Challenging Prevalent Solid Electrolyte Interphase (SEI) Models: An Atom Probe Tomography Study on a Commercial...

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Lithium-ion batteries (LIBs) are crucial for electric vehicles and electronics.
• Limited raw materials and developing recycling necessitate improved LIB long-term stability and reduced levelized cost of storage (LCOS).
• Solid electrolyte interphase (SEI) aging on anode particles is a key factor limiting battery lifespan.

Purpose of the Study:

• To investigate the complex structure of the SEI in graphite composite anodes.
• To utilize atom probe tomography for detailed SEI analysis.
• To understand SEI composition and its impact on battery performance and longevity.

Main Methods:

• Atom probe tomography (APT) was employed for high-resolution 3D imaging.
• Analysis of SEI structure in a graphite composite anode.
• 3D reconstruction to visualize SEI morphology and chemical distribution.

Main Results:

• Detailed 3D reconstruction revealed an unseen, complex mosaic-type SEI structure.
• Discovery of an apolar organic microphase uniformly distributed throughout the SEI thickness.
• This finding contradicts the traditional two-layer SEI model.

Conclusions:

• The pervasive apolar organic microphase challenges current SEI models.
• Understanding this structure is vital for improving SEI passivation capabilities.
• This research paves the way for extending lithium-ion battery lifespan.