2026-08-27 東北大学
図 1. SECCMのナノピペットを用いたシリコン-グラファイト複合負極の局所測定の模式図。各材料（シリコンやグラファイト）の反応、さらにSEI被膜が形成される領域を場所ごとに計測・マッピングし、調べることができる。
＜関連情報＞
- https://www.tohoku.ac.jp/japanese/2026/08/press20260827-02-lithium.html
- https://www.sciencedirect.com/science/article/pii/S1385894726081556
シリコン-グラファイト複合負極における局所的な電気化学的特徴とSEI形成経路 Local electrochemical signatures and SEI formation pathways in silicon-graphite composite negative electrodes
Akichika Kumatani, Yuto Sato, Yasufumi Takahashi, Hiroki Ida, Hitoshi Shiku, Tomokazu Matsue, Shinichi Komaba
Chemical Engineering Journal Available online: 13 August 2026
DOI:https://doi.org/10.1016/j.cej.2026.180693
Highlights
- SECCM mapping at 100 nm resolution reveals local electrochemistry in composites
- SEI heterogeneity is revealed beyond conventional bulk measurements
- High-resolution mapping is achieved under realistic glovebox battery conditions
- Si/C domains are resolved, showing composition-dependent electrochemical behavior
- SEI pathways depend strongly on local composition, informing electrode design
Abstract
The spatial heterogeneity of composite electrodes is a key factor governing their electrochemical performance and stability, yet local electrochemical behavior is difficult to resolve using conventional bulk techniques. This challenge is particularly critical in lithium-ion batteries, especially for composite negative electrodes, where complex distributions of active materials lead to poorly understood interfacial processes such as solid electrolyte interphase (SEI) formation. Here, we employ scanning electrochemical cell microscopy (SECCM) to visualize nanoscale electrochemical activity in silicon-graphite composite electrodes. Localized cyclic voltammetry (CV) enables high-resolution mapping of electrochemical responses, allowing clear classification of graphite-dominant, silicon-dominant, and mixed domains within a single electrode. Furthermore, we demonstrate that SEI formation strongly depends on the local composition. Silicon-rich regions exhibit pronounced irreversible reactions associated with alloying, whereas graphite-dominant regions show more stable behavior. Mixed domains display intermediate characteristics, suggesting their role in mediating interfacial processes. These findings provide direct insight into spatially heterogeneous electrochemical behavior and offer new guidelines for the design of high-performance composite electrodes.
