Performance Research On Modification Of Zinc Anode In Aqueous Zinc Ion Batteries

Zinc has been widely favored by researchers in the field of new rechargeable batteries due to its abundant resources,cheaper cost and good safety,making aqueous zinc-ion batteries（AZIBs）regarded as one of the most feasible energy storage technologies to replace lithium-ion batteries.However,zinc eletrode will inevitably undergo self-corrosion and electrochemical corrosion during the cycling process to generate by-products,and the concentration polarization on the anode surface will lead to the formation of dendrites during the charging and discharging.The further growth of dendrites will puncture the separator and result in the short circuit of the battery,which seriously limits the follow-up research of the aqueous zinc ion battery.Therefore,in view of the above problems existing in zinc anode,three modification methods of carboxymethyl cellulose（CMC）,L-aspartate（L-Asp）electrolyte additives and boehmite（Al OOH）coating were studied in this paper to enhance the electrochemical properties of aqueous zinc ion batteries.The concrete research contents are as follows:（1）Adding carboxymethyl cellulose as electrolyte additive in ZnSO₄-based electrolyte system could significantly increase the cycle life of the battery.The experimental results reveal that the addition of CMC can restrain hydrogen evolution and corrosion reactions and improve the coulomb efficiency of zinc deposition and stripping.Zinc-symmetric cells can stable cycle for up to 1000 h at current densities of 1 m A cm^-2 and area capacity 1 m Ah cm^-2 and also show prominent cycle stability（>600 h）at high current densities of 5 m A cm^-2 and area capacity 1 m Ah cm^-2.In addition,the Zn//V₂O₅ battery can obtain a high specific capacity of 173 m Ah g^-1 at the current density of 2 A g^-1,and the capacity retention rate is 54.2%after 1000 cycles,showing relatively excellent cycle stability.（2）When L-aspartic acid was used as the electrolyte additive,the zinc-symmetric battery showed a cycle life of up to 1000 h at the high current density of 5 m A cm^-2 and 5m Ah cm^-2,which effectively inhibits the formation of dendrites and by-products.At the higher current densities of 10 m A cm^-2 and area capacity 2 m Ah cm^-2,the cycle life also can achieve 600 h,and the polarization voltage is low and relatively stable.In addition,the Zn//NH₄V₄O₁₀ full battery can achieve up to 172.6 m Ah g^-1 specific capacity at a current density of 1 A g^-1,the overall stability of the battery has been greatly enhanced.（3）By scraping coating method,the layered boehmite prepared by hydrothermal synthesis method was coated on the surface of zinc foil.It was found that the modified zinc anode（Al OOH@Zn）showed good corrosion resistance,and the coating could induce uniform deposition of zinc ions to inhibit the formation of dendrites.The experimental results prove that the modified zinc anode electrochemical performances are obviously improved whether it is assembled into symmetric or asymmetric batteries.At the current density of 0.5 m A cm^-2,the cycle life of Al OOH@Zn symmetric battery is 4 times higher than that of the original Zn-symmetric battery,and the specific capacity of Al OOH@Zn//Na V₃O₈·1.5H₂O full battery is up to 238.4 m Ah g^-1 at the current density of1 A g^-1.