All-solid-state batteries have been presented as the ideal solution to address i) the safety limitations of conventional Li-ion batteries by suppressing the flammable organic electrolytes and ii) the problem of insufficient energy densities. To date, two types of solid Li-ion electrolytes have been mainly studied, namely, sulfur-based and ceramic-based materials. Despite the progress in the development of superionic conductor, many aspects of their reaction mechanisms and stability upon cycling still remain non-elucidated.

In order to get a better insight about their stability upon cycling, the development of a reliable electrochemical cells is thus of a prime importance when studying battery materials in operando mode during cycling. This is never an easy task, since the design of such cells has to be adequate to the technique of a choice and meet all necessary requirements. However, once a proper design is found, the surface, the bulk, the interfaces, and finally the combination of those can be studied and lead to the elucidation of the reaction mechanisms, thus further improving the battery technology.

Unfortunately, in most cases the electrochemical cells used for operando measurement are not ideal and suffer from low internal pressure (i.e. poor contact between the electrodes). It shorts the lifespan of the cell, especially in the case of all-solid-state-batteries. Herein we present different cell designs developed in our laboratory and used for operando studies.

Through this presentation, we will use bulk, surface and imaging techniques to better understand the limitation of all solid state batteries. As an example, Operando neutron imaging has been employed to understand the Li diffusion within the electrode and inside an all-solid state batteries employing Li₃PS₄ as solid electrolyte whereas operando X-ray microscopic tomography was employed to follow the possible electro-mechanical fracture occurring during cycling and the possible impact on the electrochemical performance.