Study On Preparation And Performance Of Zinc Anode Materials For Zinc Ion Batteries

Zinc ion battery （ZIB） is a new type secondarystoragedevice,which has uniquemerits of high power density andhigh energy density, low-cost, safe andenvironmentally friendly. However, rapidcapacity fading, hydrogen evolution andotherproblems restrictthepromotion and applicationofthezincion battery, zincanodeisone of the keystoimproveits performance. In this work, the mechanism of performancedegradation of zinc ion battery was investigated from the point of view of the zincanode. Activated carbon （AC）modification, composite additives, zinc nickel alloys andother methods were used to improve the reversibility, stability and corrosion resistanceof the zinc anode, ameliorate the cycle and discharge performance of zinc-ion battery.First, the mechanism of performance degradation of ZIB was investigated from thepoint of view of the zinc anode.Theappearance of the ZIB before and after the charginganddischarging cycles was analyzed; the hydrogen evolutionofthezinc electrodeunderthestatic condition was tested;thephase andmorphologychanges of the zinc anodebefore and aftercycles wereinvestigated.The results show that, zinc anodecorrosion,hydrogen evolution, zinc dendriteandalkalinezinc sulfateare the key factorswhich lead to Performance degradation of zinc ion battery.In order to suppresscoating of thezincdendrite andalkalinezinc sulfateon the zincanode， two proportions of activated carbon were used to modify theporouszinc anode.Theinfluence of the activated on the morphology,phase,specific surface area andporesizedistribution ofthezincanode after cycles were studied.Cycling and self-dischargetests were performed to the ZIBs with or without AC-modified Zn anode.It is found thatpores of activated carbon can accommodate the inactive deposition of ZnandZn4SO4（OH）6·5H20,so the inactive the Zn dendrites and Zn4SO4（OH）6·5H20can besuppressed. As a result, AC-modified Zn anode can significantly improve the the cycleperformance of the ZIB and reduce the self-discharge.For the Zn corrosionandhydrogen evolution, electrochemical tests, hydrogenevolution measurements, SEM and discharge tests were perform to investigated theeffects of hexadecyl trimethyl ammonium bromide （CTAB）, polyethylene glycol6000（PEG） and their composite additives on corrosion inhibition of Zn in1mol/L ZnSO4solution. It is found that both two additive can inhibit the corrosion of the zincelectrode in the ZnSO4solution, the Zn corrosion potential shifted negatively and thecorrosion current decreased.There is a notable synergistic effect between CTAB andPEG. The smallest corrosion current and the best discharge performance of the ZIBswere tested under the composite additives, inhibition efficiency of composite additivesis highest than individual inhibitors of CTAB or PEG alone.To enhance the corrosion resistance of Zn anodes, the differential pulseamperometry method was adopted to electroplate the δ Ni₃Zn₂₂and γ Ni5Zn21nanozinc-nickel alloy with better corrosion resistance in ZnSO4-NiCl system. Additives likecitric acid、boric acid、sodium citrate can promote the co-deposition of zinc-nickelalloy which can evidently improve the ZIB’s discharge capacity and cycle performance.