Physikalisch-Chemisches Institut & Center for Materials Research , Justus-Liebig-Universität Giessen , Heinrich-Buff-Ring 17 , 35392 Giessen , Germany.
Departments of Materials and Chemistry , University of Oxford , OX1 3PH Oxford , United Kingdom.
ACS Appl Mater Interfaces. 2018 Jul 5;10(26):22226-22236. doi: 10.1021/acsami.8b05132. Epub 2018 Jun 20.
All-solid-state batteries (ASSBs) show great potential for providing high power and energy densities with enhanced battery safety. While new solid electrolytes (SEs) have been developed with high enough ionic conductivities, SSBs with long operational life are still rarely reported. Therefore, on the way to high-performance and long-life ASSBs, a better understanding of the complex degradation mechanisms, occurring at the electrode/electrolyte interfaces is pivotal. While the lithium metal/solid electrolyte interface is receiving considerable attention due to the quest for high energy density, the interface between the active material and solid electrolyte particles within the composite cathode is arguably the most difficult to solve and study. In this work, multiple characterization methods are combined to better understand the processes that occur at the LiCoO cathode and the LiGePS solid electrolyte interface. Indium and LiTiO are used as anode materials to avoid the instability problems associated with Li-metal anodes. Capacity fading and increased impedances are observed during long-term cycling. Postmortem analysis with scanning transmission electron microscopy, electron energy loss spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy show that electrochemically driven mechanical failure and degradation at the cathode/solid electrolyte interface contribute to the increase in internal resistance and the resulting capacity fading. These results suggest that the development of electrochemically more stable SEs and the engineering of cathode/SE interfaces are crucial for achieving reliable SSB performance.
全固态电池 (ASSB) 具有提供高功率和能量密度以及增强电池安全性的巨大潜力。虽然已经开发出具有足够高离子电导率的新型固态电解质 (SE)，但具有长工作寿命的 SSB 仍很少见。因此，在实现高性能和长寿命 ASSB 的道路上，更好地了解在电极/电解质界面发生的复杂降解机制至关重要。虽然由于追求高能量密度，锂金属/固态电解质界面受到了相当大的关注，但活性材料与复合阴极中固态电解质颗粒之间的界面可能是最难解决和研究的。在这项工作中，结合了多种表征方法来更好地理解 LiCoO 阴极和 LiGePS 固态电解质界面发生的过程。铟和 LiTiO 被用作阳极材料，以避免与锂金属阳极相关的不稳定性问题。在长期循环过程中观察到容量衰减和阻抗增加。使用扫描透射电子显微镜、电子能量损失光谱、X 射线衍射和 X 射线光电子能谱进行的事后分析表明，电化学驱动的机械故障和阴极/固态电解质界面的降解导致内阻增加和容量衰减。这些结果表明，开发电化学稳定性更高的 SE 和阴极/SE 界面的工程化对于实现可靠的 SSB 性能至关重要。
