Orderly Arranged Dipoles Regulate Anion-Derived Solid-Electrolyte Interphase for Stable Lithium Metal Chemistry

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium (Li) metal batteries are crucial for next-generation high-energy-density storage.
• Unstable solid-electrolyte interphase (SEI) formation leads to impedance, Li dendrites, and poor battery cyclability.

Purpose of the Study:

• To develop a functional layer for polypropylene separators to stabilize the SEI in Li metal batteries.
• To investigate the role of ferroelectric Barium Titanate (BTOV) with ordered dipoles in regulating SEI chemistry.

Main Methods:

• Integration of ferroelectric BaTiO3 (BTOV) into polypropylene separators.
• Surface characterizations and theoretical calculations to understand dipole ordering and anion adsorption.
• Electrochemical testing of Li-Li cells and LiFePO4 || Li full cells.

Main Results:

• Ordered dipoles in BTOV selectively adsorb anions (TFSI-, NO3-), promoting inorganic SEI formation (LiF, LiNxOy).
• The functional layer facilitates Li+ transfer and suppresses Li dendrite growth.
• Li-Li cells achieved over 7000 hours of cycling; LiFePO4 || Li cells exceeded 1760 cycles.

Conclusions:

• Ferroelectric BTOV functional layer effectively regulates SEI formation for improved Li metal battery performance.
• Ordered dipoles offer a novel strategy for controlling anion distribution and reactions at the SEI.
• This approach enhances Li+ transport and dendrite suppression, leading to ultra-long cycle life.