Ferroelectric Dipoles Tailoring Solid-Electrolyte-Interphase Chemistry to Enable Reversible Lithium Metal Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• The solid-electrolyte interphase (SEI) is critical for reliable lithium metal batteries.
• Anion scarcity in the Helmholtz layer (HL) leads to inferior solvent-derived SEI, causing dendrites and 'dead' lithium.
• Regulating anion distribution in the electric double layer (EDL) is key for stable lithium plating/stripping.

Purpose of the Study:

• To develop a method for enhancing SEI formation by controlling anion distribution in the EDL.
• To promote the generation of robust, anion-derived SEI with improved lithium-ion conductivity.
• To achieve stable lithium plating/stripping and enhance battery performance.

Main Methods:

• Utilized reduced graphene oxide (rGO) with controlled defects and ferroelectric BaTiO₃ (BTO) to create an rGO-BTO composite layer.
• Investigated the composite's ability to attract anions (TFSI^- and NO₃^-) into the anion-deficient HL.
• Evaluated the SEI composition, lithium deposit morphology, and electrochemical performance of Li metal cells and LiFePO₄ full cells.

Main Results:

• The rGO-BTO composite successfully attracted more anions into the HL, promoting favorable anion decomposition.
• Generated a robust SEI with high Li⁺ transport, rich in inorganic LiF and Li₃N species, leading to dendrite-free lithium deposits.
• Achieved enhanced Li plating/stripping stability (2700 h) and rate capability in Li//Cu cells, and improved capacity retention (82.0% @ 430 cycles) in LiFePO₄ full cells.

Conclusions:

• The rGO-BTO composite effectively regulates anion distribution in the EDL to construct a superior anion-derived SEI.
• This approach significantly enhances lithium metal battery stability, Coulombic efficiency, and cycle life.
• Provides a novel strategy for designing robust SEI layers by manipulating anion behavior within the electric double layer.