Novel Electrode Materials Based Zn-Air Batteries for Energy Storage: From Fundamental Aspects to System Engineering

金属空气电池（MAB），特别是锌空气电池（ZABs）因其高能量密度、低成本和高安全性等优点而受到广泛关注。然而，ZAB的技术应用受到一些基本问题的阻碍，例如：(i)缺乏合适的双功能氧还原/析出（ORR/OER）催化剂，可能与新型气体扩散电极结构相结合；（ii） Zn阳极上Zn沉积（充电）过程中枝晶的形成，导致ZAB短路；（iii）维持长循环寿命所需的电池质量/热管理缺陷。本项目通过结合实际双功能ORR/OER催化剂材料和功能锌阳极的制备、系统修饰和原位表征，以及结构/化学定义良好的模型电极的实验研究和基于适应电化学环境的密度泛函理论的理论描述来解决这些问题。阴离子或阳离子掺杂尖晶石氧化物被认为是高效、低成本的双功能ORR/OER催化剂，因为它们允许我们以不同的方式改变活性中心（金属表面离子）的化学性质，这是ORR和OER双功能催化剂所需要的。为了改善气液质量传递，设计了一种新型多孔气体扩散电极，将双功能催化剂负载在Ni泡沫上，Ni泡沫的疏水性通过疏水性聚吡咯膜得到优化。在阳极处锌枝晶的形成应通过制备多孔壳限制Zn晶粒来抑制Zn2+离子的扩散，并通过添加特定的吸附离子来抑制Zn枝晶的生长。这将伴随着在技术模拟的基础上确定优化的操作条件和技术电极结构，如多孔氧电极，并通过优化电池的质量和热传递设计。该策略的结果将在半电池测量和全电池测试中得到验证。

Metal-air batteries (MAB) and especially zinc-air batteries (ZABs) have attracted much attention as promising electrochemical energy storage techniques because of their high energy density, low cost and high safety. The technical application of ZABs is hindered, however, by basic problems such as (i) the lack of suitable bi-functional oxygen reduction/evolution (ORR/OER) catalysts, possibly combined with novel gas diffusion electrode structures, (ii) dendrite formation during Zn deposition (charging) on the Zn anode, leading to short-circuiting of the ZAB, and (iii) deficits in the mass/heat management of the battery required to sustain a long cycling life. These problems are addressed in the present project by combining the preparation, systematic modification and in situ characterization of realistic bi-functional ORR/OER catalyst materials and of functional zinc anodes with experimental studies of structurally/ chemically well-defined model electrodes and the theoretical description based on density functional theory adapted to an electrochemical environment. Anion or cation doped spinel oxides are proposed as efficient, low cost bi-functional ORR/OER catalysts, as they allow us to vary the chemical properties of the active centers (metal surface ions) in different ways, as required for bi-functional catalysts active for ORR and OER. For an improved gas/liquid mass transport a novel porous gas diffusion electrode will be designed, where the bi-functional catalyst is loaded on a Ni foam whose hydrophobicity is optimized by a hydrophobic polypyrrole film. Zinc dendrite formation at the anode shall be addressed by preparing porous shell confined Zn grains to inhibit the diffusion of Zn2+ ions and by adding specifically adsorbed ions to suppress the growth of Zn dendrites. This will be accompanied by identifying optimized operating conditions and technical electrode structures such as porous oxygen electrodes on the basis of technical simulations, and by optimizing the battery design with respect to mass and heat transport. The results of this strategy will be validated in half-cell measurements and full cell battery tests.