Institute of Physical Chemistry , Justus Liebig University Giessen , Heinrich-Buff-Ring 17 , 35392 Giessen , Germany.
Helmholtz-Zentrum Berlin for Materials and Energy , Hahn-Meitner-Platz 1 , 14109 Berlin , Germany.
ACS Appl Mater Interfaces. 2019 Mar 6;11(9):9539-9547. doi: 10.1021/acsami.8b19973. Epub 2019 Feb 20.
Most commercial lithium-ion batteries and other types of batteries rely on liquid electrolytes, which are preferred because of their high ionic conductivity, and facilitate fast charge-transfer kinetics at the electrodes. On the other hand, hybrid battery concepts that combine solid and liquid electrolytes might be needed to suppress unwanted shuttle effects in liquid electrolyte-only systems, in particular if mobile redox systems are involved in the cell chemistry. However, at the then newly introduced interface between liquid and solid electrolytes, a solid-liquid electrolyte interphase forms. In this study, we analyze the formation of such an interphase between the solid electrolyte lithium phosphorous oxide nitride (Li PO N , "LiPON") and various liquid electrolytes using in situ neutron reflectometry, quartz crystal microbalance, and atomic force microscopy measurements. Our results show that the interphase consists of two layers: a nonconducting layer directly in contact with "LiPON" and a lithium-rich outer layer. Initially, a fast growth of the solid-liquid electrolyte interphase is observed, which slows down significantly afterward, resulting in a thickness of about 20 nm eventually. Here, a formation mechanism is proposed, which describes the solid-liquid electrolyte interphase growth as the fast deposition of a film, which mostly covers the "LiPON", with only a little degree of remaining porosity. The residual void space is then slowly filled, thus blocking the remaining channels for ionic conduction, which leads to increasing resistance of the interphase. The results obtained imply that hybrid battery concepts with liquid electrolyte and solid electrolyte can be hampered by highly resistive interphases, whose formation cannot be simply slowed down or suppressed. Further research is required regarding possible countermeasures.
大多数商业锂离子电池和其他类型的电池都依赖于液态电解质，因为它们具有较高的离子电导率，并能促进电极处快速的电荷转移动力学。另一方面，为了抑制仅含液态电解质系统中不需要的穿梭效应，可能需要结合使用固态和液态电解质的混合电池概念，特别是如果在电池化学中涉及移动氧化还原体系。然而，在液态和固态电解质之间新引入的界面处，会形成固-液电解质界面相。在这项研究中，我们使用原位中子反射测量、石英晶体微天平测量和原子力显微镜测量，分析了固体电解质磷酸氧锂氮（LiPO N，“LiPON”）与各种液态电解质之间形成的这种界面相。我们的结果表明，该界面相由两层组成：与“LiPON”直接接触的非导电层和富锂的外层。最初，观察到固-液电解质界面相的快速生长，随后生长速度显著减慢，最终厚度约为 20nm。在此，提出了一种形成机制，该机制将固-液电解质界面相的生长描述为快速沉积一层膜，该膜主要覆盖“LiPON”，只有很小的剩余孔隙度。然后，剩余的空隙空间会缓慢填满，从而阻塞了剩余的离子传导通道，导致界面相的电阻增加。所得到的结果表明，具有液态电解质和固态电解质的混合电池概念可能会受到高电阻界面相的阻碍，而不能简单地减缓或抑制其形成。需要进一步研究可能的对策。
