以臨場穿透式X光顯微術探索鋅-空氣電池負極鋅枝晶形成及抑制機制

Revealing the mechanisms of zinc dendrite formation and suppression for zinc-air battery anodes by in operando transmission X-ray microscopy

鋅-空氣電池因具有高理論能量密度和良好的環境相容性等優點而引起了高度的研究關注。新穎的二次鋅-空氣電池也正積極發展以應用於儲能裝置、電動載具和國防科技等領域。然而，目前二次鋅-空氣電池的發展仍面臨幾個關鍵挑戰，其中包含了鋅負極的鋅枝晶形成及介面副反應。負極表面不穩定的鋅枝晶生長和介面副反應將會促使電極表面劣化，導致電池性能衰退和快速失效，從而阻礙了二次鋅-空氣電池的商業化進程。本研究中，通過電化學曲線分析、結構與形態測量以及臨場/原位X光顯微鏡探測，探索了鋅-空氣電池負極的鋅枝晶形成和抑制機制。臨場/原位同步輻射穿透式X光影像清楚解析了在不同施加電壓和PEI添加劑濃度下鋅沉積物的微觀結構演變和電極的介面反應。結果表明，通過控制鋅沉積動力可抑制負極上的鋅枝晶生長。隨著施加電壓的降低和PEI的添加，沉積的鋅核形態由尖晶狀的樹枝結構轉變為緻密的岩石狀和薄膜狀結構，所形成的鋅核形態進而主導了隨後鋅沉積物的結構演變。這些結果可為二次鋅-空氣電池的開發提供有價值的訊息。

Zinc-air batteries have attracted high research attention due to the advantages of high theoretical energy density and good environmental compatibility. The novel secondary zinc-air batteries are actively developing to apply in the fields of energy storage devices, electric vehicles, and defense technology. However, the development of secondary zinc-air batteries still faces several key challenges, including dendritic zinc formation and interfacial side reactions on zinc anodes. The unstable zinc dendrite growth and interfacial side reactions on anodes would promote electrode surface degradation resulting in performance decay and fast failure in battery, thereby obstructing the commercialization process of secondary zinc-air batteries. In this study, the zinc dendrite formation and suppression mechanisms of zinc-air battery anodes are explored by electrochemical curves analysis, structural and morphological measurements, and in operando/in situ X-ray microscopy probing. The in operando/in situ synchrotron transmission X-ray images clearly reveals the microstructural evolution of zinc deposits and the interfacial reaction of electrodes in different applied voltages and PEI additive concentrations. The results show that the zinc dendrite growth on anode can be suppressed by controlling zinc deposition kinetics. The morphology of deposited zinc nuclei is changed from a spiky dendritic structure to dense rock-like and film structures with the applied voltage decreasing and PEI adding. The morphology of formed zinc nuclei further dominates the structural evolution of zinc deposits later on. These results could provide valuable information for the development of secondary zinc-air batteries.