Interfaces and Interphases in Batteries: How to Identify and Monitor Them Properly Using Surface Sensitive Characterization Techniques

Interfaces, interphases, surfaces, and bulk are the main elements in a battery that require to be monitored and understood to control battery life during cycling and electrochemical ageing. To date, bulk-related processes are generally easier to address in terms of characterization techniques because in-depth investigations of most of these processes can be performed in operando mode (that is, during battery cycling). However, investigations of surfaces, interfaces, and interphases possess some challenges due to the involved nanosize dimensions, which render it difficult to select adequate techniques and interpret data appropriately. In addition, the evolving chemistry can suffer beam damage during investigation, and the use of postmortem/ex situ samples are not fully reliable. Moreover, the definitions of the terms interface, interphase, interfacial, and interfacial region are not clearly consistent, the details of which will be discussed in this study. Finally, techniques that can address interfacial processes in batteries are reviewed by highlighting their primary advantages and disadvantages.

Automated summary

Interfaces, interphases, surfaces, and bulk are crucial elements in batteries, with bulk processes being easier to characterize compared to surface and interface processes. Challenges arise in studying surfaces, interfaces, and interphases due to nanoscale dimensions, inconsistent definitions of terms, and potential beam damage during investigation. Techniques addressing interfacial processes in batteries are reviewed, highlighting their advantages and disadvantages.