MESSAI.iO

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75% confidence

The paper challenges the mainstream view that solid electrolyte interphase (SEI) growth causes low initial Coulombic efficiency in silicon anodes, proposing instead that SEI stripping occurs as silicon shrinks during discharge. A mathematical model confirms this mechanism results in a 62% ICE, and applying external pressure to inhibit stripping improves ICE by 14%.

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Coulombic efficiency2%

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Abstract

Silicon has emerged as a premier candidate for next-generation lithium-ion battery anodes. Nevertheless, the low initial Coulombic efficiency (ICE) hinders its commercialization. The mainstream view is that the continuous growth of the solid electrolyte interphase (SEI) on the silicon surface depletes the lithium inventory. In this work, a new mechanism is proposed that the SEI strips off the interphase with silicon as the silicon shrinks during discharge, which is the origin of the low ICE. A mathematical model is developed to describe this phenomenon, and the results demonstrate the ICE of 62%. Based on these findings, an external pressure inhibition mechanism of the interphase stripping is proposed, which can realize a 14% improvement. As a proof-of-concept, a capacity utilization improvement of 63% is also achieved under proper external pressure. This mechanistic and pressure modulation strategy establish a paradigm-shifting approach to overcome the limitations of silicon anodes.

Key findings

  • The low initial Coulombic efficiency of silicon anodes is primarily caused by SEI stripping due to silicon volume shrinkage during discharge, rather than continuous SEI growth.
  • A developed mathematical model demonstrates that this interphase stripping mechanism limits the initial Coulombic efficiency to approximately 62%.
  • Implementing an external pressure inhibition strategy effectively suppresses interphase stripping, achieving a 14% improvement in Coulombic efficiency and a 63% increase in capacity utilization.

Keywords

SiliconFaraday efficiencyInterphaseStripping (fiber)AnodeElectrolyte

Identifiers

DOI
10.1021/acs.nanolett.5c04643
PubMed
41348935
Journal
Nano letters (Print)
Year
2025