Designing Dendrite-Free Zinc Anodes for Advanced Aqueous Zinc Batteries
Designing Dendrite-Free Zinc Anodes for Advanced Aqueous Zinc Batteries
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DOI：
10.1002/adfm.202001263
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发表时间：
2020-06-05
影响因子：
19
通讯作者：
Guo, Zaiping
中科院分区：
文献类型：
--
作者：
Hao, Junnan;Li, Xiaolong;Guo, Zaiping
金属锌因其高容量、低成本、环保等优点而被认为是最有前途的水电池负极材料。然而，在微酸性电解质中，由于副反应和枝晶生长，锌阳极的库仑效率仍然很低。本文对1 m ZnSO4电解液中Zn的镀/剥离机理进行了深入的研究，结果表明，在温和的电解液中，Zn金属的不良性能应归因于多孔副产物(Zn4SO4(OH)（6)中心点xH(2)O）层的形成和严重的枝晶生长。为了抑制副反应和枝晶生长，通过简单的自旋涂覆策略，在Zn表面均匀沉积了一种具有高粘弹性的聚乙烯醇丁醛膜，作为人工固体/电解质界面相（SEI）。这种致密的人工SEI膜具有良好的附着力、亲水性、离子电导率和机械强度，不仅能有效地阻挡锌表面的水分，还能引导膜下锌离子的均匀剥离/电镀。因此，这种无副反应和无枝晶的锌电极具有很高的循环稳定性和提高的库仑效率，当它与MnO2和LiFePO4阴极耦合时，也有助于提高全电池性能。
Zn metal has been regarded as the most promising anode for aqueous batteries due to its high capacity, low cost, and environmental benignity. Zn anode still suffers, however, from low Coulombic efficiency due to the side reactions and dendrite growth in slightly acidic electrolytes. Here, the Zn plating/stripping mechanism is thoroughly investigated in 1 m ZnSO4 electrolyte, demonstrating that the poor performance of Zn metal in mild electrolyte should be ascribed to the formation of a porous by-product (Zn4SO4(OH)(6)center dot xH(2)O) layer and serious dendrite growth. To suppress the side reactions and dendrite growth, a highly viscoelastic polyvinyl butyral film, functioning as an artificial solid/electrolyte interphase (SEI), is homogeneously deposited on the Zn surface via a simple spin-coating strategy. This dense artificial SEI film not only effectively blocks water from the Zn surface but also guides the uniform stripping/plating of Zn ions underneath the film due to its good adhesion, hydrophilicity, ionic conductivity, and mechanical strength. Consequently, this side-reaction-free and dendrite-free Zn electrode exhibits high cycling stability and enhanced Coulombic efficiency, which also contributes to enhancement of the full-cell performance when it is coupled with MnO2 and LiFePO4 cathodes.