SiO-induced thermal instability and interplay between graphite and SiO in graphite/SiO composite anode

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Silicon monoxide (SiO) offers higher capacity than graphite for lithium-ion batteries (LIBs).
• Incorporating SiO into graphite anodes degrades LIB cycle and calendar life, with aging mechanisms poorly understood.
• Thermal instability of graphite/SiO composite anodes is a critical issue for LIB performance.

Purpose of the Study:

• Investigate the SiO-induced thermal instability in graphite/SiO composite anodes.
• Elucidate the aging mechanisms responsible for LIB degradation.
• Identify strategies to enhance the shelf life of SiO-containing LIBs.

Main Methods:

• Thermal exposure experiments on graphite/SiO composite anodes.
• Analysis of lithium inventory loss and de-intercalation from graphite.
• Investigation of parasitic reactions at the SiO interface.
• Study of electron and lithium-ion migration dynamics.

Main Results:

• SiO accelerates lithium inventory loss under thermal stress.
• SiO facilitates lithium de-intercalation from graphite, causing self-discharge.
• Preferential parasitic reactions on the SiO interface drive this phenomenon.
• Spontaneous electron and ion migration equilibrates energy imbalance between graphite and SiO.

Conclusions:

• The electron-level interplay between graphite and SiO is crucial for understanding LIB aging.
• SiO's thermal instability contributes significantly to self-discharge in composite anodes.
• Addressing these interfacial reactions is vital for improving the shelf life and performance of next-generation LIBs.