A Successive Conversion-Deintercalation Delithiation Mechanism for Practical Composite Lithium Anodes.

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium (Li) metal anodes offer high energy density but suffer from "dead Li" formation during delithiation, reducing battery lifespan.
• Dead Li generation depletes active Li and electrolyte, hindering practical application of Li metal batteries.

Purpose of the Study:

• To propose and validate a successive conversion-deintercalation (CTD) delithiation mechanism to suppress dead Li formation.
• To enhance the cycle life and stability of Li metal anodes through controlled delithiation processes.

Main Methods:

• Manipulating anode overpotential to trigger a two-stage delithiation process: initial conversion reaction followed by deintercalation.
• Investigating the delithiation mechanism by controlling anode overpotential during cycling.
• Evaluating battery performance using coin cells and a 1 Ah pouch cell under practical conditions.

Main Results:

• The CTD mechanism significantly reduces dead Li formation by utilizing a reversible deintercalation reaction.
• Batteries with the CTD mechanism achieved 210 cycles with 80% capacity retention, compared to 110 cycles for bare Li anodes.
• A 1 Ah pouch cell demonstrated 150 cycles using the CTD delithiation approach.

Conclusions:

• The CTD delithiation mechanism effectively restrains dead Li generation, offering a novel strategy for designing stable Li metal anodes.
• This approach provides a fresh concept for practical composite Li anodes, improving battery longevity and performance.
• The findings contribute to advancing high-energy-density battery technologies through improved anode design.