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.
- 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