Direct observation of lithium-ion movement around an in-situ-formed-negative-electrode/solid-state-electrolyte interface during initial charge–discharge reaction

Solid-state lithium batteries (SSBs) are highly likely to replace conventional lithium batteries with flammable liquid electrolytes because of their advantages in safety, lifetime, and energy densities. However, the SSBs exhibit large lithium-ion (Li+) transfer resistance at the electrode/solid-electrolyte interfaces. Here we use in-situ electron holography (EH) to visually evaluate the Li+ movement around the interface that has low interfacial resistance (100 Ωcm2). A prepared SSB sample possesses the negative-electrode grown from the parent solid electrolyte by partial Li+ insertion reaction into the electrolyte. EH clearly show how the negative electrode material is formed inside the solid electrolyte during the initial charging process of the SSB. Also, EH produces the presence of smooth potential distribution at the negative-electrode/solid-electrolyte interface. Furthermore, EH reveals a subtle potential-change in the solid electrolyte, showing where the Li+ movement is disturbed during the charge–discharge reaction.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► In-situ observation of Li+s during battery reaction by electron holography ► Visualization of a negative electrode material grown from a solid-state electrolyte ► Smooth potential distribution is formed at an interface with low resistance. ► Existence of a wide retardant region of Li+ transfer in a solid-state electrolyte