⁺is guided,and the dendritic growth of Zn anode is inhibited.The free H₂O molecules is adsorbed by hydrophilic modification layer and the occurrence of side reactions are suppressed.The SAW@Zn symmetrical battery maintained cyclic stability for 500 h at a current density of 0.5 m A cm^-2.After 200cycles at a current density of 0.5 A g^-1,the capacity of SAW@Zn//Mn O₂ full battery is105.4 m Ah g^-1 with a capacity retention rate of 61.3%.The results show that the construction of SAW modified layer on the surface of Zn anode is beneficial to improve the cycle stability of Zn ion battery.In this research,the B-PVDF,SA and SAW modified layer are designed on the surface of Zn anode,the direct contact between electrolyte and anode is obstructed,and the flux of Zn²⁺is uniformed.Therefore,the side reactions and the dendrites growth are inhibited and the cycle stability of Zn anode is improved.