| Aqueous zinc ion batteries have attracted increasing attention due to their virtues of environmental friendliness,high energy density,and abundant raw material resources.However,zinc dendrites,hydrogen evolution,corrosion and passivation of zinc anode hinder the development of zinc ion batteries.To solve these problems,a multifunctional interfacial protective layer can be constructed on zinc anode surface to inhibit zinc dendrites and harmful side reactions,which improves the long-term cycling stability of zinc ion batteries.Herein,inorganic compound,organic polymer and inorganic/organic polymer composite materials were used as the protective layer to construct dendrite-free and highly stable zinc anode.The specific work is as follows:Sn-doped sodium titanium phosphate（NaTi2（PO4）3,NTP）nanomaterials were synthesized by sol-gel method as zinc anode protective coating（NTP/Sn）.3D framework structure of NTP could regulate zinc-ions transport through confinement effect.Sn doping could increase unit cell volume of NTP to broaden channels and improve zinc-ions transport rate.NTP/Sn coating also improved the wettability of zinc anode surface,reduced free energy between Zn anode and electrolyte interface,and avoided zinc dendrite formation.Electrochemical test showed that Zn@NTP/Sn symmetrical cell had the lowest average voltage hysteresis and the longest stable cycle performance among all cells.After 500 cycles at the current density of 1.2 A·g-1,Zn@NTP/Sn-Mn O2full cell had the highest discharge specific capacity and capacity retention rate(124.2 m Ah·g-1 and 73.62%)among Zn@NTP/Sn-Mn O2,Zn@NTP-Mn O2(74.2 m Ah·g-1 and 60.8%)and Zn-Mn O2 full cell(39.3 m Ah·g-1 and 37.5%).A covalent organic framework material with sulfonic acid groups and fluorine atoms（COF-S-F）was used as a protective layer of zinc anode.Zinc anode with dendrite-free,high stability,and long-term life was realized through the dual effects of ion confinement and rapid desolvation effect.Highly electronegative fluorine atoms and sulfonic acid groups could increase the affinity with zinc ions through electrostatic attraction,which facilitated the fast and uniform transport of zinc ions along the 1D arranged channels.In addition,hydrogen ions dissociated from the sulfonic acid groups and the hydrophobic effect of fluorine atoms could promote the rapid desolvation of the zinc hydrated ions,thus reducing the harmful side reactions.Zn@COF-S-F symmetric cell had low voltage hysteresis and nucleation overpotential and could be cycled stably for 1000 h at 1.5 m A·cm-2.Zn@COF-S-F-Mn O2 full cell could maintain a high discharge specific capacity(207.1 m Ah·g-1)and high capacity retention rate（81.1%）at 1.2 A·g-1 after 800 cycles.Polyaniline（PANI）was grown on zinc foil surface to obtain modified zinc anode.PANI with different morphologies and structures were obtained through concentration regulation,and the influence of PANI on electrochemical performance of zinc anode was explored.Porous structure of PANI could effectively regulate the flux of zinc ions and obtain dendrite-free homogeneous zinc deposition layer through confinement effect.Functional groups-NH-and=N-allowed rapid desolvation of zinc hydrated ions,thus inhibiting harmful side reactions caused by active water molecules in the electrolyte.Cells assembled with PANI modified zinc anode had excellent stability.Zn@PANI-Mn O2 full cell maintained high discharge specific capacity(134 m Ah·g-1)and retention rate（94.3%）after 1000 cycles at 1.0A·g-1,while Zn-Mn O2 full cell reduced to 48.7 m Ah·g-1,and retention rate was only 41.9%.Polyvinyl alcohol（PVA）and silicon dioxide（SiO2）composites were used as zinc anode coating to improve electrochemical performance through the synergistic effect of organic-inorganic substances.Functional group-OH in PVA could change the solvent shell structure of zinc-ions and reduce by-products by promoting the process of desolvation.Porous structure of Si O2 could form rapid and orderly zinc ions transport channels through confinement effect,promoting the formation of homogeneous deposition layer.Compared with single coating,PVA-Si O2 composites showed the lowest lag voltage and the most stable voltage distribution.In addition,when the ratio of PVA to Si O2 was 50:1,Zn@PVA-Si O2-Mn O2 full cell had the highest initial discharge specific capacity(142.5 m Ah·g-1)and the best stability.Discharge specific capacity of Zn@PVA-Si O2-Mn O2 full cell remained 121.5m Ah·g-1 after 500 cycles at 1.2 A·g-1.Figure 120;Table 2;Reference 202... |
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