The stabilization of a solid electrolyte interphase (SEI) is one of the great challenges to utilize superior theoretical capacity (about 3,600 mAh g^-1, almost 10 times higher than that of graphite) of a silicon (Si) as an anode in a next-generation advanced lithium-ion battery (LIB). A SEI remains a poorly understood and hardly studied topic relative to the research devoted to battery components due to its intrinsic properties of complexity, reactivity and continuous evolution.¹ However, the SEI plays a key role in prevention of further electrolyte reduction and desolvation of Li⁺ ions, which is directly related to electrochemical performance, lifetime and safety of batteries. For example, the unstable SEI on a Si anode leads to initial irreversible capacity losses, poor cycling stability and a limited cycle life.^2-4

In this study each ‘individual’ component of SEI on a Si anode was prepared as a thin film, and the physical, electrochemical, mechanical and structural properties of prepared films were characterized using a variety of analytical equipment including electrochemical impedance spectroscopy, operando X-ray photoelectron spectroscopy, atomic force microscope, Fourier-transform infrared spectroscopy, scanning spreading resistance microscopy and time-of-flight secondary ion mass spectrometry. This study can provide a strong guidance to aid in the development of new electrolytes, additives and binders to stabilize SEI layer on a silicon anode by identifying beneficial components and providing mechanical explanation of a variety of reactions and phenomena in a SEI.

References

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2. B. Philippe, R. Dedryvere, M. Gorgoi, H. Rensmo, D. Gonbeau, and K. Edstrom, Chem. Mater. 2013, 25, 394.
3. T. Jaumann, J. Balach, M. Klose, S. Oswald, U. Langklotz, A. Michaelis, J. Eckerta, and L. Giebelera, Phys. Chem. Chem. Phys. 2015, 17, 24956.
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