Quantifying Capacity Losses due to Solid Electrolyte Interphase Evolution

Sketch of the SEI growth during a-Si thin film (de)lithiation: SEI starts to grow in the first cycle and continues to grow over the following cycles. Coulombic efficiency extracted from capacity measured in operando and cone cell, and extracted from the volume expansion from XRR. Cumulative capacity lost due to SEI growth over cycle number.

Scientific Achievement

We quantified the capacity loss originating in solid electrolyte interphase (SEI) growth during each cycle and extracted the proportionality constant for SEI growth following a parabolic growth law. This continuous SEI growth contributes to the increasing overpotential, leading to capacity fading at a given constant current cycling rate.

Significance and Impact

The model system based approach allows a quantitative portioning of the loss processes in lithium-ion batteries that will aid in developing ways to reduce parasitic losses. The proposed methodology can be utilized to screen the qualitative passivation properties of electrolytes in terms of quantifying their continued growth and growth law.

Research Details

  • Model system: 515 Å thick amorphous silicon (a-Si) thin film on silicon carbide (SiC) in half-cell geometry using LP30 electrolyte.
  • Precise electrochemistry measurement to obtain the overall coulombic efficiency

Operando X-ray reflectivity (XRR): to obtain the capacity consumed due to active material loss during a-Si (de)lithiation

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DOI: 10.1063/1.5142643

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