Regulating cathode electrical double layer via electrolyte engineering for stable cycling of NCM811 cathode at 4.8 V

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• High-voltage cathodes are crucial for next-generation lithium-ion batteries (LIBs).
• Achieving stable cycling at high voltages (e.g., 4.8 V) remains a significant challenge due to electrolyte decomposition and cathode degradation.
• The cathode electrolyte interphase (CEI) plays a critical role in battery performance and stability.

Purpose of the Study:

• To design a novel electrolyte formulation for regulating the cathode electrical double layer (EDL).
• To enable stable cycling of LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) cathodes at a high charge cutoff voltage of 4.8 V.
• To introduce and validate a new "EDL engineering" strategy for high-voltage LIBs.

Main Methods:

• Rational design of a novel electrolyte formulation.
• Investigation of the electrical double layer (EDL) structure at the cathode-electrolyte interface.
• Characterization of the cathode electrolyte interphase (CEI) formation on NCM811 surfaces.
• Electrochemical cycling tests of NCM811 cathodes at 4.8 V.

Main Results:

• The novel electrolyte successfully regulated the cathode EDL.
• An anion-dominated CEI was formed on the NCM811 surface via an inner Helmholtz plane (IHP).
• NCM811 cathodes demonstrated stable cycling at 4.8 V with superior capacity retention.
• The proposed
• EDL engineering
• strategy proved effective.

Conclusions:

• The developed electrolyte formulation enables stable high-voltage operation of NCM811 cathodes.
• EDL engineering is a promising strategy for enhancing the stability of high-voltage LIBs.
• This work paves the way for developing advanced LIBs with improved energy density and cycle life.