Direct visualization of electrochemical reactions in batteries by in-situ transmission electron microscopy

Abstract

Flexible Extensive research for new energy storage materials has created a high demand for experimental techniques that can provide real-time, single-particle-level information on the dynamic electrochemical processes taking place at the electrode materials during battery charge/discharge cycles. In situ transmission electron microscopy (TEM) on lithium ion batteries has offered exceptional opportunities for monitoring the dynamic processes of electrode materials during electrochemical reaction at both spatial and temporal resolution. In this talk, I will introduce in situ TEM studies on silicon anodes that suffer the anomalous volumetric changes and fracture during lithiation process. Previously, the lithiation behaviour of a single silicon particle system has been explained in detail by simulation data and experimental observation. However, in real batteries, since lithiation occurs simultaneously in clusters of silicon in a confined medium, understanding how the individual silicon structures interact during lithiation in a closed space is necessary. Ex situ SEM and in situ TEM studies reveal that compressive stresses change the reaction kinetics so that preferential lithiation occurs on free surfaces when the pillars are mechanically clamped. This experiment reveals the surprising effects of nanostructure shape, size, and void space for lithiation and the results will contribute to improved design of silicon structures at the electrode level for high-performance lithium-ion batteries.