Fully Lithiated Li_xTiO_2-δ Layer Coated Separator for Securing a Lithium-less Anode in an Ester-Based Electrolyte

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Ester-based electrolytes are cost-effective for lithium metal batteries (LMBs) but suffer from poor compatibility with lithium metal (Li ⁰).
• This incompatibility leads to irreversible decomposition and dendrite growth, hindering the development of high-energy-density LMBs.

Purpose of the Study:

• To develop an electrochemical prelithiation strategy for stabilizing lithium metal anodes in ester-based electrolytes.
• To improve the safety, cycling stability, and energy density of lithium metal batteries.

Main Methods:

• Electrochemical prelithiation of a polypropylene (PP) separator to form a Li$_{x}$TiO$_{2-δ}$ coating with oxygen vacancies.
• Fabrication and testing of symmetric Li cells and full cells (NMC811 cathodes) using the modified separator.

Main Results:

• The Li$_{x}$TiO$_{2-δ}$ coating effectively prevented lithium depletion and promoted uniform lithium plating.
• Symmetric Li cells achieved over 5000 hours of stable cycling.
• Full cells demonstrated 90% capacity retention after 100 cycles with high average Coulombic efficiency (>99.85%).
• Anode-free cells showed promising Coulombic efficiency (98.36% after 60 cycles).

Conclusions:

• The electrochemical prelithiation strategy offers a cost-effective solution for enhancing LMB performance.
• The Li$_{x}$TiO$_{2-δ}$ coated separator stabilizes the solid electrolyte interface (SEI) and suppresses side reactions.
• This approach is crucial for advancing next-generation high-energy-density lithium metal batteries.