Real-Time NMR Investigations of Structural Changes in Silicon Electrodes for Lithium-Ion Batteries

Lithium-ion batteries (LIBs) containing silicon negative electrodes have been the subject of much recent investigation because of the extremely large gravimetric and volumetric capacity of silicon. The crystalline-to-amorphous phase transition that occurs on electrochemical Li insertion into crystalline Si, during the first discharge, hinders attempts to link structure in these systems with electrochemical performance. We apply a combination of static, in situ and magic angle sample spinning, ex situ (7)Li nuclear magnetic resonance (NMR) studies to investigate the changes in local structure that occur in an actual working LIB. The first discharge occurs via the formation of isolated Si atoms and smaller Si-Si…